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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    GROUNDWATER FLOW MODELING AND ASSESSING THE IMPACT OF FERTILIZERS ON GROUNDWATER QUALITY: THE CASE OF HORMAT-GOLINA SUB-BASIN, AWASH BASIN, ETHIOPIA
    (Hawassa University, 2019-10-23) MENGESHA TESFAW ABAY
    Groundwater is the source of water supply for different purposes including domestic, irrigation and depending on its capacity, it is suitable for industrial activities. Groundwater in many parts of the world is under risk because of increasing demands, mismanagement and contamination. All previous studies had not been explored the predicted groundwater flow dynamics in relation to climate change and anthropogenic stress, but this study has developed on the groundwater fluctuation with respect to human pressure and climate change. Visual mod flow flex 5.1 was used for simulating the groundwater flow in response to different stress periods. Groundwater flow and transport modeling in this Sub-basin have provided information about groundwater quantity as well as the quality aspect for decision makers about the groundwater accessibility. The initial head measured values in before and after irrigation season has varied to a maximum of 0.8 m. The groundwater head level in before and after irrigation season was varied from 9.3 m to 8.26 m in the Southern boundary and from 41.5 m to 38.83 m in Northwestern boundary of the Sub-basin respectively. While the predicted groundwater head and drawdown of increased pumping rate with decreased recharge rate scenario was magnify the bad effects in the Sub basin. The maximum depth of 0.27 m and 2.6 m drawdown was found in before and after irrigated season around the pumped wells respectively. The increased pumping rate with decreased recharge rate was replied to the groundwater head at the end of 2021has decreased by 2.81 min the Northwestern boundary of the Sub-basin as compared as using constant pumping rate with constant recharge rate. While decreased pumping rate with increased recharge rate was replied to the groundwater head at the end of 2021has increased by 2.23 m in the Northwestern boundary of the Sub-basin as compared as using constant pumping rate. The impacts of climate change and human pressure on groundwater have been the greatest threats in those supply wells. Decreased in pumping rate with increased recharge rate has accomplished to restore and protect the groundwater resources which is the best option for groundwater restoration and monitoring. Anthropogenic pressures including the application of fertilizers were a considerable cause of degraded groundwater quality in relation to Nitrate and Phosphate concentration with series of time. The groundwater quality has deteriorating with the applied Urea and DAP fertilizes in the selected wells of Hormat-Golina Sub-basin. Farmers have encouraged using practices that minimize the risk of groundwater pollution by carefully controlling and timing of the use of fertilizers to avoid over application.
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    Land Degradation Dynamics Under Land Use Land Cover and Climate Change Projection Towards the Appraisal of Potential Soil and Water Conservation Practices in the Gidabo Watershed, Ethiopian Rift Valley Lakes Basin
    (Hawassa University, 2024-10-11) Rediet Girma Legesse
    The intricate relationship between land use, climate dynamics, and land degradation profoundly impacts the sustainability of ecosystems and human well-being in Ethiopia. This study, conducted in the Gidabo Watershed (GW) within the Ethiopian Rift Valley Lakes Basin (ERVLB), aimed to assess the long-term land use land cover (LULC), evaluate regional climate models (RCMs), assess land degradation indicators, and propose management alternatives. To address these objectives, multidisciplinary approach integrating, remote sensing, geospatial analysis, statistical metrics and hydrological modeling were used. The study identified nine major LULC classes i.e., water body, grass land, forest, agriculture, bare/barren land, built-up, agroforestry, shrub and marsh land. The watershed experienced significant LULC changes between 1985 and 2021, predominantly driven by agricultural expansion at the expense of forest, shrub, and grasslands. Future (2035 and 2050) projections using a hybrid Multi-Layer Perceptron (MLP) and Cellular Automata-Markov chain (CA-MC) model indicated further agricultural expansion, accompanied by declines in forest and grasslands. Furthermore, the study evaluated 11 CORDEX-Africa RCMs and their mean ensemble performance, revealing varied accuracies in reproducing rainfall and temperature patterns over GW from 1991 to 2005. The observed climate trends indicated a significant declining rainfall (-13.38 mm/year) and warming temperatures, with future projections (RCP4.5 and RCP8.5) showing consistent temperature increases. Additionally, the study investigated the impact of LULC and climate change on surface runoff and sediment yield using SWAT model. The results revealed notable increases in surface runoff and sediment yield attributed to LULC changes. Whereas, climate change alone exhibited a diverse influence, with both increases and decreases in surface runoff and sediment yield. Similarly, the combined effects of LULC and climate change demonstrated that certain scenarios led to the increases in surface runoff and sediment yield, while others reduced these processes. This might be attributed to the offset of runoff and sediment reduction by climate change. Soil erosion rates were found to be high, particularly most of the southern and eastern parts of the watershed will generate the highest amount of surface runoff and sediment yield in to the future. Addressing these concerns, soil/stone bund, terracing, contour farming, and reforestation practice can significantly reduce the annual sediment yield in the future. The land degradation neutrality (LDN) assessment from 1985–2003 to 2003–2021 revealed land productivity decline, land cover degradation, SOC loss, and the expansion of land degradation trajectories by 26%. Overall, the findings provide valuable information for stakeholders.
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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.