A Geospatial Analysis for Thriving Agricultural Sector at the Koyra Upazila, Khulna, Bangladesh by Identifying Suitable Rainwater Harvesting Structure Site Integrating SCS-CN

A Geospatial Analysis for Thriving Agricultural Sector at the Koyra Upazila, Khulna, Bangladesh by Identifying Suitable Rainwater Harvesting Structure Site Integrating SCS-CN | 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 A Geospatial Analysis for Thriving Agricultural Sector at the Koyra Upazila, Khulna, Bangladesh by Identifying Suitable Rainwater Harvesting Structure Site Integrating SCS-CN Labib Intisar, Rowdra Dip Chackroborty, Dulal Sarkar This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6857794/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 Water is one of the most valuable resources on the verge of extinction. The continued depletion of fresh water poses a tremendous threat to humanity. Koyra Upazila in Khulna with flood-susceptible zones, causing unavailability of fresh water. Additionally, the salinity problem in that area is causing the decline in soil fertility, biodiversity loss, and freshwater pollution. This research proposes a GIS-based system that uses data from remote sensing to determine appropriate locations for rainwater gathering structures as a solution. The methodology is developed incorporating the Surface elevation, land use/land cover, soil, drainage, and depression maps, which are examined to determine depression volume and surface runoff availability using the Soil Conservation Service - Curve Number (SCS-CN) approach. The selection suitability will be used to identify potential locations, ultimately helping to develop a sustainable water management system for Koyra. The marginalized community will be able to attain fresh water and sweet water for cultivation. Adding in, the regeneration of Shakbaria Khal will bring a prominent change in the watershed, improving the community living standard and agricultural conditions. The research helps to develop a community that is resilient to disasters caused by climate change by providing a sustainable water management system. Disaster SCS-CN Geospatial Modelling Water Management Sustainability Climate Change Agriculture Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 INTRODUCTION Water, exclusively freshwater, can be defined as safe drinking water for human consumption and meets established quality standards. It plays a pivotal role in daily living, from essential hydration and health to hygiene and sanitation (Mironov et al., 2019). Access to clean water is especially critical in regions where water scarcity is a pressing issue, as it directly impacts communities' health, economic stability, and social harmony. The global situation concerning fresh drinking water is critical due to numerous difficulties like climate change, geographical locations, and so on, which are obstacles to fostering sustainable development and improving living standards. With the world population expected to reach 8 billion by 2025, the demand for clean water will significantly increase (Kluge, 2015 ). Approximately 900 million to 1 billion people do not have access to clean drinking water, resulting in about 15 million deaths annually from waterborne diseases (Bhargava, 2018 ). Water quality and safety continue to be a significant international health crisis, affecting both developing and developed countries, with water shortages and contamination causing severe health impacts worldwide, and people are prompting the need for sustainable solutions to ensure the quality of fresh water in vulnerable areas (Mironov et al., 2019; Kluge, 2014 ). Bangladesh, a vulnerable location for safe drinking water, is complicated by several significant challenges: arsenic contamination in groundwater and high salinity in coastal regions. Koyra Upazila in Khulna, Bangladesh, lacks an adequate fresh water supply, which is predominantly caused by the intrusion of saline water, affecting surface and groundwater sources. Moreover, its geographical isolation and marginalized communities from mainstream development efforts define it as an HtR (Hard to Reach) area in the National Strategy for Water and Sanitation (NSWS) report. Majorly rising levels of salinity in the area's rivers, canals, and tube wells, leading to significant degradation of water quality for both irrigation and drinking purposes (Chowdhury & Ahmed, 2012; Molla Rahman Shaibur et al., 2021 ). This salinity intrusion has further resulted in substantial challenges for aquatic macrophytes, whose reduced population and abundance serve as indicators of the critical and deteriorating conditions within Koyra's freshwater ecosystems (T. K. Das et al, 2021). The hazard-susceptible locations of Koyra Upazila have further influenced the freshwater availability for irrigation purposes, causing a substantial economic loss in agriculture over many years. It is essential to implement durable and sustainable solutions to address these challenges, including optimizing community management models to ensure active local involvement and exploring blended public finance strategies to mobilize necessary resources (Mateen, 2010 ). Moreover, strategies like shared water systems often fail due to low community participation and inadequate management regulations, leading to their dysfunction (Fischer et al., 2020 ; Muhammad Badrul Hasan, 2022 ; Rahman et al., 2021 ; Syed Ashik-E-Elahi & Khondoker Mokaddem Hossain, 2023). The increasing reliance on privately installed, unregulated tubewells raises concerns about maintaining water quality and reliability to achieve Sustainable Development Goal 6.1, which aims for universal access to safe and affordable drinking water (Fischer et al., 2020 ). In Koyra Upazila, local farmers adapt their agricultural practices to cope with the increasing salinity and waterlogging. This strategic shift to more resilient crops highlights the urgent need for sustainable farming practices to withstand ongoing environmental stressors (Md. Hafiz Iqbal & Aziz, 2022). So, the research aims for a suitable water management system for irrigation and drinking purposes, identifying appropriate locations for rainwater gathering structures through geospatial analysis. The methodology is developed incorporating the Surface elevation (ASTER-DEM), land use and land cover (LULC), soil, drainage, and depression maps, which are examined to determine depression volume and surface runoff availability using the Soil Conservation Service - Curve Number (SCS-CN) approach. This helps develop suitable water drainage and rainwater harvesting locations on a large scale for community purposes. The SCS-CN method is widely adopted for predicting surface runoff in hydrology and is known for its simplicity and effectiveness. The advanced iterations of the model, such as Model M5, surpass earlier versions by incorporating additional variables like rain duration and adjusting initial abstraction based on rainfall intensity. These enhancements lead to significantly more precise runoff predictions, addressing limitations found in earlier models (Singh et al., 2023 ; Verma & Ravindra Kumar Verma, 2023 ). The versatile adaptability to various climatic and topographical conditions of the method makes it a valuable tool for hydrological analysis and water resource management practices (Abed Alataway, 2023 ; Hemin Nasraldin M.Amim & Azzadeen Jumaa Darwish, 2022). In the case of rainwater harvesting, the method is essential for assessing water harvesting potential in rainwater harvesting (RWH) projects. This approach determines surface runoff by considering land cover, soil hydrology, and rainfall amounts (I & Dalli KH, 2022). Furthermore, the suitability of selection will be used to identify potential locations that help in developing a sustainable water management system for Koyra Upazila. The research will bring a prominent change in the watershed, improving the community's living standards and agricultural conditions. STUDY AREA Koyra Upazila, in the southeastern part of Khulna District, is significant due to its strategic and economic importance. The study area profile in Figure 1 presents the geographic location of the upazila that is positioned at 22.3417°N latitude and 89.3000°E longitude, covering an area of 1775.41 square kilometers with 45,750 households. Paikgacha borders the Upazila to the north, the Sundarbans and Dacop to the southeast, and Satkhira District to the west. Koyra was upgraded to an Upazila in 1983 and consisted of seven unions: Amadi, Bagali, Maheswaripur, Maharajpur, Koyra, Uttar Bedkashi, and Dakshin Bedkashi. The administrative region spans only 263.12 square kilometers, as 1512.29 square kilometers are part of the Sundarbans, a key economic area. The proximity to the Bay of Bengal introduces salinity challenges but also supports shrimp. Farming and fisheries contribute to the local river-dependent economy. With a population of 193,931, the area is vulnerable to frequent disasters, compounded by a literacy rate of 50.4% and sanitation coverage of 70%, heightening health risks. Koyra comprises 135 villages within 72 mouzas, relying heavily on agriculture and fisheries, including 28.01 acres of Kash land and 115 Jalmahal. Three forest stations manage the Sundarbans, and seventeen rivers connect the area to the Bay of Bengal. Educational institutions include three colleges, forty government primary schools, thirty-seven secondary schools, and twenty-eight madrasas. Health facilities feature 27 community clinics and five health and family welfare centers. Enhancing infrastructure is crucial for disaster resilience, and ongoing research aims to improve the living conditions in Koyra Upazila. METHODOLOGY The research methodology addresses critical subjects such as site selection, development of methods to attain objectives, a survey to gather relevant data, and subsequent data analysis and recommendations. The methodological approach was developed to identify a rainwater harvesting site in Koyra Upazila for the development of an agricultural irrigation system extensively using geospatial techniques and the SCS-CN method. Framework for Rainwater Harvesting Site Identification The analysis for flood susceptibility ends with the mapping from both FR and AHP values. Then, to evaluate the field scenario, PRA is assigned to address the challenges faced by the community and the problems arising from floods. The method also helps to find out the reasons and effects behind the human impact on nature. That’s why a nature-based solution is the primary solution to ensure suitable drinking water and salinity-free water for agriculture. Preparing a rainwater harvesting site will be a sustainable solution for Koyra. The government has initiated many projects by providing tanks to store rainwater. The analysis of the rainwater harvesting site is in two sections: 1. Depression site analysis and 2. Runoff analysis. Depression Site Analysis of Koyra Upazila The depression analysis is a GIS-based methodology conducted through DEM analysis. As seen in Fig. 2 , we attain the depression and depression volume using the ACPF (Agriculture Conservation Planning Framework) V4 toolkit. The ACPF is being utilized in hundreds of watersheds throughout the Corn Belt to educate and involve local farmers in agricultural conservation. It uses high-resolution geospatial data to assist local farming communities in meeting their soil and water conservation needs. After attaining the depression location, the primary suitable depression is found based on the drainage line buffer area. Then, those sites are classified into three suitable classes based on LULC and Volume-Area ratio. After the analysis of suitable depression sites, the runoff volumes are calculated for different watersheds within the study area. In this stage, the SCS-CN method is initiated. SCS-CN Method Analysis for Runoff Calculation The runoff from the study area was determined using the SCS-CN method, which was developed by the Soil Conservation Service of the United States Department of Agriculture (USDA) in 1956. This agency is called the Natural Resources Conservation Service (NRCS). The technique is a prominent model for estimating surface runoff in diverse landscapes, including agricultural, forest, rural, and urban settings (Singh, 2013 ; Surendra Kumar Mishra & Singh, 2003). Although the conventional SCS-CN model is favored for its straightforwardness and practicality, it overlooks critical elements such as the slope of the land, the duration of precipitation events, and prior soil moisture levels (Shi & Wang, 2020 ). To overcome these deficiencies, several studies have suggested improvements to the model, introducing adjustments to account for factors like slope steepness, soil wetness, length of storm events, and an enhanced soil moisture calculation method (Shi et al., 2017 ; Surendra Kumar Mishra & Singh, 2001). These enhancements have led to more precise runoff predictions, particularly in areas such as the Chinese Loess Plateau, by remedying the original model’s flaws and providing a more detailed analysis of runoff based on an expanded range of watershed features. The estimate of runoff according to the SCS-CN method (Govindaraju et al., 2024) can be expressed as: \(\:Runoff=\frac{{(Rainfall-.2S)}^{2}}{(Rainfall-.8S)}\) (if rainfall > 0.2S) ………………………………… (1) Runoff = 0 (if rainfall ≤ 0:2S) ………………………………… (2) In this investigation, curve numbers were adjusted according to the area of the watershed as follows: \(\:{CN}_{wt}=\frac{\sum\:{CN}_{i}\times\:{A}_{i}}{{A}_{t}}\) ) ………………………………… (3) where CN wt is the weighted curve number, CN i is the curve number for land use type, A i is the area according to curve number and land use, and A t is the total study area. Runoff Volume = Runoff Depth × Catchment Area ……………………… (4) Where the catchment area varies based on the watershed. The study area is subdivided into the watershed, and runoff quantity varies according to the size and rainfall of the watershed. SCS-CN helps delineate suitable watersheds and locations to reserve the maximum amount of rainwater to meet local needs and the development of agriculture. Data Collection and Factors Description The secondary-based data collection is conducted to develop the required factors at the RWH (Rain Water Harvesting) site. Moreover, the analysis requires additional raster analysis for the detailed assessment of the local area. In the case of Rainwater harvesting site analysis data that are necessary cumulated in Table 1 , Table 1 Data Required for Rainwater Harvesting Site Identification Analysis in Koyra Upazila Factor File Type Source WS = Watershed DEM (30m*30m) USGS LULC Sentinel-2, Landsat 8 (10m*10m) ESRI RF = Rainfall IDW Bangladesh Metrological Department ST = Soil Type BARC EL = Elevation DEM (30m*30m) USGS The rainwater harvesting site analysis depends on the DEM data to identify suitable rain reserving locations. The quantity of water attained from the HSG (hydrological soil group) and precipitation quantity help develop the runoff graph to delineate the appropriate site. Koyra Upazila has issues with rising salinity and agricultural production loss, which can be resolved through water management and nature-based solutions. For the analysis, SCS-CN is considered. Where the location is categorized based on the LULC and HSG to calculate the runoff and analyze the watershed with DEM. The CN varies with LULC and the type of soil as the infiltration rate changes with the categories, as seen in Table 2 . Table 2 The CN (Curve Number) Required for SCS-CN analysis Based on LULC and HSG Land Use/Land Cover Hydrologic Soil Group Curve Numbers A B C D Annual Crop 67 78 85 88 Brush/Shrubs 30 48 65 73 Fishpond 99 99 99 99 Built-up 89 92 94 93 Grassland 30 58 71 78 Inland Water 99 99 99 99 Mangrove Forest 98 98 98 98 Marshland/Swamp 72 81 88 91 Open Forest 36 60 79 79 Open/Barren 63 77 85 88 Perennial Crop 45 66 77 83 The attained factors significantly influence rainwater flow, which fundamentally changes the quantity