Assess ing  the Influence of Geotechnical and Geomorphological Characteristics on the Erosional Processes of Two Geologic Units in Udi and Aguata, SE Nigeria

Assess ing the Influence of Geotechnical and Geomorphological Characteristics on the Erosional Processes of Two Geologic Units in Udi and Aguata, SE Nigeria | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Assess ing the Influence of Geotechnical and Geomorphological Characteristics on the Erosional Processes of Two Geologic Units in Udi and Aguata, SE Nigeria Chinanu O. Unigwe, Ogbonnaya Igwe, Obialo S. Onwuka, Johnbosco C. Egbueri This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1950040/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract In southeastern Nigeria, gullies occurrence has seriously threatened humans and the environment. In this study, through a detailed field survey, geotechnical and geomorphological investigation, the erodibility extent of two erosion-prone geologic units in southeastern Nigeria was assessed. According to field observations, the investigated gullies were primarily composed of loose lateritic unconsolidated soils from the Ajali and Nanka geological formations. Based on the grain size study, it was discovered that the soil components for the Ajali and Nanka formations, respectively, contained gravel (0 − 3% and 5 − 22.5%), sand (7.75 − 95.0% and 66.5 − 89%), and fines (4.42 − 17.7% and 4.7 − 22.2%). The soil permeability coefficients ranged from 1.13 x 10 − 5 to 2.45 x 10 − 4 m/s and 6.18 x 10 − 5 to 5.25 x 10 − 4 m/s for the Ajali and Nanka formations, respectively. The MDD ranged from 1.69 to 1.90g/cm 3 and 1.72 to 2.10g/cm 3 , whereas OMC ranged from 11.0 to 14.30% and 12.12 to 18.10% in the compaction test. The NMC results and the Atterberg limit indicate that the soils are non-plastic to low-plastic. The values for soil cohesion range from 0 − 6 kPa to 1 − 7 kPa. The friction angle ranges from 23 − 28 o and 32 − 38 o . The geomorphological characteristics revealed that the region is characterized by uneven topography and severe gully slope gradients, with the gullies within the Ajali Formation being more frequently linked with landslides. Both formations are vulnerable to erosion, according to the research. In order to combat this awful disaster, some type of mitigation strategy must be employed. Gully erosion Erosion-prone Geomorphology Geotechnical characteristics Multivariate statistical analysis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1 Introduction Environmental disasters such as gullies and landslides have long been a major threat to humans and ecosystems worldwide. These hazards have recently been a significant concern in several fields of study, particularly geoscientists, environmentalists, geotechnics, and civil engineers. Gullies and landslides have similar occurrence mechanisms and dynamic/complex in mitigating, whereby one could happen in association with the other. It is believed that as gravity pulls soil materials from the region of higher elevation to lower elevation, the mechanism is termed landslide, and it is an integral part of the progression of erosion (Khamkar and Mhaske 2018 ). Gully erosion, on the other hand, refers to the process by which soil particles are detached from their original soil mass and mechanically transported by running water, ice, and wind (Egbueri et al. 2021 ). Gully erosion processes impact both the biophysical and socio-economic components of the environment. Gully formation is highly influenced by surface runoff; as raindrops strike the soil surface, soil particles are sparsely thrown apart through the air over several centimeters. As continuous exposure to high rainfall considerably weakens the soil. Over time, soil mass is broken down through weathering processes, both mechanically and biochemically (Nwajide 1992 ; Nazari Samani et al. 2009 ). The threat of gully erosion has been experienced across southeast Nigeria. This is a conception of the nature of the geologic formations (poorly consolidated sediments) underlying the study area (Egbueri and Igwe 2020 ). Gully occurrence in the study area poses a threat to many environmental issues, including the loss of enormous amounts of arable land, the destruction of the transportation system and engineering structures, the abandonment of ancestral homes, the migration of communities, and the deterioration of water quality (Hudec et al. 2006 ; Bell, 2007 ; Igwe and Egbueri, 2018 ; Egbueri and Igwe 2020 ; Nebeokike et al. 2020 ). Research has proven that numerous geogenic factors and anthropogenic activities contribute highly to the initiation, development, and expansion of gullies. These factors may include geology, geomorphology, land use/land cover, hydrologic conditions, excavation, and mining activities (Poesen 2011 ; Emeh and Igwe 2017 ; Egbueri and Igwe 2020 ). According to studies, out of the five states in Nigeria's southeast, Anambra State appears to have the most gullies, with over 700. Enugu, Imo, Abia, and the Ebonyi States follow with 600, 450, 300, and 250 gullies, respectively. Most of these gullies have not been successfully controlled (Igbokwe et al. 2008 ; Egboka et al. 2019 ; Egbueri and Igwe 2020 ). Coincidentally, Anambra State, with the highest number of gullies (700 gullies) is underlined by the youngest, poorly-consolidated geologic formations. In contrast, Ebonyi State, with the fewest number of gullies (250 gullies), has the oldest, firmly-consolidated geologic formations (Egbueri and Igwe 2020 ). Many methods such as remote sensing, geospatial models, multivariate statistical analysis, and the RUSLE model (revised universal soil loss equation) have been utilized in gully erosion studies. Each method adopted is employed upon the peculiarity of the problem intended to be solved. In this study, statistical analysis was adopted to help reveal the interrelationship of the analyzed soil geotechnical parameters. Statistical analysis was employed in this study to aid in demonstrating how the evaluated soil geotechnical parameters are interrelated. The SPSS software (v. 22) would be used to achieve this. Pearson's correlation analysis (CA) and the factor analysis (FA) tools were considered. The CA uses a correlation coefficient to correlate two variables (x) and (y), with values between + 1 and − 1. A coefficient of + 1 means a positive correlation (direct relationships), while the coefficient of − 1 means a negative correlation (indirect relationships) (Hotelling 1953 ). Correlations have been categorized as strong, moderate, and weak, depending on the coefficient. Thus, the larger the coefficient, the stronger the association (Egbueri et al. 2019 ; Nebeokike et al. 2020 ). The FA describes observation among variables and aims to find independent latent variables (Thompson, 2004 ). This study utilized the Varimax rotation method to optimize the factor loadings at eigenvalue ≥ 1. Like the CA, the FA considers factor loading low, medium, and high (Egbueri et al. 2019 ; Nebeokike et al. 2020 ). Numerous studies have been done on the initiation and development of gullies in southeast Nigeria, including those by Nwajide and Hogue (1979), Egboka and Nwankwor ( 1985 ), Okagbue and Ezechi ( 1988 ), Okagbue ( 1988 ), Obiadi et al. ( 2011 ), Emeh and Igwe ( 2017 ); Igwe et al. (2017), Igwe and Egbueri ( 2018 ) and Nebeokike et al. ( 2020 ). Okagbue and Ezechi ( 1988 ) described gullies as catastrophic. Depths and widths far beyond several kilometers, which would be termed a canyon (Obiadi et al. 2011 ). Nwajide and Hogue (1979) and Okagbue ( 1988 ) quoted and believed that these gullies are caused by a combination of geogenic, biotic, and anthropogenic factors. Meanwhile, Egboka and Nwankwor ( 1985 ) argue that they can be attributed to rock's significant hydrogeochemical and geotechnical properties. Recent research on the erodibility and slope characteristics of gullies in the Udi region was conducted by Nebeokike et al. ( 2020 ), and it was noted that the soils are erodible. There is evidence that the soils of the Anambra state are erodible, which was reported in recent studies by Emeh and Igwe ( 2017 ), Igwe et al. (2017), Igwe and Egbueri ( 2018 ), and Egbueri et al. ( 2021 ). At this time, no study has given importance to assessing the influence of geotechnical and geomorphological characteristics on the erosional processes in Udi and Aguata, southeast Nigeria. Therefore, it is essential to assess the erosional processes of both geologic formations in Udi and Aguata due to their propensity for gullying in the region. The current research is focused on evaluating the geotechnical and geomorphological influence on the occurrence of gullies in Udi and Aguata, southeastern Nigeria. The study objectives are to (1) determine the gully distribution within the geologic formations; (2) compare and characterize the geologic formation and determine their erodibility characteristic; (3) identify the key factors initiating/facilitating gullying through the integration of multivariate statistical analysis (CA and FA) and (4) determine the impact of geomorphological characteristics on the gullying processes. It is believed that the information obtained from this research would contribute immensely to the mitigation planning and control of the erodible soils within the study region. 2 Study Area Description 2.1 Location, economy, and geology The research area covers the western part of Enugu State and the southern Anambra State, both in southeastern Nigeria. It lies within latitude 05º55' to 06º29' N and longitude 06º58' to 07º26' E with an elevation ranging from 169 to 433m above sea level (Fig. 1 ). The area under study is a fast developing and populated suburb with an estimated population of over 850,000. Some gullies can be reached through major and minor roads, while others can be achieved through a historic pathway (Fig. 1 ). However, due to the nature of the gullies in the area, specific accessible routes have been halted. Some residential buildings in the study region were built without adequate environmental planning and regulation. Such structures have been pillaged by erosion, thereby leading to their desertion (Fig. 2 ). This study captured fourteen different communities: Obinagu, Obioma, Udi, 9th Mile, Ngwo, Umuagu, Nsude (Enugu State), Ekwulobia, Nanka, Agulu, Igbo-Ukwu, Oraukwu, Uga, Nimo, Umuchu (Anambra State). These communities have been threatened by gully erosion, which has resulted in many environmental problems, some of which were described previously in the introduction. Many mitigation strategies have been used in these places to control the gully occurrence effectively; some have been successful, while others have proven recalcitrant following such techniques. The study region lies within the tropical rainforest having two distinct seasons; the rainy and dry seasons. The rainy season usually starts in April and ends around October, while the dry season picks up from November and ends around March (Inyang 1978). The mean-monthly temperature in the area varies in the wet season from 22 to 28°C and in the dry season from 28 and 32°C (Igwe, 2017 ; Egbueri and Igwe 2020 ). The study region is characterized by a V-shaped valleys type and flat hilltops with uneven (undulating) landscape terrain. These features facilitate erosional processes in the area. The vegetation comprises short-tall trees (like palms, iroko, mahogany, and banana trees), shrubs, and grasses (Nebeokike et al. 2020 ). A dendritic drainage system that is highly influenced by the topography is found in the study region and is characterized by surface water (streams and rivers) in the area (Fig. 1 ). Geologically, the area under study is underlain by two erosion-prone geologic units (Ajali and Nanka formations) belonging to the Anambra basin and Niger-Delta basin respectively (Nwajide 2013 ) (Fig. 1 ). The Ajali Formation is dated early Maastrichtian in age, its thickness varies from less than 300m to over 1000m at the center of the basin. It is characterized by a friable, unconsolidated, poorly-cemented mix of sandstone and siltstone, which exhibits profuse cross-bedding with several ranges of alternating lithologic colors (Obaje 2009 ; Nwajide 2013 ). The Ajali Formation is underlined by the Mamu Formation, while above the Ajali Formation lies the Nsukka Formation, which is known as a coal-bearing facies (Reyment 1965 ; Murat 1972 ; Obi 2000 ) (Fig. 2 ). The Nanka Formation (Eocene) on the other hand, is a member of the Ameki Group comprising the Ameki Formation, Nanka Sand and Nsugbe Sandstone (Ekwenye 2014) (Fig. 2 ). The Nanka Formation is notorious for its proneness to gullying and the desolation wrecks within the Anambra state. It is characterized by friable fine to medium-grained sands with little mud content (Nwajide 2013 ). The Ameki Group (Ameki Formation, Nanka Sand, and Nsugbe Sandstone) overlies the Imo Formation and underlies the Ogwashi Formation (Fig. 2 ) (Odunze and Obi 2011; Nwajide 2013 ). The geologic formations (Ajali and Nanka formations) possess similar characteristics, such as friable and loose unconsolidated sand, poorly to moderately sorted sandstones, and low mudrocks. 3 Materials And Methods 3.1 Field mapping, soil sampling, and laboratory analysis After several desk studies and site surveys, the proper field mapping was implemented in November 2019. During the mapping, various gully sites were visited and carefully studied. Coordinates for the different visited gully sites were obtained using a geographical positioning system (GPS). Also, observable features like lithology and gully geometric features (width, depth, and lateral extent) were recorded (Table 1 ). Samples were carefully collected using a hand drill at a depth of 35 − 40cm. The soil samples were preserved in a sample bag, labeled according to their sample location number, and cared carefully to avoid distorting the grain properties. In this study, a total of sixteen (16) gully sites were carefully studied and recorded randomly as (AJ1 to AJ8) for Ajali and (NK1 to NK8) for Nanka formations. Table 1 Visited gully sites and field observations Gully Site/ Location Latitude (N) Longitude (E) Elevation (m) Gully Depth (m) Gully Width (m) Average Lateral Extent (m) Lithology Udi (FRSC) Academy 06 0 18′01.2" 07 0 23′26.1" 402 22 8 50 Loose lateritic Obioma (Udi) 06 0 21′01.4" 07 0 24′45.3" 433 25 5 80 Fine- medium grained sand Ngwo (I) 06 0 27′53.1" 07 0 26′01.2" 387 18 4 55 Medium-coarse grained sand Ngwo (II) 06 0 27′56.9" 07 0 26′02.3" 391 15 6 58 Medium-coarse grained sand Ngwo (III) 06 0 28′12.7" 07 0 26′01.5" 389 16 9 68 Medium-coarse grained sand 9th Mile (I) 06 0 25′57.3" 07 0 24′04.8" 299 27 5 38 Lateritic fine grained sand 9th Mile (II) 06 0 18′21.2" 07 0 23′26.1" 375 25 7 33 Lateritic fine grained sand 9th Mile quarry site 06 0 24′09.7" 07 0 22′58.5" 380 18 5 38 Fine grained sand Ekwulobia 06 0 02′25.2" 07 0 04.53.5" 226 35 90 800 Fine- medium grained sand Uga 05 0 56′06.4" 07 0 04′46.8" 223 65 22 450 Loose lateritic sand Nanka gully complex 06 0 02′33.4" 07 0 04′53.9" 205 160 450 1000 Medium- coarse grained sand Agulu gully complex 06 0 04′50.3" 07 0 03′48.7" 179 40 50 750 Fine- medium lateritic sand Oraukwu 06 0 06′04.1" 06 0 58′46.6" 169 60 55 700 Loose lateritic sand Umuchu 05 0 55′56.8" 07 0 07′54.7" 265 24 12 320 Medium sand Nimo 06 0 ′09.27.3" 06 0 ′58.18.6" 184 33 15 800 Lateritic fine sand Igbo-Ukwu 06 0 00′55.7" 07 0 01′04.8" 351 26 8 55 Loose lateritic sand The soil samples were analyzed in the laboratory to reveal soil properties such as grain size analysis, Atterberg limits (liquid limit, plastic limit, and plasticity index), natural moisture content, compaction, permeability, and shear strength (cohesion and friction angle). The laboratory tests were carried out based on the relevant American Society for Testing and Materials (ASTM) standard of soil testing. The grain size analysis was done to distinguish fines, sand, and gravel the percentages in the soil material (material passing the No. 200 sieve). It was done following the ASTM D421 method, using sieve analysis for coarser materials. The Atterberg limits test was used to ascertain how much water affected the mechanical characteristics of the soil. This was performed in line with ASTM D4318 standards, whereas the NMC was done in accordance with ASTM D4959 standards. The compaction characteristics were measured at standard effort following the ASTM D698 guideline. The soil permeability test is done using two methods; the constant head permeability test is preferred for highly granular soils, and the falling head permeability for fine-grained soils. In this study, the constant head permeability test was adopted for its suitability for the soil materials and was carried out following the ASTM D5084 standard. The soil's shear strength was tested using a shear box device to determine the soil strength parameter (C and Ø). It followed the procedures given in ASTM D3080. However, Kalinski's (2011) soil mechanics laboratory manual was equally helpful in geotechnical analysis. 3.3 Multivariate statistical analysis of geotechnical parameters In this study, the SPSS software (v. 22) was considered and utilized in the statistical analyses. The twelve (12) obtained geotechnical parameters were subjected to Pearson's correlation analysis (CA) and factor analysis (FA) in other to determine interrelationships among the parameters. For the CA rating coefficients were considers as; (r) > 0.7 (strong correlation), 0.5 < r < 0.7 (moderate correlation), and r < 0.5 (weak correlation). The Varimax rotation method was considered and utilized for the FA at eigenvalue ≥ 1. Factor loading was considered as 0.75 for high loading. It implies that the bigger the coefficient, the stronger the parameters' association (Egbueri et al. 2019 ; Nebeokike et al. 2020 ). 