PERFORMANCE ASSESSMENT OF URBAN DRAINAGE SYSTEM USING STORM WATER MANAGEMENT MODEL (SWMM): THE CASE OF ALETA WONDO TOWN, SIDAMA REGIONAL STATE

Abstract

The drainage system were one of the most important factors to be considered in the urban drainage infrastructure plan. Now in adequate urban storm water drainage problems represent one of the most common source of compliant numerous town of Ethiopia. Drainage problem in Aleta wondo Town is the worest issue of over flooding on the surface runoff at highly rainfall season. Unfortunately, street flooding and overtopping drainage system problem are occurring at the rainy season in a Town.The main objective of this study was to assess the hydraulic performance of drainage system Aleta Wondo Town. The study employed both primary and secondary data collection from the field surveying work was conducted to inspect the existing drainage condition and to measure channel geometric conditions. The meteorological approaches employed in this study include, the identification of the existing drainage network flow direction and delineation of contributing area. The Storm Water Management Model( SWMM5.1) was applied to simulate the water level in the links and junctions. The simulated result indicate that 1.162m3 /s average flow rate,1.632m3 /s maximum flow rate and 12.457*103 m 3 total annual volume runoff. The hydrological analysis was computed by the the rational method. The result shows the existing drainage system of Aleta Wondo Town were not well connected drainage lines and silted by different waste material because of the capacity of drainage system can‟t handle the current runoff that flows over the area. Therefore, some adjustment or improvement to give the best service and needs a series of regular maintenance and drainage should be well designed and constructed to the standard and managed properly