Groundwater potential zone identification at Plio-Pleistocene elevated tract, Bangladesh: AHP-GIS and remote sensing approach

Abstract

Water is pondered as a strategic resource that has a great ascendancy on human life and socio-economic development. The present study has toted to understand the groundwater potential (GP) zone at the drought-prone Plio-Pleistocene elevated tract in Bangladesh using geographical information system (GIS) and remote sensing (RS) technique. Ten thematic layers have been escorted for the current study that is extracted from different secondary sources. Thematic layers have been co-registered and rectified to the UTM 45 projection and world geodetic system (WGS) 1984 datum. All thematic layers have been assimilated using weighted linear combination (WLC) and GIS-based multi-criteria evaluation for class normalization using Saaty's Analytic Hierarchy Process (AHP). Different classes of each layer are prepared for the determination of weight and ranking to generate the pairwise comparison matrix (PWCM). Thematic layers viz. drainage density (DD), slope (SLO), geomorphology (GM), soil thickness (ST), groundwater table depth (GWTD) have a negative influence, besides lineament density (LD), rainfall (RF), infiltration rate (IR) have a positive influence with increasing class range values for GP. Surface lithology (SL) and land use/land cover (LULC) are reliant on porosity and presence of water bodies for percolation into the aquifer. Map removal sensitivity analysis (MRSA) and the single parameter sensitivity analysis (SPSA) are also carried for assessing the effect after removing a thematic layer and the effective weight of thematic layers on the GP map, respectively. GP map has been classified into five zones i.e. very low (26% area or 511 km2); low (56% area or 1075 km2); moderate (15% area or 282 km2); high (2% area or 38 km2); and very high (1% area or 25 km2). MRSA results show that groundwater table depth is more sensitive with a mean variation index of 8.9%, besides SPSA results show that the effective thematic layer is slope (weight 29.7%).