3.4 Geomorphologic model The geomorphology of the study area was done to determine the effect of landslides on the gullying processes. In this study, the GARMIN GPS was utilized to acquire the latitude, longitude, and elevation of different locations. The data was further integrated with the DEM (Digital Elevation Model) data obtained by SRTM (Shuttle Radar Topographic Mission) with the permission of the USGS using ArcGIS (v. 10.4) modeling and analytical tool. Following the methods described in Crozier ( 1984 ), Highland and Bobrowsky ( 2008 ), Igwe ( 2015 , 2017 ), and Egbueri and Igwe ( 2020 ), the 2D and 3D maps of the study area were generated. The Slope gradients and aspects were measured and estimated using the Brunton compass, while slope curvature was evaluated using an empirical approach (based on the field observation). 4 Results And Discussion 4.1 Field observations The study area is commonly composed of loose lateritic unconsolidated soils, geologically belonging to Ajali and Nanka formations. Studies by Egboka and Okpoko 1984 ; Igwe 2012 ; Igwe and Fukuoka 2010 ; Nwajide 2013 ; Igwe and Egbueri, 2018 have described the loose nature of these soils to factor the increase in erodibility potentials. There were a few sightings of collapsed slopes, failed drainage channels, and major-minor landslides. Some gullies in the research area were associated with landslides, while others were found to have unstable slopes that could collapse at any time. (Fig. 3 ). There was evidence of an uneven landform in the area, and low to sparse vegetation was present in some gullies. There were larger gullies in the region with low vegetation than in the areas with more vegetation. This implies that the vegetation cover may decrease some gullies' capacity to infiltrate the soil, which would help the soil resist shearing forces. The gully geometry properties include; gully width (4 to 450m), gully depth (15 to 160m), and lateral extent (33 to over 1000m), which were carefully studied, and the results are shown in Table 1 . Furthermore, the gullies within the Nanka Formation were observed to have larger gully geometry than the ones within the Ajali Formation. Generally, these gullies were observed to have similar V − shaped and are irregularly patterned (Fig. 4 ). Quicksand was observed at different gully toes, indicating soil materials liquefied under high rainfall infiltration. Emeh and Igwe ( 2017 ) note that high sand content and low cohesion explain the V − shaped gully profiles observed in the field. The loose nature of the gully's soil material is believed to be factored by the high rainfall intensity within the study area. 4.2 Geotechnical properties for characterizing soil erodibility 4.2.1 Grain size distribution and USCS The obtained results for the particle size analysis are presented in Table 2 . The particle size distribution results reveal that the content of gravel, sand, and fines are in a range of 0 − 3%, 7.75 − 95.0%, and 5 − 22.5%, respectively, for Ajali Formation (Table 2 a) and 4.42 − 17.7%, 66.5 − 89%, 4.7 − 22.2% respectively for Nanka Formation (Table 2 b). These results show a high percentage of sand with a low percentage of gravel and fines. It also reveals a sand-dominated material with a low cohesive slope observed in the field. This also correlates with previous studies in the area (Igwe and Egbueri 2018 ; Emeh and Igwe 2018 ; Nebeokike et al. 2020 ). However, the particle size distribution curves (Fig. 5 ) have similar S-shaped for all gully sites, confirming the predominance of sands in the slope materials. Research shows that a high amount of sand in the slope material strongly implies gully occurrence (Nebeokike et al. 2020 ). Following the results' observations, these soils are highly vulnerable to erosion due to the low clay/silt content, which may serve as natural binders that hold the soil materials together and resist erosion (Kahlon and Khera 2000 ). Furthermore, the coefficient of uniformity (Cc) and coefficient of curvature (Cu) of the soils ranges from 2.86 − 4.26 and 1.01 − 1.46, respectively, for the Ajali Formation (Table 2 a). However, for the Nanka Formation, Cc ranged from 3.12 to 5.62 while Cu ranged from 1.03 to 2.01. Comparing the results to Arora, 2008 which proposed that soils having Cu > 6 and Cc = 1 to 3 are well graded, it depicts that the soils of both Ajali and Nanka formations in this study are well-graded. Table 2 Particle size distribution and soil classification of the studied area Samples ID A: Ajali Formation Sample ID B: Nanka Formation Gravel (%) Sand (%) Fines (%) USCS Gravel (%) Sand (%) Fines (%) USCS AJ1 0.00 85.80 14.20 SM NK1 13.50 77.40 9.10 SP AJ2 0.00 95.00 5.00 SP NK2 7.45 77.55 15.00 SP AJ3 0.00 86.30 13.70 SM NK3 17.70 69.20 13.1 SP AJ4 3.00 91.20 5.80 SP NK4 11. 36 83.94 4.70 SW AJ5 2.00 90.00 8.00 SP NK5 4.42 73.35 22.23 SC AJ6 1.40 92.50 6.10 SP NK6 5.80 89.00 5.20 SW AJ7 1.00 85.40 13.60 SM NK7 15.28 66.47 18.25 SC AJ8 0.00 77.50 22.50 SM NK8 6.20 73.10 20.7 SC The Unified Soil Classification System scheme (USCS) results are presented in Table 2 . The USCS system has helped classify soil material with erodibility tendency. The soil types are classified as silty sand (SM) and poorly graded sands (SP) for Ajali Formation (Table 2 a) and Nanka Formation are poorly graded sands (SP), well-graded sand (SW) and clayey sand (SC) (Table 2 b). Comparing these results to the particle size distribution reveals that these soils show a high amount of sand in the slope material and attribute a high significance to gully occurrence and development. Research by Egbueri and Igwe ( 2018 ) has shown that high erodibility potential is influenced by the low percentages of the fines and the low cohesion value. 4.2.2 Permeability characteristics In gully erosional study, factors such as permeability, degree of saturation, vegetation, and rainfall intensity play a significant part in the infiltration capacity of the soil (Manyatsi 1998 ). Permeability measures the hydraulic conductivity of engineering materials. The obtained results for permeability in the study are presented in Table 3 . It ranges from 5.92 𝚡 10 −5 to 1.39 𝚡 10 −3 m/s for Ajali Formation (Table 3 a) and 5.92 𝚡 10 −5 to 1.19 𝚡 10 − 3 m/s for Nanka Formation (Table 3 b). Based on the results, Igwe et al. ( 2013 ) stated that permeability coefficient (k) that ranged from 10 − 7 –10 − 5 m/sec are characterized as moderately to highly permeable; whereas Casagrande and Fadum ( 1940 ) characterized the ranges of (k) from 10 − 4 to 10 2 cm/sec as good, 10 − 6 to 10 − 4 cm/sec as poor, and 10 − 9 to 10 − 6 cm/sec as practically impervious. From the results presented in Table 3 , the soils k are moderate to highly permeable, showing that the soil infiltration capacity is moderately high. Furthermore, it indicates the predominance of sands as revealed in the particle size distribution. Following the predominance of sand, the k nature of the soil materials, and high rainfall intensity in the study area, these factors are believed to facilitate gullying in the study region (Igwe and Egbueri 2018 ; Nebeokike et al. 2020 ). Table 3 Permeability (m/sec) of the various soil samples Sample ID A: Ajali Formation Sample ID B: Nanka Formation Permeability Permeability AJ1 2.45 𝚡 10 −4 NK1 8.6 𝚡 10 −5 AJ2 9.36 𝚡 10 −5 NK2 6.18 𝚡 10 −5 AJ3 3.08 𝚡 10 −5 NK3 6.36 𝚡 10 −5 AJ4 5.49 𝚡 10 −5 NK4 5.25 𝚡 10 −4 AJ5 7.15 𝚡 10 −5 NK5 9.43 𝚡 10 −5 AJ6 8.66 𝚡 10 −5 NK6 4.87 𝚡 10 −4 AJ7 1.32 𝚡 10 −5 NK7 8.31 𝚡 10 −5 AJ8 1.13 𝚡 10 −5 NK8 8.73 𝚡 10 −5 4.2.3 Compaction characteristics The compaction test helps reveal if a soil material is loose or compacted and establishes a relationship between the compaction level and optimum water content (MDD and OMC) of soil material. In this study, the compaction test results are presented in Table 4 , and the compaction graph is shown in Fig. 6 for Ajali and Nanka formations. The compaction test results in this study, as illustrated in Table 4 , reveal that the maximum dry density (MDD) ranges from 1.69 to 1.90g/cm 3, with the optimum moisture content (OMC) ranging from 11.0 to 14.30% for the soils belonging to Ajali Formation (Table 4 a). For the Nanka Formation, the MDD ranges from 1.72 to 2.10g/cm 3, with the OMC ranging from 12.12 to 18.10% (Table 4 b). Based on the results, these soil materials have a poor MDD and a very low optimum moisture content OMC, suggesting loose soil materials that may require little or no force to weather or erode the soil materials. Furthermore, the compaction curve shown in Fig. 6 has a similar n-shape for all soil samples. The loose nature of these soils, as revealed in the compaction test, can be attributed to the water holding capacity or the infiltration capacity and hydraulic conductivity of the soil materials as an increase in rainfall intensity weakens the soil materials (Igwe and Egbueri 2018 ; Nebeokike et al. 2020 ). It is believed that soil permeability has an effect on the compaction nature of the soil as an increase in the infiltration capacity weakens the soil materials. Hence, activities such as borrowing and quarrying also play a role in the loose nature of the soil materials. As an increase in infiltration capacity weakens the soil materials, soil permeability is assumed to impact the soil's tendency to compact. Therefore, the loose nature of the soil materials is also influenced by activities like mining and quarrying. Table 4 Results from the compaction test Sample ID A: Ajali Formation Sample ID B: Nanka Formation MDD (g/cm 3 ) OMC (%) NMC w (%) MDD (g/cm 3 ) OMC (%) NMC w (%) AJ1 1.89 15.30 5.00 NK1 2.3 12.89 3.00 AJ2 1.76 13.60 2.00 NK2 1.91 14.23 2.00 AJ3 1.73 11.85 6.00 NK3 1.98 13.65 3.00 AJ4 1.83 13.90 4.00 NK4 2.10 16.00 2.00 AJ5 1.72 12.40 3.00 NK5 1.72 18.10 5.00 AJ6 1.90 14.30 4.00 NK6 1.89 17.10 2.00 AJ7 1.83 12.90 7.00 NK7 1.88 14.65 4.00 AJ8 1.69 11.00 9.00 NK8 1.76 12.12 5.00 4.2.4 Natural moisture content and Atterberg limits Soil natural moisture content (NMC) helps understand soil material's bearing capacity and behavior. The results of the NMC presented in Table 4 range from 2 − 9% and 2 − 5% for Ajali and Nanka formations, respectively. These results reveal an unsaturated soil state, indicating a low moisture content. Isikwue et al. ( 2012 ) suggested that low moisture content reduces cohesion in soil particles, making them easily dispersible, especially during the dry season when there is a decline in the water table. The Atterberg limit results in this study are presented in Table 5 . The liquid limit (LL) ranges from 15 to 28%, and the plastic limit (PL) and plasticity index (PI) is non-plastic (NP) for the soil belonging to Ajali Formation (Table 5 a). However, for the Nanka Formation, the LL ranges from NP–25%, PL ranges from NP–15%, and PI ranges from NP–10%. This result reveals a low LL indicating a soil material dominated by sand with a deficiency in clayey material. Igwe and Egbueri ( 2018 ) suggested that soils with a very low plasticity index are highly sensitive to erosion and predispose the soil to a high water erodibility tendency. Soils having a high PI tend to be clay, those with a lower PI tend to be silt, and those with a PI of 0 (NP) tend to have little or no silt or clay. Following the findings from the results, it is believed that the soils in the study area have lower PI and NP. This suggests that little or no clay is present in the soil materials, which also agrees with the results of the grain size analysis, USCS and permeability characteristics. Studies have shown that soils lacking clay content are vulnerable to erosive forces like water because clay serves as a natural binder that holds the soil materials (Igwe and Egbueri 2018 ; Nebeokike et al. 2020 ). Research shows that the plasticity index (PI) depends on the water content, i.e. the lower the NMC, the higher the PI (Kalinski 2011 ). Table 5 Results of the Atterberg limit test Sample ID A: Ajali Formation Sample ID B: Nanka Formation LL (%) PL (%) PI (%) LL (%) PL (%) PI (%) AJ1 25 NP NP NK1 23 NP NP AJ2 15 NP NP NK2 25 NP NP AJ3 26 NP NP NK3 25 NP NP AJ4 19 NP NP NK4 NP NP NP AJ5 17 NP NP NK5 22 13 9 AJ6 19 NP NP NK6 NP NP NP AJ7 27 NP NP NK7 24 15 9 AJ8 28 NP NP NK8 23 13 10 4.2.5 Shear strength characteristics Shear strength parameters (cohesion and friction angle) of soil material are the intrinsic capacity in which a soil resists failure when external forces act on the soil mass (Arora 2008 ). It plays a significant role in determining the erodibility characteristics of a gully. The shear strength parameters of the analyzed soil samples are presented in Table 6 . The results reveal that the soil materials have a similar cohesion and friction angle ranging from 0 − 6kPa and 23 − 28º for the Ajali Formation and 1 − 7kPa and 32 − 38º for the Nanka Formation. The values indicate a minimal/negligible cohesion linked to the low proportion of fines and a low friction angle, revealing a soil material susceptible to erosive forces (Chaulya 1993 ; Egbueri et al. 2017; Igwe and Egbueri 2018 ; Nebeokike et al. 2020 ). The low to minimal values of the shear strength parameters is attributed to the lower percentage of fines, as revealed in the grain size analysis. The type of fines lacking in the soil materials is clay, as they help resist failure by erosive forces. As shown by the particle size distribution, the permeability characteristics, and the Atterberg limit test, the soils are lacking in clay. This predisposes the soils of the Ajali and Nanka geologic units to erosion by water. Table 6 Results showing the shear strength characteristics of the soils Sample ID A: Ajali Formation Sample ID B: Nanka Formation Cohesion (C,kPa) Friction angle (ϕ, º) Cohesion (C,kPa) Friction angle (ϕ, º) AJ1 2 23 NK1 3 34 AJ2 0 27 NK2 3 35 AJ3 3 26 NK3 2 33 AJ4 1 28 NK4 1 38 AJ5 2 26 NK5 7 32 AJ6 1 28 NK6 2 37 AJ7 4 23 NK7 4 34 AJ8 6 24 NK8 5 33 4.3 Multivariate statistical analysis of geotechnical parameters 4.3.1 Pearson's correlation analysis The Pearson's correlation analysis (C.A.) in this study was done separately for the Ajali and the Nanka formations and the results are presented in Tables 7 and 8 , respectively. Significant values were placed in bold (Tables 7 and 8 ). Results of the Ajali Formation (Table 7 ) show a strong negative correlation (− 0.960) between sand and fine percentages. Also, a strong negative correlation (− 0.985) exists between sand percent and cohesion. Although gravel was observed to have a low negative correlation (− 0.337) with cohesion, a strong positive correlation (0.936) was found between fine percent and cohesion. Nebeokike et al. ( 2020 ) observed that negative correlations signify indirect relationships between parameters. This implies that the strong negative correlation (-0.960) observed between sand and fine indicates a huge impact the sand and fines percentage plays in this study. The soil materials have a greater percentage of sand and a deficiency in fine content, which is believed to be that an increase in sand content decreases the fine content of the soil materials. In a situation whereby the soil materials have a little amount of clay which is expected to serve as natural binders, the soil materials are eventually exposed to erosive force. Cohesion, on the other hand, is dependent on grain sizes, as an increase in gravel, sand, and fines content decreases cohesion in soil (Nebeokike et al. 2020 ). It is believed that soil material with higher clay dominance withstands erosion more than the ones with higher sand percent (Horton 1945 ). This is true because an increase in clay content in the soil material increases cohesion, thereby increasing the soil moisture content (Brady and Weil 2008). The soil cohesion was observed to have a strong positive correlation with the soil LL and NMC (0.855 and 0.950, respectively). In contrast, the friction angle reveals a negative relationship with the LL (− 0.754) and NMC (-0.640), indicating an inverse proportionality among the shear strength parameter (cohesion and friction angle). Thus, this reveals that the presence of fluid impacts the soil properties as the moisture content increases the cohesion and the friction angle decreases. Table 7 Pearson correlation matrix of analyzed soil geotechnical parameters for Ajali formation Gravel Sand Fines LL NMC MDD OMC k C Ø Gravel 1 Sand 0.403 1 Fines -0.556 -0.985 1 LL -0.452 -0.891 0.895 1 NMC -0.353 -0.942 0.923 0.937 1 MDD 0.229 0.362 -0.372 -0.082 -0.237 1 OMC 0.185 0.562 -0.545 -0.365 -0.548 0.889 1 K -0.200 0.216 -0.158 -0.160 -0.381 0.563 0.793 1 C -0.337 -0.960 0.936 0.855 0.950 -0.448 -0.703 -0.442 1 Ø 0.520 0.731 -0.763 -0.754 -0.640 0.053 0.142 -0.184 -0.679 1 Significant values are in bold Table 8 Pearson correlation matrix of analyzed soil geotechnical parameters for Nanka formation Gravel Sand Fines LL PL PI NMC MDD OMC k C Ø Gravel 1 Sand -0.467 1 Fines -0.216 -0.862 1 LL 0.251 -0.851 0.756 1 PL -0.210 -0.609 0.826 0.397 1 PI -0.279 -0.577 0.841 0.394 0.991 1 NMC -0.192 -0.653 0.861 0.542 0.891 0.921 1 MDD 0.567 0.254 - 0.696 -0.156 -0.668 -0.693 -0.564 1 OMC -0.435 0.407 -0.131 -0.536 0.039 0.005 -0.103 -0.322 1 K -0.208 0.834 -0.768 -0.998 -0.409 -0.409 -0.564 0.179 0.514 1 C -0.474 -0.486 0.884 0.539 0.812 0.837 0.884 -0.643 0.144 -0.573 1 Ø -0.046 0.800 -0.849 -0.865 -0.578 -0.599 -0.808 0.380 0.273 0.885 -0.772 1 Significant values are in bold The CA for the Nanka Formation is presented in Table 8 . It was observed that PL, PI, and NMC have a strong positive correlation (0.812, 0.837, and 0.884, respectively) with cohesion. However, friction angle (Ø) was observed to correlate negatively with these parameters LL (− 0.849), NMC (− 0.808), PL (− 0.578), and PI (− 0.599). These were of similar observation to the above Ajali Formation. Revealing the presence of fluid impacts the soil cohesion and friction angle, i.e., increase in cohesion and decrease in friction angle, depending on the soil moisture content. Furthermore, a strong negative (− 0.862) correlation was observed between sand percentage and fines percentage, which suggests an indirect relationship between the parameters. The grain size analysis revealed a predominance of sand with little presence of fine (clay/silt) in the soil samples. This shows that the soil is highly susceptible to erosions, and the moisture content influences the gully development (Emeh and Igwe 2017 ; Igwe and Egbueri 2018 ; Egbueri and Igwe 2020 ). 