Assessment of Sub-surface Hydrogeology of Coastal Aquifer using Geophysical Technique in Sagar Island, West Bengal

Assessment of Sub-surface Hydrogeology of Coastal Aquifer using Geophysical Technique in Sagar Island, West Bengal | 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 Assessment of Sub-surface Hydrogeology of Coastal Aquifer using Geophysical Technique in Sagar Island, West Bengal Poulami Ray, Saurabh Kumar Basak, Sekh Mohinuddin, Malabika Biswas Roy, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8858443/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 The Vertical Electrical Sounding method is used in this study to discover the subsurface hydrogeology of Sagar Island. The major goal is to interpret the sub-surface formation and to identify aquifer features of this Island. The geophysical investigation that has involved the electrical resistivity method, indicates that all the major subsurface formations occur throughout the Island are extensive. In general, five major subsurface formations are interpreted. These are the top highly unconsolidated sediments underlain by a saline water zone comprising clay, silt and sand lenses continuing to a depth of 21–34 m. Below this, a brackish water zone occurs within 21–150 m depth, which is underlain by thick impermeable clay layer. Further down, fresh water aquifer occurs within fine and medium sand layers. To circumscribe the brackish water-fresh water zones and to illustrate the groundwater potential zones, Dar-Zarrouk parameters are estimated such as longitudinal conductance, transverse resistance, average longitudinal resistivity, average transverse resistivity, coefficient of anisotropy. It is also found that the southern section of the region has extremely high transverse resistance and more promise than that of northern part in this study region. The analysed data of coastal aquifer characteristics like hydraulic conductivity and transmissivity is found as 5.619–15.493 m/day and 1571.44–4555 m 2 /day respectively. Spatial variation maps of aquifer parameters are also prepared using geospatial software. Vertical Electrical Sounding (VES) Survey Dar-Zarrouk Parameters Sagar Island Transmissibility Hydraulic Conductivity Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction An assortment of coastal risks such as rising sea levels and its associated consequences are present in coastal zones (Richardson et al., 2024 ). They also show greater rates of urbanisation and population increase and are more densely populated than the hinterland. Humans have long been drawn to coastal areas for a variety of reasons including their abundance of resources, especially those needed for subsistence, logistical advantages such as providing access to aquatic commerce and transportation, recreational or cultural pursuits, or just a unique sense of location at the meeting point of land and sea. Coasts are experiencing significant socio-economic and environmental changes and the development and use of coastal zones has significantly grown in recent decades (Turner et al., 1998 ). The rapid increase in population at Sagar Island, coupled with growing rate of pilgrims at Kapil Muni Ashram have emerged the needs of groundwater for drinking purposes (Das, 2022 ). Domains of important land usage are impacted and the freshwater supply is restricted in coastal plain regions due to environmental salinization. The existence of saline soils significantly restricts many activities including agriculture. As a result of population over burst, the demand for portable water is increasing day by day and for this reason there is a need to have optimal utilization of water resources. To determine the sub-surface geology and hydraulic characteristics of aquifer, pumping test is one of the most satisfactory practice (Ekwe et al., 2020 ; Akhter et al., 2022 ). But it is quite expensive process and therefore seldom 72 hours pumping test is accomplished in practice. Surface geoelectric measurements provide a trailblazing approach for the estimation of aquifer attributions. Henceforth, we have employed 30 no. s vertical electrical sounding survey at different locations Sagar Island. From the data from geophysical survey, the thickness of sub-surface layers is interpreted and also the aquifer characteristics such as hydraulic conductivity and transmissivity are also calculated (Mohasin et al., 2024 ). These aquifer parameters are necessary for the management of groundwater resources (Soupios et al., 2007 ). Dar-Zarrouk parameters are estimated such as longitudinal conductance, transverse resistance, average longitudinal resistivity, average transverse resistivity, coefficient of anisotropy and aquifer characteristics like hydraulic conductivity and transmissivity are also determine to understand the complete groundwater and saline water zonation of this study area. 2. Study Area Sagar Island (Fig. 1 ) is the largest continental mass in the Ganga Delta [21° 37’ N to 21° 52’ N, 88° 02’ 35″ E to 88° 11’ E], lying in the N-S direction (approximately 30 km length) and has varying width in E-W direction with 12km in the southern portion of this Island. It is surrounded in the north, west, east and south by the Hooghly, Gabtala, Muriganga rivers and Bay of Bengal respectively (Sen & Paul, 2023 ). Sagar Island has a flat terrain having an elevation of about 4 m from mean sea level (Thakur et al., 2021 ). The Island is having an area of 235 km 2 , comprises of 46 villages and the holy Kapil Muni Temple. Furthermore, Gangasagar has been designated by the Government as a tourism centre. Potable groundwater in the deeper aquifers are found under confined condition and is drawn using tube-wells fitted with hand pump. Dug-wells in this region extract saline water. The Island is entirely dependent on ground water for its drinking requirements. The average temperature on the Island is around 27 degrees Celsius. After the winter season (20 o C to 23 o C), the temperature progressively climbs, becoming unbearably hot throughout the summer months (27 o C to 30 o C). It steadily lowers at the arrival of monsoon and remains within the range of 28 o C to 29 o C for four monsoon months before gradually rising with the monsoon's retreat. This Island receives an average of 1700 mm of rain per year. Sagar Island is located at the southernmost portion of the world's biggest alluvial tract, the Indo-Gangetic Plain. The Ganga River and its tributaries have deposited quaternary alluvial fill on this plain. Here, Tertiary layers (upper Cretaceous to Pleistocene) lie beneath Quaternary sediments, suggesting a buildup in a tectonic depression that is sinking. Both deltaic and flood plain deposits make up the Bengal Plain's Quaternary sediments. The high tide zone on this tidal-dominated deltaic island is between 5 and 6 meters. This island's coastal characteristics include mudflats, mangrove swamps, tidal flats, sand dunes or ridges, marine terraces, tidal inlets, and coastal marshes (Paul & Bandyopadhyay, 1987 ). 3. Materials and Methodology Determination of Electrical Resistivity of Subsurface Materials at Varying Depths The resistivity method has been extensively used for geotechnical investigation, to infer hydrological characteristics, saline water intrusion, geological and geothermal investigation purposes (Mansourian et al., 2023 ; Adamo et al., 2021 ; Gallas, 2023 ). Schlumberger sounding array (Fig. 2 ) is utilized in this study to to identify the aquifer zones and to determine the subsurface formations of Sagar Island by detecting the vertical change of resistivity along depth. All four electrodes are maintained in a single line using this technique. Two exterior current electrodes send current into the ground, and two interior electrodes made of carbon pots assess the potential difference that results from this. Then the resistance of the ground is measured for various sets of electrode spacing while the current electrode spacing is progressively raised. The measured resistance relates to the resistivity of the deeper bodies, and current penetrates deeper as the distance between the current electrodes increases. Corresponding to each spacing of electrodes, apparent resistivity is calculated at the centre of the spread using the following equation as Eq. 1 , $$\:{\rho\:}_{a}=\pi\:\left[\frac{{\left(\frac{AB}{2}\right)}^{2}-{\left(\frac{MN}{2}\right)}^{2}}{MN}\right]R$$ 1 ………………. Where, AB= Distance between the current electrodes MN= Distance between potential electrodes R= Resistance Resistivity meter Aquameter CRM 500 manufactured by M/s ANVIS SYSTEMS is deployed to measure the resistance of the ground. Here, AB is the distance between the current electrodes (C1 and C2) and MN is the distance between potential electrodes (P1 and P2). Thus, the data for a sounding curve is generated for each sounding point or sounding location. These data of apparent resistivity vs. half the current electrode separation have been plotted on a Log-Log scale of 62.5mm modulus. These curves are initially interpreted by curve matching technique with a set of master curves of Orellena and Mooney and finally by 1-D software RESIST and/or IPI2WIN. The interpreted parameters, thus acquired are the resistivity and thickness of each subsurface layer up to the depth of investigation. Finally, the aquifer zone and geological formations are used to explain these resistivity values of the strata. Interpreted parameters viz. resistivity and thickness of different subsurface layers are described in this chapter. All the interpretations have been carried out subject to the usual assumptions and limitations of the resistivity method. Estimation Dar-Zarrouk Parameters for Subsurface Saline and Freshwater Zones Two pairs of electrodes are used to measure resistivity in the resistivity method: one pair of current electrodes transmits current into the ground, while the other pair monitors the potential difference between two potential electrodes. A total of 30 vertical electrical soundings (VES) are performed utilising the Schlumberger electrode array with AB = 300 m spacing in the current investigation and geographic coordinates of the VES surveying locations are also marked using Geographical Positioning System (GPS) (GRAMIN GPS MODEL ETREX 20X CG). Also, a map of VES sounding points is prepared (Fig. 3 ). An SSRMP-ATS resistivity metre provided by IGIS, Hyderabad, is used to conduct the research. The current electrode is symmetrically raised while the potential electrode is fixed at its starting interval in the Schlumberger arrangement until the resistance measured becomes too tiny (White, 1994 ). The criterion AB/2 ≥ 5(MN/2) is met at all times. The sounding curves are generated by plotting the apparent resistivity against the matching half electrode spacing (AB/2) on a bi-logarithm graph. The sounding curves are analysed using the IPI2WIN programme, which is a computer-assisted 1-D forward modelling approach (Bobachev & Gorbunov, 2003 ). The geo-electrical parameters (layer resistivity and layer thickness) are calculated using VES field data displayed on a double log graph sheet with apparent resistivity vs. electrode spacing, indicating a 3–5 layered structure in the research region. There are a number of analytical techniques for interpreting resistivity data that are commonly utilised in exploratory research. However, resolution is sometimes hindered and the stigma of ambiguity is prevalent due to certain geophysical similarities in the behaviour of different subsurface layers. Other geophysical indices other than the primary elements (resistivity and thickness) are required to overcome uncertainty in resistivity data interpretation in order to provide additional, more practical, and confident support that can lead to reliable solutions, both in terms of interpreting and understanding the geoelectric model. In the model, these characteristics are linked to various combinations of layer thickness and layer resistivity (Mooney et al., 1966 ; Singh et al., 2005 ). In electrical resistivity soundings, Dar-Zarrouk (D-Z) characteristics (also known as secondary geophysical indicators) play a critical role, as defined by Maillet ( 1947 ). The D-Z parameters (transverse resistance and longitudinal conductance) are sufficient for estimating surface potential distributions and, as a result, electrical resistivity charts (Henriet 1976 ). Several researchers have looked at the importance of D-Z factors in determining aquifer hydrological characteristics (Naidu et al. 2021 ). The subsurface salty and freshwater zones in the research region are delineated using these indicators. To further evaluate the data, the D-Z parameters such as longitudinal conductance(S) and (T) are determined using the following equations Eq. 2 and Eq. 3. The D-Z parameters are defined as, \(\:S=\frac{{h}_{1}}{{p}_{1}}+\frac{{h}_{2}}{{p}_{2}}+\frac{{h}_{3}}{{p}_{3}}+\dots\:\frac{{h}_{n}}{{p}_{n}}=\:\sum\:_{i}^{n}\frac{{h}_{i}}{{p}_{i}}\) (Eq. 2) \(\:T={p}_{1}{h}_{1}+{p}_{2}{h}_{2}+{p}_{3}{h}_{3}+\dots\:{+p}_{n}{h}_{n}=\sum\:_{i}^{n}{p}_{n}{h}_{n}\) (Eq. 3) The transverse resistivity ( \(\:{p}_{t}\) ), longitudinal resistivity ( \(\:{p}_{l}\) ), and electrical anisotropy coefficient (λ) have also been calculated from S and T as Eq. 4–6, \(\:{p}_{t}=\frac{H}{S}\) (Eq. 4) \(\:{p}_{t}=\frac{T}{H}\) (Eq. 5) \(\:⋋=\sqrt{\frac{{p}_{t}}{{p}_{l}}}\) (Eq. 6) Where, H= \(\:\sum\:_{i=1}^{n}{h}_{i}\) Data Analysis and Interpretation Vertical Electrical Soundings (VES) have been conducted at 30 locations in the study area to delineate the various lithological units, to evaluate groundwater conditions and to identify the aquifer zones. The obtained resistivity data is analysed and based on the