Morphometric analysis of runoff contributing watershed to adama-asella roadside soil erosion and its prioritization for intervention

Soil erosion has been recognized as a serious socio-economic problem in Ethiopia.. Roadside soil erosion of Adama-Asella highway is among the problems affected the traffic from the two zones to the country’s capital city, Addis Ababa. Studies concerning the alignment of the road versus natural runoff flow has not been studied. The objective of this study was to characterize runoff contributing watershed to the Adama-Asella roadside erosion and prioritize of its micro-watersheds for watershed management intervention. To identify runoff contributing watersheds and extraction of drainage lines, area encompassing the damaged road were delineated using DEM. By overlaying natural runoff flow lines of the watershed against the road alignment was evaluated in the GIS. To analysis morphology of the micro-watersheds, areal, linear and relief aspects were used. Using compound values of 4 linear parameters, 4 shape parameters and 1relief parameter, prioritization of four micro-watersheds (MW1, MW2, MW3 and MW4) connected to the road were done. The study identified that micro-watersheds MW3 is the highest priority micro-watershed while MW4 is the least priority micro-watershed. MW1 and MW2 are the second and third priority micro-watershed, respectively. Therefore, implementation of watershed management intervention per the identified priority micro-watershed is important.