Hydraulic Engineering

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    EVALUATION OF SMALL SCALE HYDROPOWER WITH DIFFERENT DEVELOPMENT APPROACH AT UPSTREAM OF GIDABO RIVER FOR RURAL ELECTRIFICATION
    (Hawassa University, 2023-12-07) HABTAMU HAILU
    Hydropower is considered as one of the most desirable source of electrical energy due to its environmental friendly and extensive potential available throughout the world. The main objective of this study has to evaluate the small scale hydropower potential for rural electrification of Gidabo river, estimation of discharge to power generation for each selected sites, study energy demand for rural community and finally to prioritize and rank the best suitable site based on multi criteria decision analysis. The materials such as, RET Screen model with the objective to make complete pre-feasibility studies, GPS also used to estimate elevations at different points and ArcGIS was used to delineate watersheds and to determine heads by developing contours. The study method, conducted by reviewed different literatures related with power potential assessment and the collection of hydrological and meteorological data after collected those data, then analyzing data’s by using different software models, after analyzed the data making prefeasibility study for site selection, and transferred flow data for ungauged sites by using area ratio method then calculated power produce potential for each sites then develop flow and power duration curves to select design flows and ranked potential sites based on multi criteria decision analysis to select best suitable sites ,finally energy demand forecasted by using end use method. There was six (6) potential study sites had been selected by using Geographical Positioning System (GPS) of field surveying along the river and represented each site by code with respect to the discharge, power, head, nearest town and road accessibility. Analytical hierarchy process was chosen in combination with GIS as a method of multi criteria decision making to prioritize and select best hydropower site. ArcGIS, MCDA, GPS and Google earth were used for visualization, data analysis and interpretation. Based on multi criteria decision analysis of suitability index value (SI)the site code A@D$ become first choice and site code A@C$ become the last . The total annually energy potential of the selected site code A@D$ was estimated about 33146.0 MWh, 24076.16MWh and 5263.18 MWh for 30 %, 50 % and 90 % of time exceedance respectively. All six potential sites in the study area are classified as small scales hydropower based on installed capacity and also medium based on head. Finally, the forecasted of energy demand for community and load analysis was performed by using end-use method, for this study consider residential, Community and commercial load analysis to energy demand forecasting and evaluation. Generally, this research will give a piece of information about the study area for those concerned body for future work also additional works and for the implementation of SHP Plants
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    Estimation of Groundwater Recharge Using GIS Based Wetspass-M Model: The Case of Dedaba Watershed, Rift Valley Lakes Basin, Ethiopia
    (Hawassa University, 2024-10-18) JIBRIL WAKEYO WARIO
    The Dedaba watershed, located within the Rift Valley Lakes Basin in Oromia, Ethiopia, is experiencing significant changes driven by agricultural expansion, land use and land cover (LULC) changes, and a growing population. These dynamics, combined with insufficient watershed management, have resulted in water resource depletion, pollution, and environmental degradation. The escalating demand for groundwater, driven by the population increase, present a considerable challenge in this region. This study utilized the WetSpass-M (Water and Energy Transfer between Soil, Plants, and Atmosphere under quasi Steady State – Monthly) model, a spatially-distributed water balance model, to assess seasonal and annual groundwater recharge, actual evapotranspiration, and surface runoff in the Dedaba watershed. The model integrates spatially distributed data on precipitation, potential evapotranspiration, temperature, wind speed, soil types, LULC, and topography. These datasets, processed using GIS techniques, allowed for the generation of detailed spatial water balance components. Calibration and validation of the model were conducted using observed groundwater levels and streamflow data, ensuring accurate simulations. The calibrated WetSpass-M model revealed groundwater recharge estimates ranging from 0.46 to 65.4 mm/year, with an average of 37.47 mm/year, representing 3.4% of the total recharge. To understand the impacts of LULC changes on groundwater recharge, the model was applied using LULC data from 1990 and 2020. Results indicated a continuous decline in recharge rates over this period, underscoring the significant influence of LULC on groundwater resources. Specifically, the model estimated recharge at 3.29 mm in January 1990, peaking at 6.03 mm in September, and dropping to 0.13 mm in December. By 2005, these values had decreased, with January at 2.84 mm, September at 5.2 mm, and December at 0.12 mm. The downward trend persisted into 2020, with recharge starting at 2.61 mm in January, peaking at 4.52 mm in September, and reaching 0.12 mm in December. The study highlights the critical need to consider temporal variability and long-term trends in groundwater recharge for sustainable water management in the Dedaba watershed. The analysis of LULC changes shows a rapid urban expansion, reduction of forests and grasslands, and consequent threats to groundwater recharge. Mitigating these risks requires collaborative efforts, including promoting afforestation, water-conserving urban farming, sustainable agricultural practices, and artificial recharge techniques. Future research should incorporate climate change projections to enhance groundwater recharge predictions and improve water resource management strategies.