known geology of the area, our past experience and present VES investigation, correlation has been made between the various lithological units including ground water zone and the true resistivity values interpreted in the area. These are generally as Table 1 , Table 1 Subsurface Formation Analysis from Obtained Resistivity Data Resistivity (Ohm-m) Lithology 40–80 Saturated Medium/coarse Sand 28–40 Saturated Fine Sand 8–28 Sandy clay, clayey sand, very fine sand 4–7 Clay 1.5-4 Brackish Zone < 1.2 Saline Zone The above resistivity values are considered as a general guide line only. 4. Results and Discussion: Details of Interpreted Vertical Electrical Soundings (VES) are given in Table 2 . Table 2 Interpreted VES Parameters – Sagar Island VES No. ρ 1 (Ohm-m) d 1 (m) ρ 2 (Ohm-m) d 2 (m) ρ 3 (Ohm-m) d 3 (m) ρ 4 (Ohm-m) d 4 (m) ρ 5 (Ohm-m) d 5 (m) ρ 6 (Ohm-m) VES-1 2.68 0.9 0.7 30.5 6.1 139.4 4.4 231.8 36 288.4 49 VES-2 2.4 1.0 0.8 28.3 5.9 131.5 4.0 205.6 32.4 290.7 48.4 VES-3 2.2 1.6 1.0 23.6 2.8 90.6 5.4 154.6 26.4 277.6 44 VES-4 2.3 1.1 0.8 29.5 5.6 128.5 4.1 204.4 32.4 288.2 47 VES-5 2.2 1.6 1.0 23.6 2.8 90.6 5.4 154.6 26.4 277.6 44 VES-6 3.2 1.2 0.80 33.8 6.6 148.5 4.2 234.8 28 289.0 38 VES-7 2.4 0.9 0.7 27.4 6.2 131.5 5.1 199.3 34.5 284.6 47 VES-8 2.80 1.0 0.8 29.9 6.5 141.3 4.8 240.4 38 293 50 VES-9 4.7 0.6 1.0 9.2 0.3 21.4 5.8 137.6 28 238.5 42 VES-10 3.0 1.1 0.70 30.6 6.4 143.1 5.9 230.8 26.7 280.5 38 VES-11 3.1 1.3 0.80 30.8 6.0 141.3 4.6 228.4 29.4 277.0 38 VES-12 2.7 1.1 0.5 27.6 5.4 128.5 4.0 235.5 35.5 278.2 49 VES-13 4.1 0.9 1.0 29.4 5.8 128.2 4.1 232.6 36 292 54 VES-14 2.28 1.0 0.6 28.7 5.9 124.3 4.2 231.2 35.1 269.9 50 VES-15 4.5 0.8 1.0 27.8 5.5 137.7 4.1 232.8 38 285.3 55 VES-16 2.70 0.9 0.8 28.4 6.5 141.0 5.0 236.4 38 290 48 VES-17 2.0 0.9 0.7 27.9 5.7 131 4.4 222 36 279 52 VES-18 2.2 1.6 0.8 26.6 3.2 88.2 5.1 152.8 23.7 288 46 VES-19 2.4 1.0 0.7 26.6 5.8 134.5 4.0 199.7 31.5 294.7 48 VES-20 3.0 1.2 0.9 26.3 6.0 118.5 4.2 237.8 40.0 291.3 54 VES-21 2.1 0.9 0.8 28.0 5.2 127.6 4.2 210.5 36 282.6 52 VES-22 4.5 0.8 1.0 29.4 5.8 139.2 4.1 241.9 38 296.2 56 VES-23 2.0 0.9 0.7 29.5 4.9 128.8 4.4 215.4 37 277.4 53 VES-24 3.0 1.3 0.9 25.5 6.0 120 4.4 243.8 41.3 287.2 54 VES-25 4.7 0.7 1.0 10.6 0.3 20.4 5.8 136.0 26 236 41 VES-26 2.4 1.0 0.6 27.6 5.8 122.6 4.0 241 33 284 49 VES-27 2.1 1.3 1.0 25.2 2.8 93.1 5.1 158.5 27.4 269.6 44 VES-28 3.1 1.2 0.8 24.7 6.0 126.5 4.8 228.6 39.0 283.4 54 VES-29 9.4 1.0 1.3 24.7 6.4 146.5 4.3 242.6 40.2 294 56 VES-30 8.4 1.0 1.1 26.8 5.9 139.5 4.1 233.0 37.6 286 55 Where, ρ 1 = > Resistivity of first layer d 1 = > Lower Depth of first layer ρ 2 = > Resistivity of second layer d 2 = > Lower depth of second layer and so on From the interpreted VES data, it is observed as, VES-1 The top soil is 0.9 m thick followed by a saline zone up to 30.5m. Below this, one brackish zone with some sand lenses occurs up to 139. 4m underlain by an impermeable clay layer up to 231.8m. Further down, an aquifer comprising fine and medium sand are likely. VES-2 The top soil is 1.0 m thick followed by a saline zone up to 28.3 m. Below this, one brackish zone with some sand lenses occurs up to 131.5m underlain by an impermeable brackish clay layer up to 205.6m. Further down, an aquifer comprising fine and medium sand are likely. VES-3 The top soil is 1.6 m thick followed by a saline zone up to 23.6m. Below this, one brackish zone with some sand lenses occurs up to 90.6 m underlain by an impermeable clay layer up to 154.6m. Further down, clayey sand/very fine sand followed by medium sand (from 277 m) is likely. VES-4 The top soil is 1.1 m thick followed by a saline zone up to 29.5m. Below this, one brackish zone with some sand lenses occurs up to 128.5 m underlain by an impermeable clay layer up to 204.4m. Further down, an aquifer comprising fine and medium sand are likely. VES-5 The top soil is 1.6 m thick followed by a saline zone up to 23.6m. Below this, one brackish zone with some sand lenses occurs up to 90.6 m underlain by an impermeable clay layer up to 154.6m. Further down, an aquifer comprising very fine sand and medium sand are likely. VES-6 The top soil is 1.2 m thick followed by a saline zone up to 33.8m. Below this, one brackish zone with some sand lenses occurs up to 148.5m underlain by an impermeable clay layer up to 234.8m. Further down, an aquifer comprising fine and medium sand are likely. VES-7 The top soil is 0.9 m thick followed by a saline zone up to 27.4m. Below this, one brackish zone with some sand lenses occurs up to 131.5 m underlain by an impermeable clay layer up to 199.3m. Further down, an aquifer comprising fine and medium sand are likely. VES-8 The top soil is 1.0 m thick followed by a saline zone up to 29.9m. Below this, one brackish zone with some sand lenses occurs up to 141.3 m underlain by an impermeable clay layer up to 240.4m. Further down, an aquifer comprising fine and medium sand are likely. VES-9 The top soil is 0.6 m thick followed by a saline zone up to 21.4m. Below this, one brackish zone with some sand lenses occurs up to 137.6 m underlain by a sandy clayey sand layer up to 238.5m. Further down, an aquifer comprising fine and medium sand are likely. VES-10 The top soil is 1.1 m thick followed by a saline zone up to 30.6m. Below this, one brackish zone with some sand lenses occurs up to 143.1m underlain by an impermeable clay layer up to 230.8m. Further down, an aquifer comprising very fine and medium sand are likely. VES-11 The top soil is 1.3 m thick followed by a saline zone up to 30.8m. Below this, one brackish zone with some sand lenses occurs up to 141.3m underlain by an impermeable clay layer up to 228.4m. Further down, an aquifer comprising fine and medium sand are likely. VES-12 The top soil is 1.1 m thick followed by a saline zone up to 27.6m. Below this, one brackish zone with some sand lenses occurs up to 128.5m underlain by an impermeable clay layer up to 235.5m. Further down, an aquifer comprising fine and medium sand are likely. VES-13 The top soil is 0.9 m thick followed by a saline zone up to 29.4m. Below this, one brackish zone with some sand lenses occurs up to 128.2m underlain by an impermeable clay layer up to 232.6m. Further down, an aquifer comprising fine and medium sand are likely. VES-14 The top soil is 1.0 m thick followed by a saline zone up to 28.7m. Below this, one brackish zone with some sand lenses occurs up to 124.3m underlain by an impermeable clay layer up to 231.2m. Further down, an aquifer comprising fine and medium sand are likely. VES-15 The top soil is 0.8 m thick followed by a saline zone up to 27.8m. Below this, one brackish zone with some sand lenses occurs up to 137.7m underlain by an impermeable clay layer up to 232.8m. Further down, an aquifer comprising fine and medium sand are likely. VES-16 The top soil is 0.8 m thick followed by a saline zone up to 27.8 m. Below this, one brackish zone with some sand lenses occurs up to 137.7m underlain by an impermeable clay layer up to 232.3m. Further down, an aquifer comprising fine and medium sand are likely. VES-17 The top soil is 0.9 m thick followed by a saline zone up to 27.9 m. Below this, one brackish zone with some sand lenses occurs up to 131m underlain by an impermeable clay layer up to 222m. Further down, an aquifer comprising fine and medium sand are likely. VES-18 The top soil is 1.6 m thick followed by a saline zone up to 26.6 m. Below this, one brackish zone with some sand lenses occurs up to 88.2m underlain by an impermeable clay layer up to 152.8m. Further down, an aquifer comprising very fine sand and medium sand are likely. VES-19 The top soil is 1.0 m thick followed by a saline zone up to 26.6 m. Below this, one brackish zone with some sand lenses occurs up to 134.5m underlain by an impermeable clay layer up to 199.7m. Further down, an aquifer comprising fine and medium sand are likely. VES-20 The top soil is 1.2 m thick followed by a saline zone up to 26.3 m. Below this, one brackish zone with some sand lenses occurs up to 118.5m underlain by an impermeable brackish clay layer up to 237.8m. Further down, an aquifer comprising medium sand is likely. VES-21 The top soil is 0.9m thick followed by a saline zone up to 28.0 m. Below this, one brackish zone with some sand lenses occurs up to 127.6m underlain by an impermeable clay layer up to 210.5m. Further down, an aquifer comprising fine and medium sand are likely. VES-22 The top soil is 0.8m thick followed by a saline zone up to 29.4 m. Below this, one brackish zone with some sand lenses occurs up to 139.2 m underlain by an impermeable clay layer up to 241.9m. Further down, an aquifer comprising fine and medium sand are likely. VES-23 The top soil is 0.9m thick followed by a saline zone up to 29.5m. Below this, one brackish zone with some sand lenses occurs up to 128.8m underlain by an impermeable clay layer up to 215.4m. Further down, an aquifer comprising fine and medium sand are likely. VES-24 The top soil is 1.3 m thick followed by a saline zone up to 25.5 m. Below this, one brackish zone with some sand lenses occurs up to 120m underlain by an impermeable clay layer up to 243.8m. Further down, an aquifer comprising medium sand is likely. VES-25 The top soil is 0.7 m thick followed by a saline zone up to 20.4 m. Below this, one brackish zone with some sand lenses occurs up to 136 m underlain by a very fine sand layer up to 236m. Further down, an aquifer comprising medium sand is likely. VES-26 The top soil is 1.0m thick followed by a saline zone up to 27.6 m. Below this, one brackish zone with some sand lenses occurs up to 122.6m underlain by an impermeable clay layer up to 241m. Further down, an aquifer comprising fine sand is inferred up to 284 m followed by medium sand. VES-27 The top soil is 1.3m thick followed by a saline zone up to 25.2m. Below this, one brackish zone with some sand lenses occurs up to 93.1 m underlain by an impermeable clay layer up to 158.5m. Further down, an aquifer comprising very fine and medium sand are likely. VES-28 The top soil is 1.2m thick followed by a saline zone up to 24.7m. Below this, one brackish zone with some sand lenses occurs up to 126.5m underlain by an impermeable clay layer up to 228.6m. Further down, an aquifer comprising fine and medium sand are likely. VES-29 The top soil is 1.0 m thick followed by a saline zone up to 24.7 m. Below this, one brackish zone with some sand lenses occurs up to 146.5 m underlain by an impermeable clay layer up to 242.6m. Further down, an aquifer comprising medium sand is likely. VES-30 The top soil is 1.0 m thick followed by a saline zone up to 26.8 m. Below this, one brackish zone with some sand lenses occurs up to 139.5 m underlain by an impermeable clay layer up to 233 m. Further down, an aquifer comprising fine and medium sand are likely. Dar-Zarrouk Parameters estimation for subsurface salty and freshwater zones To compute the secondary geophysical indicators, data from 30 VES stations are used (D-Z parameters, i.e. S and T, which is the combination of layer resistivity and thickness). To demarcate the saline water-fresh water bodies and to delineate the groundwater potential zones in the study region, spatial variation maps are created for longitudinal conductance (S), transverse resistance (T), and transverse resistivity, longitudinal resistivity, and anisotropy (λ). The above parameters' spatial variation maps are displayed in this work using the conventional kriging methodology in ArcGIS 10.4. Longitudinal Conductance (S) 30 sounding locations with a contour interval of 3 S are used to create a spatial variation map of longitudinal conductance (S) for the studied region. The S map (Fig. 4) shows how the cumulative thickness of low resistivity features increases from one location to the next, with values ranging from 61 to 100 S. The study region's S values of 61 to 64 are found in the north and lower eastern portion. The value 65 to 68 are found at VES 25, 28, and 30, but high S values ranging from 97 to 100S are found at VES stations 12, 14, and 24 in the southern half of the research region, indicating saline water incursion because presumably owing to fertilizer enrichment and human activity, which increases TDS and, in turn, increases electrical conductivity. The soil is said to operate as a natural filter for percolating fluid, and its ability to keep back fluid is a measure of its protective capability (de Almeida et al., 2021 ). Higher S values imply a relatively thick overburden sequence, which protects the underlying aquifer from pollution. Oladapo & Akintorinwa ( 2007 ), classified aquifer protective capacity zones as poor, weak, moderate, good, very good, and excellent. The longitudinal conductance map shows that 59 percent of the examined region has a low aquifer protection capacity rating. Roughly 7% of the region has an excellent protective capacity rating, while about 23% has a moderate protective capacity rating and the other 11% has a weak protective capacity rating. This signifies that a large portion of the study area has a low to moderate capacity rating, making it more susceptible to seeping pollutants. The zones with considerable clayey overburden, which are enough to protect the aquifer from pollution, correlate to areas with moderate to high aquifer protective capacity. Transverse Resistance (T) For 30 VES sites, a spatial variation map of transverse resistance (T) with a contour interval of 200 m 2 is created (Fig. 4). Increasing T values indicate that the thickness of the high resistivity materials is increasing. The T value ranges from 2391 m 2 at VES 14, 12, 11 and 26 to 3955 m 2 at VES 7 and 19. Low T values (2391 m 2 ) include multiple sounding stations in the south, south-east, and south-west