of water stored and runoff. ArcGIS attained the necessary factors like LULC, Elevation, Rainfall, Soil type, and Watershed maps. These factors have the highest level of significance in runoff difference and water conservation model development. The combined methodological process helps create a strong community against the scarcity of suitable sweet water for irrigation. The nature-based solution will solve the water issue sustainably. Data Analysis and Discussion Rainwater harvesting (RWH) is a technology that collects surface runoff during periods of yielding rain and uses it for rainfed agriculture or household water supply, reducing water scarcity in developing countries and providing safe drinking water. For coastal megaregions Koyra, water is so precious to be found and used for community purposes. Moreover, the systems can improve community water supplies by offering a different water source, which is especially helpful in areas with limited water resources. RWH systems may be managed effectively to reduce the effects of flooding, replenish groundwater, and preserve traditional water supplies by being included in larger schemes for the management of water resources (Huang et al., 2021 ; Islam et al., 2021 ; Kim et al., 2016 ). The factor description helps in providing a broader look at Koyra upazila and the reasons behind the scarcity of sweet water. Evaluating LULC, Slope, and Soil Type Analysis of Koyra Upazila The key influencing factors justifying cumulative changes in the runoff variations are slope, soil type, and LULC. In the SCS_CN process, the hydrological soil group and LULC are considered for the difference in curve number, largely the runoff values. Urban runoff production is positively correlated with the number of impervious surfaces, and the contribution of impervious and pervious surfaces to runoff production is influenced by the pattern and intensity of rainfall events (Guan et al., 2015 ). Table 3 Parameter Description of Koyra Upazila, Khulna Parameter Class Name Class Pixel Class (%) Area (Km2) Land use/Land Cover Water 965914 0.3632 95.56 Vegetation 37801 0.0142 3.74 Flooded Vegetation 3949 0.0015 0.39 Crop Land 1341080 0.5042 132.68 Buildup Area 303651 0.1142 30.04 Bare Land 3434 0.0013 0.34 Range Land 3728 0.0014 0.37 Soil Texture Thionic Fluvisols 8363 0.1819 47.85 Eutric Gleysols 37624 0.8181 215.27 Slope (In Degree) 0–1.3 136053 53.63 141.11 1.301–2.3 82065 32.35 85.12 2.301 -3.3 27089 10.68 28.10 3.301–4.3 6490 2.56 6.73 4.301–5.3 1993 0.79 2.07 In terms of the slope factor, in low-land or gentle slopes (LL/GS), there's a marked correlation between the runoff speed and the terrain's curvature. The terrain gradient spans from flat to steep, ranging from zero to 5.3 degrees. Notably, the region with slopes between 0 and 1.3 degrees, characterized by minimal incline, emerges as a lower speed of runoff. Conversely, areas featuring steeper gradients, specifically within the range of 4.3 to 5.3 degrees, exhibit substantially higher runoff and less ground infiltration. The remarked scenario is that the majority of Koyra upazila belongs to the lower slope area of about 141.11 km2, severing a large basin for groundwater infiltration. The Khal side areas have higher slopes and higher runoff towards Khal, and these drainage line areas are considered suitable for RWH site development. The LULC classification system divides the land into seven unique categories: water, vegetation, flooded vegetation, cropland, built-up areas, bare land, and rangeland. Among these, cropland occupies the most significant area at 132.67 square kilometers. Conversely, rangeland covers a much smaller area, approximately 0.37 square kilometers. A decrease in rangeland coverage from 1984 to 2011 was associated with increased peak levels of runoff (Quast et al., 2011 ). Additionally, the bare land and water portion has a massive influence on the climatic influence and is the least important in developing RWH sites. The fisheries and water body take a huge area of 95 km 2 in the Koyra Upazila, making it one of Khulna's most climate-vulnerable zones. However, the highest portion of land is taken by agricultural land and has the maximum potential for being considered suitable RHW sites. Additionally, the Koyra area has major clay soil, which justifies quick runoff and less infiltration. The soil texture is mainly divided into two types: Eutric Gleysols and Thionic Fluvisols. The composition of soil texture, particularly Thionic Fluvisols and Eutric Gleysols, can significantly impact flood occurrences. The spatial arrangement of soil texture plays a pivotal role in governing water dynamics and moisture recharging during dry spells (Patel et al., 2021 ). In regions with contrasting textural boundaries and sandy layers, the humidity flow may encounter hindrances, impeding groundwater replenishment (József Dezső et al., 2019 ). Furthermore, the balance between clay, silt, and sand content in the soil influences its permeability and capacity to retain water, thus affecting the infiltration of precipitation into aquifers (Ahmad et al., 2022 ). Here, Eutric Gleysols soil covers a large area of 215.27 square kilometers, and Thionic Fluvisols covers a lower area of 47.85 square kilometers. The arrangement of soil groups influences groundwater infiltration and runoff quantity, which helps in identifying generalized suitable RWH sites for the lesser infiltration, reserving the maximum water for the dry season, and using it further for irrigation. Evaluation of Metrological Parameters of Koyra Upazila The analysis portion includes temperature change that has a huge impact on river flow, precipitation quantity, and suitable living conditions. Temperature impacts flood intensity via the Clausius-Clapeyron relation, with higher temperatures enabling more moisture to be stored. However, changes in circulation regimes may alter these predicted effects (Blenkinsop et al., 2015 ). Koyra, Bangladesh's annual variations in the maximum average temperature between 1989 and 2017 represent considerable variability rather than a linear pattern, indicating dynamic weather conditions where there was a significant variation in 2001, with an average maximum temperature of 29 degrees Celsius and a sudden increase to 32 degrees Celsius the following year according to Fig. 4 . Over a three-decade period, there is no discernible increase or decreasing trend in the general temperature pattern. With temperatures rising and dropping around a central average value, the graph mimics ocean waves. The record starts and finishes at the same time, with the highest average maximum temperatures of 32 degrees Celsius occurring in 1989 and 2017. The temperature scenario has a massive influence on the rainfall intensity. Rainfall movement influences runoff response, peak discharge, hydrograph forms, and flooded regions; higher velocities and directions result in larger peaks (Ghomash et al., 2022 ). Koyra’s geographical status makes it a major vulnerable place for heavy rainfall and flood that can be taken under management with channelized stored excess rainwater towards a sustainable water management system for agricultural development. The rainfall map in Koyra Upazila shows a fluctuating pattern from 1989 to 2017, indicating unpredictable weather. Some years saw heavy rainfall, while others saw significant precipitation, such as floods in Bangladesh in 1998, 2007, and 1990. These floods caused considerable damage to crops and people, with an estimated total damage of USD 10.64 million. Conversely, years like 1996, 2009, and 2010 saw minimal rainfall, resembling a drought. According to the data from WDB (Water Development Board), Khulna, there is a complex relationship between precipitation and temperature in Koyra Upazila, with significant year-to-year variability. Temperature may not be the sole driver of rainfall, as other atmospheric or geographical factors may also play a role. The temperature line shows a slight undulating pattern with periodic rises and falls but not a pronounced long-term upward or downward trend. Years like 1990 and 1998 saw high rainfall, but temperature readings showed an inverse relationship. Severe rainfall intensity is linked to air temperature, potentially increasing flash floods. The growth of the upazila is crucial for maintaining ecological balance, and nature-based solutions are essential for managing rainwater and high-temperature rates. The attaining of agricultural sustainability is possible through the development of sustainable drainage of runoff and its storage and distribution management. The initiative starts with the identification of suitable RWH sites and, further, the runoff calculation to delineate the reservoir strength for sustaining in the dry seasons. Identification of Suitable RWH Site for Koyra Upazila Identifying suitable RWH in Koyra incorporates local participation and geography-based analysis for better and more sustainable solutions for the community. The development includes two phases: 1. Runoff calculation at the watershed and 2. Depression and suitable locations for RWH's infrastructure development. Watershed Identification for Koyra Upazila Watersheds are defined by topographic limits and characterized by the flow of water within them, which is frequently delimited by ridgelines from which water flows to a shared outlet. A watershed's integrity is characterized by its potential to support and preserve biological processes and activities necessary for biodiversity and the benefits supplied to society despite human-induced changes (Gou, 2013; Flotemersch et al., 2016 ). Watershed management entails the balanced use of land and water resources, with hydrological models helping to plan and implement soil and water conservation measures. Through the management that had been considered concerning engineering and infrastructure development for community resilience, the focus of integrated watershed management approaches has shifted from engineering-focused techniques to ones that emphasize poverty reduction and livelihood enhancement, highlighting the need for comprehensive ecosystem management (Prasad et al., 2020 ; Darghouth et al., 2009 ). Koyra upazila in Khulna district had been suffering from a huge salinity problem. For establishing suitable RWH sites, watershed delineation is a prime consideration when analyzing the quantity of water that can be attained from the rain to support the community. The watershed is prepared from the DEM data, and then the major catchments collect water within the study area. The watershed analysis presented in Fig. 5 classifies the study area into eight watersheds delineated based on DEM characteristics. Each watershed includes different landforms and soil groups. As a result, runoff varies, ultimately causing different water quantities to be consumed in other watersheds. The variations are valued through curve number (CN). The CN values represent the tendency of runoff for certain HSG and particular LULC. The values are taken from Table 2 . The watershed detail criteria map flows of the LULC and HSG map are presented in Fig. 3 . The criterion provides a particular CN and Area under the CN value. That ultimately helps quantify the water attained from specific watersheds tabulated in Table 4 . Table 4 Watershed details based on Watershed, HSG (Hydrological Soil Group), and LULC (Land Use and Land Cover) in Koyra Upazila FID WS HSG LULC CN AREA (KM2) 1 WS 1 A Bare Land 88 0.000857 2 WS 1 A Buildup Area 89 3.326377 3 WS 1 A Crop Land 67 15.031598 4 WS 1 A Range Land 30 0.014432 5 WS 1 A Vegetation 36 1.063782 6 WS 1 A Water 99 2.655875 7 WS 2 A Bare Land 88 0.000526 8 WS 2 A Buildup Area 89 1.096782 9 WS 2 A Crop Land 67 5.590702 10 WS 2 A Flooded Vegetation 72 0.003251 11 WS 2 A Range Land 30 0.01032 12 WS 2 A Vegetation 36 0.503924 13 WS 2 A Water 99 4.408249 14 WS 3 A Bare Land 88 0.002501 15 WS 3 A Buildup Area 89 2.388522 16 WS 3 A Crop Land 67 15.677003 17 WS 3 A Flooded Vegetation 72 0.000478 18 WS 3 A Range Land 30 0.009174 19 WS 3 A Vegetation 36 0.276141 20 WS 3 A Water 99 7.350427 21 WS 4 A Buildup Area 89 0.024415 22 WS 4 A Crop Land 67 0.156973 23 WS 4 A Water 99 0.12815 24 WS 5 A Bare Land 88 0.002646 25 WS 5 A Buildup Area 89 2.279154 26 WS 5 A Crop Land 67 22.8293 27 WS 5 A Range Land 30 0.046956 28 WS 5 A Vegetation 36 0.254356 29 WS 5 A Water 99 2.232439 30 WS 6 A Bare Land 88 0.0001 31 WS 6 A Buildup Area 89 0.442983 32 WS 6 A Crop Land 67 2.206819 33 WS 6 A Range Land 30 0.014878 34 WS 6 A Water 99 3.324089 35 WS 7 A Bare Land 88 0.070736 36 WS 7 A Buildup Area 89 3.053413 37 WS 7 A Crop Land 67 11.130655 38 WS 7 A Flooded Vegetation 72 0.004775 39 WS 7 A Range Land 30 0.108654 40 WS 7 A Vegetation 36 0.019494 41 WS 7 A Water 99 6.397443 42 WS 8 A Bare Land 88 0.000068 43 WS 8 A Buildup Area 89 2.58862 44 WS 8 A Crop Land 67 8.265964 45 WS 8 A Vegetation 36 0.038077 46 WS 8 A Water 99 0.529522 Watershed details are discussed in Table 3 based on the different watersheds and LULC. A total of eight watersheds are discussed. Here, the hydrological soil A group is mentioned. Hydrological Soil Group A includes soils with the highest infiltration rates when saturated, leading to low runoff potential. These soils are primarily sandy, with textures ranging from sand to sandy loam, characterized by large pore spaces and high permeability. Each watershed has a different land use and land cover according to the watershed zone. Based on the soil type and LULC, the curve number (CN) is defined. This CN mainly defined how much water flow would occur based on the LULC and HSG. Finally, the surface runoff base is calculated by incorporating the rainfall data using Eq. 4. The Area for the watershed is divided into different LULC and HSG. As seen in Table 4 , cropland takes up the maximum amount of land in the watershed except for WS 6. That helps initiate locations for RWH and helps with community development. Calculation of Surface Runoff for Koyra Upazila Rainfall data are used to calculate the runoff depth in the analysis of surface runoff. According to rainfall data from June 2022, the runoff depth (Q) is calculated for every watershed zone. The bar chart in Fig. 6 represents the runoff depth in millimeters for eight different zones of Koyra Upazila in Khulna. It measures the runoff depth in millimetres on the vertical axis, with the zones measured along the horizontal axis as Ws1 through Ws8. From the results obtained in this section, it can be noted that there is no uniformity in the runoff depth of the different zones. It is evidenced by a scenario where Ws5 has the highest runoff depth of 724.60 millimetres, and Ws6 has the lowest depth of 236.87 millimetres. Noted is that Ws1 and Ws8 have the same runoff depth at 671.31 millimetres, while Ws2 and Ws7 present it with equal depth, measured at 289.29 millimetres. The same zones, Ws3 and Ws4, project a moderate runoff depth at 310.53 and 270.13 millimetres. This graphical representation clearly shows the upazila distribution of runoff to identify primary and minor runoffs, which may contribute to local water management practices—ultimately forming the weight of different watersheds tabulated in Table 5 , which represents the quality of watershed that can be taken for the development of the RWH site. Table 5 Details of the watershed and their weight in Koyra Upazila Id WS Approx. CN Runoff depth Q (Mm) Area Of Watershed Total Area of Basin Weight (W) 1 WS 1 73 671.3145375 22.092921 125.5616 118.1862 2 WS 2 80 289.2903995 11.613754 125.5616 26.77284 3 WS 3 78 310.5346949 25.704246 125.5616 63.60670 4 WS 4 82 270.1285744 0.309538 125.5616 0.666303 5 WS 5 71 724.6036642 27.644851 125.5616 159.6256 6 WS 6 86 236.8726036 5.988869 125.5616 11.30440 7 WS 7 80 289.2903995 20.78517 125.5616 47.75237 8 WS 8 73 671.3145375 11.422251 125.5616 61.10343 Table 5 puts down meticulously the characteristics of eight watersheds within Koyra Upazila, giving a detailed overview of Curve Number (CN)—meaning the potential runoff of the area, the