Water Resource
Permanent URI for this collectionhttps://etd.hu.edu.et/handle/123456789/71
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Item STREAMFLOW RESPONSE TO CLIMATE CHANGE ON TIKUR WUHA SUB WATERSHED, RIFT VALLEY BASIN, ETHIOPIA(Hawassa University, 2018-10-23) BROOK LEGESE DADHIClimate changes alter regional hydrologic conditions and results in a variety of impacts on water resource systems. Such hydrologic changes will affect almost every aspect of human well-being. Simulation models of watershed hydrology and water quality are extensively used for water resources planning and management. This study aims to assess the streamflow response to Climate Change on Tikur Wuha Sub-watershed, Rift Valley Basin of Ethiopia. In the study the daily hydro-meteorological data values for the baseline period of 1981-2005 were used. Historical Representative Concentration Pathway (RCP) data along with observed data of precipitation and temperature were used for extraction and bias correction using CMhyd tool. After evaluation of bias correction methods using residual plot, and RMSE, MAE and RE, the downscaled climate data such as, RCP4.5 and RCP8.5 scenarios was used for the future period assessment. Soil Water Assessment Tool (SWAT) models were used to assess the streamflow response to Climate Change. Calibration and validation of the model output were performed by comparing simulated streamflow with corresponding measurements from the Tikur Wuha outlet for the periods of 1992-2001 for calibration and 2002-2005 for validation using SWAT-CUP(SUFI-2). The model calibration and validation results shows a good agreement with the observed flow with the coefficient of determination 0.79 and 0.86, and a Nash Sutcliffe efficiency was 0.56 and 0.64, respectively. The result of projected temperature reveals a systematic increase in all future time periods for both RCP 4.5 and RCP 8.5 scenarios, and for all considered period whereas the projected result of precipitation was inconsistent throughout all future time periods and for both RCP 4.5 and RCP 8.5 scenarios. The dynamically downscaled daily climate variables (precipitation and temperature) were used to simulate future projections of streamflow. Streamflow projections for future time periods showed that mean annual streamflow may increase by 15.43, 23.48, and 25.42% in 2020s, 2050s, and 2080s, respectively, from the baseline period for RCP 4.5 scenario, whereas for RCP 8.5 scenario, it will be expected to increase by 29.58, 34.20, and 38.72% in 2020s, 2050s, and 2080s, respectively. The model simulations considered only future climate change scenarios assuming all spatial data constant. Therefore, future study need to consider impact of land use/cover change on the sub-watershed for future sustainable development plan.Item MODELLING THE IMPACT OF LANDUSE/LAND COVER CHANGE ON THE STREAM FLOW OF UPPER GUDER RIVER CATCHMENT USING SWAT, ABBAY BASIN, ETHIOPIA(Hawassa University, 2021-10-23) TAKELE DUFERA TASGARAWater resources are a critical component of any type of socio-economic development all over the world. Due to extensive agricultural practices, the LU/LC change was the cause of streamflow changes. The main objective of this research was to model the impact of landuse/land cover change on the streamflow of Upper Guder River Catchment using the SWAT model, by using meteorological data in the period between 1989 -2018. Upper Guder River Catchment was one of the catchment of the headwaters in the south Abbay Basin. In this study, the impact of LU/LC change was carried out by using the Soil Water Assessment Tool (SWAT2012) model, which was integrated with GIS10.3 software. GIS and ERDAS IMAGINE2014 were used to generate landuse/land cover maps from Landsat TM, TM, and ETM+ acquired in the years 1989, 2002, and 2018 respectively. The land cover maps were generated using the maximum likelihood algorithm of supervised classification. The classified maps were assessed using confusion metrics. The results of the analysis showed that the Agricultural land has expanded during the study period of 1989-2018. During the study period, forest land, and shrub and grassland decreased by 6.48% and 4.23% respectively while Agricultural land and Built-up area increased by 8.04% and 2.69% respectively. Using three land cover maps, three SWAT model setup were run to evaluate the impacts of landuse/land cover changes on the streamflow of the study catchment. The performance of the SWAT model was evaluated through sensitivity analysis, calibration, and validation by using SWAT-CUP. Statistical measures like coefficients of determination and Nash–Sutcliffe were used to evaluate the model and it resulted in 0.84 and 0.74 for calibration and 0.83 and 0.72 for validation respectively. During the study periods, the simulation result indicated that streamflow increased in the wet season and short rainy season streamflow by 10.04% and 5.25% respectively, while decreasing by 6.60% in the dry season. The Surface Flow (SURQ) increased by 5.73% while Groundwater Flow (GWQ) decreased by 2.26% due to the increment of Agricultural land. The model results showed that the streamflow characteristics changed due to the landuse/land cover changes during the study period. The catchment was sensitive to past LU/LC change, so it needs an effective integrated participatory approach for catchment management.Item ASSESSING THE IMPACTS OF CLIMATE CHANGE ON STREAMFLOW UNDER CMIP6 CLIMATE PROJECTION IN THE UPPER OMO GIBE RIVER BASIN, ETHIOPIA(Hawassa University, 2023-03-25) LEMLEM GETNET MOLAClimate Change is projected to have an impact on future streamflow in various watersheds. This study examined the impacts of climate change on streamflow in the Upper Omo River Basin using a Soil and Water Analysis Tool (SWAT). Projected climate variables (precipitation and temperature) ensemble of 5 Global Circulation Models (GCMs) were obtained from the World Climate Research Programme (WCRP), downscaled by the SDSM4.2 model and applied under the Shared Socioeconomic concentration pathways (SSP2-4.5) and (SSP5-8.5) scenarios. The downscaled SSPs data cannot be directly used to the hydrological model (SWAT) to simulate flow so, Distribution Mapping bias correction method was selected for this study. SWAT was calibrated and validated before it was used for simulation purpose. The performance measures R2 and NSE for calibration (2000-2013) and validation (2014-2019) were 0.79 and 0.71 and 0.86 and 0.85 respectively. Mann Kendall (MK) trend testing was used to determine if a change is statistically significant and to detect trends in temperature and precipitation. According to RCP4.5 and RCP8.5, the emission scenarios predicted significant increasing temperature, but significant decreasing precipitation. Streamflow was simulated for two consecutive periods from 2020 to 2045 and from 2046 to 2071 for both scenarios and compared with the base period from 2000 to 2019 to explore the impact of climate change on Streamflow. The results indicated that the basin is likely to experience increased temperatures and altered precipitation patterns, whereas overall annual flow was projected to be significantly decreasing under SSP2-4.5 and SSP5- 8.5 emission scenarios in the mid and near future. These changes are likely to have major implications for water resources management in the region, particularly for agriculture, hydropower generation, and ecosystem services. The findings suggest the need for adaptive measures to address these impacts, including improved water management strategies and increased investment in climate-resilient infrastructure.