regions of the research area. It's worth noting that the relatively low T values found at VES 11, 12, 14 and 26 correspond to a very high S value (97–100S), which is typical of salty water aquifers. Several locations in the research region are characterized by fairly high T values (3401–3600 m 2 ), indicating freshwater zones, as shown in Fig. 26. It is also found that the southern section of the research region has more promise than the northern part. The southern part of the study region has extremely high T values (> 3801 m 2 ). It's safe to assume that the boundary between salty and fresh water is distinct and that they don't mix. Transverse resistance values are frequently associated with zones of high transmissivity, making them extremely permeable to fluid flow. This suggests that when transverse resistance increases, the possible aquifer zones in the study region expand, which is most likely owing to changes in hydraulic conductivities and electrical anisotropy (Salem 1999 ). Average Transverse Resistivity ( \(\:\varvec{\rho\:}\) t ) and Average Longitudinal Resistivity (ρ l ) The transverse resistivity follows the same pattern as the spatial variation in the T map. The Transverse resistivity map (Fig. 5 ) has been divided into nine classes, ranging from 8.6 to 14.73 m. The range from 8.6 to 9.5 m has been seen southern- eastern, north-east and southeast of the area. The range from 10.01 to 12m has been seen mainly in the central and northern parts of the region. The range of 12.01 to 12.5 m has been found in the north western and southern parts of the study area. The range of 13.01 to 14.73 has been found in some pockets of the north western portion and some pockets of the southern portion of the Sagar Island. The longitudinal resistivity map (Fig. 5 ) has been divided into nine classes, ranging from 2.78 to 4.82 m. The range from 2.78 to 2.8m has been seen southern- to the centre of the area. The range from 3.01 to 3.6m has been seen in the northern-central, southern eastern, and western parts of the region. The range of 3.61 to 4 m has been found in the central and southern parts of the study area. The range of 4.01 to 4.82 has been found in the northern portion of the Island and some pockets of the southern portion of the Sagar Island. In the longitudinal resistivity values, similar tendencies may be seen. If the medium is heterogeneous, the transverse resistivity is frequently greater than the longitudinal resistivity (Flathe 1955 ); otherwise, the two quantities will be identical. This means that the current flow and average hydraulic conduction are stronger along the longitudinal border than they are normal to the boundary plane. Furthermore, Keller ( 1967 ) believed that the more conductive layers (in this example, clay, and weathered/fractured basalts) reduce longitudinal resistance, but transverse resistivity grows fast even if just a tiny percentage of resistive layers are present. Electrical Anisotropy (λ) The fracture of rocks and the orientation of the distributed grains in the rock are the major causes of variation in electrical anisotropy within the subsurface (Su & Yue, 2017 ). This parameter's value is between 1 and 2. If the value reaches 2.0, it is frequently due to high resistive intrusive bodies, which cause a resistivity unconformity, leading to very high coefficients of anisotropy (Isife & Obasi, 2012 ). 30 VES in the research region are used to calculate the spatial variation in anisotropy, with values ranging from 0.9 to 5.1 (Fig. 6). As rock hardness and compaction rise, so does the amount of water in them. The coefficient of anisotropy rises from SW to NE, as well as from SE to NW, in this example. Anisotropy has a crucial role in fracturing since it is not uniform in all directions. As a result, these parts are more fragmented, suggesting that a potential groundwater zone exists. In addition, various lineaments cross the research region, with the crossing locations of the lineaments serving as possible groundwater zones. Several portions of the study region in coastal rely substantially on local water supplies, including groundwater and local storage, based on the above. As a result, the availability and appropriateness of this resource are critical. It's also assumed that salty water intrusion is widespread in the western half of the research region, as evidenced by high longitudinal and electrical conductance values, contaminating the coastal freshwater aquifers. Improved water usage and management should be implemented to boost water supply dependability while reducing pollution impacts to conserve sustainability. This will improve ecosystem and water supply resilience to climate change impacts, protect aquifers from pollution, and promote groundwater recharge, and so on. Coastal conservation will benefit from these activities; as coastal agriculture is a significant source of revenue. Water quality may be impacted by unregulated agricultural water usage and excessive pumping of water from coastal aquifers, resulting in aquifer degradation and, as a result, impacting the health of the region's population. Hydraulic Conductivity and Transmissivity Hydraulic conductivity (K) is a measure of how ease a fluid can move through a porous media. Hydraulic conductivity and transmissivity can be estimated from VES data by using empirical correlations as Eq. 7, when pumping test data are not available (Sattar et al., 2016 ). K (m/day) = [(0.3712 * A) – 7.3727] ……………………………..(7) Where, A= Aquifer Total Resistivity Similarly, transmissivity can be obtained as, Transmissivity (m 2 /day) = Hydraulic conductivity X Aquifer Thickness 30 no. s VES locations data of hydraulic conductivity and transmissivity are appraised and tabulated in Table 3 for better visualization of aquifer characteristics of Sagar Island. Table 3 Calculated Coastal Aquifer Characteristics of Sagar Island VES No. Longitudinal Conductance (S) Transverse Resistance (T) Average Longitudinal Resistivity Average Transverse Resistivity Electrical Anisotropy Hydraulic Conductivity (K) (m/day) Transmissivity (m 2 /day) VES-1 83.046 3131.582 3.473 10.858 1.768 11.143 3213.571 VES-2 73.185 3686.76 3.972 12.682 1.787 9.517 2766.563 VES-3 63.167 3805.92 4.395 13.710 1.766 6.659 1848.444 VES-4 74.755 3605.96 3.855 12.512 1.802 9.406 2710.677 VES-5 63.167 3805.92 4.395 13.710 1.766 6.659 1848.444 VES-6 80.987 2667 3.568 9.228 1.608 8.515 2460.737 VES-7 70.789 3954.76 4.020 13.896 1.859 10.779 3067.698 VES-8 75.651 3224.5 3.873 11.005 1.686 12.264 3593.288 VES-9 73.032 3514.24 3.266 14.735 2.124 7.401 1765.153 VES-10 76.813 2588.37 3.652 9.228 1.590 8.478 2377.950 VES-11 76.299 2520.13 3.630 9.098 1.583 8.923 2471.665 VES-12 100.045 2504.93 2.781 9.004 1.799 10.482 2916.098 VES-13 72.867 3171.67 4.007 10.862 1.646 11.559 3375.082 VES-14 89.364 2390.29 3.020 8.856 1.712 10.475 2827.093 VES-15 71.736 3019.96 3.977 10.585 1.631 12.338 3520.037 VES-16 72.522 3270.13 3.999 11.276 1.679 12.301 3567.261 VES-17 79.374 3060.77 3.515 10.971 1.767 10.742 2996.979 VES-18 69.599 3754.34 4.138 13.036 1.775 5.619 1618.358 VES-19 74.907 3899.44 3.934 13.232 1.834 9.109 2684.299 VES-20 73.398 3220.45 3.969 11.055 1.669 12.709 3702.196 VES-21 75.198 3485.27 3.758 12.333 1.812 10.556 2983.199 VES-22 74.187 3153.51 3.993 10.647 1.633 12.449 3687.506 VES-23 82.930 3183.43 3.345 11.476 1.852 10.816 3000.386 VES-24 72.259 2929.82 3.975 10.201 1.602 13.266 3810.001 VES-25 66.493 3286.61 3.549 13.926 1.981 6.659 1571.444 VES-26 92.032 2461.96 3.086 8.669 1.676 9.628 2734.426 VES-27 65.647 3594.43 4.107 13.332 1.802 6.881 1855.220 VES-28 69.405 3260.6 4.083 11.505 1.679 12.561 3559.714 VES-29 60.996 3299.24 4.820 11.222 1.526 15.493 4555.007 VES-30 66.890 3077.86 4.276 10.762 1.586 13.823 3953.327 Conclusion The subsurface of the Sagar Island comprises of 5–6 major electrical resistivity layers whose values range from 0.3 Ohm-m to more than 50 Ohm-m. The lowest resistivity range 0.5 Ohm-m to 1.2 Ohm-m represents the saline zones. Resistivity of 1.5 Ohm-m to 6 Ohm-m generally indicates brackish water zones, whereas, the resistivity range 4Ohm-m to 7 Ohm-m is interpreted as brackish clay/clay. Fresh water aquifer in the investigated area comprising fine and medium sand is associated with a resistivity range of 28 Ohm-m to more than 50 Ohm-m. The higher the resistivity, the larger is the grain size and consequently more would be the yield of ground water. Resistivity survey indicates that all the major subsurface formations occur throughout the Island and are extensive. In general, 5 major subsurface formations are interpreted. These are the top highly unconsolidated (loose) sediments occurring up to 1m depth underlain by a saline water zone comprising clay, silt and some sand lenses continuing to a depth of 21m-34m. Below this, a brackish water zone with some clay and sand lenses occurs within the depth range 21m-150m, which is underlain by thick impermeable clay layer in the depth range 90m-242m. Further down, fresh water (potable) occurs within fine and medium sand layers. Large thickness of the saline zones in the subsurface across the length and breadth of the Island indicates that all the areas are susceptible to sea water ingression even when these are located far away from the coast line. This could be made easily possible if the present-day Sagar Island had consisted of a number of small Islands formed by tides and sedimentation in the marine environment and separated by creeks in the geological past. Subsequently with the narrowing of creeks, all the smaller Islands merged in to a bigger present-day Sagar Island. Declarations “All authors have read, understood, and have complied as applicable with the statement on "Ethical responsibilities of Authors" as found in the Instructions for Authors.” Competing Interests The authors declare that they have no conflict of interest to disclose. Funding Poulami Ray declares that the funds, grants, or other supports are received from the AICTE Doctoral Fellowship (ADF) Contingency fund (Beneficiary ID: BININ01594998) during the research and collection of data. Author Contributions All the authors have contributed to design the manuscript. Data collection and analysis has been done by Poulami Ray, Saurabh Kumar Basak and Sk Mohinuddin. The first draft of the manuscript has been written by Poulami Ray. Pankaj Kumar Roy and Malabika Biswas Roy have gone through the entire manuscript for necessary modification. The final manuscript is read, rectified and approved by Pankaj Kumar Roy. Acknowledgments Authors would like to express their sincere gratitude to the School of Water Resources Engineering, Jadavpur University, for providing the necessary facilities to carry out the present study. Data availability All data generated or analysed during this study are included within the manuscript. Code availability Not applicable References Adamo N, Al-Ansari N, Sissakian V, Laue J, Knutsson S (2021) Geophysical methods and their applications in dam safety monitoring. J Earth Sci Geotech Eng 11(1):291–345. https://doi.org/10.47260/jesge/1118 Akhter G, Ge Y, Hasan M, Shang Y (2022) Estimation of hydrogeological parameters by using pumping, laboratory data, surface resistivity and thiessen technique in lower bari doab (indus basin), Pakistan. Appl Sci 12(6):3055. https://doi.org/10.3390/app12063055 Bobachev AA, Gorbunov AA (2003) The stationary electric field in the air: application to low frequency non-contact (electrostatic) resistivity prospecting. 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Hydrol Earth Syst Sci 3(3):421–427. https://doi.org/10.5194/hess-3-421-1999 Sattar GS, Keramat M, Shahid S (2016) Deciphering transmissivity and hydraulic conductivity of the aquifer by vertical electrical sounding (VES) experiments in Northwest Bangladesh. Appl Water Sci 6:35–45. https://doi.org/10.1007/s13201-014-0203-9 Sen T, Paul AK (2023) An Assessment of the Changing Environmental Factors of Estuarine Tidal Flats in Sagar Island. In Crisis on the Coast and Hinterland: Assessing India’s East Coast with Geomorphological, Environmental and Remote Sensing and GIS Approaches (pp. 205–213). Cham: Springer Nature Switzerland . https://doi.org/10.1007/978-3-031-42231-7_15 Singh UK, Tiwari RK, Singh SB (2005) One-dimensional inversion of geo-electrical resistivity sounding data using artificial neural networks—a case study. 