4.3.2 Factor analysis Factor analysis (FA) is applied in the gully erosion study to help validate the CA results. The obtained results for the Varimax-rotated factor analysis are presented in Tables 9 and 10 (for Ajali and Nanka formations, respectively). For the Ajali Formation, two main factor classes were obtained with a total variance of 83.545% (Table 9 ). The first class explains a total variance of 53.404%, with significant parameters including fines, LL, NMC, and C. These parameters were also captured in CA to enhance soil erodibility potential. The second class has significant loadings on the sand, OMC, and K with a total variance of 30.142%. These parameters enhance soil vulnerability and gully development in southeastern Nigeria, especially during the rainy season. Table 9 Varimax rotated factor analysis results for Ajali formation Parameter Factor 1 Factor 2 Gravel -0.601 -0.094 Sand -0.326 0.717 Fines 0.947 -0.278 LL 0.936 -0.123 NMC 0.878 -0.358 MDD -0.707 0.339 OMC -0.296 0.940 K 0.044 0.905 C 0.844 -0.502 Ø -0.883 -0.148 Total 5.340 3.014 %Variance 53.404 30.142 Cumulative% 53.404 83.546 Significant values are in bold Table 10 Varimax rotated factor analysis results for Nanka formation Parameter Factor 1 Factor 2 Gravel -0.525 -0.644 Sand -0.447 0.827 Fines 0.878 -0.442 LL 0.379 -0.878 PL 0.896 -0.166 PI 0.920 -0.151 NMC 0.875 -0.331 MDD -0.838 -0.212 OMC 0.225 0.748 K -0.409 0.856 C 0.939 -0.158 Ø -0.644 0.674 Total 6.023 4.039 %Variance 50.191 33.659 Cumulative% 50.191 83.850 Significant values are in bold The Varimax rotated factor analysis results for the Nanka Formation are presented in Table 10 . Two main factor classes were obtained, having a total variance of 83.850%. The first factor class with a total variance of 50.191% and significant loadings on fines, PL, PI, NMC, and C. These parameters were equally identified in the CA to have a positive correlation. The second-factor class reveals a total variance of 33.659%, with significant loadings on the sand, OMC, K, and Ø. The parameter observed with strong positive loading enhances soil vulnerability and impacts the moisture content of the soil material. Research on gully erosion in southeastern Nigeria has reported that soil loss impacts higher during the rainy season as the shearing resistance of the soil decreases with increasing rainfall intensity (Igwe and Egbueri 2018 ; Nebeokike et al. 2020 ). 4.4 Geomorphological Characteristics Field observations and measurements of the gully slopes presented in Table 11 showed that most of the gully slopes in the area have an angle of inclination > 35°. This predisposes the soils to the influence of denudation agents such as a landslide. Figure 7 shows the DEM of the study area. The Ajali Formation placed on the left has an elevation ranging from 52 − 579m (Fig. 7 a). The gully distribution in the area is mostly higher. However, for the Nanka Formation, the gullies are distributed both within the lowlands and highlands (Fig. 7 b). This reveals that the gullies within the Ajali Formation are more associated with a landslide because gullies with steeper slopes have a higher erodibility tendency than the level ones (Egbueri and Igwe 2020 ). The gully profiles in the study area reveal mainly sands and units of fines. The topography within various geologic units controls the gully distribution, with the erosive power of surface runoff being greatly enhanced in areas with a high gradient (Fig. 7 ). If the velocity of runoff is doubled as a result of slope variation, the cutting power increases four times, the quantity of material of a given size that can be carried increases thirty-two times and also the volume of particles that can be carried increases sixty-four times (Chow 1959). Table 11 Gully slope components Gully Site/ Location Formation Slope gradient Range ( 0 ) Number of gully slopes measured Slope aspect (direction) Udi (FRSC) Academy Ajali 38 − 56 8 Various Obioma (Udi) Ajali 40 − 66 11 Various Ngwo (I) Ajali 48 − 72 7 Various Ngwo (II) Ajali 33 − 66 12 Various Ngwo (III) Ajali 46 − 72 10 Various 9th Mile (I) Ajali 38 − 62 10 Various 9th Mile (II) Ajali 35 − 68 11 Various 9th Mile quarry site Ajali 49 − 62 10 Various Ekwulobia Nanka 40 − 72 10 Various Uga Nanka 35 − 75 8 Various Nanka gully complex Nanka 48 − 88 22 Various Agulu gully complex Nanka 42 − 74 15 Various Oraukwu Nanka 45 − 68 9 Various Umuchu Nanka 40 − 55 7 Various Nimo Nanka 42 − 56 12 Various Igbo-Ukwu Nanka 33 − 62 10 Various 5 Conclusions This research has successfully assessed the erodibility and geomorphological characteristics of Ajali and Nanka geologic formations in southeastern Nigeria through the help of some key analyzed geotechnical parameters and multivariate statistical analysis. Based on the results, both geologic formations have similar erodibility characteristics. The study area was observed to have a predominance of sand with a deficiency of fine (clay/silt) materials and is well graded. The soil permeability indicated a moderate to high infiltration capacity. Furthermore, the compaction test revealed a loose soil nature that may require little force to erode. The soils in the study area were non-plastic to low plastic having a low water holding capacity as revealed by the Atterberg limit and the NMC. These could be attributed to the soil mineralogy and the soil material's proportionate fines (clay/silt). Based on the shear strength parameters, the soil cohesion was relatively low (ranging from 0 − 6kPa for Ajali Formation and 1 − 7kPa for Nanka Formation) with a low friction angle (ranging from 23–38º for Ajali formation and 32–38º for Nanka formation) which implies a weak resistance to shearing forces. Furthermore, integrating CA and FA aided in identifying key geotechnical parameters facilitating gully development. Based on the geomorphologic characteristics, the study area has uneven topography. It was observed that the gullies within the Ajali Formation are distributed at a higher elevation and are more associated with landslides than in the Nanka Formation. Some mitigation approach should be adopted to combat this dreadful disaster. 5.1 Limitations of the study and recommendation Although this study has analyzed the erodibility and geomorphological characteristics of two erosion-prone geologic units (the Ajali and Nanka formations) in some parts of southeastern Nigeria, it is only a minor effort to spotlight the role of geotechnical properties and geomorphological attributes in the erodibility nature of the gullies within the study region and to show the similarities between the Ajali and Nanka geologic formations. Therefore it is not an exhaustive report on the overall erodibility potential of the gullying processes. Thus the authors recommend that further research on the erodibility characteristics should include advanced geotechnical study, slope stability modeling, hydrogeological study, soil loss modeling, and advanced GIS and remote sensing study to be examined in other to intensify and understand the exact prevailing factor contributing to the erosional processes in the study area. This will give an insight into adopting novel mitigation measures in combating this gully menace in the area. Declarations Ethical statement Data availability statement – There is no external data associated with this manuscript. All the data used have been provided in the submission. Compliance with ethical standard - The authors certify that this paper is written in line with the journal's ethical guidelines. Funding – No external funding was received for this research project. 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Onwuka","email":"","orcid":"","institution":"University of Nigeria","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Obialo","middleName":"S.","lastName":"Onwuka","suffix":""},{"id":128536004,"identity":"7fc6e347-ab10-43be-91e7-b23c2e777093","order_by":3,"name":"Johnbosco C. Egbueri","email":"","orcid":"","institution":"Chukwuemeka Odumegwu Ojukwu University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Johnbosco","middleName":"C.","lastName":"Egbueri","suffix":""}],"badges":[],"createdAt":"2022-08-10 16:59:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1950040/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1950040/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":25330562,"identity":"7c47e55d-2b5e-4fee-9edf-ac51fced4b12","added_by":"auto","created_at":"2022-08-17 15:59:33","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":223278,"visible":true,"origin":"","legend":"\u003cp\u003eGeologic map of the study area showing sample locations\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-1950040/v1/a0182db16de5f8eef9bf4be4.png"},{"id":25330004,"identity":"5e449994-37c6-407c-8553-16866f047186","added_by":"auto","created_at":"2022-08-17 15:54:35","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":590244,"visible":true,"origin":"","legend":"\u003cp\u003eSome\u003cstrong\u003e \u003c/strong\u003eengineering structures threatened by gully erosion in Uga and Nanka communities\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-1950040/v1/c00140251eaf67924b7b701b.png"},{"id":25330907,"identity":"3ecb56da-bfc4-4f89-ba97-937ca6cc73f0","added_by":"auto","created_at":"2022-08-17 16:04:33","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":177665,"visible":true,"origin":"","legend":"\u003cp\u003eStratigraphic succession in the Anambra Basin and outcropping Niger Delta (Ekwenye, 2014)\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-1950040/v1/61923b713cd8b64d16982c5b.png"},{"id":25330003,"identity":"8696c9a7-8fe2-4fc2-b900-8918e55265b8","added_by":"auto","created_at":"2022-08-17 15:54:33","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":717080,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Gully at Obioma representing Ajali Formation; \u003cstrong\u003eb\u003c/strong\u003e Gully at Uga representing Nanka Formation; both showing a typical V-shaped gully type\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-1950040/v1/635124512f6bfa4fb984176c.png"},{"id":25329998,"identity":"a06f1375-fb9a-4b50-98df-27e4e258d1f5","added_by":"auto","created_at":"2022-08-17 15:54:33","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":119814,"visible":true,"origin":"","legend":"\u003cp\u003eGrain size distribution for the soil samples (a) Ajali Formation, (b) Nanka Formation\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-1950040/v1/e07bfa6c5d487bbd254b6c4e.png"},{"id":25330000,"identity":"3d49352b-41d1-40a9-bf13-9b45557eabd4","added_by":"auto","created_at":"2022-08-17 15:54:33","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":132601,"visible":true,"origin":"","legend":"\u003cp\u003eCompaction curves for the soil samples (a) Ajali Formation, (b) Nanka Formation\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-1950040/v1/94567413fc70b986c000235d.png"},{"id":25330001,"identity":"51ff7bf0-a32a-4688-a6c8-493485e416c2","added_by":"auto","created_at":"2022-08-17 15:54:33","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":855224,"visible":true,"origin":"","legend":"\u003cp\u003eDEM and gully location of the study area\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-1950040/v1/7e8ad8a67ba85df8677e14c1.png"},{"id":29241882,"identity":"c977b3db-0b13-4535-849d-2ef0cc6480a5","added_by":"auto","created_at":"2022-11-18 13:59:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3458939,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1950040/v1/af142866-9f21-49ad-831c-708d8cc9c6dd.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Assess ing the Influence of Geotechnical and Geomorphological Characteristics on the Erosional Processes of Two Geologic Units in Udi and Aguata, SE Nigeria","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eEnvironmental disasters such as gullies and landslides have long been a major threat to humans and ecosystems worldwide. These hazards have recently been a significant concern in several fields of study, particularly geoscientists, environmentalists, geotechnics, and civil engineers. Gullies and landslides have similar occurrence mechanisms and dynamic/complex in mitigating, whereby one could happen in association with the other. It is believed that as gravity pulls soil materials from the region of higher elevation to lower elevation, the mechanism is termed landslide, and it is an integral part of the progression of erosion (Khamkar and Mhaske \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Gully erosion, on the other hand, refers to the process by which soil particles are detached from their original soil mass and mechanically transported by running water, ice, and wind (Egbueri et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Gully erosion processes impact both the biophysical and socio-economic components of the environment. Gully formation is highly influenced by surface runoff; as raindrops strike the soil surface, soil particles are sparsely thrown apart through the air over several centimeters. As continuous exposure to high rainfall considerably weakens the soil. Over time, soil mass is broken down through weathering processes, both mechanically and biochemically (Nwajide \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Nazari Samani et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe threat of gully erosion has been experienced across southeast Nigeria. This is a conception of the nature of the geologic formations (poorly consolidated sediments) underlying the study area (Egbueri and Igwe \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Gully occurrence in the study area poses a threat to many environmental issues, including the loss of enormous amounts of arable land, the destruction of the transportation system and engineering structures, the abandonment of ancestral homes, the migration of communities, and the deterioration of water quality (Hudec et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Bell, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Igwe and Egbueri, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Egbueri and Igwe \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Nebeokike et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Research has proven that numerous geogenic factors and anthropogenic activities contribute highly to the initiation, development, and expansion of gullies. These factors may include geology, geomorphology, land use/land cover, hydrologic conditions, excavation, and mining activities (Poesen \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Emeh and Igwe \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Egbueri and Igwe \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). According to studies, out of the five states in Nigeria's southeast, Anambra State appears to have the most gullies, with over 700. Enugu, Imo, Abia, and the Ebonyi States follow with 600, 450, 300, and 250 gullies, respectively. Most of these gullies have not been successfully controlled (Igbokwe et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Egboka et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Egbueri and Igwe \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Coincidentally, Anambra State, with the highest number of gullies (700 gullies) is underlined by the youngest, poorly-consolidated geologic formations. In contrast, Ebonyi State, with the fewest number of gullies (250 gullies), has the oldest, firmly-consolidated geologic formations (Egbueri and Igwe \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eMany methods such as remote sensing, geospatial models, multivariate statistical analysis, and the RUSLE model (revised universal soil loss equation) have been utilized in gully erosion studies. Each method adopted is employed upon the peculiarity of the problem intended to be solved. In this study, statistical analysis was adopted to help reveal the interrelationship of the analyzed soil geotechnical parameters. Statistical analysis was employed in this study to aid in demonstrating how the evaluated soil geotechnical parameters are interrelated. The