actual measured Runoff Depth (Q), the physical Area of the Watershed and a calculated Weight (W) for each of the watersheds. The weight summarizes an interplay between the watershed size and its runoff capacity. Higher weights mean either big sizes of watersheds or large depths of runoff. It is evident in the case of the fifth zone of the watershed, which stands with the most significant weight of 159.63 due to having the largest area of 27.64 square kilometers and the most excellent runoff depth of 724.60 millimeters among the zones—conversely, a smaller basin area or lower runoff depth results in a lower weight value. Zone, 4 of a watershed, has been assigned a markedly lower value at 0.67, corresponding to its relatively minor area of 0.3095 square kilometers and even runoff depth of 270.13mm. Ultimately, the runoff volume is calculated by multiplying runoff depth (Q) by the watershed area. The relationship of the physical characteristics of the watersheds with the runoff features suggests a balanced hydrological balance in the basin. The weighted nature of this table approach in hydrologic assessment offers an analytical strategic framework that could be useful in water resource management, especially in identifying and prioritizing zones relating to rainfall harvesting initiatives. The various values of the weights sum up to estimate the relative hydrological impact of each of the watersheds and sensitize practices and infrastructure development for sustainability in optimizing the use and conservation of water resources within Koyra Upazila. Thus, from this analytical lens, we take the understanding and forecast not only the present water dynamics but also the future challenges based on water within the region. Runoff management through proper elevation and surface quality will enhance the water flow condition and conserve water to an extent sufficient for the community. Depression Site Analysis for Koyra Upazila Depressions in digital elevation models (DEMs) can reflect actual landscape features or mistakes; a novel approach for drainage network extraction retains these characteristics without modifying the original DEM (Wang et al., 2009). To better comprehend and manage the intricate topography of depressions for hydrological modeling and terrain analysis, the idea of a depression hierarchy has been proposed. This represents a better modeling technique for identifying natural retaining zones for rainwater conservation (Barnes et al., 2020). In the analysis process, a GIS-based technique, including the ACPF V4 toolkit, is used to identify depressions in the site area. However, the depression is primarily based on the closed proximity to the drainage line incorporating the buffer zone of the drainage network. About 44 depressions are taken within the buffer zone of the drainage network. In the secondary phase of site selection, the sites are eliminated according to the suitable criteria that the area of the depression should be more than 1.5 hectors (IMSD, 1995 ) and the volume-to-area ratio of the sites should be more than equal to 2 (Tiwari et al., 2018 ). After the criteria-based selection, we obtained about 17 suitable rainwater harvesting locations, as shown in Fig. 7 . The 17 sites are suitable for the infrastructural development of RWH. But, based on their physical properties and land uses, the sites are categorized into Suitable, Moderately Suitable, and Not Suitable. The suitability category is formed on the criteria of, The sites are out of High Flood Vulnerable Zones presented in the FSM map The majority of the site portion falls within the agricultural land, so land acquisitions become much easier Depression locations in and around built-up areas are eliminated and are not considered for additional study. This is due to the likelihood of higher land acquisition costs for locations following populated areas. Sites with depressions that adequately absorb runoff volume are ideal for constructing RWH structures (Tiwari et al., 2018). With the proper utilization of criteria-based assessment, the sites are classified as shown in Table 6. Table 6 Suitability Specification of different RWH Sites of Koyra Upazila Site Area (m2) Max depth (m) Volume (m3) Watershed Category Site 1 34646.26 3.6 124726.536 WS 1 Suitable Site 2 21189.75 3.4 72045.15 WS 1 Suitable Site 3 400189.9 4.4 1760835.692 WS 1 Suitable Site 4 61245.21 3.1 189860.151 WS 1 Suitable Site 5 217402.5 3.1 673947.688 WS 1 Suitable Site 6 75250.32 2 150500.64 WS 3 Not Suitable Site 7 39811.17 2.5 99527.925 WS 5 Not Suitable Site 8 73147.03 3.5 256014.605 WS 4 Not Suitable Site 9 199989.8 5 999948.95 WS 6 Moderately Suitable Site 10 208726 2.6 542687.496 WS 6 Suitable Site 11 73599.13 7.2 529913.736 WS 6 Not Suitable Site 12 91252.93 2.5 228132.325 WS 6 Moderately Suitable Site 13 102793.1 5.2 534524.276 WS 6 Moderately Suitable Site 14 201613.3 3.5 705646.375 WS 6 Not Suitable Site 15 35428.16 2.6 92113.216 WS7 Not Suitable Site 16 34152.25 2 68304.5 WS7 Suitable Site 17 107786.7 4 431146.64 WS8 Suitable The 17 suitable depression sites are crucial locations for the project's development. The criterion-based classification has helped identify the most influential sites for the maximum water for use. Koyra, being a coastal area, had to face several climatic events like floods, cyclones, and salinity intrusion. The frequent effect damages the agricultural condition at a rapid rate. In coastal countries afflicted by salinity, such as Bangladesh, rainwater collecting provides a low-cost option for potable water supply, with systems built to meet local building layouts and rainfall circumstances (Islam, K et al., 2014 ). To overcome the scenario, a suitable ranking and establishment of RWH is far more critical for the development of the community The suitable rainwater harvesting map in Fig. 8 represents the location of suitable sites in green colour. As can be seen, about five suitable sites exist in WS1 in Amadi Union. Another two suitable sites are found in WS6 at Maharajpur Union. The last site is placed in the Koyra Union. These eight suitable sites fall within the criteria. The watersheds have different capacities or water volumes based on their cumulative CN, rainfall, and area. The use of RWH can considerably help to satisfy irrigation demands and be a cost-effective and ecologically beneficial alternative in locations suffering water constraints (Terêncio et al., 2017 ; Preeti et al., 2022 ; Ejegu & Yegizaw, 2020 ). The Amadi Union holds one of the most significant location values for the best suitability of rain-supported structures. As the union has a lower flood frequency than other unions, it can be one of the essential locations for initiating the project. Table 7 describes the capacity details and supported water quality from the basin. The table includes data from all eight watersheds in Koyra Upazila. The integrated water management system helps the irrigation system for the development of agriculture. Table 7 Watershed Characteristics and Water storage capacity of Koyra upazila Watershed Runoff depth Q (mm) Area of Watershed (km 2 ) Volume of Runoff (m 3 ) The capacity of Suitable Locations (m 3 ) WS1 671.3145375 22.092921 1483129.904 2821415.217 WS2 289.2903995 11.613754 335974.7534 0 WS3 310.5346949 25.704246 798206.0188 150500.64 WS4 270.1285744 0.309538 8361.505865 266014.605 WS5 724.6036642 27.644851 2003156.033 99527.925 WS6 236.8726036 5.988869 141859.8993 3540853.158 WS7 289.2903995 20.78517 601295.0132 160417.716 WS8 671.3145375 11.422251 766792.3148 431146.64 Total Amount of Water Provided by the Execution of RWH 24,84,944.231 m 3 Koyra, one of the most vulnerable areas to climate change, had to deal with the devastating effects on agricultural production. The continuous effect and lack of suitable water significantly impact the farmers. The constant use of groundwater is causing the water table to decline, and the porous space is filled with sea salt water. That’s why groundwater use will be impossible in the upcoming years. Farmers in areas with salty groundwater use "blended water" solutions, which combine saline and freshwater to reduce soil salinity and sustain agricultural yields, especially for salt-sensitive crops like strawberries (Bani et al., 2020 ). To support agriculture, RWH is one of the crucial methods for developing agriculture in Koyra Upazila. As seen in Table 7 , WS 1 Amadi Union has a runoff volume of 1483129.904 m 3 , but its suitable site capacity is twice as high as the runoff volume. In WS2, there is no suitable location where 335974.7534 m3 of rainwater can be managed with interconnected khals for suitable water movement into the ground or for fishing purposes. Also, the WS3 and WS4 have a runoff volume of 798206.0188 m 3 and 8361.50 m 3 of water. However, WS1 has a suitable capacity of 150500.64 m 3 only. WS4 has enough capacity at the suitable site to collect the water condition. Though WS5 has a huge amount of runoff water, it only has a capacity of 99527.925 m 3 . Moreover, the excess water can be managed with a regenerated interconnected Khal at the upazila. Similarly, WS6, WS7 and WS8 has capacity to provide 141859.8993 m3, 160417.716 m3 and 431146.64m3 of water. The cumulative support is enough to sustain agricultural production throughout the year without affecting the groundwater. Based on the rainfall runoff and capacity of a suitable location, the total amount of water that the execution of RWH can provide is 24,84,944.231 m 3 . Koyra Upazila's socio-economic development mainly relies on small and medium-sized businesses, but it also depends on agriculture, fishing, tourism, industry, weaving, and livestock rearing. However, Koyra is significantly impacted by climate change; although the residents are aware of this, they have not yet made the necessary adjustments (Islam et al., 2014 ). Moreover, the scarcity of water has made the job of production at a massive level for years. That amount of water can be fruitful to sustain agricultural development. Koyra mainly has two seasons of paddy production. One is Boro, another is Aush. According to the Koyra Upazila agricultural administration, 36,000 bighas of Boro paddy will be grown this season in 2023. In 2022-23, paddy produced was about 73,000 metric tons. The Bangladesh Rice Research Institute (BRRI) estimates that one kilogram of Boro rice and Aush rice requires about 3400 liters (Hossain et al., 2016 ). Based on the data, the necessary amount of water and support facilities from the rainwater harvesting are given in Table 8 . Table 8 Water requirements in agriculture and Support from the RWH project in Koyra Upazila The Amount of Water Required for Paddy Production 24,82,000.000 m 3 Total Amount of Water Provided by the Execution of RWH 24,84,944.231 m 3 With the project's execution, it will be possible to ensure the crops' yearly production without affecting groundwater extraction. The initiative can be developed by regenerating rivers and the Khal to distribute rainwater and groundwater recharge. Additionally, sweet rainwater can be mixed with saltwater and used on agricultural land, reducing the overall cost and quantity of sweet water use. Thus, RWH harvesting can help develop integrated water management in Koyra Upazila and modify the existing water resource condition for a sustainable future. RECOMMENDATION Koyra’s vulnerable location in the southeast coastal region of Bangladesh makes it an emerging area for severe climatic events, poor water resources, and poor sanitation conditions. The yearly continuation of the climatic effects vastly affects the upazila's agricultural and suitable water conditions. Implementing RWH sites is a vital solution for managing water resources, particularly given the challenges of frequent flooding and salinity intrusion, while developing an integrated water management system for the upazila. The RWH method encompasses various techniques to collect and utilize rainwater for different purposes. RWH technologies can improve crop production by conserving soil moisture (Kayombo, 2016 ). The geospatial analysis formulates the critical zones at the upazila for collecting Rainwater and using it for agricultural growth. With the mitigation of the negligible evaporation of the water, it is possible to ensure about 80% rice production for the Koyra upazila. The usability of rainwater can be intensified with more significant modification and development of interconnected canals with sites and rivers. The unlimited saltwater source can be reformed with the mix-up with sweet water to decrease the saline intensity of the river water and further use it for irrigation purposes. The water resource scenario of Koyra upazila is marked with heavily resourced khals and bills supporting agriculture and fisheries cultivation. The constant effect of devastating hazards like floods, Aila, etc., damaged the regulation of dams and polders, ultimately causing the death of many vital khals of the upazila. Channel restoration initiatives would be crucial to environmental conservation and habitat enhancement. Also, implementing vortex rock weirs (VRWs) in channel design will help to maintain channel stability, prevent erosion, and improve aquatic habitats while facilitating fish passage (Mielhausen et al., 2023 ). Wetlands are natural buffers against floodwaters, reducing the impact on human settlements and agricultural lands. Restoring or establishing wetlands is are initiatives that enhance the natural capacity of the environment and reservoir for rainwater. In addition to the environmental benefits, RWH supports the community by providing a reliable water source for irrigation, which is critical for agricultural activities. A participatory approach would help to delineate significant, influential information that should be incorporated in planning for the community development of farmers and fishermen. This reliable water source ensures that crops can be grown throughout the year, regardless of rainfall variability, thus enhancing food security. This approach aligns with the broader goals of integrated water resource management, which seeks to balance the needs of human consumption, agriculture, and ecosystem health. It also promotes community resilience by providing a sustainable water supply that can be managed locally. By adopting RWH, Koyra Upazila can achieve greater resilience against climate change impacts, such as increased flooding and changing precipitation patterns, enhance agricultural productivity, and ensure a more sustainable and secure water future for its residents. Additionally, these measures can foster economic growth by stabilizing farm production and providing opportunities for community-based water management initiatives. CONCLUSION Koyra, a significant coastal area in Bangladesh, frequently holds one of the major shareholders in the economic and agricultural sectors of the Khulna division. Additionally, aquaculture provides a major share of the country's overall GDP. But, one of the key hazards is that floods cause substantial loss of life and property, disrupt economic and social stability, and spread pollutants and bacteria, leading to serious health risks. The country’s geographical and climatic conditions worsen the impact of flooding, resulting in riverbank erosion, infrastructure damage, and harm to homes and vegetation. Climate change further exacerbates these challenges. Since Cyclone Aila in 2009, Koyra Upazila has faced numerous natural disasters, including cyclones, floods, and riverbank erosion. Efforts by NGOs and locals to rebuild housing have only provided short-term relief. Social media plays a crucial role in reducing cyclone damage by disseminating information. At the same time, farmers have adapted to salinity and waterlogging by growing resilient crops such as hybrid sunflower, mustard, cotton, maize, wheat, and Aman paddy. Despite these adaptations, the ecosystem continues to suffer, affecting habitats, biodiversity, and livelihoods. A sustainable measure is proactively required for a drastic change in improving the quality of life and finding solutions for water salinity and resource management. The agricultural sector at the coastal koyra is taken under consideration in the Delta 2100 plan resolving issues with sustainable solutions where the paper advocates rainwater harvesting (RWH) as a method to collect and conserve water, which helps address groundwater scarcity and combat saltwater intrusion into freshwater sources. The identification of suitable locations for RWH facilities, based on the SCS-CN method, has the potential to significantly boost paddy production and support the agricultural needs of the upazila. The watershed delineation with capacity identification helps in finding important and suitable locations for rainwater restoration and further use in necessary periods. The initiative will help reduce the salinity of existing khals with a mixture of sweet rainwater for the development of agricultural production. The initiative will be more fruitful through the regeneration of illegally occupied khals and waterbodies at the Koyra upazila. Properly implementing these recommendations can minimize most issues in Koyra Upazila, leading to economic growth and sustainable resource use and benefiting future generations. It will help in forming a climate-resilient and resource-optimized framework in Koyra Upazila, supporting the overall development of the upazila. Declarations Data availability statement The data used is accessible and there by no issue in sharing while requested. Funding This research received no specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author’s Contribution Labib Intisar: Formal analysis, Software, Writing—Original Draft. Rowdra Dip Chackroborty: Conceptualization, Formal analysis, Writing—Original Draft, Methodology, Software, Data Curation, Visualization. 