KULFO RIVER CHANNEL STABILITY ANALYSIS, SOUTHERN ETHIOPIA

Abstract

Rivers are a process or system characterized by constant or changes due to change of land use and other natural factors in catchments. These changes vary spatially according to the position with in the basin and influenced the factors that affect stability. Consequently Kulfo River is one of the river systems faced by such changes at the lower reaches of the river. Hence this thesis deals with evaluation of the stability analysis corresponding to the sediment transport capacity of the river with a specific objectives of studying the stability of both left and right banks of the river degradation and aggradation effects, quantify the sediment transport capacity by the river, identified possible causes of stability problems and mitigation measurement .To achieve this objective, field investigations and surveying was carried out to collect the required data. Subsequently data collection gradations of bed and bank materials were determined in laboratory using sieve analysis. Design discharges of different return periods of study has been analyzed from measured maximum daily instantaneous discharge data. After this method was established, a connection of HEC-RAS model and spatial display of flood plain data in Arc-GIS and Hec-GeoRAS extension had simplified the exchange of data between the two soft wares. Then HEC-RAS 4.1 beta version was used for simulation of Steady flow and the sediment transport capacity of the river. Hence, the simulated maximum sediment transport capacity was 183400, 249700 and 230800 tons/day at station 12104.22 and the minimum sediment transport capacity was 3062, 12110 and 13290 at station 9175.354 with return period of 2, 50 and 100 years each respectively. Based on these results, stabilization measures were proposed and should be implemented with further engineering, economical and hydraulic analysis for effective and sustainable stabilization of the rivers.