SPSS software (v. 22) would be used to achieve this. Pearson's correlation analysis (CA) and the factor analysis (FA) tools were considered. The CA uses a correlation coefficient to correlate two variables (x) and (y), with values between +\u0026thinsp;1 and \u0026minus;\u0026thinsp;1. A coefficient of +\u0026thinsp;1 means a positive correlation (direct relationships), while the coefficient of \u0026minus;\u0026thinsp;1 means a negative correlation (indirect relationships) (Hotelling \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e1953\u003c/span\u003e). Correlations have been categorized as strong, moderate, and weak, depending on the coefficient. Thus, the larger the coefficient, the stronger the association (Egbueri et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Nebeokike et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The FA describes observation among variables and aims to find independent latent variables (Thompson, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). This study utilized the Varimax rotation method to optimize the factor loadings at eigenvalue\u0026thinsp;\u0026ge;\u0026thinsp;1. Like the CA, the FA considers factor loading low, medium, and high (Egbueri et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Nebeokike et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNumerous studies have been done on the initiation and development of gullies in southeast Nigeria, including those by Nwajide and Hogue (1979), Egboka and Nwankwor (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e1985\u003c/span\u003e), Okagbue and Ezechi (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e1988\u003c/span\u003e), Okagbue (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e1988\u003c/span\u003e), Obiadi et al. (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), Emeh and Igwe (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e); Igwe et al. (2017), Igwe and Egbueri (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) and Nebeokike et al. (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Okagbue and Ezechi (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e1988\u003c/span\u003e) described gullies as catastrophic. Depths and widths far beyond several kilometers, which would be termed a canyon (Obiadi et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Nwajide and Hogue (1979) and Okagbue (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e1988\u003c/span\u003e) quoted and believed that these gullies are caused by a combination of geogenic, biotic, and anthropogenic factors. Meanwhile, Egboka and Nwankwor (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e1985\u003c/span\u003e) argue that they can be attributed to rock's significant hydrogeochemical and geotechnical properties. Recent research on the erodibility and slope characteristics of gullies in the Udi region was conducted by Nebeokike et al. (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), and it was noted that the soils are erodible. There is evidence that the soils of the Anambra state are erodible, which was reported in recent studies by Emeh and Igwe (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), Igwe et al. (2017), Igwe and Egbueri (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), and Egbueri et al. (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). At this time, no study has given importance to assessing the influence of geotechnical and geomorphological characteristics on the erosional processes in Udi and Aguata, southeast Nigeria. Therefore, it is essential to assess the erosional processes of both geologic formations in Udi and Aguata due to their propensity for gullying in the region. The current research is focused on evaluating the geotechnical and geomorphological influence on the occurrence of gullies in Udi and Aguata, southeastern Nigeria. The study objectives are to (1) determine the gully distribution within the geologic formations; (2) compare and characterize the geologic formation and determine their erodibility characteristic; (3) identify the key factors initiating/facilitating gullying through the integration of multivariate statistical analysis (CA and FA) and (4) determine the impact of geomorphological characteristics on the gullying processes. It is believed that the information obtained from this research would contribute immensely to the mitigation planning and control of the erodible soils within the study region.\u003c/p\u003e"},{"header":"2 Study Area Description","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Location, economy, and geology\u003c/h2\u003e \u003cp\u003eThe research area covers the western part of Enugu State and the southern Anambra State, both in southeastern Nigeria. It lies within latitude 05\u0026ordm;55' to 06\u0026ordm;29' N and longitude 06\u0026ordm;58' to 07\u0026ordm;26' E with an elevation ranging from 169 to 433m above sea level (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The area under study is a fast developing and populated suburb with an estimated population of over 850,000. Some gullies can be reached through major and minor roads, while others can be achieved through a historic pathway (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). However, due to the nature of the gullies in the area, specific accessible routes have been halted. Some residential buildings in the study region were built without adequate environmental planning and regulation. Such structures have been pillaged by erosion, thereby leading to their desertion (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This study captured fourteen different communities: Obinagu, Obioma, Udi, 9th Mile, Ngwo, Umuagu, Nsude (Enugu State), Ekwulobia, Nanka, Agulu, Igbo-Ukwu, Oraukwu, Uga, Nimo, Umuchu (Anambra State). These communities have been threatened by gully erosion, which has resulted in many environmental problems, some of which were described previously in the introduction. Many mitigation strategies have been used in these places to control the gully occurrence effectively; some have been successful, while others have proven recalcitrant following such techniques.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe study region lies within the tropical rainforest having two distinct seasons; the rainy and dry seasons. The rainy season usually starts in April and ends around October, while the dry season picks up from November and ends around March (Inyang 1978). The mean-monthly temperature in the area varies in the wet season from 22 to 28\u0026deg;C and in the dry season from 28 and 32\u0026deg;C (Igwe, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Egbueri and Igwe \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The study region is characterized by a V-shaped valleys type and flat hilltops with uneven (undulating) landscape terrain. These features facilitate erosional processes in the area. The vegetation comprises short-tall trees (like palms, iroko, mahogany, and banana trees), shrubs, and grasses (Nebeokike et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). A dendritic drainage system that is highly influenced by the topography is found in the study region and is characterized by surface water (streams and rivers) in the area (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Geologically, the area under study is underlain by two erosion-prone geologic units (Ajali and Nanka formations) belonging to the Anambra basin and Niger-Delta basin respectively (Nwajide \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The Ajali Formation is dated early Maastrichtian in age, its thickness varies from less than 300m to over 1000m at the center of the basin. It is characterized by a friable, unconsolidated, poorly-cemented mix of sandstone and siltstone, which exhibits profuse cross-bedding with several ranges of alternating lithologic colors (Obaje \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Nwajide \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). The Ajali Formation is underlined by the Mamu Formation, while above the Ajali Formation lies the Nsukka Formation, which is known as a coal-bearing facies (Reyment \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1965\u003c/span\u003e; Murat \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1972\u003c/span\u003e; Obi \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2000\u003c/span\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The Nanka Formation (Eocene) on the other hand, is a member of the Ameki Group comprising the Ameki Formation, Nanka Sand and Nsugbe Sandstone (Ekwenye 2014) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The Nanka Formation is notorious for its proneness to gullying and the desolation wrecks within the Anambra state. It is characterized by friable fine to medium-grained sands with little mud content (Nwajide \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). The Ameki Group (Ameki Formation, Nanka Sand, and Nsugbe Sandstone) overlies the Imo Formation and underlies the Ogwashi Formation (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) (Odunze and Obi 2011; Nwajide \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). The geologic formations (Ajali and Nanka formations) possess similar characteristics, such as friable and loose unconsolidated sand, poorly to moderately sorted sandstones, and low mudrocks.\u003c/p\u003e \u003c/div\u003e"},{"header":"3 Materials And Methods","content":"\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Field mapping, soil sampling, and laboratory analysis\u003c/h2\u003e \u003cp\u003eAfter several desk studies and site surveys, the proper field mapping was implemented in November 2019. During the mapping, various gully sites were visited and carefully studied. Coordinates for the different visited gully sites were obtained using a geographical positioning system (GPS). Also, observable features like lithology and gully geometric features (width, depth, and lateral extent) were recorded (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Samples were carefully collected using a hand drill at a depth of 35\u0026thinsp;\u0026minus;\u0026thinsp;40cm. The soil samples were preserved in a sample bag, labeled according to their sample location number, and cared carefully to avoid distorting the grain properties. In this study, a total of sixteen (16) gully sites were carefully studied and recorded randomly as (AJ1 to AJ8) for Ajali and (NK1 to NK8) for Nanka formations.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eVisited gully sites and field observations\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGully Site/\u003c/p\u003e \u003cp\u003eLocation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLatitude\u003c/p\u003e \u003cp\u003e(N)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLongitude\u003c/p\u003e \u003cp\u003e(E)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eElevation (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eGully Depth\u003c/p\u003e \u003cp\u003e(m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGully Width\u003c/p\u003e \u003cp\u003e(m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eAverage Lateral Extent (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eLithology\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUdi (FRSC) Academy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e18\u0026prime;01.2\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e23\u0026prime;26.1\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e402\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eLoose lateritic\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eObioma (Udi)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e21\u0026prime;01.4\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e24\u0026prime;45.3\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e433\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eFine- medium grained sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNgwo (I)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e27\u0026prime;53.1\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e26\u0026prime;01.2\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e387\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMedium-coarse grained sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNgwo (II)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e27\u0026prime;56.9\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e26\u0026prime;02.3\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e391\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMedium-coarse grained sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNgwo (III)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e28\u0026prime;12.7\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e26\u0026prime;01.5\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e389\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMedium-coarse grained sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9th Mile (I)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e25\u0026prime;57.3\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e24\u0026prime;04.8\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e299\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eLateritic fine grained sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9th Mile (II)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e18\u0026prime;21.2\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e23\u0026prime;26.1\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e375\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eLateritic fine grained sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9th Mile quarry site\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e24\u0026prime;09.7\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e22\u0026prime;58.5\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e380\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eFine grained sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEkwulobia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e02\u0026prime;25.2\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e04.53.5\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e226\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eFine- medium grained sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUga\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e05\u003csup\u003e0\u003c/sup\u003e56\u0026prime;06.4\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e04\u0026prime;46.8\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e223\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e450\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eLoose lateritic sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNanka gully complex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e02\u0026prime;33.4\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e04\u0026prime;53.9\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e205\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e160\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e450\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMedium- coarse grained sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAgulu gully complex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e04\u0026prime;50.3\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e03\u0026prime;48.7\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e179\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e750\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eFine- medium lateritic sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOraukwu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e06\u0026prime;04.1\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e58\u0026prime;46.6\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e169\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eLoose lateritic sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUmuchu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e05\u003csup\u003e0\u003c/sup\u003e55\u0026prime;56.8\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e07\u0026prime;54.7\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e265\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e320\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMedium sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNimo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e\u0026prime;09.27.3\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e\u0026prime;58.18.6\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e184\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eLateritic fine sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgbo-Ukwu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e06\u003csup\u003e0\u003c/sup\u003e00\u0026prime;55.7\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e07\u003csup\u003e0\u003c/sup\u003e01\u0026prime;04.8\"\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e351\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eLoose lateritic sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe soil samples were analyzed in the laboratory to reveal soil properties such as grain size analysis, Atterberg limits (liquid limit, plastic limit, and plasticity index), natural moisture content, compaction, permeability, and shear strength (cohesion and friction angle). The