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Chackroborty","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuElEQVRIiWNgGAWjYJACCQYGGzkQ48ADErSkGYO1JJCg5XBiA4hFlBbz9h7D2xU1zOnzww4/BNpiJ6fbQECLzJkzxpZnjrHlbrydZgDUkmxsdoCQoyRyt0k2sPHkbpydANJyIHEbcVr+SaQbzk7/QIKWxjaDBHnpHGJt4Tn/2bKxL8Fwg3ROwYEEA2L8wt6WeLPh2395+dnpmz98qLCTI6gFDgzAKg2IVQ4C8g2kqB4Fo2AUjIIRBQDYQUQsol06TwAAAABJRU5ErkJggg==","orcid":"","institution":"Rajshahi University of Engineering and Technology","correspondingAuthor":true,"prefix":"","firstName":"Rowdra","middleName":"Dip","lastName":"Chackroborty","suffix":""},{"id":534308900,"identity":"8dde7d00-d73d-4656-9138-9c8170af640c","order_by":2,"name":"Dulal Sarkar","email":"","orcid":"","institution":"Rajshahi University of Engineering and Technology","correspondingAuthor":false,"prefix":"","firstName":"Dulal","middleName":"","lastName":"Sarkar","suffix":""}],"badges":[],"createdAt":"2025-06-10 00:38:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6857794/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6857794/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":94456963,"identity":"7e6b76c9-d6fe-4506-93c7-76b5808290b8","added_by":"auto","created_at":"2025-10-27 14:45:18","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1703762,"visible":true,"origin":"","legend":"\u003cp\u003eStudy Area Map of Koyra Upazila, Khulna\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/b53b56299e533eb1a2293ad4.png"},{"id":94456471,"identity":"e2ce9a6a-e7ef-4ec0-bc1a-e5bab365a24e","added_by":"auto","created_at":"2025-10-27 14:44:32","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":126765,"visible":true,"origin":"","legend":"\u003cp\u003eMethodology for the Identification of a Suitable RWH site for Koyra Upazila\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/87762d566b4b99519751cbbf.png"},{"id":94456845,"identity":"d4c8fce4-7db9-4d9a-84f6-b3a8783aa75f","added_by":"auto","created_at":"2025-10-27 14:45:11","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1659112,"visible":true,"origin":"","legend":"\u003cp\u003eSlope, LULC, and Soil Type Map of Koyra Upazila\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/4948fd078b4b568a0f694e39.png"},{"id":94456976,"identity":"81deb61a-63f0-437d-8c31-8024d69a4832","added_by":"auto","created_at":"2025-10-27 14:45:19","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":87390,"visible":true,"origin":"","legend":"\u003cp\u003eChange in Precipitation vs Average Temperature in Koyra from 1989-2017\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/3b27598ade4e17e44b8dd277.png"},{"id":94456622,"identity":"5cab8922-d62c-4972-8f4b-271b9531ca3f","added_by":"auto","created_at":"2025-10-27 14:44:51","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":115081,"visible":true,"origin":"","legend":"\u003cp\u003eWatershed Map of Koyra Upazila\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/139578de96f565482ceec5a2.png"},{"id":94456008,"identity":"823a5716-d587-434c-b9eb-0dda3e97e92d","added_by":"auto","created_at":"2025-10-27 14:44:06","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":35117,"visible":true,"origin":"","legend":"\u003cp\u003eRunoff depth of different watersheds in Koyra Upazila\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/b22c6b7ab557c33a418e1e3f.png"},{"id":94456009,"identity":"a0a7b3d9-d1e3-4091-aa20-63569430fa44","added_by":"auto","created_at":"2025-10-27 14:44:06","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":327774,"visible":true,"origin":"","legend":"\u003cp\u003eSuitable RWH site location at Koyra Upazila\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/b21cacdac39975c389f9fdc0.png"},{"id":94456764,"identity":"b6265abb-665b-4106-9d57-9642b0c2bd81","added_by":"auto","created_at":"2025-10-27 14:45:09","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":474917,"visible":true,"origin":"","legend":"\u003cp\u003eSuitability Map of RWH site of Koyra Upazila\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/d3968c8fa1e9022f9d613803.png"},{"id":94469031,"identity":"e0b2bb9f-f711-45ca-bdf0-d7f5e825f94d","added_by":"auto","created_at":"2025-10-27 15:26:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6050326,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/f7dbf817-7fd6-4e0c-98c4-94ec3dc97cee.pdf"},{"id":94456314,"identity":"0441c503-fb29-48ec-baf3-11ec76ef1e3f","added_by":"auto","created_at":"2025-10-27 14:44:25","extension":"xlsx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":13010,"visible":true,"origin":"","legend":"","description":"","filename":"SitevolumetoArearatiokoyra.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/ab2318271c0070a87de852eb.xlsx"},{"id":94456612,"identity":"826f7599-57d0-4eca-b28c-fe70cdaf818a","added_by":"auto","created_at":"2025-10-27 14:44:48","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":59526,"visible":true,"origin":"","legend":"","description":"","filename":"BASINDETAILSKoyra.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-6857794/v1/2b9312a9c3d61a3165625bf6.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"A Geospatial Analysis for Thriving Agricultural Sector at the Koyra Upazila, Khulna, Bangladesh by Identifying Suitable Rainwater Harvesting Structure Site Integrating SCS-CN","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eWater, exclusively freshwater, can be defined as safe drinking water for human consumption and meets established quality standards. It plays a pivotal role in daily living, from essential hydration and health to hygiene and sanitation (Mironov et al., 2019). Access to clean water is especially critical in regions where water scarcity is a pressing issue, as it directly impacts communities' health, economic stability, and social harmony. The global situation concerning fresh drinking water is critical due to numerous difficulties like climate change, geographical locations, and so on, which are obstacles to fostering sustainable development and improving living standards. With the world population expected to reach 8\u0026nbsp;billion by 2025, the demand for clean water will significantly increase (Kluge, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Approximately 900\u0026nbsp;million to 1\u0026nbsp;billion people do not have access to clean drinking water, resulting in about 15\u0026nbsp;million deaths annually from waterborne diseases (Bhargava, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Water quality and safety continue to be a significant international health crisis, affecting both developing and developed countries, with water shortages and contamination causing severe health impacts worldwide, and people are prompting the need for sustainable solutions to ensure the quality of fresh water in vulnerable areas (Mironov et al., 2019; Kluge, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Bangladesh, a vulnerable location for safe drinking water, is complicated by several significant challenges: arsenic contamination in groundwater and high salinity in coastal regions.\u003c/p\u003e\u003cp\u003eKoyra Upazila in Khulna, Bangladesh, lacks an adequate fresh water supply, which is predominantly caused by the intrusion of saline water, affecting surface and groundwater sources. Moreover, its geographical isolation and marginalized communities from mainstream development efforts define it as an HtR (Hard to Reach) area in the National Strategy for Water and Sanitation (NSWS) report. Majorly rising levels of salinity in the area's rivers, canals, and tube wells, leading to significant degradation of water quality for both irrigation and drinking purposes (Chowdhury \u0026amp; Ahmed, 2012; Molla Rahman Shaibur et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). This salinity intrusion has further resulted in substantial challenges for aquatic macrophytes, whose reduced population and abundance serve as indicators of the critical and deteriorating conditions within Koyra's freshwater ecosystems (T. K. Das et al, 2021). The hazard-susceptible locations of Koyra Upazila have further influenced the freshwater availability for irrigation purposes, causing a substantial economic loss in agriculture over many years. It is essential to implement durable and sustainable solutions to address these challenges, including optimizing community management models to ensure active local involvement and exploring blended public finance strategies to mobilize necessary resources (Mateen, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Moreover, strategies like shared water systems often fail due to low community participation and inadequate management regulations, leading to their dysfunction (Fischer et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Muhammad Badrul Hasan, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Rahman et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Syed Ashik-E-Elahi \u0026amp; Khondoker Mokaddem Hossain, 2023). The increasing reliance on privately installed, unregulated tubewells raises concerns about maintaining water quality and reliability to achieve Sustainable Development Goal 6.1, which aims for universal access to safe and affordable drinking water (Fischer et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn Koyra Upazila, local farmers adapt their agricultural practices to cope with the increasing salinity and waterlogging. This strategic shift to more resilient crops highlights the urgent need for sustainable farming practices to withstand ongoing environmental stressors (Md. Hafiz Iqbal \u0026amp; Aziz, 2022). So, the research aims for a suitable water management system for irrigation and drinking purposes, identifying appropriate locations for rainwater gathering structures through geospatial analysis. The methodology is developed incorporating the Surface elevation (ASTER-DEM), land use and land cover (LULC), soil, drainage, and depression maps, which are examined to determine depression volume and surface runoff availability using the Soil Conservation Service - Curve Number (SCS-CN) approach. This helps develop suitable water drainage and rainwater harvesting locations on a large scale for community purposes.\u003c/p\u003e\u003cp\u003eThe SCS-CN method is widely adopted for predicting surface runoff in hydrology and is known for its simplicity and effectiveness. The advanced iterations of the model, such as Model M5, surpass earlier versions by incorporating additional variables like rain duration and adjusting initial abstraction based on rainfall intensity. These enhancements lead to significantly more precise runoff predictions, addressing limitations found in earlier models (Singh et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Verma \u0026amp; Ravindra Kumar Verma, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The versatile adaptability to various climatic and topographical conditions of the method makes it a valuable tool for hydrological analysis and water resource management practices (Abed Alataway, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Hemin Nasraldin M.Amim \u0026amp; Azzadeen Jumaa Darwish, 2022). In the case of rainwater harvesting, the method is essential for assessing water harvesting potential in rainwater harvesting (RWH) projects. This approach determines surface runoff by considering land cover, soil hydrology, and rainfall amounts (I \u0026amp; Dalli KH, 2022). Furthermore, the suitability of selection will be used to identify potential locations that help in developing a sustainable water management system for Koyra Upazila. The research will bring a prominent change in the watershed, improving the community's living standards and agricultural conditions.\u003c/p\u003e\u003ch2\u003eSTUDY AREA\u003c/h2\u003e\n\u003cp\u003eKoyra Upazila, in the southeastern part of Khulna District, is significant due to its strategic and economic importance. The study area profile in Figure 1 presents the geographic location of the upazila that is positioned at 22.3417\u0026deg;N latitude and 89.3000\u0026deg;E longitude, covering an area of 1775.41 square kilometers with 45,750 households. Paikgacha borders the Upazila to the north, the Sundarbans and Dacop to the southeast, and Satkhira District to the west. Koyra was upgraded to an Upazila in 1983 and consisted of seven unions: Amadi, Bagali, Maheswaripur, Maharajpur, Koyra, Uttar Bedkashi, and Dakshin Bedkashi. The administrative region spans only 263.12 square kilometers, as 1512.29 square kilometers are part of the Sundarbans, a key economic area. The proximity to the Bay of Bengal introduces salinity challenges but also supports shrimp.\u003c/p\u003e\n\u003cp\u003eFarming and fisheries contribute to the local river-dependent economy. With a population of 193,931, the area is vulnerable to frequent disasters, compounded by a literacy rate of 50.4% and sanitation coverage of 70%, heightening health risks. Koyra comprises 135 villages within 72 mouzas, relying heavily on agriculture and fisheries, including 28.01 acres of Kash land and 115 Jalmahal. Three forest stations manage the Sundarbans, and seventeen rivers connect the area to the Bay of Bengal. Educational institutions include three colleges, forty government primary schools, thirty-seven secondary schools, and twenty-eight madrasas. Health facilities feature 27 community clinics and five health and family welfare centers. Enhancing infrastructure is crucial for disaster resilience, and ongoing research aims to improve the living conditions in Koyra Upazila.\u003c/p\u003e"},{"header":"METHODOLOGY","content":"\u003cp\u003eThe research methodology addresses critical subjects such as site selection, development of methods to attain objectives, a survey to gather relevant data, and subsequent data analysis and recommendations. The methodological approach was developed to identify a rainwater harvesting site in Koyra Upazila for the development of an agricultural irrigation system extensively using geospatial techniques and the SCS-CN method.\u003c/p\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003eFramework for Rainwater Harvesting Site Identification\u003c/h3\u003e\n\u003cp\u003eThe analysis for flood susceptibility ends with the mapping from both FR and AHP values. Then, to evaluate the field scenario, PRA is assigned to address the challenges faced by the community and the problems arising from floods. The method also helps to find out the reasons and effects behind the human impact on nature.