Analysis on the Spatiotemporal Changes of Groundwater Potential Zone in Sylhet, Bangladesh: An AHP and GIS based approach

Groundwater Potential Zone (GWPZ) refers to the appropriate locations for groundwater recharge and infiltration. However, groundwater resources have been constantly under stress due to rapid population increases, contributing to the increase in impermeable structures. This research article aims to analyze spatiotemporal changes in GWPZ’s in Sylhet district, Bangladesh using Remote Sensing datasets, Geographic Information System techniques, and one of the Multi-Criteria Decision Making (MCDM) models known as Analytical Hierarchy Process (AHP). Nine influential parameters, such as Rainfall amounts, Surface Geology, Slope, Land Use Land Cover (LULC) with accuracy assessment, Drainage Density, Lineament Density, Hydrological Soil Group, Groundwater Depth below surface level, and Topographical Wetness Index have been weighted by the AHP decision matrix to identify GWPZ for the years 1998 and 2024 in Sylhet district using the weighted overlay analysis in ArcGIS. The northern part of the district has shown greater potential in both years, whereas the southern and eastern regions comparatively have lower potential. The GWPZ in 2024 at Sylhet exhibits a major shift in groundwater potentiality, particularly in the high potential zone categories, which decreased by approximately 16% compared to 1998. The increasing trend of the moderate potential zones in 2024 has also been identified. Modification of the GWPZ is examined by addressing the spatiotemporal changes in the three most influential variables, which are LULC changes, Groundwater Depth Deviation, and Rainfall Variability. Validation of the research is performed with the groundwater level data collected from Bangladesh Water Development Board (BWDB). The study reflects the critical need for sustainable groundwater managing policies to alleviate the declining trend in high-potential zones and ensure water security in the region.