Africa Center of Excellence for Water Management

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Browsing Africa Center of Excellence for Water Management by Subject "Arcswat"

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    Land Use Land Cover and Climate Change Impact on Surface Hydrology in Borkena Watershed, Awash Basin, Ethiopia
    (Addis Ababa University, 2020-06-24) Abebe, Esayas; Atatnaw, Fasikaw (PhD)
    The rapid land use/land cover and continuous change of climate have direct impact on catchment hydrology. This study assessed the individual and coupled impact of land use land cover and climate change impact on hydrological components of Borkena watershed, Awash basin, Ethiopia. The land use land cover data were obtained from Land Sat image and processed by ERDAS IMAGINE 2014 software for years 1994, 2007 and 2018. The coordinated regional climate downscaling experiment (CORDEX)-Africa data outputs of ensemble average two RCMs derived from MPI-ESM-LR, and EC-EARTH under intermediate and high emission scenarios were analyzed in two-time frames: mid-century and end-century. Both time frames were analyzed using both RCP scenarios from the baseline period (1974-2004). Semi distributed physically-based hydrological (Soil and Water Assessment Tool) model in the ArcGIS interface was used to realize the purpose of assessing the impact of these changes. The highest gain in land use land covers are agriculture and urbanization, the highest losses are forest land followed by shrubland and grassland were observed in the study area. The calibration and validation were done by SWAT CUP which was evaluated using three criteria;R2, NSE, and PIAS (0.667, 0.67, and 2.2%) respectively during calibration and (0.71, 0.69 and -14.22 %) during validation, indicating that a good agreement between observed and simulated streamflow. Due to a decreased in rainfall by 14.56% (mid-century) and 16.51% (end century) under RCP4.5, The change in mean annual surface runoff is predicted to decrease. The annual decreasing change in surface runoff was 21.45% and 30.66% in MC and EC under RCP 4.5 scenario respectively, similarly under RCP8.5 the 22.45% and 30.0% in MC and EC respectively. The mean annual and seasonal surface runoff amplified with combined land use land cover and climate change response compared to climate change impact alone. On the other hand; evapotranspiration has reduced due to the expansion of agriculture and urbanization. Generally From the result, the SWAT model has the capability to simulate the rainfallrunoff for Borkena watershed and LULC change had more impact than climate change on water balance components. These changes need to be mitigated through land management and afforestation, to reduce the surface runoff and increase the availability of water for the future.