Design and simulation of an aquifer recharge system for Rubongi sub county, Tororo district

Abstract

The water supply for Rubongi sub county in Tororo district is highly reliant on groundwater. This project is aimed at coming with a technique that will be used in artificial groundwater recharge of the existing aquifer in the area with an increasing population having a recent growth factor of 2.73%, groundwater demand is on the rise. For me to solve this problem I first of all needed to determine the groundwater supply and availability in the sub county and also other surface water sources including surface runoff from precipitation. This was done using the aquifer potential map of the sub county on a GIS platform, establishing the water demand of the area through population projection, hydrological analysis and water systems engineering and finally getting the specifications of the recharge system. The water balance for the area was obtained and this indicated the water supply would cater for the needs of the area. It was observed that the area has high evaporation rates therefore the amount of recharge of the rainfall (108.88 MCM/year) and runoff(27.47MCM/year) was minimal but all the same due to the fissure characteristics in the area and the direction of flow recharge does occur. With the design of the structure, open trapezoidal channels were used due to their design and maintenance ease and these trapezoidal basins therefore serve a horizontal recharge purpose. The main aim of recharging the aquifer is because as the population increases the water demand also increases also leading to increased demand. As demand increases most people tum to groundwater for sustenance which may lead to over abstraction. To prevent this, we have to recharge what is currently there and ensure continuous supply of water. The simulation of the system was then done using MODFLOW, a groundwater modelling and simulation software that yielded the results for recharge rate based on the aquifer characteristics and recharge parameters of the study area in majorly six main steps leading to the performance of a steady-state flow simulation i.e. Create a new model, Assign model data, Perform the flow simulation, check simulation results, calculate sub regional water budget, Produce output