Hydraulic Engineering
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Item ANALYSIS AND PRIDICTION OF METEOROLOGICAL DROUGHT USING STANDARDIZED PRECIPITATION INDEX: CASE STUDY OF EASTERN OROMIA(Hawassa University, 2019-02-14)Ethiopia is one of the most drought affected country in Africa and suffered from acute drought many time in recent years. The objective of this study is to understand the rainfall variation and conduct an in-depth analysis and prediction of drought for to Eastern Oromia. Standardized precipitation index (SPI) was selected to characterize drought condition in the region. Drought characteristics at a time scale of 2-month, 3-month, 6month and 12-month were computed separately for 22 selected rain gauge station. The most maximum drought characteristics at 2-month, 3-month, 6-month and 12-month time scales have been found in Hararegie over last 36 years (1979-2015). The spacial extent of drought and rainfall variation were determined from SPI and CV values computed separately for each rainfall have been interpolated between station in Arc view GIS environment. The rainfall variation shows that the rainfall over the study area is highly variable and increases from Arsi to East Harargie and in the recent last decade (2005-2015) the map of SIP-3 (Belg) shows that a spacial extent drought over study area was irregular and there were no period in recent decades (2005-2015) without drought at least mild drought and this shows that the area is vulnerable to drought. The maximum intensity of (5.33) was recorded at Fedis Station for SPI-3 (kiremt season) in a year 1996, maximum intensity of (4.04) was recorded at Kobo Station in a year 1985 for SPI-3 (Belg season), maximum intensity of (4.77 and 4.5) were recorded at Ticho Station for SPI-6 (both seasons) and SPI-12 (annual) respectively. The drought prediction was made until 2043, using the Representative Concentration Path way (RCP) 8.5 Scenario.on the basis of the drought index measured by SPI. From the analysis of the drought index through the RCP 8.5 Scenario, extreme drought intensity will be more likely to occur. The long-term forecast (12-month period unit) showed that extreme drought would occur severely at station Diksis Sude, Hirna and Adelle from 2035 to 2040 and need more attention for this areaItem EVALUATION OF THE EXISTING URBAN WATER SUPPLY SYSTEM: A CASE OF HARGEISA CITY, SOMALILAND(Hawassa University, 2020-12-17) MOHAMOUD MOHAMED ISMAILUrban water supply and demand challenges are widespread problems in most of the developing countries such as Somaliland. This thesis paper focuses on the evaluation of the existing urban water supply system of Hargeisa, capital city of Somaliland. The main objectives of this study is to spot the issues of Hargeisa water system by assessing the current status of the water supply system in the town, evaluating the Hydraulic performance of the WSS and eventually propose remedial measures. The current status was evaluated rely on the difference in the supply and demand of the town by forecasting its population while the water losses was used the difference between the production and consumption data. Moreover, to investigate the existing water supply and distribution system, an EPANET software was used to develop the model. The model can be used to customize the high pressure and low pressure zones in junctions and the level of velocity through pipe. The model run was performed for average, maximum, peak and low demand situations to investigate the system model. The analysis result shows that the supplied water in the town is only covering 13.5% of the demand. Hence, this result indicates that there’s a high gap between the demand & supply. In Addition, from three years obtain data of production and consumption the average loss became 9.75%. Moreover, the result and discussion shows that there are totally different issues of the system like high pressures and low pressure whereas, the utmost pressure occurred at gravity main pipe line in night demand was 85.92m which is above the suggested value and also in the low hour demand (LHD), 100% of the velocity in the pipes is less than 0.5m/s. To handle the problems, it needs providing extra pumps to increase the production, rehabilitate the prevailing well sources, maximizing the capacity of distribution pipe line by putting new pipesItem EVALUATING THE STABILITY OF EMBANKMENT DAM BY INTRODUCING CONCRETE FACE ROCK FILL DAM (CASE OF LEGEMERA DAM SOUTH WOLLO, ETHIOPIA)(Hawassa University, 2018-03-13) JEMAL KASSIM MOHAMMEDDesign of an embankment dam is a vital issue from the standpoint of safety, economy, controlling seepage, and speed of construction. Concrete face rock fill dams (CFRDs) virtually impervious, resistant to erosion and aging, workable, shorter period of construction and small volume of construction material. It is very well suited when there is no ample amount of impervious material within economically feasible hauling distance and severe weather conditions during construction. This study was aimed at addressing biggest challenge of hauling distance of the impervious clay core material by changing earth fill dam with central clay core to concrete face rock fill dam in case of Legemera micro earth dam, found in South