PERFORMANCE ASSESEMENT OF WOLAITA SODDO TOWN STRORM WATER DRAINAGE SYSTEM, SOUTHERN ETHIOPIA

Abstract

Urbanization of an area invariably leads to increase in overall imperviousness of the area. When land becomes impervious storm water will stagnate on the surface thereby affecting the infrastructure, transportation and causing inconvenience to general populace. Storm water drainage problem is one of the major challenges facing many countries in Ethiopia in general and Wolaita Soddo town also faced the problem. This study has investigated the hydraulic performance of drainage system of Wolaita Soddo town and some drainage problems . Rapid expansion of built environment, poor urban drainage managements and location of Wolaita Soddo town being at the foothills of mount Damota are the major problems in the study area. The objective of this study is to overview the current hydraulic performance storm water drainage system and associated problems. This research involves collection of both primary and the secondary data in order to make it ready for analysis and to achieve the specific objective by using SWMM5 model. Design of storm drainage system evaluated in this thesis includes hydraulic performance for existing situation by using manning’s and fixing new size of reinforced concrete pipe for existing and proposed area. Based on the result of this thesis the drainage system is insufficient at different area and most of the drainage system of the catchments were investigated that required construction of additional storm drainage system and its existing coverage and its proposed based on assessing and hydrologic and hydraulic calculation of this study the existing drainage convening discharge capacity is insufficient at different catchments and the some areas requires new drainage system for different catchment at existing and proposed. Finally, appropriate mitigation measures were proposed for required of new drainage system in order to serve the area from different negative effect and drainage structures for the future purposes sustainably and Sustainable Urban Drainage Systems is important to reduce this risk. Additionally managing and improper construction alignment problem for the existing system were investigated and to avoid this problem periodic cleaning and modification of slope is recommended.