Design and simulation of a water diversion pipe line from Elgon zone to Karamoja : case study : Namalu sub county Nakapiripirit district

Abstract

Through out the human history floods have been an integral part of the civilization. Still, men have not quite coped well to live with floods. Flooding is the most frequent global natural disaster; rural areas are becoming more vulnerable to flooding due to effect of climate change. Flash flood is one of the most prominent phenomena caused by heavy rains. In developing countries drainage channels is the most common strategy employed for flood control. The failure of preventive measures has led to most authors and researchers to advocate a shift in thinking from preventive measures to flood risk and structural management measures. On the other hand, areas on the lee ward side of the mountain like Karamoja experience water scarcity and basing on the flooding conditions, this excess water causing flooding can be diverted. Recently, The advancement in computer-aided technology has been extensively used in formulating models used for flood calculation and hazard analysis. This study focuses on using a hydraulic model HEC-HMS and HEC-RAS in a GIS environment for the affected areas of Elgon zone i.e.Bulambuli and Kween, generates the inundation area and the return period for the specified flood events. The research involved studying various literatures and collecting data in form of journals and reports. This helped to formulate the methodology for the whole project. It was followed by the modelling stage. This started with data collection from various Sources i.e .from offices. Data collected included:-DEM, discharge flow data, land use/land cover data, rainfall data and soil data. These datasets were conditioned and processed in the GIS environment using the ArcGIS software. Land use and soil data was used to generate Curve number grid and later GeoHMS was used to set up a project which involved basin characteristics and processing and exported into HMS to generate hydrograph (peakdischarges) to be used in the HECRAS.The GeoRAS file was exported to the HEC-RAS program to compute for a steady flow simulation. The RAS mapper export from HEC-RAS program was then imported into ArcMap to delineate a flood plain map which was overlaid to a Google image to determine flood prone areas. The villages included among others like Chepsikunya,Ngenge,and along Mbale Moroto road. This was followed by design of the system components like pipes, reservoir tank, trapezoidal flood channel and sluice gates and there after simulating the flow in Epanet.