Wollo. Universally recommended standard values beside to primary and secondary data essential for the work has been used. GeoStudio 2012 software was used for stability, seepage and deformation analysis of the dams. Consequently, by using this software good result of safety factor has been found for concrete face rock fill dam with regard to stability of the dam during maximum pool level, steady state condition and end of construction. During steady state condition, the upstream and downstream factor of safety computed for the dam is 1.954 and 1.544 respectively. Likewise, at the end construction, the upstream and downstream safety factor is 1.824 and 1.59 respectively. The seepage is also reduced to values of 2.42 x10-6 m 3 /sec by implementation of concrete face rock fill dam. Economic analysis result similarly shows that, concrete face rock fill dam is more economical by saving 22,441,387.75 ETB due to fast rate construction of the dam independent of weather condition. Generally, application of CFRD can fulfill the basic requirement and minimum factor of safety under all loading condition, and dam of such types is seepage freeItem EVALUATION OF SMALL SCALE HYDROPOWER WITH DIFFERENT DEVELOPMENT APPROACH AT UPSTREAM OF GIDABO RIVER FOR RURAL ELECTRIFICATION(Hawassa University, 2023-12-07) HABTAMU HAILUHydropower 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 PlantsItem IMPACTS OF LAND USE LAND COVER CHANGE ON RESERVOIR SEDIMENTATION (THE CASE OF RIBB DAM, IN LAKE TANA SUB BASIN, ETHIOPIA)(Hawassa University, 2020-10-21) MEBRATU ESUBALEW ENGIDALand use land cover (LULC) change is the challenge and continuous drivers of environmental change. Understanding the rate and process of change is, therefore, basic for managing the water resources and the environment at large. This study was intended to analyze the LULC changes impacts on sediment load from 2000 to 2018 periods, and select critical (hot spot area) sub basins and recommend best management practice for Ribb watershed of Lake Tana sub basin, Ethiopia. Both climate and hydrometric (flow and sediment) data were collected and analyzed over the period 1990 to 2018. Two time satellite imageries of the Land sat product (2000 and 2018) were used for land use change detection. The hybrid classification technique for extracting thematic information from satellite images were employed by using ERDAS model for classification of LULC. The Soil and Water Assessment Tool (SWAT) model was calibrated and validated to estimate sediment load of the watershed during the period 1992 to 2001 and 2002 to 2007 respectively. To manage the sediment load best management practices (BMP) as a scenario (filter strip, grassed water way and contouring) were implemented on 2018 LU map. The land use change detection result indicate that cultivated land has expanded from 66.87% in 2000 to 75.53% in 2018. Between 2000 and 2018 periods, it was increased by 8.66 %. The rate of increment during 2000–2018 periods were 608.915 ha/year. Similarly, settlement area had also increased by 2.09% from 2000–2018 periods. Similarly, shrub land and bare land also decreased at a rate of 412.868 and 227.651 ha/year, respectively, between 2000 and 2018 periods. Also the water body decreased at a rate of 1.593 ha/year between 2000 and 2018. The SWAT model result depict that the model give reasonable fit of sediment flux with observation during calibration and validation as evaluated with ENS ( 0.63 ) , R2 ( 0.67) and percent bias (17%) during calibration and ENS ( 0.58) , R2 ( 0.71) and percent bias of (12%) during validation period. Moreover, the severity of soil loss rate was increased with the average of 26.89 ton/ha/year from 2000 to 2018 LULC, which indicates that the management practice, was weak within the watershed. The BMP scenarios depict that filter strip was significant amount of LULC conversions practice and soil loss rate had occurred in the watershed from 2000 to 2018 periods, and expected to continue in the future. Thus, appropriate conservation and management practice are very much crucial to safe guard the life of the reservoirItem ESTIMATION OF RUNOFF AND SEDIMENT YIELD USING SWAT MODEL: THE CASE OF KATAR WATERSHED, RIFT VALLEYLAKE BASIN OF ETHIOPIA(Hawassa University, 2019-07-27) Dulo HusenEstimating of runoff and sediment yield at watershed level is important for better understanding of hydrologic processes and identifying appropriate measures to combat erosion. In this study, Soil and Water Assessment Tool (SWAT) was used to calibrate and validate a hydrologic component on Katar river discharges at Habura gauging station and predict the stream flow of Katar watershed. The objective of the study was estimating the runoff and sediment yield for the Katar watershed using SWAT model. Sensitivity analysis, model calibration and validation were also performed to assess the model performance. From the result of Global sensitivity analysis, twelve(12) highly sensitive parameters were identified, and coefficient of determination (R2 ), Nash-Sutcliffe (ENS) and percent bias (PBIAS) were used as objective function to evaluate model calibration and validation on the monthly basis, and it could simulate runoff to a good level of accuracy. The results obtained were