\u003c/p\u003e\n\u003cp\u003eThat\u0026rsquo;s why a nature-based solution is the primary solution to ensure suitable drinking water and salinity-free water for agriculture. Preparing a rainwater harvesting site will be a sustainable solution for Koyra. The government has initiated many projects by providing tanks to store rainwater. The analysis of the rainwater harvesting site is in two sections: 1. Depression site analysis and 2. Runoff analysis.\u003c/p\u003e\n\u003ch3\u003eDepression Site Analysis of Koyra Upazila\u003c/h3\u003e\n\u003cp\u003eThe depression analysis is a GIS-based methodology conducted through DEM analysis. As seen in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e, we attain the depression and depression volume using the ACPF (Agriculture Conservation Planning Framework) V4 toolkit. The ACPF is being utilized in hundreds of watersheds throughout the Corn Belt to educate and involve local farmers in agricultural conservation. It uses high-resolution geospatial data to assist local farming communities in meeting their soil and water conservation needs.\u003c/p\u003e\n\u003cp\u003eAfter attaining the depression location, the primary suitable depression is found based on the drainage line buffer area. Then, those sites are classified into three suitable classes based on LULC and Volume-Area ratio. After the analysis of suitable depression sites, the runoff volumes are calculated for different watersheds within the study area. In this stage, the SCS-CN method is initiated.\u003c/p\u003e\n\u003ch3\u003eSCS-CN Method Analysis for Runoff Calculation\u003c/h3\u003e\n\u003cp\u003eThe runoff from the study area was determined using the SCS-CN method, which was developed by the Soil Conservation Service of the United States Department of Agriculture (USDA) in 1956. This agency is called the Natural Resources Conservation Service (NRCS).\u003c/p\u003e\n\u003cp\u003eThe technique is a prominent model for estimating surface runoff in diverse landscapes, including agricultural, forest, rural, and urban settings (Singh, \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e; Surendra Kumar Mishra \u0026amp; Singh, 2003). Although the conventional SCS-CN model is favored for its straightforwardness and practicality, it overlooks critical elements such as the slope of the land, the duration of precipitation events, and prior soil moisture levels (Shi \u0026amp; Wang, \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). To overcome these deficiencies, several studies have suggested improvements to the model, introducing adjustments to account for factors like slope steepness, soil wetness, length of storm events, and an enhanced soil moisture calculation method (Shi et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e; Surendra Kumar Mishra \u0026amp; Singh, 2001). These enhancements have led to more precise runoff predictions, particularly in areas such as the Chinese Loess Plateau, by remedying the original model\u0026rsquo;s flaws and providing a more detailed analysis of runoff based on an expanded range of watershed features.\u003c/p\u003e\n\u003cp\u003eThe estimate of runoff according to the SCS-CN method (Govindaraju et al., 2024) can be expressed as:\u003c/p\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:Runoff=\\frac{{(Rainfall-.2S)}^{2}}{(Rainfall-.8S)}\\)\u003c/span\u003e\u003c/span\u003e (if rainfall\u0026thinsp;\u0026gt;\u0026thinsp;0.2S) \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip; (1)\u003c/p\u003e\n\u003cp\u003eRunoff\u0026thinsp;=\u0026thinsp;0 (if rainfall\u0026thinsp;\u0026le;\u0026thinsp;0:2S) \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip; (2)\u003c/p\u003e\n\u003cp\u003eIn this investigation, curve numbers were adjusted according to the area of the watershed as follows:\u003c/p\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{CN}_{wt}=\\frac{\\sum\\:{CN}_{i}\\times\\:{A}_{i}}{{A}_{t}}\\)\u003c/span\u003e\u003c/span\u003e) \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip; (3)\u003c/p\u003e\n\u003cp\u003ewhere CN\u003csub\u003ewt\u003c/sub\u003e is the weighted curve number, CN\u003csub\u003ei\u003c/sub\u003e is the curve number for land use type, A\u003csub\u003ei\u003c/sub\u003e is the area according to curve number and land use, and A\u003csub\u003et\u003c/sub\u003e is the total study area.\u003c/p\u003e\n\u003cp\u003eRunoff Volume\u0026thinsp;=\u0026thinsp;Runoff Depth \u0026times; Catchment Area \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip; (4)\u003c/p\u003e\n\u003cp\u003eWhere the catchment area varies based on the watershed. The study area is subdivided into the watershed, and runoff quantity varies according to the size and rainfall of the watershed. SCS-CN helps delineate suitable watersheds and locations to reserve the maximum amount of rainwater to meet local needs and the development of agriculture.\u003c/p\u003e\n\u003ch3\u003eData Collection and Factors Description\u003c/h3\u003e\n\u003cp\u003eThe secondary-based data collection is conducted to develop the required factors at the RWH (Rain Water Harvesting) site. Moreover, the analysis requires additional raster analysis for the detailed assessment of the local area. In the case of Rainwater harvesting site analysis data that are necessary cumulated in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e,\u003c/p\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eData Required for Rainwater Harvesting Site Identification Analysis in Koyra Upazila\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFactor\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFile Type\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSource\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS\u0026thinsp;=\u0026thinsp;Watershed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDEM (30m*30m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUSGS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLULC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSentinel-2, Landsat 8 (10m*10m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eESRI\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRF\u0026thinsp;=\u0026thinsp;Rainfall\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIDW\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBangladesh Metrological Department\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eST\u0026thinsp;=\u0026thinsp;Soil Type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBARC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEL\u0026thinsp;=\u0026thinsp;Elevation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDEM (30m*30m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUSGS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003cp\u003eThe rainwater harvesting site analysis depends on the DEM data to identify suitable rain reserving locations. The quantity of water attained from the HSG (hydrological soil group) and precipitation quantity help develop the runoff graph to delineate the appropriate site. Koyra Upazila has issues with rising salinity and agricultural production loss, which can be resolved through water management and nature-based solutions. For the analysis, SCS-CN is considered. Where the location is categorized based on the LULC and HSG to calculate the runoff and analyze the watershed with DEM. The CN varies with LULC and the type of soil as the infiltration rate changes with the categories, as seen in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThe CN (Curve Number) Required for SCS-CN analysis Based on LULC and HSG\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eLand Use/Land Cover\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eHydrologic Soil Group Curve Numbers\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eB\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eD\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAnnual Crop\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBrush/Shrubs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFishpond\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuilt-up\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGrassland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eInland Water\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMangrove Forest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMarshland/Swamp\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e91\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen Forest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen/Barren\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePerennial Crop\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e83\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003cp\u003eThe attained factors significantly influence rainwater flow, which fundamentally changes the quantity of water stored and runoff. ArcGIS attained the necessary factors like LULC, Elevation, Rainfall, Soil type, and Watershed maps. These factors have the highest level of significance in runoff difference and water conservation model development. The combined methodological process helps create a strong community against the scarcity of suitable sweet water for irrigation. The nature-based solution will solve the water issue sustainably.\u003c/p\u003e"},{"header":"Data Analysis and Discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003cp\u003eRainwater harvesting (RWH) is a technology that collects surface runoff during periods of yielding rain and uses it for rainfed agriculture or household water supply, reducing water scarcity in developing countries and providing safe drinking water. For coastal megaregions Koyra, water is so precious to be found and used for community purposes. Moreover, the systems can improve community water supplies by offering a different water source, which is especially helpful in areas with limited water resources. RWH systems may be managed effectively to reduce the effects of flooding, replenish groundwater, and preserve traditional water supplies by being included in larger schemes for the management of water resources (Huang et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e; Islam et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e; Kim et al., \u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e). The factor description helps in providing a broader look at Koyra upazila and the reasons behind the scarcity of sweet water.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eEvaluating LULC, Slope, and Soil Type Analysis of Koyra Upazila\u003c/h3\u003e\n\u003cp\u003eThe key influencing factors justifying cumulative changes in the runoff variations are slope, soil type, and LULC. In the SCS_CN process, the hydrological soil group and LULC are considered for the difference in curve number, largely the runoff values. Urban runoff production is positively correlated with the number of impervious surfaces, and the contribution of impervious and pervious surfaces to runoff production is influenced by the pattern and intensity of rainfall events (Guan et al., \u003cspan class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e\n\u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eParameter Description of Koyra Upazila, Khulna\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eClass Name\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eClass Pixel\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eClass (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eArea (Km2)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"7\"\u003e\n \u003cp\u003eLand use/Land Cover\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e965914\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.3632\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e95.56\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e37801\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.0142\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.74\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlooded Vegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3949\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.0015\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.39\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCrop Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1341080\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.5042\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e132.68\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuildup Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e303651\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.1142\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30.04\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBare Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3434\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.0013\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRange Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3728\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.0014\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eSoil Texture\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eThionic Fluvisols\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8363\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.1819\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e47.85\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEutric Gleysols\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e37624\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.8181\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e215.27\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"5\"\u003e\n \u003cp\u003eSlope (In Degree)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;1.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e136053\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e53.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e141.11\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.301\u0026ndash;2.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e82065\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e32.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e85.12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.301 -3.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27089\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e28.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.301\u0026ndash;4.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6490\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6.73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.301\u0026ndash;5.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.07\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eIn terms of the slope factor, in low-land or gentle slopes (LL/GS), there\u0026apos;s a marked correlation between the runoff speed and the terrain\u0026apos;s curvature. The terrain gradient spans from flat to steep, ranging from zero to 5.3 degrees. Notably, the region with slopes between 0 and 1.3 degrees, characterized by minimal incline, emerges as a lower speed of runoff. Conversely, areas featuring steeper gradients, specifically within the range of 4.3 to 5.3 degrees, exhibit substantially higher runoff and less ground infiltration. The remarked scenario is that the majority of Koyra upazila belongs to the lower slope area of about 141.11 km2, severing a large basin for groundwater infiltration. The Khal side areas have higher slopes and higher runoff towards Khal, and these drainage line areas are considered suitable for RWH site development.