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    FLOODPLAIN MODELING AND MAPPING USING GIS & HEC-RAS ON DOWNSTREAM REACH OF DIJO RIVER, ALAGE, ETHIOPIA
    (Hawassa University, 2022-10-08) MEKA TIRA WUDA
    Flood is the most dominant common, continuously frequent and destructive natural disaster in the world. It causes loss of life and property, displacement of people, breaking of socio-economic activities and loss of fertile agricultural lands. Dijo River flood affects Alage ATVET Collage during rain seasons. The main objective of this research is to map the flood inundation area on downstream reach (Alage ATVET collage) of Dijo River. GIS 10.3, HEC-Geo RAS, HEC- RAS 5.0.6, excel 2016 and easy fit 5.5 software’s are used for this research. primary data’s (total station surveying data, field observation) and secondary data (Dijo and furfuro stream flow data and Manning’s n value) are used to conduct the research. Flood frequency analysis, pre-processing, processing/model execution and post-processing methods are used and got 101.22m3 /s, 164.6 m3 /s, 175.8 m 3 /s, 207.58 m3 /s and 227.83m 3 /s peak discharge for 2, 10, 25, 50 and 100- years return period respectively. 27 x-section cut lines are drawn on 4km river reach geometry, among these 55.6 % of the x-sections are severely flood venerable x- sections from all return period peak flood discharges and to both side of the river reach. The flood inundation area of 2, 10, 25, 50 and 100 years return periods were 5702, 8154.71, 8499.96, 9271.9 and 9851.84m2 respectively. This area includes both Alage ATVET collage and neighboring kebeles of the collage. Therefore, the responsible body makes remedial measures to control the flood like repair and increase the height of the exiting earthen dykes at upstream of alage Bera Bridge, construction of new dykes and levees at the chefe agricultural area, grassland area and desilting siltation-filled x-section, afforestation from upper watershed of the river
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    GROUNDWATER POTENTIAL MAPPING USING SWAT MODEL AND GIS BASED MULTI-CRITERIA DECISION ANALYSIS: A CASE STUDY IN GIDABO WATERSHED, RIFT VALLEY LAKES BASIN, ETHIOPIA
    (Hawassa University, 2022-07-08) BIRUK TAMIRU TADELE
    Groundwater is the water that is located in the subsurface and saturates the rocks and soil beneath the ground surface. Groundwater is the most valuable natural resources for mankind for drinking, industrialization and irrigation in present day, but the availability is reduced gradually due to over exploitation and lack of management. However, identifying the groundwater potential zones in certain areas of Ethiopia is still challenging in terms of time and cost for resolving water scarcity problems and the management system of groundwater. A systematic assessment and identification of groundwater is essential for proper utilization and management of this precious natural resource. In recent years, Geographic information system based studies have gained much prominence in groundwater exploration, because it is rapid and will provide first-hand information on the resource for further developments. Therefore, the present study was conducted with an objective to identify the groundwater potential of Gidabo catchment, Rift Valley Lakes Basin of Ethiopia using SWAT and GIS-based MCDA techniques. Thematic maps were developed, for ten major parameters (recharge, soil, lineament density, lithology, land-us/ land-cover, geomorphology, slope, drainage density, Roughness and Topographic wetness index (TWI)) that affect the occurrence and movements of groundwater. Recharge was simulated by using SWAT model, the rest thematic layers were developed using ArcGIS 10.4 and Weights assigned to each thematic maps were based on their characteristics and water potential capacity through analytic hierarchy approach (AHP). The thematic layers were subjected to weight sum overlay in ArcGIS spatial analysis tool box, to delineate groundwater potential zone map. The resulted groundwater potential zone was categories in to four classes, namely high, moderate, low and very low. Generally Low and very low groundwater potential zones were found around highland area which coincide with structural hills, peak of the mountain and hard geological formation. The accuracy of the output was cross-validated with information on groundwater prospects of the catchment. Finally, it can be concluded that SWAT and GIS-based MCDA-AHP techniques is very effective and useful for the delineation and identification of groundwater potential zones in the study area.
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    GROUNDWATER POTENTIAL MAPPING USING GIS AND REMOTE SENSING: A CASE STUDY IN WELMEL WATERSHEDE, GENALE-DAWA RIVER BASIN, SOUTHEAST ETHIOPIA
    (Hawassa University, 2023-08-03) HAILEYESUS HIFAMO HILLO
    To fulfil the demand of a rapidly growing population in drought-prone areas with high rate of urbanization, identification and management of groundwater resources are required. In the welmel catchment, a search for an alternative source of water has been always a major issue. The current practice of groundwater potential zone (GWPZ) identification is time consuming and uneconomical. This study applied integration of GIS-Remote Sensing (RS) and Analytical Hierarchy Process (AHP) for mapping the GWPZ of welmel catchment , Southeast Ethiopia. This technique is a fast, accurate, and feasible technique. Groundwater potential zone influencing parameters were derived from Operational Land Imager 8, digital elevation model(DEM) 20*20 resolution and secondary sources were utilized in this research. These were geomorphology, lineament density , lithology, rainfall, drainage density , slope , elevation , LULC, and soil texture were prepared . Borehole data were used for results validation. All thematic layers were reclassified based knowledge based analysis that was reviewed from different kinds of literature. Then the weight for each factor was assigned according to their relative importance as per suitable based on Saatty's scale of AHP. The important factors result show that geomorphology and lineament density have a higher weight and soil texture has the lowest weight for identifying groundwater potential zone . For weights allocated to each parameter, the consistency ratio obtained was 0.061, which is less than 0.1, showing the weight allocated to each parameter is acceptable. The resulting GWPZ of the study area indicates four zones representing Very Low, Low, Moderate and High . The areal extent of high and moderate GWPZ is 350 km2 and 2256 km2 , respectively. low and very low GWPZ covers 10356 km2 and 1547km2 areas. The particular direction of groundwater flow is towards the NE and SE, coinciding with the direction of surface water flow. The validation result of 82.08% confirms the very good agreement among the groundwater record data and groundwater potential classes delineated. Thus, the identification of GWPZ by using GIS and RS through AHP is reliable for conducting similar studies.