laboratory tests were carried out based on the relevant American Society for Testing and Materials (ASTM) standard of soil testing. The grain size analysis was done to distinguish fines, sand, and gravel the percentages in the soil material (material passing the No. 200 sieve). It was done following the ASTM D421 method, using sieve analysis for coarser materials. The Atterberg limits test was used to ascertain how much water affected the mechanical characteristics of the soil. This was performed in line with ASTM D4318 standards, whereas the NMC was done in accordance with ASTM D4959 standards. The compaction characteristics were measured at standard effort following the ASTM D698 guideline. The soil permeability test is done using two methods; the constant head permeability test is preferred for highly granular soils, and the falling head permeability for fine-grained soils. In this study, the constant head permeability test was adopted for its suitability for the soil materials and was carried out following the ASTM D5084 standard. The soil's shear strength was tested using a shear box device to determine the soil strength parameter (C and \u0026Oslash;). It followed the procedures given in ASTM D3080. However, Kalinski's (2011) soil mechanics laboratory manual was equally helpful in geotechnical analysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Multivariate statistical analysis of geotechnical parameters\u003c/h2\u003e \u003cp\u003eIn this study, the SPSS software (v. 22) was considered and utilized in the statistical analyses. The twelve (12) obtained geotechnical parameters were subjected to Pearson's correlation analysis (CA) and factor analysis (FA) in other to determine interrelationships among the parameters. For the CA rating coefficients were considers as; (r)\u0026thinsp;\u0026gt;\u0026thinsp;0.7 (strong correlation), 0.5\u0026thinsp;\u0026lt;\u0026thinsp;r\u0026thinsp;\u0026lt;\u0026thinsp;0.7 (moderate correlation), and r\u0026thinsp;\u0026lt;\u0026thinsp;0.5 (weak correlation). The Varimax rotation method was considered and utilized for the FA at eigenvalue\u0026thinsp;\u0026ge;\u0026thinsp;1. Factor loading was considered as \u0026lt;\u0026thinsp;0.5 for low loading, 0.5\u0026ndash;0.75 for medium loading, and \u0026gt;\u0026thinsp;0.75 for high loading. It implies that the bigger the coefficient, the stronger the parameters' association (Egbueri et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Nebeokike et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Geomorphologic model\u003c/h2\u003e \u003cp\u003eThe geomorphology of the study area was done to determine the effect of landslides on the gullying processes. In this study, the GARMIN GPS was utilized to acquire the latitude, longitude, and elevation of different locations. The data was further integrated with the DEM (Digital Elevation Model) data obtained by SRTM (Shuttle Radar Topographic Mission) with the permission of the USGS using ArcGIS (v. 10.4) modeling and analytical tool. Following the methods described in Crozier (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e1984\u003c/span\u003e), Highland and Bobrowsky (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), Igwe (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2015\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), and Egbueri and Igwe (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), the 2D and 3D maps of the study area were generated. The Slope gradients and aspects were measured and estimated using the Brunton compass, while slope curvature was evaluated using an empirical approach (based on the field observation).\u003c/p\u003e \u003c/div\u003e"},{"header":"4 Results And Discussion","content":"\u003cdiv class=\"Section2\" id=\"Sec9\"\u003e\n \u003ch2\u003e4.1 Field observations\u003c/h2\u003e\n \u003cp\u003eThe study area is commonly composed of loose lateritic unconsolidated soils, geologically belonging to Ajali and Nanka formations. Studies by Egboka and Okpoko \u003cspan class=\"CitationRef\"\u003e1984\u003c/span\u003e; Igwe \u003cspan class=\"CitationRef\"\u003e2012\u003c/span\u003e; Igwe and Fukuoka \u003cspan class=\"CitationRef\"\u003e2010\u003c/span\u003e; Nwajide \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e; Igwe and Egbueri, \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e have described the loose nature of these soils to factor the increase in erodibility potentials. There were a few sightings of collapsed slopes, failed drainage channels, and major-minor landslides. Some gullies in the research area were associated with landslides, while others were found to have unstable slopes that could collapse at any time. (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). There was evidence of an uneven landform in the area, and low to sparse vegetation was present in some gullies. There were larger gullies in the region with low vegetation than in the areas with more vegetation. This implies that the vegetation cover may decrease some gullies\u0026apos; capacity to infiltrate the soil, which would help the soil resist shearing forces. The gully geometry properties include; gully width (4 to 450m), gully depth (15 to 160m), and lateral extent (33 to over 1000m), which were carefully studied, and the results are shown in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. Furthermore, the gullies within the Nanka Formation were observed to have larger gully geometry than the ones within the Ajali Formation. Generally, these gullies were observed to have similar V\u0026thinsp;\u0026minus;\u0026thinsp;shaped and are irregularly patterned (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). Quicksand was observed at different gully toes, indicating soil materials liquefied under high rainfall infiltration. Emeh and Igwe (\u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e) note that high sand content and low cohesion explain the V\u0026thinsp;\u0026minus;\u0026thinsp;shaped gully profiles observed in the field. The loose nature of the gully\u0026apos;s soil material is believed to be factored by the high rainfall intensity within the study area.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec10\"\u003e\n \u003ch2\u003e4.2 Geotechnical properties for characterizing soil erodibility\u003c/h2\u003e\n \u003cdiv class=\"Section3\" id=\"Sec11\"\u003e\n \u003ch2\u003e4.2.1 Grain size distribution and USCS\u003c/h2\u003e\n \u003cp\u003eThe obtained results for the particle size analysis are presented in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. The particle size distribution results reveal that the content of gravel, sand, and fines are in a range of 0\u0026thinsp;\u0026minus;\u0026thinsp;3%, 7.75\u0026thinsp;\u0026minus;\u0026thinsp;95.0%, and 5\u0026thinsp;\u0026minus;\u0026thinsp;22.5%, respectively, for Ajali Formation (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea) and 4.42\u0026thinsp;\u0026minus;\u0026thinsp;17.7%, 66.5\u0026thinsp;\u0026minus;\u0026thinsp;89%, 4.7\u0026thinsp;\u0026minus;\u0026thinsp;22.2% respectively for Nanka Formation (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb). These results show a high percentage of sand with a low percentage of gravel and fines. It also reveals a sand-dominated material with a low cohesive slope observed in the field. This also correlates with previous studies in the area (Igwe and Egbueri \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e; Emeh and Igwe \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e; Nebeokike et al. \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). However, the particle size distribution curves (Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e) have similar S-shaped for all gully sites, confirming the predominance of sands in the slope materials. Research shows that a high amount of sand in the slope material strongly implies gully occurrence (Nebeokike et al. \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). Following the results\u0026apos; observations, these soils are highly vulnerable to erosion due to the low clay/silt content, which may serve as natural binders that hold the soil materials together and resist erosion (Kahlon and Khera \u003cspan class=\"CitationRef\"\u003e2000\u003c/span\u003e). Furthermore, the coefficient of uniformity (Cc) and coefficient of curvature (Cu) of the soils ranges from 2.86\u0026thinsp;\u0026minus;\u0026thinsp;4.26 and 1.01\u0026thinsp;\u0026minus;\u0026thinsp;1.46, respectively, for the Ajali Formation (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea). However, for the Nanka Formation, Cc ranged from 3.12 to 5.62 while Cu ranged from 1.03 to 2.01. Comparing the results to Arora, \u003cspan class=\"CitationRef\"\u003e2008\u003c/span\u003e which proposed that soils having Cu\u0026thinsp;\u0026gt;\u0026thinsp;6 and Cc\u0026thinsp;=\u0026thinsp;1 to 3 are well graded, it depicts that the soils of both Ajali and Nanka formations in this study are well-graded.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u0026nbsp;\u003ctable border=\"1\" id=\"Tab2\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eParticle size distribution and soil classification of the studied area\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"width: 7.3278%;\"\u003e\n \u003cp\u003eSamples\u003c/p\u003e\n \u003cp\u003eID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\" style=\"width: 32.1202%;\"\u003e\n \u003cp\u003eA: Ajali Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 9.1597%;\"\u003e\n \u003cp\u003eSample ID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\" style=\"width: 32.1202%;\"\u003e\n \u003cp\u003eB: Nanka Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003eGravel (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003eSand (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003eFines (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eUSCS\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 9.1597%;\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003eGravel (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003eSand (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003eFines (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eUSCS\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.3278%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAJ1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e85.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e14.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 9.1597%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e13.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e77.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e9.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.3278%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAJ2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e95.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 9.1597%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e7.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e77.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e15.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.3278%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAJ3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e86.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e13.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 9.1597%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e17.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e69.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e13.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.3278%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAJ4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e3.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e91.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e5.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 9.1597%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e11. 36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e83.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e4.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSW\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.3278%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAJ5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e90.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e8.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 9.1597%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e4.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e73.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e22.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.3278%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAJ6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e1.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e92.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e6.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 9.1597%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e5.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e89.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e5.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSW\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.3278%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAJ7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e85.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e13.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 9.1597%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e15.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e66.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e18.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.3278%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAJ8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e77.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e22.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 9.1597%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 9.8925%;\"\u003e\n \u003cp\u003e6.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.3048%;\"\u003e\n \u003cp\u003e73.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 8.5491%;\"\u003e\n \u003cp\u003e20.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 5.3737%;\"\u003e\n \u003cp\u003eSC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\u003cbr/\u003e\n \u003cp\u003eThe Unified Soil Classification System scheme (USCS) results are presented in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. The USCS system has helped classify soil material with erodibility tendency. The soil types are classified as silty sand (SM) and poorly graded sands (SP) for Ajali Formation (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea) and Nanka Formation are poorly graded sands (SP), well-graded sand (SW) and clayey sand (SC) (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb). Comparing these results to the particle size distribution reveals that these soils show a high amount of sand in the slope material and attribute a high significance to gully occurrence and development. Research by Egbueri and Igwe (\u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e) has shown that high erodibility potential is influenced by the low percentages of the fines and the low cohesion value.