Institute of Technology

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The Institute of Technology focuses on education, research, and innovation in engineering, technology, and applied sciences to support sustainable development.

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    IMPACT OF CLIMATE CHANGE ON THE GROUNDWATER HYDROLOGY OF LAKE ZIWAY WATERSHED, ETHIOPIA
    (Hawassa University, 2022-10-23) MIERAF ABEBE DONKA
    Climate change poses uncertainties to the supply and management of water resources. The relationship between the changing climate variables and groundwater is more complicated and poorly understood. Groundwater resources are related to climate change through the direct interaction with surface water resources, such as lakes and rivers, and indirectly through the recharge process. The impact may be worse for developing countries like Ethiopia because of their economies are strongly dependent on basic forms of natural resources. This thesis presents the likely impact of climate change on groundwater hydrology of Lake ziway watershed located in the Rift Valley basin of Ethiopia, The RCP scenarios of types 4.5, and 8.5 were used for the climate projection from the CORDEX Africa domain from CMIP5. The RCM of RCA4 was used to generate future possible local meteorological variables in the study area. These data were used as input to the Soil and Water Assessment Tool (SWAT) model to simulate the corresponding future streamflow Variability in the Ziway watershed. SWAT-CUP, a program for calibration and uncertainty was utilized for uncertainty analysis. The two projected time periods for this study were the 2040s, and 2070s. In the Lake Ziway watershed, there exists a climate change in the study period of 1989-2019. Since, there is a significant change from the base period to the projected time periods, therefore there would exist a climate change impact for the projected time periods under both scenarios in the Lake Ziway watershed. Therefore, climate change shows a significant decreasing impact on the groundwater flow of Lake Ziway watershed, which in turn affects the level of Lake Ziway significantly
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    IMPACT OF CLIMATE AND LAND USE LAND COVER CHANGE ON STREAMFLOW: A CASE STUDY OF YADOT RIVER WATERSHED, GENALE DAWA BASIN, ETHIOPIA
    (Hawassa University, 2021-12-15) ABAY MUSTEFA ABDULE
    Both climate and land use land cover (LULC) change are the main factors that influence hydrological regimes by altering the magnitude of ground water recharge and river flow. Thus, for predicting future stream flow both climate and LULC changes projection should be accounted. In this study, Cellular Automata (CA)-Markov in IDRISI software was used to predict the future LULC scenarios and the ensemble mean of three regional climate models (RCMs) in the coordinated regional climate downscaling experiment (CORDEX)-RCM daily precipitation and temperature for Ethiopia under RCP 4.5 (medium emission scenarios) and RCP 8.5(higher emission scenarios) were used for the future climate scenarios. Power transformation and variance scaling method were used to correct bias the RCMs outputs, with respect to the observed precipitation and temperature. The separate and combined impact of climate and LULC change on stream flow was analyzed using SWAT hydrological model. The calibrated and validated for stream flow simulation using SWAT-CUP with a method of SUFI2.The performance of the model was assessed through calibration and validation process and resulted R2 = 0.8 and ENS = 0.73 during calibration and R2 = 0.83 and ENS = 0.77 during validation on monthly base simulation. The results of the ensemble mean of the three RCMs (CCLM4.8, RACMO22T and EC-EARTH) output show parallel precipitation and temperature increasing trends in the future under RCP4.5 and RCP8.5 scenarios but vary on monthly basis. The increases in mean annual maximum and minimum temperatures are higher for higher emission scenarios than medium emission scenarios. The LULC results showed that both in the past and future period, agricultural and settlement are significantly increased while forest land and scrub/bush lands continuously declined conversely grass/range lands and wood land show decline in the past and increased from 2015 to 2035 and again decreased from 2035 to 2055 in the future period. The past LULC caused an increased mean annual flow by 1.26%, and wet season flow by 2.68% but dry season flow decreased by 2.22% while the future LULC 2015 to 2055 will cause mean annual flow increased by 1.19%, and wet season flow by 2.9% but by decreased for dry season flow by 3.14%. The mean annual flow is projected to increase under both climate and combined scenarios by 7.63% (8.13%) and 5.76% (6.26%) in the near (2021-2050), while in the midterm (2051 – 2080) flow increased by 5.76% (6.26) and 6.07% (6.72%) at the outlet of the watershed under RCP4.5 and RCP8.5 scenarios, respectively. Generally, results of future stream flow projection indicated that the combined change of climate and LULC have relatively higher than the climate changed alone. Such studies enhance better understanding of the various impacts of climate and LULC change scenarios on stream flow, which can be used for better adaptation and mitigation of water resources management problem in the watershed by Appling different water and soil conservation measures.
