Modelling stream flow and Sediment using SWAT in Gumara-Maksegnit watershed

Abstract

The coincidence of intensive rainfall events at the beginning of the rainy season and the unprotected soil conditions after exhaustive dry spells expose the Ethiopian Highlands to severe soil erosion. Massive efforts are being made in soil conservation strategies by the government of Ethiopia. However, the effectiveness of this soil and water conservation on the dynamics of the nutrient, stream flow and sediment loading is not sufficiently studied. Soil and water conservation measures (SWC) have been applied to counteract land degradation in the endangered areas, but SWC efficiency may vary related to the heterogeneity of the landscape. In this research simulation modelling was conducted to assess the spatially distributed impact of SWC structures at different scales (main watershed: sub-watersheds). Runoff/erosion plot experiments were also conducted to obtain further data to support modelling, in addition to the hydrological data measured at watershed outlets described in section 1.1 of this report. The plot studies were the subject of research for several junior researchers and MSc students from BOKU University. Their theses are published and available for consultation, the results are not summarized here for reasons of space. The results obtained through SWAT modelling at the scale of the main watershed (Gumara-Maksegnit) are currently in publication (article under revision) and are only briefly summarized in Part I of this report section. At the sub-watershed scale the study is still ongoing and is the subject of a PhD research that will continue until the end of 2017.