\u003c/p\u003e\n\u003cp\u003eThe LULC classification system divides the land into seven unique categories: water, vegetation, flooded vegetation, cropland, built-up areas, bare land, and rangeland. Among these, cropland occupies the most significant area at 132.67 square kilometers. Conversely, rangeland covers a much smaller area, approximately 0.37 square kilometers. A decrease in rangeland coverage from 1984 to 2011 was associated with increased peak levels of runoff (Quast et al., \u003cspan class=\"CitationRef\"\u003e2011\u003c/span\u003e). Additionally, the bare land and water portion has a massive influence on the climatic influence and is the least important in developing RWH sites. The fisheries and water body take a huge area of 95 km\u003csup\u003e2\u003c/sup\u003e in the Koyra Upazila, making it one of Khulna\u0026apos;s most climate-vulnerable zones. However, the highest portion of land is taken by agricultural land and has the maximum potential for being considered suitable RHW sites.\u003c/p\u003e\n\u003cp\u003eAdditionally, the Koyra area has major clay soil, which justifies quick runoff and less infiltration. The soil texture is mainly divided into two types: Eutric Gleysols and Thionic Fluvisols. The composition of soil texture, particularly Thionic Fluvisols and Eutric Gleysols, can significantly impact flood occurrences. The spatial arrangement of soil texture plays a pivotal role in governing water dynamics and moisture recharging during dry spells (Patel et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e). In regions with contrasting textural boundaries and sandy layers, the humidity flow may encounter hindrances, impeding groundwater replenishment (J\u0026oacute;zsef Dezső et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). Furthermore, the balance between clay, silt, and sand content in the soil influences its permeability and capacity to retain water, thus affecting the infiltration of precipitation into aquifers (Ahmad et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e). Here, Eutric Gleysols soil covers a large area of 215.27 square kilometers, and Thionic Fluvisols covers a lower area of 47.85 square kilometers. The arrangement of soil groups influences groundwater infiltration and runoff quantity, which helps in identifying generalized suitable RWH sites for the lesser infiltration, reserving the maximum water for the dry season, and using it further for irrigation.\u003c/p\u003e\n\u003ch3\u003eEvaluation of Metrological Parameters of Koyra Upazila\u003c/h3\u003e\n\u003cp\u003eThe analysis portion includes temperature change that has a huge impact on river flow, precipitation quantity, and suitable living conditions. Temperature impacts flood intensity via the Clausius-Clapeyron relation, with higher temperatures enabling more moisture to be stored. However, changes in circulation regimes may alter these predicted effects (Blenkinsop et al., \u003cspan class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eKoyra, Bangladesh\u0026apos;s annual variations in the maximum average temperature between 1989 and 2017 represent considerable variability rather than a linear pattern, indicating dynamic weather conditions where there was a significant variation in 2001, with an average maximum temperature of 29 degrees Celsius and a sudden increase to 32 degrees Celsius the following year according to Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e. Over a three-decade period, there is no discernible increase or decreasing trend in the general temperature pattern. With temperatures rising and dropping around a central average value, the graph mimics ocean waves. The record starts and finishes at the same time, with the highest average maximum temperatures of 32 degrees Celsius occurring in 1989 and 2017.\u003c/p\u003e\n\u003cp\u003eThe temperature scenario has a massive influence on the rainfall intensity. Rainfall movement influences runoff response, peak discharge, hydrograph forms, and flooded regions; higher velocities and directions result in larger peaks (Ghomash et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e). Koyra\u0026rsquo;s geographical status makes it a major vulnerable place for heavy rainfall and flood that can be taken under management with channelized stored excess rainwater towards a sustainable water management system for agricultural development. The rainfall map in Koyra Upazila shows a fluctuating pattern from 1989 to 2017, indicating unpredictable weather. Some years saw heavy rainfall, while others saw significant precipitation, such as floods in Bangladesh in 1998, 2007, and 1990. These floods caused considerable damage to crops and people, with an estimated total damage of USD 10.64 million. Conversely, years like 1996, 2009, and 2010 saw minimal rainfall, resembling a drought.\u003c/p\u003e\n\u003cp\u003eAccording to the data from WDB (Water Development Board), Khulna, there is a complex relationship between precipitation and temperature in Koyra Upazila, with significant year-to-year variability. Temperature may not be the sole driver of rainfall, as other atmospheric or geographical factors may also play a role. The temperature line shows a slight undulating pattern with periodic rises and falls but not a pronounced long-term upward or downward trend. Years like 1990 and 1998 saw high rainfall, but temperature readings showed an inverse relationship. Severe rainfall intensity is linked to air temperature, potentially increasing flash floods. The growth of the upazila is crucial for maintaining ecological balance, and nature-based solutions are essential for managing rainwater and high-temperature rates. The attaining of agricultural sustainability is possible through the development of sustainable drainage of runoff and its storage and distribution management. The initiative starts with the identification of suitable RWH sites and, further, the runoff calculation to delineate the reservoir strength for sustaining in the dry seasons.\u003c/p\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003eIdentification of Suitable RWH Site for Koyra Upazila\u003c/h2\u003e\n \u003cp\u003eIdentifying suitable RWH in Koyra incorporates local participation and geography-based analysis for better and more sustainable solutions for the community. The development includes two phases: 1. Runoff calculation at the watershed and 2. Depression and suitable locations for RWH\u0026apos;s infrastructure development.\u003c/p\u003e\n \u003ch2\u003eWatershed Identification for Koyra Upazila\u003c/h2\u003e\n \u003cp\u003eWatersheds are defined by topographic limits and characterized by the flow of water within them, which is frequently delimited by ridgelines from which water flows to a shared outlet. A watershed\u0026apos;s integrity is characterized by its potential to support and preserve biological processes and activities necessary for biodiversity and the benefits supplied to society despite human-induced changes (Gou, 2013; Flotemersch et al., \u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eWatershed management entails the balanced use of land and water resources, with hydrological models helping to plan and implement soil and water conservation measures. Through the management that had been considered concerning engineering and infrastructure development for community resilience, the focus of integrated watershed management approaches has shifted from engineering-focused techniques to ones that emphasize poverty reduction and livelihood enhancement, highlighting the need for comprehensive ecosystem management (Prasad et al., \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e; Darghouth et al., \u003cspan class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eKoyra upazila in Khulna district had been suffering from a huge salinity problem. For establishing suitable RWH sites, watershed delineation is a prime consideration when analyzing the quantity of water that can be attained from the rain to support the community. The watershed is prepared from the DEM data, and then the major catchments collect water within the study area.\u003c/p\u003e\n \u003cp\u003eThe watershed analysis presented in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e classifies the study area into eight watersheds delineated based on DEM characteristics. Each watershed includes different landforms and soil groups. As a result, runoff varies, ultimately causing different water quantities to be consumed in other watersheds. The variations are valued through curve number (CN).\u003c/p\u003e\n \u003cp\u003eThe CN values represent the tendency of runoff for certain HSG and particular LULC. The values are taken from Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. The watershed detail criteria map flows of the LULC and HSG map are presented in Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e. The criterion provides a particular CN and Area under the CN value. That ultimately helps quantify the water attained from specific watersheds tabulated in Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eWatershed details based on Watershed, HSG (Hydrological Soil Group), and LULC (Land Use and Land Cover) in Koyra Upazila\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFID\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWS\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eHSG\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLULC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCN\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAREA (KM2)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBare Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.000857\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuildup Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.326377\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCrop Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e15.031598\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRange Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.014432\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.063782\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.655875\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBare Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.000526\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuildup Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.096782\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCrop Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e5.590702\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlooded Vegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.003251\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRange Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.01032\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.503924\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.408249\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBare Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.002501\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuildup Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.388522\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCrop Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e15.677003\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlooded Vegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.000478\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRange Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.009174\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.276141\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7.350427\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuildup Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.024415\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCrop Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.156973\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.12815\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBare Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.002646\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuildup Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.279154\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCrop Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e22.8293\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRange Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.046956\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.254356\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.232439\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBare Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuildup Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.442983\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCrop Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.206819\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRange Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.014878\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e3.324089\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBare Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.070736\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuildup Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.053413\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCrop Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e11.130655\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlooded Vegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.004775\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRange Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.108654\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.019494\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6.397443\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBare Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.000068\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBuildup Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.58862\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCrop Land\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e8.265964\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVegetation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.038077\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.529522\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003eWatershed details are discussed in Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e based on the different watersheds and LULC. A total of eight watersheds are discussed. Here, the hydrological soil A group is mentioned. Hydrological Soil Group A includes soils with the highest infiltration rates when saturated, leading to low runoff potential. These soils are primarily sandy, with textures ranging from sand to sandy loam, characterized by large pore spaces and high permeability. Each watershed has a different land use and land cover according to the watershed zone. Based on the soil type and LULC, the curve number (CN) is defined. This CN mainly defined how much water flow would occur based on the LULC and HSG. Finally, the surface runoff base is calculated by incorporating the rainfall data using Eq. 4. The Area for the watershed is divided into different LULC and HSG. As seen in Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e, cropland takes up the maximum amount of land in the watershed except for WS 6. That helps initiate locations for RWH and helps with community development.\u003c/p\u003e\n \u003cp\u003eCalculation of Surface Runoff for Koyra Upazila\u003c/p\u003e\n \u003cp\u003eRainfall data are used to calculate the runoff depth in the analysis of surface runoff. According to rainfall data from June 2022, the runoff depth (Q) is calculated for every watershed zone. The bar chart in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e represents the runoff depth in millimeters for eight different zones of Koyra Upazila in Khulna.