Groundwater potential zone identification using an analytic hierarchy process in Dhaka City, Bangladesh

Water scarcity is increasing throughout the world due to the effects of increasing groundwater abstraction and climatic change. The present study was undertaken to evaluate groundwater potential zones (GP) in Dhaka city using GIS and remote sensing (RS) techniques. A weighted linear combination (WLC) was used in association with GIS techniques to identify GP zones for an area that encompassed the city to 5 km outside of the city boundaries. Declining groundwater levels are a significant issue for the city, and these are influenced by the rate of groundwater abstraction, potential evapotranspiration (PET), rainfall, land use/land cover pattern, surface lithology, drainage pattern, recharge conditions, and geomorphology. Seven thematic layers were used for the GP calculation, where drainage density and infiltration zone maps were modified for the settlement area to reduce the negative influence on the final result. The GP calculation indicated that 188 km2 (24%) had a ‘very low’ groundwater potential; 150 km2 (19%) had a ‘low’ potential; 138 km2 (18%) had a ‘moderate’ potential; 143 km2 (19%) had a ‘high’ potential; and 154 km2 (20%) had a ‘very high’ potential. Surface lithology was found to be the most sensitive parameter. This parameter had standard deviations of 4.18% and 36.39% were found for a map removal sensitivity analysis (MRSA) and a single parameter sensitivity analysis (SPSA), respectively. The validation result shows that 93% area with a ‘high’ groundwater potential zone falls in the area where the groundwater depth is in the range 6–22 m below the land surface.