ASSESSEMENT OF URBAN STORM WATER DRAINAGE NETWORK SYSTEM AND ROAD FLOODING RISK MANAGEMENT IN ADDIS ABABA, NEFAS SILK LAFTO SUB-CITY

Abstract

Drainage is an important consideration as one of the major components in the road construction. For this reason in most designs of the road, the first thing to be put in place is drainage system. Urbanization along with its impervious structures is the major challenge of urban centers. Poor managed storm water increases total flow, flow rate, flow velocity and depth of water in downstream channels. Properly designed storm water management facilities, particularly detention/recharge basins, can also be used to mitigation-point source pollution impacts by providing extended containment durations, thereby allowing settlement of suspended solids In Addis Ababa, control of runoff at source, flood protection, and safe disposal of excess water/runoff through proper drainage facilities becomes essential. This study was carried out in three sample (kebele 01/02,01/12 and 03/04) within nefas silk lafto sub-city. These kebeles were selected because of they are representative to address the objectives of this study. To assess the status of road drainage network system and risk mitigation measures and strategies are the major problems in the study area. An exploratory and Descriptive type of research design methods were used to describe and explore the existing condition of the general urban drainage system and the natural water ways. Data collection methods were carried out using both primary and secondary data sources. The secondary data source was only relevant to reinforce the primary data. The collected data were analyzed with Ms-excel. The results have been presented with known statistical tools. The findings of this study indicated that the major causes of flooding were found to be deforestation of dertu and surrounding mountain, and inadequate integration between road and urban storm water drainage lines. Solid and liquid waste damping was also the biggest challenges on the general urban drainage system. This study strongly recommends improvement in the integration of road and urban storm water drainage system and over flowing of flooding as a result of blockage of drains.