Design of flood attenuation drainage system :

Abstract

Throughout the human history floods have been an integral part or 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. 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 HECRAS in a GIS environment for the affected 'areas of Butaleja generates the inundation area and the return period for the specified flood events. The research involved studying various Literature and collecting ancillary data in form of Journals and reports. This helped to formulate the methodology tor 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 und 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 Iater geo.hms was used to set up a project which involved basin characteristics and processing and exported into HMS to generate hydrograph (peak discharges) to be used in the HECRAS. The IDF curves were generated for a return period at 50 years that gave peak intensity of 804.6mm/hr and therefore aided in calculating the design flood. The GeoRAS file Was exported (6 the HEC-RAS, Frogram to compute; far 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 Goggle image to determine flood prone areas. The village included among others like Doho, Kangalabaand wangale. Filially after the hydrological and hydraulic modelling, the drainage system was then designed with the design parameters already generated