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J Clean Prod 284:124764. https://doi.org/10.1016/j.jclepro.2020.124764 Turner RK, Lorenzoni I, Beaumont N, Bateman IJ, Langford IH, McDonald AL (1998) Coastal management for sustainable development: analysing environmental and socio-economic changes on the UK coast. Geogr J 269–281. https://doi.org/10.2307/3060616 White PA (1994) Electrode arrays for measuring groundwater flow direction and velocity. Geophysics 59(2):192–201. https://doi.org/10.1190/1.1443581 AI, Disclosure The authors do not used generative AI and AI-assisted technologies in the writing process and authors are ultimately responsible and accountable for the contents of the work Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8858443","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":590059273,"identity":"50d2d096-3006-4548-b771-2a18c1be88eb","order_by":0,"name":"Poulami Ray","email":"","orcid":"https://orcid.org/0000-0002-9330-2205","institution":"Jadavpur University","correspondingAuthor":false,"prefix":"","firstName":"Poulami","middleName":"","lastName":"Ray","suffix":""},{"id":590059274,"identity":"d8fef6ae-11d9-4b72-b831-6269d9346fe6","order_by":1,"name":"Saurabh Kumar Basak","email":"","orcid":"","institution":"Jadavpur 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Map\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8858443/v1/4159b7e489b7e2f763d82095.png"},{"id":102559676,"identity":"1294b690-88ee-4c62-b8d8-8c2dbd0da8e7","added_by":"auto","created_at":"2026-02-13 03:40:20","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":27697,"visible":true,"origin":"","legend":"\u003cp\u003eSchlumberger Electrode Configuration\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8858443/v1/248b03722cb2caef0caad68c.png"},{"id":102559670,"identity":"7ebdc9c8-713c-4e30-a372-346eaaf38fc6","added_by":"auto","created_at":"2026-02-13 03:40:19","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":80317,"visible":true,"origin":"","legend":"\u003cp\u003eLocation Map of the Resistivity Survey (VES) Points\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8858443/v1/ddc11b0c503e847e38fd3c81.jpg"},{"id":102559674,"identity":"10732df9-8dd7-43a5-95b0-9acbaad0b04a","added_by":"auto","created_at":"2026-02-13 03:40:20","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2081820,"visible":true,"origin":"","legend":"\u003cp\u003eMap showing the spatial distribution of\u003cstrong\u003e \u003c/strong\u003eLongitudinal Conductance and Transverse Resistance Map\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8858443/v1/42c919b71398ec1f1bc65139.png"},{"id":102559675,"identity":"a069b89b-7f5e-47ac-89d3-24bfe9a5d83a","added_by":"auto","created_at":"2026-02-13 03:40:20","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":2182028,"visible":true,"origin":"","legend":"\u003cp\u003eMap showing the spatial distribution of Average Transverse Resistivity and Average Longitudinal Resistivity\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8858443/v1/4957a703a03e476eb89f474d.png"},{"id":102559673,"identity":"1d4a9a52-9bbd-4188-9f00-aef3293701a0","added_by":"auto","created_at":"2026-02-13 03:40:20","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":113398,"visible":true,"origin":"","legend":"\u003cp\u003eMap showing the spatial distribution of Electrical Anisotropy Coefficient\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8858443/v1/937576429b5733354cfd47a1.jpg"},{"id":102559672,"identity":"3a1fc9c3-4289-4e8d-8387-47510debc3b2","added_by":"auto","created_at":"2026-02-13 03:40:20","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":2201885,"visible":true,"origin":"","legend":"\u003cp\u003eMap showing the spatial distribution of Hydraulic Conductivity and Transmissivity\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8858443/v1/21f00863ae1c28104b1ec7f0.png"},{"id":102747157,"identity":"41dba589-2152-44eb-b191-d0586be2f85a","added_by":"auto","created_at":"2026-02-16 09:04:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":9089152,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8858443/v1/90a79c2a-f6c3-445b-8bef-10fe20534667.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eAssessment of Sub-surface Hydrogeology of Coastal Aquifer\u003c/strong\u003e \u003cstrong\u003eusing Geophysical Technique in Sagar Island, West Bengal\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAn assortment of coastal risks such as rising sea levels and its associated consequences are present in coastal zones (Richardson et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). They also show greater rates of urbanisation and population increase and are more densely populated than the hinterland. Humans have long been drawn to coastal areas for a variety of reasons including their abundance of resources, especially those needed for subsistence, logistical advantages such as providing access to aquatic commerce and transportation, recreational or cultural pursuits, or just a unique sense of location at the meeting point of land and sea. Coasts are experiencing significant socio-economic and environmental changes and the development and use of coastal zones has significantly grown in recent decades (Turner et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1998\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe rapid increase in population at Sagar Island, coupled with growing rate of pilgrims at Kapil Muni Ashram have emerged the needs of groundwater for drinking purposes (Das, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Domains of important land usage are impacted and the freshwater supply is restricted in coastal plain regions due to environmental salinization. The existence of saline soils significantly restricts many activities including agriculture. As a result of population over burst, the demand for portable water is increasing day by day and for this reason there is a need to have optimal utilization of water resources. To determine the sub-surface geology and hydraulic characteristics of aquifer, pumping test is one of the most satisfactory practice (Ekwe et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Akhter et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). But it is quite expensive process and therefore seldom 72 hours pumping test is accomplished in practice. Surface geoelectric measurements provide a trailblazing approach for the estimation of aquifer attributions. Henceforth, we have employed 30 no. s vertical electrical sounding survey at different locations Sagar Island. From the data from geophysical survey, the thickness of sub-surface layers is interpreted and also the aquifer characteristics such as hydraulic conductivity and transmissivity are also calculated (Mohasin et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). These aquifer parameters are necessary for the management of groundwater resources (Soupios et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). Dar-Zarrouk parameters are estimated such as longitudinal conductance, transverse resistance, average longitudinal resistivity, average transverse resistivity, coefficient of anisotropy and aquifer characteristics like hydraulic conductivity and transmissivity are also determine to understand the complete groundwater and saline water zonation of this study area.\u003c/p\u003e"},{"header":"2. Study Area","content":"\u003cp\u003eSagar Island (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003e) is the largest continental mass in the Ganga Delta [21\u0026deg; 37\u0026rsquo; N to 21\u0026deg; 52\u0026rsquo; N, 88\u0026deg; 02\u0026rsquo; 35\u0026Prime; E to 88\u0026deg; 11\u0026rsquo; E], lying in the N-S direction (approximately 30 km length) and has varying width in E-W direction with 12km in the southern portion of this Island. It is surrounded in the north, west, east and south by the Hooghly, Gabtala, Muriganga rivers and Bay of Bengal respectively (Sen \u0026amp; Paul, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Sagar Island has a flat terrain having an elevation of about 4 m from mean sea level (Thakur et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The Island is having an area of 235 km\u003csup\u003e2\u003c/sup\u003e, comprises of 46 villages and the holy Kapil Muni Temple. Furthermore, Gangasagar has been designated by the Government as a tourism centre. Potable groundwater in the deeper aquifers are found under confined condition and is drawn using tube-wells fitted with hand pump. Dug-wells in this region extract saline water. The Island is entirely dependent on ground water for its drinking requirements.\u003c/p\u003e \u003cp\u003eThe average temperature on the Island is around 27 degrees Celsius. After the winter season (20\u003csup\u003eo\u003c/sup\u003eC to 23\u003csup\u003eo\u003c/sup\u003eC), the temperature progressively climbs, becoming unbearably hot throughout the summer months (27\u003csup\u003eo\u003c/sup\u003eC to 30\u003csup\u003eo\u003c/sup\u003eC). It steadily lowers at the arrival of monsoon and remains within the range of 28\u003csup\u003eo\u003c/sup\u003eC to 29\u003csup\u003eo\u003c/sup\u003eC for four monsoon months before gradually rising with the monsoon's retreat. This Island receives an average of 1700 mm of rain per year.\u003c/p\u003e \u003cp\u003eSagar Island is located at the southernmost portion of the world's biggest alluvial tract, the Indo-Gangetic Plain. The Ganga River and its tributaries have deposited quaternary alluvial fill on this plain. Here, Tertiary layers (upper Cretaceous to Pleistocene) lie beneath Quaternary sediments, suggesting a buildup in a tectonic depression that is sinking. Both deltaic and flood plain deposits make up the Bengal Plain's Quaternary sediments. The high tide zone on this tidal-dominated deltaic island is between 5 and 6 meters. This island's coastal characteristics include mudflats, mangrove swamps, tidal flats, sand dunes or ridges, marine terraces, tidal inlets, and coastal marshes (Paul \u0026amp; Bandyopadhyay, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1987\u003c/span\u003e).\u003c/p\u003e"},{"header":"3. Materials and Methodology","content":"\u003cp\u003e \u003cb\u003eDetermination of Electrical Resistivity of Subsurface Materials at Varying Depths\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe resistivity method has been extensively used for geotechnical investigation, to infer hydrological characteristics, saline water intrusion, geological and geothermal investigation purposes (Mansourian et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Adamo et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Gallas, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Schlumberger sounding array (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e) is utilized in this study to to identify the aquifer zones and to determine the subsurface formations of Sagar Island by detecting the vertical change of resistivity along depth. All four electrodes are maintained in a single line using this technique. Two exterior current electrodes send current into the ground, and two interior electrodes made of carbon pots assess the potential difference that results from this. Then the resistance of the ground is measured for various sets of electrode spacing while the current electrode spacing is progressively raised. The measured resistance relates to the resistivity of the deeper bodies, and current penetrates deeper as the distance between the current electrodes increases. Corresponding to each spacing of electrodes, apparent resistivity is calculated at the centre of the spread using the following equation as Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e,\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:{\\rho\\:}_{a}=\\pi\\:\\left[\\frac{{\\left(\\frac{AB}{2}\\right)}^{2}-{\\left(\\frac{MN}{2}\\right)}^{2}}{MN}\\right]R$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;.\u003c/p\u003e \u003cp\u003eWhere,\u003c/p\u003e \u003cp\u003eAB= Distance between the current electrodes\u003c/p\u003e \u003cp\u003eMN= Distance between potential electrodes\u003c/p\u003e \u003cp\u003eR= Resistance\u003c/p\u003e \u003cp\u003eResistivity meter Aquameter CRM 500 manufactured by M/s ANVIS SYSTEMS is deployed to measure the resistance of the ground. Here, AB is the distance between the current electrodes (C1 and C2) and MN is the distance between potential electrodes (P1 and P2). Thus, the data for a sounding curve is generated for each sounding point or sounding location. These data of apparent resistivity vs. half the current electrode separation have been plotted on a Log-Log scale of 62.5mm modulus. These curves are initially interpreted by curve matching technique with a set of master curves of Orellena and Mooney and finally by 1-D software RESIST and/or IPI2WIN. The interpreted parameters, thus acquired are the resistivity and thickness of each subsurface layer up to the depth of investigation. Finally, the aquifer zone and geological formations are used to explain these resistivity values of the strata. Interpreted parameters viz. resistivity and thickness of different subsurface layers are described in this chapter. All the interpretations have been carried out subject to the usual assumptions and limitations of the resistivity method.