Integrated GIS-based approach for mapping and modelling groundwater resources :

Abstract

Due to effects of increasing demand on water, attributed to increasing population and increased industrialization, sustainable development in terms of water management has become a big challenge. Some boreholes in Kibalinga sub county are experiencing reduced water production and others complete drying, which is likely due to the over extraction of water from neighboring boreholes or natural causes. Sustainable groundwater management based on groundwater basin (GWB) must be equipped with comprehensive information including the characteristic of hydrogeology. This management method is very useful for governments to design some regulations concerning groundwater conservation. This study involved an integrated GIS-based approach for mapping and modeling groundwater resources in Kibalinga sub county, Mubende district. The project aimed to identify and map potential groundwater resources including the recharge and discharge zones using geological data and existing hydrogeological information, and develop a hydrological model to simulate groundwater using GIS tools and MODFOW 6. Groundwater characteristics such as first water strike, main water strike, static water level, different characteristics of rock bearing structure were identified using maps and graphs. The project involved data collection, processing, and analysis using various GIS tools and techniques within a hydrological modeling framework. The proposed approach has the potential to provide valuable insights into the availability and distribution of groundwater resources in the study area, which can inform water resources management decisions. Furthermore, this study provided information about the changes in groundwater considering the different extractions and recharges over a period of ten years. The study has also identified the different aquifer characteristics that can help and guide on the location of groundwater extraction points. The sub county consists of the unconfined and confined aquifer of High Plain Aquifer, where the groundwater flows from north and east heading southward and westward. The methods applied to the study are mapping the geological and hydrogeological condition, reconstruction of subsurface stratigraphic condition, overlay of different maps of given parameters of the recharge-discharge zone, running models with different packages in MODFLOW. The groundwater yield potential from the results indicated that the yield ranges from 0.1007%m3 /hr-10.008%m3 /hr. therefore the total yield per hour is 66.71m3 /hr. therefore the annual water yield was 584,400m3 /hr. MODFOW model calibration yielded an R 2 value of 0.78746.