satisfactory for the gauging station (R2 = 0.80, ENS = 0.6 and PBIAS=0) for calibration and (R2 = 0.6, ENS = 0.55 and PBIAS=1.2) validation period. The simulated runoff and sediment yield of Katar watershed was quantified and also the utmost erodible part of the watershed was identified and prioritized. Among all sub-watersheds, nine (9) sub watersheds were more vulnerable to soil loss and potentially prone to erosion risk, which was out of range of tolerable soil loss rate (18 tha-1 yr-1 ). Large area of watershed covered by Haplic Luvisols(high clay content) and agriculture is the dominant activities in area. The simulated mean of sediment yield and runoff loss from watershed for 26 years were 11 tha-1 yr-1 and 12.3 m 3 s -1 respectively. The result of the study could help stakeholders to plan and implement appropriate watershed management strategies based prioritizations of severity of erosion. In conclusion, the SWAT model could be effectively used to predict runoff and sediment yield and result of the study could help different stakeholders to plan and implement appropriate interventions strategies in the Katar watershed.Item EFFECT OF BAFFLE BLOCK PARAMETERS ON HYDRAULIC JUMP CHARACTERISTICS(Hawassa University, 2023-08-07) MEKONNEN BEKELE WORKUThe experimental determination of baffle blocks installed on stilling basins has been also utilized to stabilize the formation of the jump and increase the turbulence, there by assisting in the dissipation of energy. The main objective of this study is to assess the effects of baffle block parameters on hydraulic jump characteristics. Investigate the influence of baffle blocks on hydraulic jump properties of flow over a weir, to evaluate the effects of different shapes and arrangements of baffle blocks on hydraulic jump characteristics and identify the best shape and arrangement of baffle blocks increasing efficiency of energy loss. The experimental work was performed in a rectangular flume with a dimension of (14 m* 0.3 m* 0.45 m) long, wide, and deep, respectively with Steel, different shapes of baffle blocks (Trapezoidal, Rectangular, and Triangular) with the dimension of (0.05 m*0.0375 m*0.06 m) height, width and length bed material. The experiment was being tested with various flow rates for different shapes and arrangements to analyze the effect on the sequent depth ratio, energy loss, Froud number, and efficiency. Each shape and arrangement baffle have five discharges that were used to maintain the upstream depth the relationship between the Froude number and the discharge for different baffle depth and different velocity; where the average value of the depth was varied (10mm - 50mm). Froude number decreases (1.92-1.54) with the decreases in the average value of loss of energy (0.20–0.14), as the sequent of depth ratio decreases (17.85*10-3 –13.41*10-3 ). The relation between Shape of Baffle Block, Energy Dissipation, and efficiency Trapezoidal (32.19, 70.86%), Rectangular (37.35, 83.98%), Triangular (32.03, 67.23%), and Mixed (34.41, 74.08%) respectively. From above clearly shows that rectangular baffle blocks have higher energy dispassion and efficiency which indicate that the energy dispassion and efficiency in row three and four arrangement 4*3*2 and 4*3*2*1 obtained best are energy dispassion (32.77%) and efficiency (83.98%) receptively under rectangular shapes, which is highest from baffle block shapes relatively better than the other baffle block shapes this is due to may be part of energy dissipate increases efficiency. From this observation rectangular baffle blocks are better for energy dissipation since higher efficiencyItem DAM BREACH ANALYSIS OF BISANDIMA DAM, SIDAMA REGINAL STATE, ETHIOPIA(Hawassa University, 2023-07-23) TAFESE FONA DEBESADue to the construction of Bisandima dams, the downstream ecosystem is highly changed in that a huge area is covered with irrigation farms, new settlements, and residence areas of inhabitants living on the farms, and fishery communities were formed due to this dam. All these investments and newly settled inhabitants are highly exposed to flooding and they are at risk from the possible failure of this dam. The objective of this study was to model the Bisandima dam breach phenomena and to develop flood inundation maps. In this study dam breach, flood routing was carried out by using unsteady flow routing in HEC-RAS 2D model using geometric data to determine flood-susceptible areas downstream of the dam for the study area. The key inputs required in the dam breach flood routing processes include Precipitation data to determine PMF, digital Elevation model, and land use data were used as input for the HEC-RAS model. Some parametric methods were also used to predict dam breach parameters for use in the model. The breach discharge resulted from the HEC-RAS model for all methods such as Thun & Gillete (1990), Froehlich (2008), Froehlich (1995), MacDonald and Langridge –Monopolis (1984), Xu & Zhang (2009) were 2079.01, 1040.21, 1332.49, 531.91, 592.22 m3 /s and 1796.52, 620.37, 572.02, 530.53, 498.46 m3 /s for overtopping failure and piping failure respectively and also breach outflow at the downstream cross-section were 969.32, 625.48, 699.46, 538.96, 592.38 m 3 /s for overtopping failure