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eEstimation Dar-Zarrouk Parameters for Subsurface Saline and Freshwater Zones\u003c/b\u003e \u003c/p\u003e \u003cp\u003eTwo pairs of electrodes are used to measure resistivity in the resistivity method: one pair of current electrodes transmits current into the ground, while the other pair monitors the potential difference between two potential electrodes. A total of 30 vertical electrical soundings (VES) are performed utilising the Schlumberger electrode array with AB\u0026thinsp;=\u0026thinsp;300 m spacing in the current investigation and geographic coordinates of the VES surveying locations are also marked using Geographical Positioning System (GPS) (GRAMIN GPS MODEL ETREX 20X CG). Also, a map of VES sounding points is prepared (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). An SSRMP-ATS resistivity metre provided by IGIS, Hyderabad, is used to conduct the research. The current electrode is symmetrically raised while the potential electrode is fixed at its starting interval in the Schlumberger arrangement until the resistance measured becomes too tiny (White, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1994\u003c/span\u003e). The criterion AB/2\u0026thinsp;\u0026ge;\u0026thinsp;5(MN/2) is met at all times. The sounding curves are generated by plotting the apparent resistivity against the matching half electrode spacing (AB/2) on a bi-logarithm graph. The sounding curves are analysed using the IPI2WIN programme, which is a computer-assisted 1-D forward modelling approach (Bobachev \u0026amp; Gorbunov, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). The geo-electrical parameters (layer resistivity and layer thickness) are calculated using VES field data displayed on a double log graph sheet with apparent resistivity vs. electrode spacing, indicating a 3\u0026ndash;5 layered structure in the research region. There are a number of analytical techniques for interpreting resistivity data that are commonly utilised in exploratory research. However, resolution is sometimes hindered and the stigma of ambiguity is prevalent due to certain geophysical similarities in the behaviour of different subsurface layers. Other geophysical indices other than the primary elements (resistivity and thickness) are required to overcome uncertainty in resistivity data interpretation in order to provide additional, more practical, and confident support that can lead to reliable solutions, both in terms of interpreting and understanding the geoelectric model. In the model, these characteristics are linked to various combinations of layer thickness and layer resistivity (Mooney et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1966\u003c/span\u003e; Singh et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). In electrical resistivity soundings, Dar-Zarrouk (D-Z) characteristics (also known as secondary geophysical indicators) play a critical role, as defined by Maillet (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1947\u003c/span\u003e). The D-Z parameters (transverse resistance and longitudinal conductance) are sufficient for estimating surface potential distributions and, as a result, electrical resistivity charts (Henriet \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1976\u003c/span\u003e). Several researchers have looked at the importance of D-Z factors in determining aquifer hydrological characteristics (Naidu et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The subsurface salty and freshwater zones in the research region are delineated using these indicators. To further evaluate the data, the D-Z parameters such as longitudinal conductance(S) and (T) are determined using the following equations Eq.\u0026nbsp;2 and Eq.\u0026nbsp;3.\u003c/p\u003e \u003cp\u003eThe D-Z parameters are defined as,\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:S=\\frac{{h}_{1}}{{p}_{1}}+\\frac{{h}_{2}}{{p}_{2}}+\\frac{{h}_{3}}{{p}_{3}}+\\dots\\:\\frac{{h}_{n}}{{p}_{n}}=\\:\\sum\\:_{i}^{n}\\frac{{h}_{i}}{{p}_{i}}\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;2)\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:T={p}_{1}{h}_{1}+{p}_{2}{h}_{2}+{p}_{3}{h}_{3}+\\dots\\:{+p}_{n}{h}_{n}=\\sum\\:_{i}^{n}{p}_{n}{h}_{n}\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;3)\u003c/p\u003e \u003cp\u003eThe transverse resistivity (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{p}_{t}\\)\u003c/span\u003e\u003c/span\u003e), longitudinal resistivity (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{p}_{l}\\)\u003c/span\u003e\u003c/span\u003e), and electrical anisotropy coefficient (λ) have also been calculated from S and T as Eq.\u0026nbsp;4\u0026ndash;6,\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:{p}_{t}=\\frac{H}{S}\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;4)\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:{p}_{t}=\\frac{T}{H}\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;5)\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:⋋=\\sqrt{\\frac{{p}_{t}}{{p}_{l}}}\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;6)\u003c/p\u003e \u003cp\u003e Where, H= \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\sum\\:_{i=1}^{n}{h}_{i}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eData Analysis and Interpretation\u003c/b\u003e \u003c/p\u003e \u003cp\u003eVertical Electrical Soundings (VES) have been conducted at 30 locations in the study area to delineate the various lithological units, to evaluate groundwater conditions and to identify the aquifer zones. The obtained resistivity data is analysed and based on the known geology of the area, our past experience and present VES investigation, correlation has been made between the various lithological units including ground water zone and the true resistivity values interpreted in the area. These are generally as Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e,\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\u003eSubsurface Formation Analysis from Obtained Resistivity Data\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResistivity (Ohm-m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\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\u003e40\u0026ndash;80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSaturated Medium/coarse Sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e28\u0026ndash;40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSaturated Fine Sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u0026ndash;28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSandy clay, clayey sand, very fine sand\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u0026ndash;7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eClay\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1.5-4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBrackish Zone\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSaline Zone\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 above resistivity values are considered as a general guide line only.\u003c/p\u003e"},{"header":"4. Results and Discussion:","content":"\u003cp\u003eDetails of Interpreted Vertical Electrical Soundings (VES) are given in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInterpreted VES Parameters \u0026ndash; Sagar Island\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"12\"\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=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES No.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eρ\u003csub\u003e1\u003c/sub\u003e (Ohm-m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ed\u003csub\u003e1\u003c/sub\u003e (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eρ\u003csub\u003e2\u003c/sub\u003e (Ohm-m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ed\u003csub\u003e2\u003c/sub\u003e (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eρ\u003csub\u003e3\u003c/sub\u003e (Ohm-m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ed\u003csub\u003e3\u003c/sub\u003e (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eρ\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(Ohm-m)\u003c/p\u003e\u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003ed\u003csub\u003e4\u003c/sub\u003e (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eρ\u003csub\u003e5\u003c/sub\u003e (Ohm-m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003ed\u003csub\u003e5\u003c/sub\u003e (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eρ\u003csub\u003e6\u003c/sub\u003e (Ohm-m)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e30.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e139.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e231.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e288.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e28.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e131.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e205.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e32.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e290.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e48.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e90.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e154.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e26.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e277.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e44\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e128.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e204.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e32.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e288.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e47\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e90.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e154.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e26.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e277.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e44\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e33.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e148.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e234.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e289.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e131.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e199.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e34.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e284.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e47\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e141.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e240.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e293\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e21.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e137.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e238.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e30.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e143.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e230.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e26.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e280.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e30.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e141.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e228.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e29.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e277.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e128.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e235.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e35.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e278.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e128.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e232.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e292\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e28.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e124.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e231.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e35.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e269.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e137.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e232.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e285.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e28.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e141.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e236.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e290\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e131\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e222\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e279\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e88.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e152.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e23.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e288\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e134.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e199.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e31.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e294.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e118.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e237.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e40.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e291.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e28.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e127.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e210.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e282.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e139.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e241.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e296.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e128.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e215.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e277.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e53\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e243.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e41.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e287.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e20.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e136.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e236\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e122.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e241\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e284\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e93.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e158.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e27.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e269.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e44\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e126.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e228.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e39.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e283.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e146.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e242.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e40.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e294\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e139.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e233.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e37.