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec12\"\u003e\n \u003ch2\u003e4.2.2 Permeability characteristics\u003c/h2\u003e\n \u003cp\u003eIn gully erosional study, factors such as permeability, degree of saturation, vegetation, and rainfall intensity play a significant part in the infiltration capacity of the soil (Manyatsi \u003cspan class=\"CitationRef\"\u003e1998\u003c/span\u003e). Permeability measures the hydraulic conductivity of engineering materials. The obtained results for permeability in the study are presented in Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e. It ranges from 5.92 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e to 1.39 𝚡 10\u003csup\u003e\u0026minus;3\u003c/sup\u003e m/s for Ajali Formation (Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea) and 5.92 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e to 1.19 𝚡 10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e m/s for Nanka Formation (Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb). Based on the results, Igwe et al. (\u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e) stated that permeability coefficient (k) that ranged from 10\u003csup\u003e\u0026minus;\u0026thinsp;7\u003c/sup\u003e \u0026ndash;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003em/sec are characterized as moderately to highly permeable; whereas Casagrande and Fadum (\u003cspan class=\"CitationRef\"\u003e1940\u003c/span\u003e) characterized the ranges of (k) from 10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e to 10\u003csup\u003e2\u003c/sup\u003ecm/sec as good, 10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e to 10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003ecm/sec as poor, and 10\u003csup\u003e\u0026minus;\u0026thinsp;9\u003c/sup\u003e to 10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003ecm/sec as practically impervious. From the results presented in Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e, the soils k are moderate to highly permeable, showing that the soil infiltration capacity is moderately high. Furthermore, it indicates the predominance of sands as revealed in the particle size distribution. Following the predominance of sand, the k nature of the soil materials, and high rainfall intensity in the study area, these factors are believed to facilitate gullying in the study region (Igwe and Egbueri \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e; Nebeokike et al. \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u0026nbsp;\u003ctable border=\"1\" id=\"Tab3\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePermeability (m/sec) of the various soil samples\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003cp\u003eID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003eA: Ajali Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003cp\u003eID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003eB: Nanka Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003ePermeability\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003ePermeability\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eAJ1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003e2.45 𝚡 10\u003csup\u003e\u0026minus;4\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003e8.6 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eAJ2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003e9.36 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003e6.18 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eAJ3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003e3.08 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003e6.36 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eAJ4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003e5.49 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003e5.25 𝚡 10\u003csup\u003e\u0026minus;4\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eAJ5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003e7.15 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003e9.43 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eAJ6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003e8.66 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003e4.87 𝚡 10\u003csup\u003e\u0026minus;4\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eAJ7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003e1.32 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003e8.31 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003eAJ8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 34.6253%;\"\u003e\n \u003cp\u003e1.13 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 13.9535%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 37.4677%;\"\u003e\n \u003cp\u003e8.73 𝚡 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003c/div\u003e\u003cbr\u003e\n \u003cdiv class=\"Section3\" id=\"Sec13\"\u003e\n \u003ch2\u003e4.2.3 Compaction characteristics\u003c/h2\u003e\n \u003cp\u003eThe compaction test helps reveal if a soil material is loose or compacted and establishes a relationship between the compaction level and optimum water content (MDD and OMC) of soil material. In this study, the compaction test results are presented in Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e, and the compaction graph is shown in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e for Ajali and Nanka formations. The compaction test results in this study, as illustrated in Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e, reveal that the maximum dry density (MDD) ranges from 1.69 to 1.90g/cm\u003csup\u003e3,\u003c/sup\u003e with the optimum moisture content (OMC) ranging from 11.0 to 14.30% for the soils belonging to Ajali Formation (Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea). For the Nanka Formation, the MDD ranges from 1.72 to 2.10g/cm\u003csup\u003e3,\u003c/sup\u003e with the OMC ranging from 12.12 to 18.10% (Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eb). Based on the results, these soil materials have a poor MDD and a very low optimum moisture content OMC, suggesting loose soil materials that may require little or no force to weather or erode the soil materials. Furthermore, the compaction curve shown in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e has a similar n-shape for all soil samples. The loose nature of these soils, as revealed in the compaction test, can be attributed to the water holding capacity or the infiltration capacity and hydraulic conductivity of the soil materials as an increase in rainfall intensity weakens the soil materials (Igwe and Egbueri \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e; Nebeokike et al. \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). It is believed that soil permeability has an effect on the compaction nature of the soil as an increase in the infiltration capacity weakens the soil materials. Hence, activities such as borrowing and quarrying also play a role in the loose nature of the soil materials. As an increase in infiltration capacity weakens the soil materials, soil permeability is assumed to impact the soil\u0026apos;s tendency to compact. Therefore, the loose nature of the soil materials is also influenced by activities like mining and quarrying.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u0026nbsp;\u003ctable border=\"1\" id=\"Tab4\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eResults from the compaction test\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003cp\u003eID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\" style=\"width: 6.0281%;\"\u003e\n \u003cp\u003eA: Ajali Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003cp\u003eID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\" style=\"width: 35.5078%;\"\u003e\n \u003cp\u003eB: Nanka Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003eMDD (g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003eOMC (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 11.9736%;\"\u003e\n \u003cp\u003eNMC w (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003eMDD (g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003eOMC (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 12.1112%;\"\u003e\n \u003cp\u003eNMC w (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eAJ1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e15.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.9736%;\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e2.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e12.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 12.1112%;\"\u003e\n \u003cp\u003e3.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eAJ2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e13.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.9736%;\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e14.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 12.1112%;\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eAJ3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e11.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.9736%;\"\u003e\n \u003cp\u003e6.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e13.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 12.1112%;\"\u003e\n \u003cp\u003e3.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eAJ4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e13.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.9736%;\"\u003e\n \u003cp\u003e4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e2.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e16.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 12.1112%;\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eAJ5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e12.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.9736%;\"\u003e\n \u003cp\u003e3.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e18.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 12.1112%;\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eAJ6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e14.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.9736%;\"\u003e\n \u003cp\u003e4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e17.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 12.1112%;\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eAJ7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e12.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.9736%;\"\u003e\n \u003cp\u003e7.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e14.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 12.1112%;\"\u003e\n \u003cp\u003e4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003eAJ8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e11.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.9736%;\"\u003e\n \u003cp\u003e9.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.4319%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 13.2122%;\"\u003e\n \u003cp\u003e1.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 10.0468%;\"\u003e\n \u003cp\u003e12.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 12.1112%;\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003c/div\u003e\u003cbr\u003e\n \u003cdiv class=\"Section3\" id=\"Sec14\"\u003e\n \u003ch2\u003e4.2.4 Natural moisture content and Atterberg limits\u003c/h2\u003e\n \u003cp\u003eSoil natural moisture content (NMC) helps understand soil material\u0026apos;s bearing capacity and behavior. The results of the NMC presented in Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e range from 2\u0026thinsp;\u0026minus;\u0026thinsp;9% and 2\u0026thinsp;\u0026minus;\u0026thinsp;5% for Ajali and Nanka formations, respectively. These results reveal an unsaturated soil state, indicating a low moisture content. Isikwue et al. (\u003cspan class=\"CitationRef\"\u003e2012\u003c/span\u003e) suggested that low moisture content reduces cohesion in soil particles, making them easily dispersible, especially during the dry season when there is a decline in the water table.\u003c/p\u003e\n \u003cp\u003eThe Atterberg limit results in this study are presented in Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e. The liquid limit (LL) ranges from 15 to 28%, and the plastic limit (PL) and plasticity index (PI) is non-plastic (NP) for the soil belonging to Ajali Formation (Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea). However, for the Nanka Formation, the LL ranges from NP\u0026ndash;25%, PL ranges from NP\u0026ndash;15%, and PI ranges from NP\u0026ndash;10%. This result reveals a low LL indicating a soil material dominated by sand with a deficiency in clayey material. Igwe and Egbueri (\u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e) suggested that soils with a very low plasticity index are highly sensitive to erosion and predispose the soil to a high water erodibility tendency. Soils having a high PI tend to be clay, those with a lower PI tend to be silt, and those with a PI of 0 (NP) tend to have little or no silt or clay. Following the findings from the results, it is believed that the soils in the study area have lower PI and NP. This suggests that little or no clay is present in the soil materials, which also agrees with the results of the grain size analysis, USCS and permeability characteristics. Studies have shown that soils lacking clay content are vulnerable to erosive forces like water because clay serves as a natural binder that holds the soil materials (Igwe and Egbueri \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e; Nebeokike et al. \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). Research shows that the plasticity index (PI) depends on the water content, i.e. the lower the NMC, the higher the PI (Kalinski \u003cspan class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e\n \u003ctable border=\"1\" id=\"Tab5\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eResults of the Atterberg limit test\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003cp\u003eID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\" style=\"width: 2.9044%;\"\u003e\n \u003cp\u003eA: Ajali Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003cp\u003eID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\" style=\"width: 32.225%;\"\u003e\n \u003cp\u003eB: Nanka Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eLL (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003ePL (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003ePI (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eLL (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003ePL (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003ePI (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eAJ1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eAJ2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eAJ3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eAJ4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eAJ5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eAJ6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eAJ7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003eAJ8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003eNP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 11.0837%;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.8785%;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 10.2627%;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\u003cbr\u003e\n \u003cdiv class=\"Section3\" id=\"Sec15\"\u003e\n \u003ch2\u003e4.2.5 Shear strength characteristics\u003c/h2\u003e\n \u003cp\u003eShear strength parameters (cohesion and friction angle) of soil material are the intrinsic capacity in which a soil resists failure when external forces act on the soil mass (Arora \u003cspan class=\"CitationRef\"\u003e2008\u003c/span\u003e). It plays a significant role in determining the erodibility characteristics of a gully. The shear strength parameters of the analyzed soil samples are presented in Table \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e. The results reveal that the soil materials have a similar cohesion and friction angle ranging from 0\u0026thinsp;\u0026minus;\u0026thinsp;6kPa and 23\u0026thinsp;\u0026minus;\u0026thinsp;28\u0026ordm; for the Ajali Formation and 1\u0026thinsp;\u0026minus;\u0026thinsp;7kPa and 32\u0026thinsp;\u0026minus;\u0026thinsp;38\u0026ordm; for the Nanka Formation. The values indicate a minimal/negligible cohesion linked to the low proportion of fines and a low friction angle, revealing a soil material susceptible to erosive forces (Chaulya \u003cspan class=\"CitationRef\"\u003e1993\u003c/span\u003e; Egbueri et al. 2017; Igwe and Egbueri \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e; Nebeokike et al. \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). The low to minimal values of the shear strength parameters is attributed to the lower percentage of fines, as revealed in the grain size analysis. The type of fines lacking in the soil materials is clay, as they help resist failure by erosive forces. As shown by the particle size distribution, the permeability characteristics, and the Atterberg limit test, the soils are lacking in clay. This predisposes the soils of the Ajali and Nanka geologic units to erosion by water.