摘要
Groundwater potential characterization is a major component of the developmental strategies required for sustainable management of the water resources of a country. This study explores the potential of Natural Resources Conservation Service (NRCS-CN) estimated runoff/infiltration to verify a knowledge-based groundwater potential zone mapping methodology using remote sensing and GIS. Eight criteria/factors regarded as positive indicators to the existence of groundwater in the study area were mapped and weighted based on the knowledge of the local geology using analytical hierarchy process (AHP). The results from AHP were integrated using Weighted Index Overlay Analysis in a GIS environment to delineate the groundwater potential map of the area. Five classes consisting of very good, good, moderate, fair and poor groundwater potentials, each occupying 4.6, 53.3, 82.22, 37.47, and 0.43 km2, respectively, were delineated. They were found to be in agreement with the borehole information of the area. Curve number (CN) for the various land cover types was generated using the NRCS-CN approach. CN was used to compute a qualitative, terrain-based, runoff/infiltration response for rainfall events in the study area, from which a terrain-based runoff map of the area was computed. A comparison between the groundwater potential map and terrain-based runoff map was done using linear regression analysis. The coefficient of determination (R2) obtained was 0.80. The result indicates a high application efficiency of NRCS-CN method in verifying the accuracy of a GIS-based qualitative groundwater potential mapping.