Characterizing and Understanding of the Hydrological System of Didesa Sub-Basin
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Date
2016-11
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Addis Ababa University
Abstract
Understanding hydrological characteristics of watersheds in Ethiopia highlands have significance importance for the water based development of the country. The Didesa sub basin, which is one of the major sub basins in Abay river basin, has not well studied as compare with the northern sub basins of Blue Nile (Tana sub basin). The study evaluated the quality of observed meteorological and hydrological data, established SWAT hydrological model, and developed different characterization parameters for different watersheds in the sub basin. The result indicated that the SWAT model developed for the sub basin evaluated and its performance certain with the statistical measures, coefficient of determination (R2) and Nash coefficient (NS) with values ranging 0.62 to 0.8 and 0.6 to 0.8 respectively at daily time scale. The coefficient of determination R2 and NS increases at monthly time scale and ranging 0.75 to 0.92 and 0.71 to 0.91 respectively. Sensitivity analysis is performed to identify parameters those were most sensitive for the sub basin. CN2, GWQMN, CH_K, ALPHA_BNK and LAT_TIME are the most sensitive parameters in the sub basin. The hydrological system of the sub basin is also characterized with its simulated stream flow at five major tributaries watersheds, dominate land use mosaic vegetation/crop lands followed by closed to open shrub land, soil Humic Nitosols and slope 0% to 36% as catchment attributes, and the peak flow for 2-10000 return period
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Keywords
Blue Nile, Hydrological characteristics