\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003ctable border=\"1\" id=\"Tab6\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eResults showing the shear strength characteristics of the soils\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003cp\u003eID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\" style=\"width: 38.2241%;\"\u003e\n \u003cp\u003eA: Ajali Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003cp\u003eID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\" style=\"width: 38.3711%;\"\u003e\n \u003cp\u003eB: Nanka Formation\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" style=\"width: 18.0829%;\"\u003e\n \u003cp\u003eCohesion (C,kPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 19.9941%;\"\u003e\n \u003cp\u003eFriction angle (ϕ, \u0026ordm;)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 18.2299%;\"\u003e\n \u003cp\u003eCohesion (C,kPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 20.1411%;\"\u003e\n \u003cp\u003eFriction angle (ϕ, \u0026ordm;)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eAJ1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.0829%;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 19.9941%;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.2299%;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 20.1411%;\"\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eAJ2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.0829%;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 19.9941%;\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.2299%;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 20.1411%;\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eAJ3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.0829%;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 19.9941%;\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.2299%;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 20.1411%;\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eAJ4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.0829%;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 19.9941%;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.2299%;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 20.1411%;\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eAJ5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.0829%;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 19.9941%;\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.2299%;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 20.1411%;\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eAJ6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.0829%;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 19.9941%;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.2299%;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 20.1411%;\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eAJ7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.0829%;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 19.9941%;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.2299%;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 20.1411%;\"\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003eAJ8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.0829%;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 19.9941%;\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 7.9388%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 18.2299%;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 20.1411%;\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec16\"\u003e\n \u003ch2\u003e4.3 Multivariate statistical analysis of geotechnical parameters\u003c/h2\u003e\n \u003cdiv class=\"Section3\" id=\"Sec17\"\u003e\n \u003ch2\u003e4.3.1 Pearson\u0026apos;s correlation analysis\u003c/h2\u003e\n \u003cp\u003eThe Pearson\u0026apos;s correlation analysis (C.A.) in this study was done separately for the Ajali and the Nanka formations and the results are presented in Tables \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e, respectively. Significant values were placed in bold (Tables \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e). Results of the Ajali Formation (Table \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e) show a strong negative correlation (\u0026minus;\u0026thinsp;0.960) between sand and fine percentages. Also, a strong negative correlation (\u0026minus;\u0026thinsp;0.985) exists between sand percent and cohesion. Although gravel was observed to have a low negative correlation (\u0026minus;\u0026thinsp;0.337) with cohesion, a strong positive correlation (0.936) was found between fine percent and cohesion. Nebeokike et al. (\u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e) observed that negative correlations signify indirect relationships between parameters. This implies that the strong negative correlation (-0.960) observed between sand and fine indicates a huge impact the sand and fines percentage plays in this study. The soil materials have a greater percentage of sand and a deficiency in fine content, which is believed to be that an increase in sand content decreases the fine content of the soil materials. In a situation whereby the soil materials have a little amount of clay which is expected to serve as natural binders, the soil materials are eventually exposed to erosive force. Cohesion, on the other hand, is dependent on grain sizes, as an increase in gravel, sand, and fines content decreases cohesion in soil (Nebeokike et al. \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). It is believed that soil material with higher clay dominance withstands erosion more than the ones with higher sand percent (Horton \u003cspan class=\"CitationRef\"\u003e1945\u003c/span\u003e). This is true because an increase in clay content in the soil material increases cohesion, thereby increasing the soil moisture content (Brady and Weil 2008). The soil cohesion was observed to have a strong positive correlation with the soil LL and NMC (0.855 and 0.950, respectively). In contrast, the friction angle reveals a negative relationship with the LL (\u0026minus;\u0026thinsp;0.754) and NMC (-0.640), indicating an inverse proportionality among the shear strength parameter (cohesion and friction angle). Thus, this reveals that the presence of fluid impacts the soil properties as the moisture content increases the cohesion and the friction angle decreases.\u003c/p\u003e \u003ctable border=\"1\" id=\"Tab7\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePearson correlation matrix of analyzed soil geotechnical parameters for Ajali formation\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGravel\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSand\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFines\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLL\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNMC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMDD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOMC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ek\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Oslash;\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGravel\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSand\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.403\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFines\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.556\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.985\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.452\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.891\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.895\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.353\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.942\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.923\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.937\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMDD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.229\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.362\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.372\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.082\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.237\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.185\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.562\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.545\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.365\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.548\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.889\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eK\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.200\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.216\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.158\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.160\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.381\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.563\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.793\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.337\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.960\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.936\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.855\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.950\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.448\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.703\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.442\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026Oslash;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.520\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.731\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.763\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.754\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.640\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.053\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.142\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.184\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.679\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"11\"\u003eSignificant values are in bold\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cbr\u003e\u003ctable border=\"1\" id=\"Tab8\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePearson correlation matrix of analyzed soil geotechnical parameters for Nanka formation\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGravel\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSand\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFines\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLL\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePL\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePI\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNMC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMDD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOMC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ek\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Oslash;\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGravel\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSand\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.467\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFines\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.216\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.862\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.251\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.851\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.756\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.210\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.609\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.826\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.397\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.279\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.577\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.841\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.394\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.991\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.192\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.653\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.861\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.542\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.891\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.921\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMDD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.567\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.254\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003cstrong\u003e0.696\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.668\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.693\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.564\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.435\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.407\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.131\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.536\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.039\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.005\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.103\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.322\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eK\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.208\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.834\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.768\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.998\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.409\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.409\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.564\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.179\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.514\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.474\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.486\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.884\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.539\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.812\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.837\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.884\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.643\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.144\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.573\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026Oslash;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.046\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.800\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.849\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.865\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.578\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.599\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.808\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.380\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.273\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.885\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.772\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"13\"\u003eSignificant values are in bold\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\u003cbr/\u003e\n \u003cp\u003eThe CA for the Nanka Formation is presented in Table \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e. It was observed that PL, PI, and NMC have a strong positive correlation (0.812, 0.837, and 0.884, respectively) with cohesion. However, friction angle (\u0026Oslash;) was observed to correlate negatively with these parameters LL (\u0026minus;\u0026thinsp;0.849), NMC (\u0026minus;\u0026thinsp;0.808), PL (\u0026minus;\u0026thinsp;0.578), and PI (\u0026minus;\u0026thinsp;0.599). These were of similar observation to the above Ajali Formation. Revealing the presence of fluid impacts the soil cohesion and friction angle, i.e., increase in cohesion and decrease in friction angle, depending on the soil moisture content. Furthermore, a strong negative (\u0026minus;\u0026thinsp;0.862) correlation was observed between sand percentage and fines percentage, which suggests an indirect relationship between the parameters. The grain size analysis revealed a predominance of sand with little presence of fine (clay/silt) in the soil samples. This shows that the soil is highly susceptible to erosions, and the moisture content influences the gully development (Emeh and Igwe \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e; Igwe and Egbueri \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e; Egbueri and Igwe \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec18\"\u003e\n \u003ch2\u003e4.3.2 Factor analysis\u003c/h2\u003e\n \u003cp\u003eFactor analysis (FA) is applied in the gully erosion study to help validate the CA results. The obtained results for the Varimax-rotated factor analysis are presented in Tables \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e (for Ajali and Nanka formations, respectively). For the Ajali Formation, two main factor classes were obtained with a total variance of 83.545% (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e). The first class explains a total variance of 53.404%, with significant parameters including fines, LL, NMC, and C. These parameters were also captured in CA to enhance soil erodibility potential. The second class has significant loadings on the sand, OMC, and K with a total variance of 30.142%. These parameters enhance soil vulnerability and gully development in southeastern Nigeria, especially during the rainy season.