Groundwater investigations and modelling for domestic use

Abstract

Groundwater is a rich resource that contributes significantly to Uganda's entire annual water supply. Local governments in Uganda, particularly in Mukono, seek to harness the substantial groundwater resources in the district to attain the needed Safe Water Coverage in various sections of the district. This initiative primarily entails the construction of Deep Boreholes at diverse locations in the different sub-counties appropriate for groundwater abstraction. However, this initiative is not a sustainable solution for proper utilisation of the groundwater resources in the district. This is because having numerous deep boreholes in the same aquifer creates considerable drawdowns in the water table, reducing borehole yield. Furthermore, the expense of creating these deep bore holes is significant and will continue to increase as the depth of the water table drops. Therefore, the study aimed at developing an integrated map that can be used in the development of a Gravity Flow System in Kyampisi, Nama and Goma division sub-counties in Mukono district that can be used in substitute of the construction of numerous Deep Borehole. This involved hydrogeological mapping of the aquifers in the subcounties of Kyampisi, Nama and Goma Division using suitable criteria such as soil types, land use, elevation, geology, rainfall density, drainage and borehole yield. These criteria were analysed in ArcGIS due to its high ability to manage and analyse various data. In addition, the AHP (Analytical Hierarchy Process) method was used to derive the weightings of criteria, through a matrix of pairwise comparison to integrate the different criteria. This enabled the development of an integrated map using the weighted overlay in ArcGIS that can be studied to determine the potential groundwater zones with maximum yield and identify production wells that can be aggregated to be used in developing a Gravity flow scheme for the sub-counties .