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    IMPACT OF CLIMATE CHANGE ON WATER AVAILABILITY IN GIDABO WATERSHED, SOUTHERN ETHIOPIA
    (Hawassa University, 2020-04-24) ADANE MEZEMIR MENIGISTU
    Climate change significantly affects many hydrological systems, which in turn affects the water resource and the flow of rivers. The aim of this research was to investigate the impacts of future climate change on the water availability of the Gidabo watershed, which is one of the Ethiopian rift Valley sub-basins. Dynamic downscaling model was used as a representative concentration pathway (RCP) scenario for the daily precipitation, maximum and minimum temperature in the watershed. The large-scale climate variables for the RCP4.5 and RCP8.5 scenarios obtained from the Hadley Global environment model through CORDEX-Africa data outputs of HadGEM2-ES were selected under representative concentration pathway. The analysis was performed in two future projection of 2018- 2047’s and 2048-2077’s with baseline period of 1988-2017. Results showed that the average annual max/min temperature will increase by 1.23oC/1.26oC and 2.64oC/3.27oC (for 2018-2047) and by 2.57oC/0.23oC and 3.542oC/2.3oC (2048-2077) for RCP 4.5 and RCP 8.5 respectively. Average annual rainfall decreased 69.19mm and 72.3mm at RCP4.5 and RCP8.5 for (2018-2047) respectively and decreased 79.02mm and 85.12mm at RCP4.5 and RCP8.5 for (2048-2077) respectively. The SWAT hydrological model was used to simulate streamflow together with other water balance components after sensitivity analysis, calibration and validation of the model. The results indicated that water yield decrease by 21.8% and 23.9% of the rainfall in the case of RCP 4.5 and RCP 8.5 respectively. On the other hand, the trend test result on gaged data showed the presence of a no statistically significant trend in the precipitation and significant trend in the minimum temperature at most of the stations.
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    EVALUATION OF THE IMPACTS OF CLIMATE CHANGE ON SEDIMENT YIELD FROM THE KATAR WATERSHED, CENTRAL RIFT-VALLEY BASIN, ETHIOPIA
    (Hawassa University, 2021-12-10) GELILA SAMUEL
    Climate change is one of the issues that, the world facing today including Ethiopia and it is anticipated that climate change will impact sediment yield in watersheds. The purpose of this study was to investigate the impacts of climate change on sediment yield from the Katar watershed in the Eastern Lake Ziway Basin, Ethiopia. Here, used the coordinated regional climate downscaling experiment (CORDEX)-Africa data outputs of Hadley Global Environment Model 2-Earth System (HadGEM2-ES) under representative concentration pathway (RCP) scenarios (RCP4.5). The analysis was performed in two future projection of 2030’s and 2060’s under the reference of baseline period of 1987-2017 with their RCP correction. After assessment of missing, quality and consistency of data; bias, the coefficient of variation and correlation were used to evaluate the systematic error of precipitation amount, the degree of precipitation variability and bias-corrected before serving as input to the impact analysis A Soil and Water Assessment Tool (SWAT) model was constructed to simulate the hydrological and the sedimentological responses to climate change. The model performance was calibrated and validated using the coefficient of determination (R2 ) and Nash–Sutcliffe efficiency (NSE). The results of the calibration and the validation of the sediment yield R2 and NSE were 0.65 and 0.61, and 0.66 and 0.65, respectively. Climate change output from this research shows that the watershed will get warmer in the future. Both minimum and maximum temperature of the catchment have an increasing trend by 1.04 0C for 2030’s and 2.04 0C for 2060’s for minimum temperature and 0.90 0C for 2030’s and 1.56 0C for 2060’s for maximum temperature. Also, average annual rainfall shows increase by 4.8% for 2030’s and 1.6 % for 2060’s. The results of downscaled precipitation and temperature increased in both future period under RCP4.5 scenario. These climate variable increments were expected to result in intensifications in the mean annual sediment yield of 41.1% and 8.9% for RCP4.5 by the 2030s and the 2060s, respectively. The average annual sediment yield were 398 ton/km2 and 307 ton/km2 for the 2030’s and 2060’s, respectively. From this study, the results show that the sediment yield of the watershed is likely to increase under climate change scenarios. This will help water resources managers make informed decisions regarding the planning, management, and mitigation of the river basins.