Numerical simulation of aquifer contamination from an Industrial waste disposal site: Kasese, Uganda

The main objective of this study was to develop a Decision Support System (DSS) for groundwater management in an aquifer that is prone to pollution from an industrial waste disposal site in Kasese District, Uganda. The DSS should address the impacts of different scenarios of pumping polices of aquifer development on contaminant migration. Visual MODFLOW, a three dimensional finite difference groundwater flow model was used to simulate unsteady state flow in the aquifer. SURFER and ARCVIEW, both GIS based software, were used for preparing inputs of MODFLOW and aquifer parameters were obtained using AQUITEST software. The model was then calibrated and verified using a set of observed dynamic water levels for the 19-Month period of available data. It was found that the RMSE in calibration was (0.83) and verification was (1.48). Chloride ions, which are non-conservative, were then used in the particle simulation. Contaminants were considered to migrate due to the processes of dispersion, advection, sorption and diffusion and the processes of radioactive decay and biological degradation of the contaminant were neglected in the simulation. Different scenarios of aquifer stress were then generated and the model used to predict aquifer response for a 10-year simulation period. Several recommendations were given, relating to the way in which this and similar aquifers should be modeled and managed in the future.