Agizew, Nigussie (PhD)Tesfakiros, Atsbha2020-03-052023-11-282020-03-052023-11-282019-09-05http://etd.aau.edu.et/handle/12345678/20885Evaluating the impacts of land use on surface water quality and quantity based on temporal and spatial variation using the integrated watershed (SWAT) and water quality models (WASP) were the aims of this study. SWAT model’s performance was assessed using Nash– Sutcliffe coefficient (NSE) and coefficient of determination (R ) with the help of SWAT CUP software. The model was calibrated from 1989 to 1994 and validated from 1995 to 1997 for stream flow using the 1989 land use/land cover map. The monthly calibration and validation results showed (NSE = 0.74, R 2 = 0.55) respectively. Annual stream flow was evaluated on the years 1989, 2003 and 2016 and the result shows that it increases by 10.1% from (1989-2003) and by 30.3% from (1989-2016) on the downstream of Little Akaki river (reach 51). This is because urbanization increases by 63.7% and forestland decreases by 61.6% from the upstream to the downstream of the river. Sediment load decreased by 98.2% when urbanization is increased by 35.2% and barren lands decreased by 37.3% from (1989-2016). It also increased by 82.6% when urbanization increased by 53.5% and barren land decreased by 32.4% from (1989-2016). pH, Temperature, TSS, NH4-N, NO2-N, TN and TP decreases its quality by 5.9%, 0.8%, 7.0%, 59.2%, 67.0%, 34.5% and 45.9% from upstream to downstream of Great Akaki river. This is because of built up area increases by 45.7% and forestland decreases by 28.5% from upstream to downstream of Great Akaki River. Water quality of the rivers was evaluated temporally and the results showed that pH, Temperature, TSS, NH4-N, NO2-N, TN and TP decreases its quality by 5.29%, 9.11%, 48.47%, 45.88%, 43.28%, 47.1% and 17.69% respectively from (1989-2016) on little Akaki river. When the simulated result are compared to water quality guide lines pH, TSS, NH4-N, TN and TP exceeds the guideline by 2.9%, 85.8%, 5.2%, 2.3%, & 0.2% on downstream of little Akaki and by 11.1%, 87.3%, 10.7%, 31.6% & 7.35 Great Akaki rivers respectively.en-USland usesurface water quality and quantitySWATWASPAkaki catchmentThesis