\u003c/p\u003e\n \u003cp\u003eIt measures the runoff depth in millimetres on the vertical axis, with the zones measured along the horizontal axis as Ws1 through Ws8. From the results obtained in this section, it can be noted that there is no uniformity in the runoff depth of the different zones. It is evidenced by a scenario where Ws5 has the highest runoff depth of 724.60 millimetres, and Ws6 has the lowest depth of 236.87 millimetres. Noted is that Ws1 and Ws8 have the same runoff depth at 671.31 millimetres, while Ws2 and Ws7 present it with equal depth, measured at 289.29 millimetres. The same zones, Ws3 and Ws4, project a moderate runoff depth at 310.53 and 270.13 millimetres. This graphical representation clearly shows the upazila distribution of runoff to identify primary and minor runoffs, which may contribute to local water management practices\u0026mdash;ultimately forming the weight of different watersheds tabulated in Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e, which represents the quality of watershed that can be taken for the development of the RWH site.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003ctable id=\"Tab5\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eDetails of the watershed and their weight in Koyra Upazila\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eId\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWS\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eApprox. CN\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRunoff depth Q (Mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eArea Of Watershed\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal Area of Basin\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWeight (W)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e671.3145375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e22.092921\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.5616\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e118.1862\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e289.2903995\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.613754\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.5616\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e26.77284\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e310.5346949\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25.704246\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.5616\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e63.60670\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e270.1285744\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.309538\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.5616\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.666303\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e724.6036642\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27.644851\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.5616\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e159.6256\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e236.8726036\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.988869\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.5616\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.30440\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e289.2903995\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20.78517\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.5616\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e47.75237\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e671.3145375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.422251\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e125.5616\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e61.10343\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003eTable \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e puts down meticulously the characteristics of eight watersheds within Koyra Upazila, giving a detailed overview of Curve Number (CN)\u0026mdash;meaning the potential runoff of the area, the actual measured Runoff Depth (Q), the physical Area of the Watershed and a calculated Weight (W) for each of the watersheds. The weight summarizes an interplay between the watershed size and its runoff capacity. Higher weights mean either big sizes of watersheds or large depths of runoff. It is evident in the case of the fifth zone of the watershed, which stands with the most significant weight of 159.63 due to having the largest area of 27.64 square kilometers and the most excellent runoff depth of 724.60 millimeters among the zones\u0026mdash;conversely, a smaller basin area or lower runoff depth results in a lower weight value. Zone, 4 of a watershed, has been assigned a markedly lower value at 0.67, corresponding to its relatively minor area of 0.3095 square kilometers and even runoff depth of 270.13mm. Ultimately, the runoff volume is calculated by multiplying runoff depth (Q) by the watershed area. The relationship of the physical characteristics of the watersheds with the runoff features suggests a balanced hydrological balance in the basin. The weighted nature of this table approach in hydrologic assessment offers an analytical strategic framework that could be useful in water resource management, especially in identifying and prioritizing zones relating to rainfall harvesting initiatives. The various values of the weights sum up to estimate the relative hydrological impact of each of the watersheds and sensitize practices and infrastructure development for sustainability in optimizing the use and conservation of water resources within Koyra Upazila. Thus, from this analytical lens, we take the understanding and forecast not only the present water dynamics but also the future challenges based on water within the region. Runoff management through proper elevation and surface quality will enhance the water flow condition and conserve water to an extent sufficient for the community.\u003c/p\u003e\n \u003cp\u003eDepression Site Analysis for Koyra Upazila\u003c/p\u003e\n \u003cp\u003eDepressions in digital elevation models (DEMs) can reflect actual landscape features or mistakes; a novel approach for drainage network extraction retains these characteristics without modifying the original DEM (Wang et al., 2009). To better comprehend and manage the intricate topography of depressions for hydrological modeling and terrain analysis, the idea of a depression hierarchy has been proposed. This represents a better modeling technique for identifying natural retaining zones for rainwater conservation (Barnes et al., 2020).\u003c/p\u003e\n \u003cp\u003eIn the analysis process, a GIS-based technique, including the ACPF V4 toolkit, is used to identify depressions in the site area. However, the depression is primarily based on the closed proximity to the drainage line incorporating the buffer zone of the drainage network. About 44 depressions are taken within the buffer zone of the drainage network. In the secondary phase of site selection, the sites are eliminated according to the suitable criteria that the area of the depression should be more than 1.5 hectors (IMSD, \u003cspan class=\"CitationRef\"\u003e1995\u003c/span\u003e) and the volume-to-area ratio of the sites should be more than equal to 2 (Tiwari et al., \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e). After the criteria-based selection, we obtained about 17 suitable rainwater harvesting locations, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003eThe 17 sites are suitable for the infrastructural development of RWH. But, based on their physical properties and land uses, the sites are categorized into Suitable, Moderately Suitable, and Not Suitable. The suitability category is formed on the criteria of,\u003c/p\u003e\n \u003col style=\"list-style-type: lower-roman;\"\u003e\n \u003cli\u003eThe sites are out of High Flood Vulnerable Zones presented in the FSM map\u003c/li\u003e\n \u003cli\u003eThe majority of the site portion falls within the agricultural land, so land acquisitions become much easier\u003c/li\u003e\n \u003cli\u003eDepression locations in and around built-up areas are eliminated and are not considered for additional study. This is due to the likelihood of higher land acquisition costs for locations following populated areas.\u003c/li\u003e\n \u003cli\u003eSites with depressions that adequately absorb runoff volume are ideal for constructing RWH structures (Tiwari et al., 2018).\u003c/li\u003e\n \u003c/ol\u003e\n \u003cp\u003eWith the proper utilization of criteria-based assessment, the sites are classified as shown in Table 6.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003ctable id=\"Tab6\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eSuitability Specification of different RWH Sites of Koyra Upazila\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSite\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eArea (m2)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMax depth (m)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVolume (m3)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWatershed\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCategory\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34646.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e124726.536\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSuitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21189.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e72045.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSuitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e400189.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1760835.692\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSuitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e61245.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e189860.151\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSuitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e217402.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e673947.688\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSuitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e75250.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e150500.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNot Suitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e39811.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99527.925\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNot Suitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e73147.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e256014.605\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNot Suitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e199989.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e999948.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eModerately Suitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e208726\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e542687.496\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSuitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e73599.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e529913.736\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNot Suitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e91252.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e228132.325\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eModerately Suitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e102793.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e534524.276\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eModerately Suitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e201613.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e705646.375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNot Suitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35428.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e92113.216\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNot Suitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34152.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e68304.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSuitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSite 17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e107786.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e431146.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSuitable\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003eThe 17 suitable depression sites are crucial locations for the project\u0026apos;s development. The criterion-based classification has helped identify the most influential sites for the maximum water for use. Koyra, being a coastal area, had to face several climatic events like floods, cyclones, and salinity intrusion. The frequent effect damages the agricultural condition at a rapid rate. In coastal countries afflicted by salinity, such as Bangladesh, rainwater collecting provides a low-cost option for potable water supply, with systems built to meet local building layouts and rainfall circumstances (Islam, K et al., \u003cspan class=\"CitationRef\"\u003e2014\u003c/span\u003e). To overcome the scenario, a suitable ranking and establishment of RWH is far more critical for the development of the community\u003c/p\u003e\n \u003cp\u003eThe suitable rainwater harvesting map in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e represents the location of suitable sites in green colour. As can be seen, about five suitable sites exist in WS1 in Amadi Union. Another two suitable sites are found in WS6 at Maharajpur Union. The last site is placed in the Koyra Union. These eight suitable sites fall within the criteria. The watersheds have different capacities or water volumes based on their cumulative CN, rainfall, and area. The use of RWH can considerably help to satisfy irrigation demands and be a cost-effective and ecologically beneficial alternative in locations suffering water constraints (Ter\u0026ecirc;ncio et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e; Preeti et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e; Ejegu \u0026amp; Yegizaw, \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). The Amadi Union holds one of the most significant location values for the best suitability of rain-supported structures. As the union has a lower flood frequency than other unions, it can be one of the essential locations for initiating the project.\u003c/p\u003e\n \u003cp\u003eTable \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e describes the capacity details and supported water quality from the basin. The table includes data from all eight watersheds in Koyra Upazila. The integrated water management system helps the irrigation system for the development of agriculture.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003ctable id=\"Tab7\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eWatershed Characteristics and Water storage capacity of Koyra upazila\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWatershed\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRunoff depth Q (mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eArea of Watershed (km\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVolume of Runoff (m\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eThe capacity of Suitable Locations (m\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e671.3145375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.092921\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1483129.904\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2821415.217\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e289.2903995\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.613754\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e335974.7534\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e310.5346949\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.704246\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e798206.0188\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e150500.64\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e270.1285744\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.309538\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8361.505865\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e266014.605\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e724.6036642\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.644851\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2003156.033\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e99527.925\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e236.8726036\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.988869\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e141859.8993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3540853.158\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e289.2903995\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.78517\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e601295.0132\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e160417.716\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWS8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e671.3145375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.422251\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e766792.3148\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e431146.64\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eTotal Amount of Water Provided by the Execution of RWH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e24,84,944.231 m\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003eKoyra, one of the most vulnerable areas to climate change, had to deal with the devastating effects on agricultural production. The continuous effect and lack of suitable water significantly impact the farmers. The constant use of groundwater is causing the water table to decline, and the porous space is filled with sea salt water. That\u0026rsquo;s why groundwater use will be impossible in the upcoming years. Farmers in areas with salty groundwater use \u0026quot;blended water\u0026quot; solutions, which combine saline and freshwater to reduce soil salinity and sustain agricultural yields, especially for salt-sensitive crops like strawberries (Bani et al., \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). To support agriculture, RWH is one of the crucial methods for developing agriculture in Koyra Upazila.