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e286\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e55\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\u003eWhere,\u003c/p\u003e \u003cp\u003eρ\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;\u0026gt;\u0026thinsp;Resistivity of first layer d\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;\u0026gt;\u0026thinsp;Lower Depth of first layer\u003c/p\u003e \u003cp\u003eρ\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;\u0026gt;\u0026thinsp;Resistivity of second layer d\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;\u0026gt;\u0026thinsp;Lower depth of second layer and so on\u003c/p\u003e \u003cp\u003eFrom the interpreted VES data, it is observed as,\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-1\u003c/strong\u003e \u003cp\u003eThe top soil is 0.9 m thick followed by a saline zone up to 30.5m. Below this, one brackish zone with some sand lenses occurs up to 139. 4m underlain by an impermeable clay layer up to 231.8m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-2\u003c/strong\u003e \u003cp\u003eThe top soil is 1.0 m thick followed by a saline zone up to 28.3 m. Below this, one brackish zone with some sand lenses occurs up to 131.5m underlain by an impermeable brackish clay layer up to 205.6m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-3\u003c/strong\u003e \u003cp\u003eThe top soil is 1.6 m thick followed by a saline zone up to 23.6m. Below this, one brackish zone with some sand lenses occurs up to 90.6 m underlain by an impermeable clay layer up to 154.6m. Further down, clayey sand/very fine sand followed by medium sand (from 277 m) is likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-4\u003c/strong\u003e \u003cp\u003eThe top soil is 1.1 m thick followed by a saline zone up to 29.5m. Below this, one brackish zone with some sand lenses occurs up to 128.5 m underlain by an impermeable clay layer up to 204.4m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-5\u003c/strong\u003e \u003cp\u003eThe top soil is 1.6 m thick followed by a saline zone up to 23.6m. Below this, one brackish zone with some sand lenses occurs up to 90.6 m underlain by an impermeable clay layer up to 154.6m. Further down, an aquifer comprising very fine sand and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-6\u003c/strong\u003e \u003cp\u003eThe top soil is 1.2 m thick followed by a saline zone up to 33.8m. Below this, one brackish zone with some sand lenses occurs up to 148.5m underlain by an impermeable clay layer up to 234.8m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-7\u003c/strong\u003e \u003cp\u003eThe top soil is 0.9 m thick followed by a saline zone up to 27.4m. Below this, one brackish zone with some sand lenses occurs up to 131.5 m underlain by an impermeable clay layer up to 199.3m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-8\u003c/strong\u003e \u003cp\u003eThe top soil is 1.0 m thick followed by a saline zone up to 29.9m. Below this, one brackish zone with some sand lenses occurs up to 141.3 m underlain by an impermeable clay layer up to 240.4m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-9\u003c/strong\u003e \u003cp\u003eThe top soil is 0.6 m thick followed by a saline zone up to 21.4m. Below this, one brackish zone with some sand lenses occurs up to 137.6 m underlain by a sandy clayey sand layer up to 238.5m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-10\u003c/strong\u003e \u003cp\u003eThe top soil is 1.1 m thick followed by a saline zone up to 30.6m. Below this, one brackish zone with some sand lenses occurs up to 143.1m underlain by an impermeable clay layer up to 230.8m. Further down, an aquifer comprising very fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-11\u003c/strong\u003e \u003cp\u003eThe top soil is 1.3 m thick followed by a saline zone up to 30.8m. Below this, one brackish zone with some sand lenses occurs up to 141.3m underlain by an impermeable clay layer up to 228.4m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-12\u003c/strong\u003e \u003cp\u003eThe top soil is 1.1 m thick followed by a saline zone up to 27.6m. Below this, one brackish zone with some sand lenses occurs up to 128.5m underlain by an impermeable clay layer up to 235.5m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-13\u003c/strong\u003e \u003cp\u003eThe top soil is 0.9 m thick followed by a saline zone up to 29.4m. Below this, one brackish zone with some sand lenses occurs up to 128.2m underlain by an impermeable clay layer up to 232.6m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-14\u003c/strong\u003e \u003cp\u003eThe top soil is 1.0 m thick followed by a saline zone up to 28.7m. Below this, one brackish zone with some sand lenses occurs up to 124.3m underlain by an impermeable clay layer up to 231.2m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-15\u003c/strong\u003e \u003cp\u003eThe top soil is 0.8 m thick followed by a saline zone up to 27.8m. Below this, one brackish zone with some sand lenses occurs up to 137.7m underlain by an impermeable clay layer up to 232.8m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-16\u003c/strong\u003e \u003cp\u003eThe top soil is 0.8 m thick followed by a saline zone up to 27.8 m. Below this, one brackish zone with some sand lenses occurs up to 137.7m underlain by an impermeable clay layer up to 232.3m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-17\u003c/strong\u003e \u003cp\u003eThe top soil is 0.9 m thick followed by a saline zone up to 27.9 m. Below this, one brackish zone with some sand lenses occurs up to 131m underlain by an impermeable clay layer up to 222m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-18\u003c/strong\u003e \u003cp\u003eThe top soil is 1.6 m thick followed by a saline zone up to 26.6 m. Below this, one brackish zone with some sand lenses occurs up to 88.2m underlain by an impermeable clay layer up to 152.8m. Further down, an aquifer comprising very fine sand and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-19\u003c/strong\u003e \u003cp\u003eThe top soil is 1.0 m thick followed by a saline zone up to 26.6 m. Below this, one brackish zone with some sand lenses occurs up to 134.5m underlain by an impermeable clay layer up to 199.7m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-20\u003c/strong\u003e \u003cp\u003eThe top soil is 1.2 m thick followed by a saline zone up to 26.3 m. Below this, one brackish zone with some sand lenses occurs up to 118.5m underlain by an impermeable brackish clay layer up to 237.8m. Further down, an aquifer comprising medium sand is likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-21\u003c/strong\u003e \u003cp\u003eThe top soil is 0.9m thick followed by a saline zone up to 28.0 m. Below this, one brackish zone with some sand lenses occurs up to 127.6m underlain by an impermeable clay layer up to 210.5m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-22\u003c/strong\u003e \u003cp\u003eThe top soil is 0.8m thick followed by a saline zone up to 29.4 m. Below this, one brackish zone with some sand lenses occurs up to 139.2 m underlain by an impermeable clay layer up to 241.9m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-23\u003c/strong\u003e \u003cp\u003eThe top soil is 0.9m thick followed by a saline zone up to 29.5m. Below this, one brackish zone with some sand lenses occurs up to 128.8m underlain by an impermeable clay layer up to 215.4m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-24\u003c/strong\u003e \u003cp\u003eThe top soil is 1.3 m thick followed by a saline zone up to 25.5 m. Below this, one brackish zone with some sand lenses occurs up to 120m underlain by an impermeable clay layer up to 243.8m. Further down, an aquifer comprising medium sand is likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-25\u003c/strong\u003e \u003cp\u003eThe top soil is 0.7 m thick followed by a saline zone up to 20.4 m. Below this, one brackish zone with some sand lenses occurs up to 136 m underlain by a very fine sand layer up to 236m. Further down, an aquifer comprising medium sand is likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-26\u003c/strong\u003e \u003cp\u003eThe top soil is 1.0m thick followed by a saline zone up to 27.6 m. Below this, one brackish zone with some sand lenses occurs up to 122.6m underlain by an impermeable clay layer up to 241m. Further down, an aquifer comprising fine sand is inferred up to 284 m followed by medium sand.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-27\u003c/strong\u003e \u003cp\u003eThe top soil is 1.3m thick followed by a saline zone up to 25.2m. Below this, one brackish zone with some sand lenses occurs up to 93.1 m underlain by an impermeable clay layer up to 158.5m. Further down, an aquifer comprising very fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-28\u003c/strong\u003e \u003cp\u003eThe top soil is 1.2m thick followed by a saline zone up to 24.7m. Below this, one brackish zone with some sand lenses occurs up to 126.5m underlain by an impermeable clay layer up to 228.6m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-29\u003c/strong\u003e \u003cp\u003eThe top soil is 1.0 m thick followed by a saline zone up to 24.7 m. Below this, one brackish zone with some sand lenses occurs up to 146.5 m underlain by an impermeable clay layer up to 242.6m. Further down, an aquifer comprising medium sand is likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eVES-30\u003c/strong\u003e \u003cp\u003eThe top soil is 1.0 m thick followed by a saline zone up to 26.8 m. Below this, one brackish zone with some sand lenses occurs up to 139.5 m underlain by an impermeable clay layer up to 233 m. Further down, an aquifer comprising fine and medium sand are likely.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eDar-Zarrouk Parameters estimation for subsurface salty and freshwater zones\u003c/b\u003e \u003c/p\u003e \u003cp\u003eTo compute the secondary geophysical indicators, data from 30 VES stations are used (D-Z parameters, i.e. S and T, which is the combination of layer resistivity and thickness). To demarcate the saline water-fresh water bodies and to delineate the groundwater potential zones in the study region, spatial variation maps are created for longitudinal conductance (S), transverse resistance (T), and transverse resistivity, longitudinal resistivity, and anisotropy (λ). The above parameters' spatial variation maps are displayed in this work using the conventional kriging methodology in ArcGIS 10.4.\u003c/p\u003e \u003cp\u003e \u003cb\u003eLongitudinal Conductance (S)\u003c/b\u003e \u003c/p\u003e \u003cp\u003e30 sounding locations with a contour interval of 3 S are used to create a spatial variation map of longitudinal conductance (S) for the studied region. The S map (Fig.\u0026nbsp;4) shows how the cumulative thickness of low resistivity features increases from one location to the next, with values ranging from 61 to 100 S. The study region's S values of 61 to 64 are found in the north and lower eastern portion. The value 65 to 68 are found at VES 25, 28, and 30, but high S values ranging from 97 to 100S are found at VES stations 12, 14, and 24 in the southern half of the research region, indicating saline water incursion because presumably owing to fertilizer enrichment and human activity, which increases TDS and, in turn, increases electrical conductivity.\u003c/p\u003e \u003cp\u003eThe soil is said to operate as a natural filter for percolating fluid, and its ability to keep back fluid is a measure of its protective capability (de Almeida et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Higher S values imply a relatively thick overburden sequence, which protects the underlying aquifer from pollution. Oladapo \u0026amp; Akintorinwa (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2007\u003c/span\u003e), classified aquifer protective capacity zones as poor, weak, moderate, good, very good, and excellent. The longitudinal conductance map shows that 59 percent of the examined region has a low aquifer protection capacity rating. Roughly 7% of the region has an excellent protective capacity rating, while about 23% has a moderate protective capacity rating and the other 11% has a weak protective capacity rating. This signifies that a large portion of the study area has a low to moderate capacity rating, making it more susceptible to seeping pollutants. The zones with considerable clayey overburden, which are enough to protect the aquifer from pollution, correlate to areas with moderate to high aquifer protective capacity.\u003c/p\u003e \u003cp\u003e \u003cb\u003eTransverse Resistance (T)\u003c/b\u003e \u003c/p\u003e \u003cp\u003eFor 30 VES sites, a spatial variation map of transverse resistance (T) with a contour interval of 200 m\u003csup\u003e2\u003c/sup\u003e is created (Fig.\u0026nbsp;4). Increasing T values indicate that the thickness of the high resistivity materials is increasing. The T value ranges from 2391 m\u003csup\u003e2\u003c/sup\u003e at VES 14, 12, 11 and 26 to 3955 m\u003csup\u003e2\u003c/sup\u003e at VES 7 and 19. Low T values (2391 m\u003csup\u003e2\u003c/sup\u003e) include multiple sounding stations in the south, south-east, and south-west regions of the research area. It's worth noting that the relatively low T values found at VES 11, 12, 14 and 26 correspond to a very high S value (97\u0026ndash;100S), which is typical of salty water aquifers. Several locations in the research region are characterized by fairly high T values (3401\u0026ndash;3600 m\u003csup\u003e2\u003c/sup\u003e), indicating freshwater zones, as shown in Fig.