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u0026nbsp;\u003ctable border=\"1\" id=\"Tab9\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 9\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eVarimax rotated factor analysis results for Ajali formation\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFactor 1\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFactor 2\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGravel\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.601\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.094\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSand\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.326\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.717\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFines\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.947\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.278\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.936\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.123\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.878\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.358\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMDD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.707\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.339\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.296\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.940\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eK\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.044\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.905\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.844\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.502\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026Oslash;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.883\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.148\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.340\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.014\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e%Variance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e53.404\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30.142\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCumulative%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e53.404\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e83.546\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\"\u003eSignificant values are in bold\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"char\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;\u0026nbsp;\u003ctable border=\"1\" id=\"Tab10\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 10\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eVarimax rotated factor analysis results for Nanka formation\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFactor 1\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFactor 2\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGravel\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.525\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.644\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSand\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.447\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.827\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFines\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.878\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.442\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.379\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.878\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.896\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.166\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.920\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.151\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.875\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.331\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMDD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.838\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.212\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.225\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.748\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eK\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.409\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.856\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.939\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.158\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026Oslash;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e-0.644\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.674\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.039\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e%Variance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50.191\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e33.659\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCumulative%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50.191\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e83.850\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\"\u003eSignificant values are in bold\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\u003cbr/\u003e\n \u003cp\u003eThe Varimax rotated factor analysis results for the Nanka Formation are presented in Table \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e. Two main factor classes were obtained, having a total variance of 83.850%. The first factor class with a total variance of 50.191% and significant loadings on fines, PL, PI, NMC, and C. These parameters were equally identified in the CA to have a positive correlation. The second-factor class reveals a total variance of 33.659%, with significant loadings on the sand, OMC, K, and \u0026Oslash;. The parameter observed with strong positive loading enhances soil vulnerability and impacts the moisture content of the soil material. Research on gully erosion in southeastern Nigeria has reported that soil loss impacts higher during the rainy season as the shearing resistance of the soil decreases with increasing rainfall intensity (Igwe and Egbueri \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e; Nebeokike et al. \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec19\"\u003e\n \u003ch2\u003e4.4 Geomorphological Characteristics\u003c/h2\u003e\n \u003cp\u003eField observations and measurements of the gully slopes presented in Table \u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003e showed that most of the gully slopes in the area have an angle of inclination\u0026thinsp;\u0026gt;\u0026thinsp;35\u0026deg;. This predisposes the soils to the influence of denudation agents such as a landslide. Figure \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e shows the DEM of the study area. The Ajali Formation placed on the left has an elevation ranging from 52\u0026thinsp;\u0026minus;\u0026thinsp;579m (Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ea). The gully distribution in the area is mostly higher. However, for the Nanka Formation, the gullies are distributed both within the lowlands and highlands (Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eb). This reveals that the gullies within the Ajali Formation are more associated with a landslide because gullies with steeper slopes have a higher erodibility tendency than the level ones (Egbueri and Igwe \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). The gully profiles in the study area reveal mainly sands and units of fines. The topography within various geologic units controls the gully distribution, with the erosive power of surface runoff being greatly enhanced in areas with a high gradient (Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e). If the velocity of runoff is doubled as a result of slope variation, the cutting power increases four times, the quantity of material of a given size that can be carried increases thirty-two times and also the volume of particles that can be carried increases sixty-four times (Chow 1959).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Tab11\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 11\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eGully slope components\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGully Site/\u003c/p\u003e\n \u003cp\u003eLocation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFormation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSlope gradient Range (\u003csup\u003e0\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNumber of gully slopes measured\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSlope aspect\u003c/p\u003e\n \u003cp\u003e(direction)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUdi (FRSC) Academy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAjali\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e38\u0026thinsp;\u0026minus;\u0026thinsp;56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eObioma (Udi)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAjali\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u0026thinsp;\u0026minus;\u0026thinsp;66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNgwo (I)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAjali\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e48\u0026thinsp;\u0026minus;\u0026thinsp;72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNgwo (II)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAjali\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33\u0026thinsp;\u0026minus;\u0026thinsp;66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNgwo (III)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAjali\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e46\u0026thinsp;\u0026minus;\u0026thinsp;72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9th Mile (I)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAjali\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e38\u0026thinsp;\u0026minus;\u0026thinsp;62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9th Mile (II)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAjali\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35\u0026thinsp;\u0026minus;\u0026thinsp;68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9th Mile quarry site\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAjali\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e49\u0026thinsp;\u0026minus;\u0026thinsp;62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEkwulobia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNanka\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u0026thinsp;\u0026minus;\u0026thinsp;72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUga\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNanka\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35\u0026thinsp;\u0026minus;\u0026thinsp;75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNanka gully complex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNanka\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e48\u0026thinsp;\u0026minus;\u0026thinsp;88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAgulu gully complex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNanka\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e42\u0026thinsp;\u0026minus;\u0026thinsp;74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOraukwu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNanka\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45\u0026thinsp;\u0026minus;\u0026thinsp;68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUmuchu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNanka\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u0026thinsp;\u0026minus;\u0026thinsp;55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNimo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNanka\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e42\u0026thinsp;\u0026minus;\u0026thinsp;56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIgbo-Ukwu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNanka\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33\u0026thinsp;\u0026minus;\u0026thinsp;62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVarious\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"5 Conclusions","content":"\u003cp\u003eThis research has successfully assessed the erodibility and geomorphological characteristics of Ajali and Nanka geologic formations in southeastern Nigeria through the help of some key analyzed geotechnical parameters and multivariate statistical analysis. Based on the results, both geologic formations have similar erodibility characteristics. The study area was observed to have a predominance of sand with a deficiency of fine (clay/silt) materials and is well graded. The soil permeability indicated a moderate to high infiltration capacity. Furthermore, the compaction test revealed a loose soil nature that may require little force to erode. The soils in the study area were non-plastic to low plastic having a low water holding capacity as revealed by the Atterberg limit and the NMC. These could be attributed to the soil mineralogy and the soil material's proportionate fines (clay/silt). Based on the shear strength parameters, the soil cohesion was relatively low (ranging from 0\u0026thinsp;\u0026minus;\u0026thinsp;6kPa for Ajali Formation and 1\u0026thinsp;\u0026minus;\u0026thinsp;7kPa for Nanka Formation) with a low friction angle (ranging from 23\u0026ndash;38\u0026ordm; for Ajali formation and 32\u0026ndash;38\u0026ordm; for Nanka formation) which implies a weak resistance to shearing forces. Furthermore, integrating CA and FA aided in identifying key geotechnical parameters facilitating gully development. Based on the geomorphologic characteristics, the study area has uneven topography. It was observed that the gullies within the Ajali Formation are distributed at a higher elevation and are more associated with landslides than in the Nanka Formation. Some mitigation approach should be adopted to combat this dreadful disaster.\u003c/p\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003e5.1 Limitations of the study and recommendation\u003c/h2\u003e \u003cp\u003eAlthough this study has analyzed the erodibility and geomorphological characteristics of two erosion-prone geologic units (the Ajali and Nanka formations) in some parts of southeastern Nigeria, it is only a minor effort to spotlight the role of geotechnical properties and geomorphological attributes in the erodibility nature of the gullies within the study region and to show the similarities between the Ajali and Nanka geologic formations. Therefore it is not an exhaustive report on the overall erodibility potential of the gullying processes. Thus the authors recommend that further research on the erodibility characteristics should include advanced geotechnical study, slope stability modeling, hydrogeological study, soil loss modeling, and advanced GIS and remote sensing study to be examined in other to intensify and understand the exact prevailing factor contributing to the erosional processes in the study area. This will give an insight into adopting novel mitigation measures in combating this gully menace in the area.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement \u0026ndash;\u0026nbsp;\u003c/strong\u003eThere is no external data associated with this manuscript. All the data used have been provided in the submission.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompliance with ethical standard -\u0026nbsp;\u003c/strong\u003eThe authors certify that this paper is written in line with the journal\u0026apos;s ethical guidelines.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding \u0026ndash;\u0026nbsp;\u003c/strong\u003eNo external funding was received for this research project.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval \u0026ndash;\u0026nbsp;\u003c/strong\u003eNot applicable\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed contest\u003c/strong\u003e \u0026ndash; Not applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eArora KR (2008). Soil mechanics and foundation engineering (geotechnical engineering), 8th\u0026nbsp;edn. Lomus Ofset Press, Delhi, p\u0026nbsp;953\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBell FG (2007). 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ISBN 978-1591470939\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Gully erosion, Erosion-prone, Geomorphology, Geotechnical characteristics, Multivariate statistical analysis","lastPublishedDoi":"10.21203/rs.3.rs-1950040/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1950040/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn southeastern Nigeria, gullies occurrence has seriously threatened humans and the environment. In this study, through a detailed field survey, geotechnical and geomorphological investigation, the erodibility extent of two erosion-prone geologic units in southeastern Nigeria was assessed. According to field observations, the investigated gullies were primarily composed of loose lateritic unconsolidated soils from the Ajali and Nanka geological formations. Based on the grain size study, it was discovered that the soil components for the Ajali and Nanka formations, respectively, contained gravel (0\u0026thinsp;\u0026minus;\u0026thinsp;3% and 5\u0026thinsp;\u0026minus;\u0026thinsp;22.5%), sand (7.75\u0026thinsp;\u0026minus;\u0026thinsp;95.0% and 66.5\u0026thinsp;\u0026minus;\u0026thinsp;89%), and fines (4.42\u0026thinsp;\u0026minus;\u0026thinsp;17.7% and 4.7\u0026thinsp;\u0026minus;\u0026thinsp;22.2%). The soil permeability coefficients ranged from 1.13 x 10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e to 2.45 x 10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e m/s and 6.18 x 10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e to 5.25 x 10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e m/s for the Ajali and Nanka formations, respectively. The MDD ranged from 1.69 to 1.90g/cm\u003csup\u003e3\u003c/sup\u003e and 1.72 to 2.10g/cm\u003csup\u003e3\u003c/sup\u003e, whereas OMC ranged from 11.0 to 14.30% and 12.12 to 18.10% in the compaction test. The NMC results and the Atterberg limit indicate that the soils are non-plastic to low-plastic. The values for soil cohesion range from 0\u0026thinsp;\u0026minus;\u0026thinsp;6 kPa to 1\u0026thinsp;\u0026minus;\u0026thinsp;7 kPa. The friction angle ranges from 23\u0026thinsp;\u0026minus;\u0026thinsp;28\u003csup\u003eo\u003c/sup\u003e and 32\u0026thinsp;\u0026minus;\u0026thinsp;38\u003csup\u003eo\u003c/sup\u003e. The geomorphological characteristics revealed that the region is characterized by uneven topography and severe gully slope gradients, with the gullies within the Ajali Formation being more frequently linked with landslides. Both formations are vulnerable to erosion, according to the research. In order to combat this awful disaster, some type of mitigation strategy must be employed.\u003c/p\u003e","manuscriptTitle":"Assess ing the Influence of Geotechnical and Geomorphological Characteristics on the Erosional Processes of Two Geologic Units in Udi and Aguata, SE Nigeria","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-08-17 15:54:31","doi":"10.21203/rs.3.rs-1950040/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e8c5ca83-6ab3-47c6-8382-991eef4f13c1","owner":[],"postedDate":"August 17th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2022-11-18T13:59:15+00:00","versionOfRecord":[],"versionCreatedAt":"2022-08-17 15:54:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1950040","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1950040","identity":"rs-1950040","version":["v1"]},"buildId":"cBFmMYwuxLRRLfASyISRj","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}