respectively. The hazard mapping due to the combined effect of flood depth and velocity showed that an area of 28ha, 9.5ha, 11ha, 3ha, and 0.5ha are under low, medium, high, very high, and extreme hazard respectively for overtopping failure and an area of 20ha, 8ha, 10ha, 2.2ha, and 0.8ha are under low, medium, high, very high and extreme hazard respectively for piping failure. As noticed from the flood inundation map almost all critical areas downstream of the dam are in immediate danger. Based on the finding of the study outcomes the following recommendations are drawn: flood early warring, watershed treatment, provide dike at both sides of the downstreamItem EVALUATION OF THE PERFORMANCE OF TRADITIONAL IRRIGATION SYSTEM IN DEGALUNA TIJO WOREDA, ARSI ZONE, OROMIA REGION(Hawassa University, 2018-03-25) Seyoum Tadesse H/mariamThis study was carried out at Degaluna Tijo Woreda traditional irrigation scheme with the objectives of characterization of the scheme, evaluating the performance of scheme using XV selected performance efficiency indicators and analyzing water productivity in relations to water applied. In the highlands of Ethiopia, irrigation practices have long been in use since ancient times for producing food crops. It was low momentum irrigation development, whereas the developed irrigable land had not been irrigating as expected. The areas that had been to use accounts less than 20% of the total irrigable land. It was made by measuring canals capacity and efficiency, length of water flow. Performance evaluation of the scheme was made using selected performance indicators such as conveyance, application, storage efficiencies, and distribution uniformity along with the water productivity in terms of water use efficiency as well as external indicators. The result obtained showed that conveyance efficiency of 82.69%, 75.27 %, and 80.45%, respectively. In the field that application efficiency, storage efficiency and irrigation efficiency on economic eight farmers’ plot located on different ends of the command 49-58%, 42-60 % and 57-89% upper, middle and downstream irrigation scheme respectively. Regarding the output per area, Temela Gusha was better than other systems, but for the output per water supply the converse was true that is, Hobori was better than others were. The institutional arrangement was poorly to support the irrigation farm association and crop pattern trends with the crop water consumption. It observes that from time trend of remote sensing image environmental climate condition famine change rapidly accelerated from time to timeItem PERFORMANCE ASSESSMENT OF URBAN DRAINAGE SYSTEMS OF YIRBA TOWN SIDAMA REGIONAL STATE, ETHIOPIA(Hawassa University, 2023-10-22) SITOTA MATHEWOS RIKBADeveloping countries experience accelerated urbanization without adequate investment in infrastructure. Yirba town, like other towns of Ethiopia, have a lot of problems including inadequacy and poor-quality drainage infrastructure. The objective of this study is to assess the hydraulic performance of stormwater drainage systems of the study area, to identify stormwater management issues and existing urban drainage system problems, and to identify the best management practices for drainage problem mitigation measures and to achieve these specific objective SWMM5.2 model and LID structural measures were used in the study. Rainfall, infiltration, and physical characteristics of the catchment area were organized as three main inputs for the model. Rainfall depths of thirty one years (1992-2022) of Yirba station were obtained from National Meteorological Agency. According to chi-square test of the best fit probability is Log Pearson type III distribution and that is used to developed IDF curve. Infiltration of the model area is represented by Curve number method. Physical characteristics of the sub catchments including topography of the model area was analyzed using Goggle Earth and ArcGIS software. The calibration and validation of the SWMM5.2 model were done and its performance was tested by the goodness of fit using the coefficient of determination (R2) =0.97 and Nash Sutcliffe Efficiency Coefficient (NSE) =0.90. The total simulation area of sub catchment is 80 ha; the model area is divided in to 45 sub catchments with a drainage network of 38 conduits, 38 junctions and 2 outfalls. From model result 50% of conduits and 55% of junctions are flooded; at the outfall total sub-catchment runoff is 4.35m 3 /s average flow rate, 10.84m 3 /s maximum flow rate and 91.10*103 m3 total volumes of both outfalls. Among the various low impact development (LID) structural measures, infiltration trench and vegetative swale are incorporated and simulated in the model. Based on the simulation of LID's 10-year return period, improvements in terms of reduced peak discharges and increased peak discharge times were observed in sites where LID was used. In terms of a 10-year period, the peak runoff from particular sub catchments of drains is reduced by a minimum of 1.82% and a maximum of 19.91%. In general, the Yirba town urban drainage system performance infrastructure overflow was assessed and managed for the problem occurring using the possible mitigation techniques by improved LID control for all study areas.