\u0026nbsp;26. It is also found that the southern section of the research region has more promise than the northern part. The southern part of the study region has extremely high T values (\u0026gt;\u0026thinsp;3801 m\u003csup\u003e2\u003c/sup\u003e). It's safe to assume that the boundary between salty and fresh water is distinct and that they don't mix.\u003c/p\u003e \u003cp\u003eTransverse resistance values are frequently associated with zones of high transmissivity, making them extremely permeable to fluid flow. This suggests that when transverse resistance increases, the possible aquifer zones in the study region expand, which is most likely owing to changes in hydraulic conductivities and electrical anisotropy (Salem \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1999\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cb\u003eAverage Transverse Resistivity (\u003c/b\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:\\varvec{\\rho\\:}\\)\u003c/span\u003e \u003c/span\u003e \u003csub\u003e \u003cb\u003et\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e) and Average Longitudinal Resistivity (ρ\u003c/b\u003e \u003csub\u003e \u003cb\u003el\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e)\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe transverse resistivity follows the same pattern as the spatial variation in the T map. The Transverse resistivity map (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e5\u003c/span\u003e) has been divided into nine classes, ranging from 8.6 to 14.73 m. The range from 8.6 to 9.5 m has been seen southern- eastern, north-east and southeast of the area. The range from 10.01 to 12m has been seen mainly in the central and northern parts of the region. The range of 12.01 to 12.5 m has been found in the north western and southern parts of the study area. The range of 13.01 to 14.73 has been found in some pockets of the north western portion and some pockets of the southern portion of the Sagar Island.\u003c/p\u003e \u003cp\u003eThe longitudinal resistivity map (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e5\u003c/span\u003e) has been divided into nine classes, ranging from 2.78 to 4.82 m. The range from 2.78 to 2.8m has been seen southern- to the centre of the area. The range from 3.01 to 3.6m has been seen in the northern-central, southern eastern, and western parts of the region. The range of 3.61 to 4 m has been found in the central and southern parts of the study area. The range of 4.01 to 4.82 has been found in the northern portion of the Island and some pockets of the southern portion of the Sagar Island. In the longitudinal resistivity values, similar tendencies may be seen. If the medium is heterogeneous, the transverse resistivity is frequently greater than the longitudinal resistivity (Flathe \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e1955\u003c/span\u003e); otherwise, the two quantities will be identical. This means that the current flow and average hydraulic conduction are stronger along the longitudinal border than they are normal to the boundary plane. Furthermore, Keller (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1967\u003c/span\u003e) believed that the more conductive layers (in this example, clay, and weathered/fractured basalts) reduce longitudinal resistance, but transverse resistivity grows fast even if just a tiny percentage of resistive layers are present.\u003c/p\u003e \u003cp\u003e \u003cb\u003eElectrical Anisotropy (λ)\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe fracture of rocks and the orientation of the distributed grains in the rock are the major causes of variation in electrical anisotropy within the subsurface (Su \u0026amp; Yue, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). This parameter's value is between 1 and 2. If the value reaches 2.0, it is frequently due to high resistive intrusive bodies, which cause a resistivity unconformity, leading to very high coefficients of anisotropy (Isife \u0026amp; Obasi, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). 30 VES in the research region are used to calculate the spatial variation in anisotropy, with values ranging from 0.9 to 5.1 (Fig.\u0026nbsp;6). As rock hardness and compaction rise, so does the amount of water in them. The coefficient of anisotropy rises from SW to NE, as well as from SE to NW, in this example. Anisotropy has a crucial role in fracturing since it is not uniform in all directions. As a result, these parts are more fragmented, suggesting that a potential groundwater zone exists. In addition, various lineaments cross the research region, with the crossing locations of the lineaments serving as possible groundwater zones. Several portions of the study region in coastal rely substantially on local water supplies, including groundwater and local storage, based on the above. As a result, the availability and appropriateness of this resource are critical. It's also assumed that salty water intrusion is widespread in the western half of the research region, as evidenced by high longitudinal and electrical conductance values, contaminating the coastal freshwater aquifers. Improved water usage and management should be implemented to boost water supply dependability while reducing pollution impacts to conserve sustainability. This will improve ecosystem and water supply resilience to climate change impacts, protect aquifers from pollution, and promote groundwater recharge, and so on. Coastal conservation will benefit from these activities; as coastal agriculture is a significant source of revenue. Water quality may be impacted by unregulated agricultural water usage and excessive pumping of water from coastal aquifers, resulting in aquifer degradation and, as a result, impacting the health of the region's population.\u003c/p\u003e \u003cp\u003e \u003cb\u003eHydraulic Conductivity and Transmissivity\u003c/b\u003e \u003c/p\u003e \u003cp\u003eHydraulic conductivity (K) is a measure of how ease a fluid can move through a porous media. Hydraulic conductivity and transmissivity can be estimated from VES data by using empirical correlations as Eq.\u0026nbsp;7, when pumping test data are not available (Sattar et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eK (m/day) = [(0.3712 * A) \u0026ndash; 7.3727] \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;..(7)\u003c/p\u003e \u003cp\u003eWhere, A= Aquifer Total Resistivity\u003c/p\u003e \u003cp\u003eSimilarly, transmissivity can be obtained as,\u003c/p\u003e \u003cp\u003eTransmissivity (m\u003csup\u003e2\u003c/sup\u003e/day) = Hydraulic conductivity X Aquifer Thickness\u003c/p\u003e \u003cp\u003e30 no. s VES locations data of hydraulic conductivity and transmissivity are appraised and tabulated in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e for better visualization of aquifer characteristics of Sagar Island.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCalculated Coastal Aquifer Characteristics of Sagar Island\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=\"left\" 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=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES\u003c/p\u003e \u003cp\u003eNo.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLongitudinal\u003c/p\u003e \u003cp\u003eConductance\u003c/p\u003e \u003cp\u003e(S)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTransverse\u003c/p\u003e \u003cp\u003eResistance\u003c/p\u003e \u003cp\u003e(T)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAverage\u003c/p\u003e \u003cp\u003eLongitudinal\u003c/p\u003e \u003cp\u003eResistivity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAverage\u003c/p\u003e \u003cp\u003eTransverse\u003c/p\u003e \u003cp\u003eResistivity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eElectrical\u003c/p\u003e \u003cp\u003eAnisotropy\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eHydraulic\u003c/p\u003e \u003cp\u003eConductivity\u003c/p\u003e \u003cp\u003e(K)\u003c/p\u003e \u003cp\u003e(m/day)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eTransmissivity\u003c/p\u003e \u003cp\u003e(m\u003csup\u003e2\u003c/sup\u003e/day)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e83.046\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3131.582\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.473\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.858\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.768\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e11.143\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3213.571\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e73.185\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3686.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.972\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12.682\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.787\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e9.517\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2766.563\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e63.167\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3805.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.395\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13.710\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.766\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6.659\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1848.444\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e74.755\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3605.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.855\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12.512\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.802\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e9.406\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2710.677\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e63.167\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3805.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.395\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13.710\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.766\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6.659\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1848.444\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e80.987\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2667\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.568\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9.228\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.608\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e8.515\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2460.737\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70.789\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3954.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.020\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13.896\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.859\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.779\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3067.698\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e75.651\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3224.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.873\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.686\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.264\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3593.288\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e73.032\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3514.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.266\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e14.735\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.124\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7.401\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1765.153\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e76.813\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2588.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.652\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9.228\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.590\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e8.478\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2377.950\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e76.299\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2520.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.630\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9.098\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.583\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e8.923\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2471.665\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100.045\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2504.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.781\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.799\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.482\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2916.098\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e72.867\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3171.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.862\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.646\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e11.559\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3375.082\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e89.364\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2390.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.020\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8.856\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.712\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.475\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2827.093\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e71.736\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3019.