\u003c/p\u003e\n \u003cp\u003eAs seen in Table \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e, WS 1 Amadi Union has a runoff volume of 1483129.904 m\u003csup\u003e3\u003c/sup\u003e, but its suitable site capacity is twice as high as the runoff volume. In WS2, there is no suitable location where 335974.7534 m3 of rainwater can be managed with interconnected khals for suitable water movement into the ground or for fishing purposes. Also, the WS3 and WS4 have a runoff volume of 798206.0188 m\u003csup\u003e3\u003c/sup\u003e and 8361.50 m\u003csup\u003e3\u003c/sup\u003e of water. However, WS1 has a suitable capacity of 150500.64 m\u003csup\u003e3\u003c/sup\u003e only. WS4 has enough capacity at the suitable site to collect the water condition. Though WS5 has a huge amount of runoff water, it only has a capacity of 99527.925 m\u003csup\u003e3\u003c/sup\u003e. Moreover, the excess water can be managed with a regenerated interconnected Khal at the upazila. Similarly, WS6, WS7 and WS8 has capacity to provide 141859.8993 m3, 160417.716 m3 and 431146.64m3 of water. The cumulative support is enough to sustain agricultural production throughout the year without affecting the groundwater.\u003c/p\u003e\n \u003cp\u003eBased on the rainfall runoff and capacity of a suitable location, the total amount of water that the execution of RWH can provide is \u003cstrong\u003e24,84,944.231 m\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sup\u003e. Koyra Upazila\u0026apos;s socio-economic development mainly relies on small and medium-sized businesses, but it also depends on agriculture, fishing, tourism, industry, weaving, and livestock rearing. However, Koyra is significantly impacted by climate change; although the residents are aware of this, they have not yet made the necessary adjustments (Islam et al., \u003cspan class=\"CitationRef\"\u003e2014\u003c/span\u003e). Moreover, the scarcity of water has made the job of production at a massive level for years. That amount of water can be fruitful to sustain agricultural development.\u003c/p\u003e\n \u003cp\u003eKoyra mainly has two seasons of paddy production. One is Boro, another is Aush. According to the Koyra Upazila agricultural administration, 36,000 bighas of Boro paddy will be grown this season in 2023. In 2022-23, paddy produced was about 73,000 metric tons. The Bangladesh Rice Research Institute (BRRI) estimates that one kilogram of Boro rice and Aush rice requires about 3400 liters (Hossain et al., \u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e). Based on the data, the necessary amount of water and support facilities from the rainwater harvesting are given in Table \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003ctable id=\"Tab8\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eWater requirements in agriculture and Support from the RWH project in Koyra Upazila\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eThe Amount of Water Required for Paddy Production\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e24,82,000.000 m\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal Amount of Water Provided by the Execution of RWH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e24,84,944.231 m\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003eWith the project\u0026apos;s execution, it will be possible to ensure the crops\u0026apos; yearly production without affecting groundwater extraction. The initiative can be developed by regenerating rivers and the Khal to distribute rainwater and groundwater recharge. Additionally, sweet rainwater can be mixed with saltwater and used on agricultural land, reducing the overall cost and quantity of sweet water use. Thus, RWH harvesting can help develop integrated water management in Koyra Upazila and modify the existing water resource condition for a sustainable future.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"RECOMMENDATION","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003cp\u003eKoyra\u0026rsquo;s vulnerable location in the southeast coastal region of Bangladesh makes it an emerging area for severe climatic events, poor water resources, and poor sanitation conditions. The yearly continuation of the climatic effects vastly affects the upazila\u0026apos;s agricultural and suitable water conditions. Implementing RWH sites is a vital solution for managing water resources, particularly given the challenges of frequent flooding and salinity intrusion, while developing an integrated water management system for the upazila. The RWH method encompasses various techniques to collect and utilize rainwater for different purposes. RWH technologies can improve crop production by conserving soil moisture (Kayombo, \u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e). The geospatial analysis formulates the critical zones at the upazila for collecting Rainwater and using it for agricultural growth. With the mitigation of the negligible evaporation of the water, it is possible to ensure about 80% rice production for the Koyra upazila. The usability of rainwater can be intensified with more significant modification and development of interconnected canals with sites and rivers. The unlimited saltwater source can be reformed with the mix-up with sweet water to decrease the saline intensity of the river water and further use it for irrigation purposes.\u003c/p\u003e\n \u003cp\u003eThe water resource scenario of Koyra upazila is marked with heavily resourced khals and bills supporting agriculture and fisheries cultivation. The constant effect of devastating hazards like floods, Aila, etc., damaged the regulation of dams and polders, ultimately causing the death of many vital khals of the upazila. Channel restoration initiatives would be crucial to environmental conservation and habitat enhancement. Also, implementing vortex rock weirs (VRWs) in channel design will help to maintain channel stability, prevent erosion, and improve aquatic habitats while facilitating fish passage (Mielhausen et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e). Wetlands are natural buffers against floodwaters, reducing the impact on human settlements and agricultural lands. Restoring or establishing wetlands is are initiatives that enhance the natural capacity of the environment and reservoir for rainwater. In addition to the environmental benefits, RWH supports the community by providing a reliable water source for irrigation, which is critical for agricultural activities. A participatory approach would help to delineate significant, influential information that should be incorporated in planning for the community development of farmers and fishermen.\u003c/p\u003e\n \u003cp\u003eThis reliable water source ensures that crops can be grown throughout the year, regardless of rainfall variability, thus enhancing food security. This approach aligns with the broader goals of integrated water resource management, which seeks to balance the needs of human consumption, agriculture, and ecosystem health. It also promotes community resilience by providing a sustainable water supply that can be managed locally. By adopting RWH, Koyra Upazila can achieve greater resilience against climate change impacts, such as increased flooding and changing precipitation patterns, enhance agricultural productivity, and ensure a more sustainable and secure water future for its residents. Additionally, these measures can foster economic growth by stabilizing farm production and providing opportunities for community-based water management initiatives.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eKoyra, a significant coastal area in Bangladesh, frequently holds one of the major shareholders in the economic and agricultural sectors of the Khulna division. Additionally, aquaculture provides a major share of the country's overall GDP. But, one of the key hazards is that floods cause substantial loss of life and property, disrupt economic and social stability, and spread pollutants and bacteria, leading to serious health risks. The country\u0026rsquo;s geographical and climatic conditions worsen the impact of flooding, resulting in riverbank erosion, infrastructure damage, and harm to homes and vegetation. Climate change further exacerbates these challenges. Since Cyclone Aila in 2009, Koyra Upazila has faced numerous natural disasters, including cyclones, floods, and riverbank erosion. Efforts by NGOs and locals to rebuild housing have only provided short-term relief. Social media plays a crucial role in reducing cyclone damage by disseminating information. At the same time, farmers have adapted to salinity and waterlogging by growing resilient crops such as hybrid sunflower, mustard, cotton, maize, wheat, and Aman paddy. Despite these adaptations, the ecosystem continues to suffer, affecting habitats, biodiversity, and livelihoods. A sustainable measure is proactively required for a drastic change in improving the quality of life and finding solutions for water salinity and resource management. The agricultural sector at the coastal koyra is taken under consideration in the Delta 2100 plan resolving issues with sustainable solutions where the paper advocates rainwater harvesting (RWH) as a method to collect and conserve water, which helps address groundwater scarcity and combat saltwater intrusion into freshwater sources. The identification of suitable locations for RWH facilities, based on the SCS-CN method, has the potential to significantly boost paddy production and support the agricultural needs of the upazila. The watershed delineation with capacity identification helps in finding important and suitable locations for rainwater restoration and further use in necessary periods. The initiative will help reduce the salinity of existing khals with a mixture of sweet rainwater for the development of agricultural production. The initiative will be more fruitful through the regeneration of illegally occupied khals and waterbodies at the Koyra upazila. Properly implementing these recommendations can minimize most issues in Koyra Upazila, leading to economic growth and sustainable resource use and benefiting future generations. It will help in forming a climate-resilient and resource-optimized framework in Koyra Upazila, supporting the overall development of the upazila.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch5\u003eData availability statement\u003c/h5\u003e\n\u003cp\u003eThe data used is accessible and there by no issue in sharing while requested.\u003c/p\u003e\n\u003ch5\u003eFunding\u003c/h5\u003e\n\u003cp\u003eThis research received no specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003ch5\u003eDeclaration of competing interest\u003c/h5\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003ch5\u003eAuthor\u0026rsquo;s Contribution\u003c/h5\u003e\n\u003cp\u003eLabib Intisar: Formal analysis, Software, Writing\u0026mdash;Original Draft. Rowdra Dip Chackroborty: Conceptualization, Formal analysis, Writing\u0026mdash;Original Draft, Methodology, Software, Data Curation, Visualization. Dulal Sarkar: Resources, administration, Supervision, Writing\u0026mdash;Review, \u0026amp; Editing.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbdullah Harun Chowdhury, \u0026amp; Ahmed, R. (2012). Water, Sediment and Macrophyte Quality of Some Shrimp Culture Ponds and Freshwater Ecosystems of Koyra. \u003cem\u003eBangladesh Journal of Botany\u003c/em\u003e, \u003cem\u003e41\u003c/em\u003e(1), 35\u0026ndash;41. https://doi.org/10.3329/bjb.v41i1.11080\u003c/li\u003e\n\u003cli\u003eAbed Alataway. (2023). 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SCS-CN methodology further modified. \u003cem\u003eWater Supply\u003c/em\u003e, \u003cem\u003e23\u003c/em\u003e(6), 2604\u0026ndash;2622. https://doi.org/10.2166/ws.2023.129\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Disaster, SCS-CN, Geospatial Modelling, Water Management, Sustainability, Climate Change, Agriculture","lastPublishedDoi":"10.21203/rs.3.rs-6857794/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6857794/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWater is one of the most valuable resources on the verge of extinction. The continued depletion of fresh water poses a tremendous threat to humanity. Koyra Upazila in Khulna with flood-susceptible zones, causing unavailability of fresh water. Additionally, the salinity problem in that area is causing the decline in soil fertility, biodiversity loss, and freshwater pollution. This research proposes a GIS-based system that uses data from remote sensing to determine appropriate locations for rainwater gathering structures as a solution. The methodology is developed incorporating the Surface elevation, land use/land cover, soil, drainage, and depression maps, which are examined to determine depression volume and surface runoff availability using the Soil Conservation Service - Curve Number (SCS-CN) approach. The selection suitability will be used to identify potential locations, ultimately helping to develop a sustainable water management system for Koyra. The marginalized community will be able to attain fresh water and sweet water for cultivation. Adding in, the regeneration of Shakbaria Khal will bring a prominent change in the watershed, improving the community living standard and agricultural conditions. The research helps to develop a community that is resilient to disasters caused by climate change by providing a sustainable water management system.\u003c/p\u003e","manuscriptTitle":"A Geospatial Analysis for Thriving Agricultural Sector at the Koyra Upazila, Khulna, Bangladesh by Identifying Suitable Rainwater Harvesting Structure Site Integrating SCS-CN","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-27 11:42:07","doi":"10.21203/rs.3.rs-6857794/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":"015d8f68-1620-452d-9b1e-a3092ce81672","owner":[],"postedDate":"October 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-10-27T11:42:07+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-27 11:42:07","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6857794","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6857794","identity":"rs-6857794","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}