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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    ASSESSMENT OF CLIMATE CHANGE IMPACT ON STREAM FLOW OF GIDABO SUBBASIN, RIFT VALLEY BASIN, ETHIOPI
    (Hawassa University, 2022-08-10) YIDIDYA TSEGAYE ALEMU
    Climate changes alter regional hydrologic conditions and result in a variety of impacts on water resource systems. Such hydrologic changes will affect almost every aspect of human well-being. The goal of this thesis is to assess the impact of climate change on the hydrology of Gidabo subbasin located in the Rift Valley basin of Ethiopia. The RCP scenarios of types 2.6, 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 Gidabo subbasin. SWAT-CUP, a program for calibration and uncertainty was utilized for uncertainty analysis. The three projected time periods for this study were the 2040s, 2060s, and 2090s. The time series generated by RCM of RCA4 driven by MIROC5 indicate a significant increasing trend in maximum and minimum temperature values and a decreasing trend in precipitation for all RCP emission scenarios in Measso station for all time periods. The hydrologic impact analysis made with the downscaled temperature and precipitation time series indicates variation in an increasing and decreasing trend for the three RCP scenarios at different periods respectively. The model output shows that there may be a mean annual, seasonal, and mean monthly decrease in stream flow volume for all RCP scenarios in the Projected time periods in the future. It also shows most of the projections are within the uncertainty bandwidth of 95PPU