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.977\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.585\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.631\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.338\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3520.037\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e72.522\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3270.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.999\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11.276\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.679\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.301\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3567.261\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e79.374\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3060.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.515\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.971\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.767\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.742\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2996.979\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e69.599\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3754.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.138\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13.036\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.775\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e5.619\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1618.358\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e74.907\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3899.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.934\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13.232\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.834\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e9.109\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2684.299\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e73.398\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3220.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.969\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11.055\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.669\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.709\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3702.196\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e75.198\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3485.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.758\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12.333\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.812\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.556\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2983.199\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e74.187\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3153.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.993\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.647\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.633\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.449\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3687.506\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e82.930\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3183.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.345\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11.476\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.852\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.816\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3000.386\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e72.259\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2929.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.975\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.201\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.602\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e13.266\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3810.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e66.493\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3286.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.549\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13.926\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.981\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6.659\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1571.444\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e92.032\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2461.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.086\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8.669\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.676\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e9.628\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2734.426\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e65.647\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3594.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.107\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13.332\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.802\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6.881\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1855.220\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e69.405\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3260.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.083\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11.505\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.679\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.561\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3559.714\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e60.996\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3299.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.820\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11.222\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.526\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e15.493\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4555.007\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVES-30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e66.890\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3077.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.276\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.762\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.586\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e13.823\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3953.327\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Conclusion","content":" \u003cp\u003eThe subsurface of the Sagar Island comprises of 5\u0026ndash;6 major electrical resistivity layers whose values range from 0.3 Ohm-m to more than 50 Ohm-m. The lowest resistivity range 0.5 Ohm-m to 1.2 Ohm-m represents the saline zones. Resistivity of 1.5 Ohm-m to 6 Ohm-m generally indicates brackish water zones, whereas, the resistivity range 4Ohm-m to 7 Ohm-m is interpreted as brackish clay/clay. Fresh water aquifer in the investigated area comprising fine and medium sand is associated with a resistivity range of 28 Ohm-m to more than 50 Ohm-m. The higher the resistivity, the larger is the grain size and consequently more would be the yield of ground water.\u003c/p\u003e \u003cp\u003eResistivity survey indicates that all the major subsurface formations occur throughout the Island and are extensive. In general, 5 major subsurface formations are interpreted. These are the top highly unconsolidated (loose) sediments occurring up to 1m depth underlain by a saline water zone comprising clay, silt and some sand lenses continuing to a depth of 21m-34m. Below this, a brackish water zone with some clay and sand lenses occurs within the depth range 21m-150m, which is underlain by thick impermeable clay layer in the depth range 90m-242m. Further down, fresh water (potable) occurs within fine and medium sand layers.\u003c/p\u003e \u003cp\u003eLarge thickness of the saline zones in the subsurface across the length and breadth of the Island indicates that all the areas are susceptible to sea water ingression even when these are located far away from the coast line. This could be made easily possible if the present-day Sagar Island had consisted of a number of small Islands formed by tides and sedimentation in the marine environment and separated by creeks in the geological past. Subsequently with the narrowing of creeks, all the smaller Islands merged in to a bigger present-day Sagar Island.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e“All authors have read, understood, and have complied as applicable with the statement on \"Ethical responsibilities of Authors\" as found in the Instructions for Authors.”\u003c/p\u003e\n\u003cp\u003e \u003ch2\u003eCompeting Interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no conflict of interest to disclose.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003ePoulami Ray declares that the funds, grants, or other supports are received from the AICTE Doctoral Fellowship (ADF) Contingency fund (Beneficiary ID: BININ01594998) during the research and collection of data.\u003c/p\u003e\u003ch2\u003eAuthor Contributions\u003c/h2\u003e \u003cp\u003eAll the authors have contributed to design the manuscript. Data collection and analysis has been done by Poulami Ray, Saurabh Kumar Basak and Sk Mohinuddin. The first draft of the manuscript has been written by Poulami Ray. Pankaj Kumar Roy and Malabika Biswas Roy have gone through the entire manuscript for necessary modification. The final manuscript is read, rectified and approved by Pankaj Kumar Roy.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eAuthors would like to express their sincere gratitude to the School of Water Resources Engineering, Jadavpur University, for providing the necessary facilities to carry out the present study.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eAll data generated or analysed during this study are included within the manuscript.\u003c/p\u003e\u003ch2\u003eCode availability\u003c/h2\u003e \u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAdamo N, Al-Ansari N, Sissakian V, Laue J, Knutsson S (2021) Geophysical methods and their applications in dam safety monitoring. 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Geophysics 59(2):192\u0026ndash;201. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1190/1.1443581\u003c/span\u003e\u003cspan address=\"10.1190/1.1443581\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAI, Disclosure\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThe authors do not used generative AI and AI-assisted technologies in the writing process and authors are ultimately responsible and accountable for the contents of the work\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[{"identity":"20b0893d-1e27-4bb7-aec3-a8fe7a5e0381","identifier":"10.13039/501100001427","name":"All India Council for Technical Education","awardNumber":"BININ01594998","order_by":0}],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Jadavpur University","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":"Vertical Electrical Sounding (VES) Survey, Dar-Zarrouk Parameters, Sagar Island, Transmissibility, Hydraulic Conductivity","lastPublishedDoi":"10.21203/rs.3.rs-8858443/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8858443/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe Vertical Electrical Sounding method is used in this study to discover the subsurface hydrogeology of Sagar Island. The major goal is to interpret the sub-surface formation and to identify aquifer features of this Island. The geophysical investigation that has involved the electrical resistivity method, indicates that all the major subsurface formations occur throughout the Island are extensive. In general, five major subsurface formations are interpreted. These are the top highly unconsolidated sediments underlain by a saline water zone comprising clay, silt and sand lenses continuing to a depth of 21\u0026ndash;34 m. Below this, a brackish water zone occurs within 21\u0026ndash;150 m depth, which is underlain by thick impermeable clay layer. Further down, fresh water aquifer occurs within fine and medium sand layers. To circumscribe the brackish water-fresh water zones and to illustrate the groundwater potential zones, Dar-Zarrouk parameters are estimated such as longitudinal conductance, transverse resistance, average longitudinal resistivity, average transverse resistivity, coefficient of anisotropy. It is also found that the southern section of the region has extremely high transverse resistance and more promise than that of northern part in this study region. The analysed data of coastal aquifer characteristics like hydraulic conductivity and transmissivity is found as 5.619\u0026ndash;15.493 m/day and 1571.44\u0026ndash;4555 m\u003csup\u003e2\u003c/sup\u003e/day respectively. Spatial variation maps of aquifer parameters are also prepared using geospatial software.\u003c/p\u003e","manuscriptTitle":"Assessment of Sub-surface Hydrogeology of Coastal Aquifer using Geophysical Technique in Sagar Island, West Bengal","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-13 03:40:15","doi":"10.21203/rs.3.rs-8858443/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":"730cec9c-54de-4eec-aa73-fc3d7ca51c3e","owner":[],"postedDate":"February 13th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-02-13T03:40:15+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-13 03:40:15","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8858443","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8858443","identity":"rs-8858443","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}