Assessment of groundwater potential zones: Nakasongola district, Uganda

Abstract

The objective of this paper is to exploit the potential application of weighted index overlay analysis for assessing groundwater potential mapping in Nakasongola District, Uganda using remote sensing, geographic information system (GIS) technique and multi-criteria decision Analysis (MCDA). For this purpose, eight groundwater occurrences and movement controlling factors, including, Geology, slope, land use land cover (LULC), rainfall, lineaments, soil, and drainage density were mapped. The analytical hierarchy process (AHP) was used to determine the weights of various themes and their classes for identifying groundwater potential zones. The weights were applied in a linear combination to obtain four different groundwater potential zones in the study area, namely ‘low”, ‘moderate’, ‘high’, and ‘very high’. It has been concluded that about 2.23 km2 area has very high groundwater potential which is only 0.07% of the total study area and about 417.88 km2 area has high groundwater potential which is only 12.07% of the total study area. However, the area having moderate and low groundwater potential is about 1442.99 km2 and 1598.47 km2 which is about 41.69% and 46.18% respectively of the study area. The groundwater potential zone map was finally verified using the well yield data of 31 pumping wells, and the results reveal that 70.9% of groundwater inventory data agree with the corresponding groundwater potential zone classifications. As a result, the map generated using this platform could be used as a preliminary reference in selecting suitable sites for groundwater resource exploitation.