Water Resource

Permanent URI for this collectionhttps://etd.hu.edu.et/handle/123456789/71

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Start date: 2020Subject: search.filters.subject.Runoff

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    PERFORMANCE EVALUATION OF STORMWATER DRAINAGE SYSTEM OF BEDELE TOWN
    (Hawassa University, 2020-10-24) YEROSAN KEBEDE AYANA
    Various factors can degrade the drainage system and reduces its performance. As the role of drainage infrastructure is very high in preventing urban floods, their performance should be monitored and quantified. This study aimed to assess the performance of stormwater drainage systems in Bedele Town. Primary and secondary data were used in this study. The catchment that contributes runoff was delineated using ArcGIS 10.4 software. The Stormwater Management Model (SWMM 5.1) was used to simulate the peak flow rate and water level in the drainage canals by considering the current land use. The intensity duration frequency (IDF) curve was developed by using the Log-Pearson Type III. The peak runoff for 10-year and 25-year return periods was estimated by using the Rational Method. The condition of the existing drainage system was assessed and poor solid waste management, lack of well-connected drainage lines, poor liquid waste disposal, and the existence of fully uncovered areas in the town with drainage structures were identified to be the drainage problem of the Town. From the total area of Bedele Town, 41.1% is uncovered with the drainage systems. The total peak runoff generated from this study area is 15.59 m3/s and the average velocity was 2.5m/s for a 10-year return period. The result from the Rational method as well as SWMM 5.1 shows there is an overflow problem in this study due to the presence of drainage canals with insufficient capacity to carry the runoff generated from this catchment. For a sustainable drainage system, the appropriate use of hydrological analysis, hydraulic design, and stream morphological study should be implemented before carrying out the construction of drainage structures for they were not considered during the construction of the drainage system of the Town. Regular maintenance and frequent clearance of drainage lines, proper integration between roads and drainage structures, provision of additional drainage canals, and improved stormwater management were recommended to solve the stormwater drainage problem of the Tow
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    COMPARISON OF SWAT AND WEPP FOR MODELING ANNUAL RUNOFF AND SEDIMENT YIELD AND QUANTIFCATION OF NUTRENT LOSS IN AGEWU MARIYAM WATERSHED, NORTHERN ETHIOPIA
    (Hawassa University, 2022-10-22) YALELET ABIE WORKU
    Unevenly heavy rainstorms during the rainy season create runoff and soil erosion which affects soil fertility and production, especially in northern Ethiopia. In this study soil and water assessment tool (SWAT) and geographic water erosion prediction project (GeoWEPP) were applied to compare estimation of annual runoff and sediment yield and quantification of nutrient loss in Agewu-Maryam watersheds eastern Amhara, region, Ethiopia. To run both models, need spatial and temporal data distribution is required as an input. The soil textures and other selected soil properties were determined in the field and the laboratory and a soil map were derived from the digital soil map of the world. A land-use map was prepared based on manually digitizing from Google earth image. A Digital Elevation Model of the watershed was used for delineating the watershed and preparing a slope map. ArcGIS 10.4 was used for both models for basic interface for further analysis. During each runoff event, runoff samples were collected and the sediment concentrations were analyzed in the laboratory. The simulation result of long-term (24-year) average means annual runoff and sediment yield from WEPP and SWAT models were estimated. The results were performed well as indicated by R 2 0.86 and 0.91 and with NSE 0.54 and 0.71 for monthly runoff were satisfactory for SWAT and WEPP models compared with observed value respectively The estimated average mean annual runoff and sediment yield at the outlet of the watershed was 65.54mm and 146.14mm and 43t/ha/yr and 41.7t/ha/yr respectively for WEPP and SWAT models. The t statics result shows that there is no statistically significant difference with p-value (0.97 for runoff and 0.98 for sediment) between the two models' simulation results. Some of the Sub watershed were identified and prioritized as more susceptible to soil erosion and give more attention first to this area for reducing runoff and soil erosion. The total nutrients loss within the suspended sediment were 33.74kg/ha/yr N,6.79kg/ha/yr P, 642.5 OM kg/ha/yr, and 1.52 K for the watershed. Hence SWAT and WEPP models were well suited for the estimation of annual runoff and sediment yield. The sediment yield simulated from both models was high which was alarming and far beyond the soil loss tolerable rate. Therefore, the result of the model could be used as a decision-making tool
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    PERFORMANCE ASSESSMENT OF URBAN DRAINAGE SYSTEMS OF ALETA-CHUKO TOWN
    (Hawassa University, 2022-08-12) MEBIRATU MENGISTU
    As the process of urbanization accelerates, drains become increasingly overloaded and unable to cope with heavy rainfall. The main objective of this study was to assess the performance of the urban drainage system in Aleta-Chuko Town. Both primary and secondary data were collected by field survey, Resident community, agency, Municipal administration, books, and articles. Rainfall data were used from Ethiopian Meteorology Agency from 1991 to 2019 (30 years) data. To develop the Intensity Duration Frequency curve (IDF) the rainfall intensities for the different duration were selected as the best-fit probability distribution based on Easyfit professional 5.6 software and correlation coefficient. From the analysis result, log-Pearson Type III was the best fit probability distribution for this study area as confirmed goodness of fit tests statistics for different return periods. Considering the current land use, rainfall intensity, and catchment area, the peak discharge was estimated using the rational formula. The adequacy of the existing drainage systems were checked by comparing the estimated runoff with the existing drainage capacity . The Stormwater Management Model (SWMM 5.1) was applied to simulate the water level in the links and junctions by considering the current land use condition.The model allows the catchment area to be subdivided into sub-catchments. For this study area is subdivided into 32 sub-catchments. From model simulation result’s a number of the existing drainage lines are undersized, and therefore not able to handle the required capacity of a 10-year storm occurrence. Typical flooding during the rainy season sub-catchments are: S-C-02, S-C-03, S-C- 13, S-C-14, S-C-27, S-C-28, S-C-30, and S-C-31. The storm overtops the drainage system. In another hand, some stormwater drainage systems were oversized. Based on the GTZ standard, For instance total drains about 37.93% is severely degraded, and 24.2% is light around existing market and Aleta- Chuko Primary Hospital. Finally, lack of community awareness, drainage systems are not well connected,and improper construction alignment problem for the existing system were investigated, and to avoid this problem creating awareness for the community, repair degraided channel either fully or partially, providing drainage channels without drainage system’s, periodic cleaning and modification of slope is recommended
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    HYDROLOGICAL AND HYDRAULIC PERFORMANCE EVALUATION OF STORMWATER DRAINAGE SYSTEMS, OF AWASHO-ALELU KEBELE (01 AND 10) SHASHEMENE TOWN, ETHIOPIA
    (Hawassa University, 2021-04-12) USMAN TUSA WAKO
    Shashemene town is one of the fastest-growing towns to urbanization and increases the amount of runoff generated from the urban catchment. This study intended to hydrological and hydraulic performance evaluation of stormwater drainage systems, of Awasho-Alelu kebele (01 and 10). Due to urbanization, lack of proper design and management, the transport infrastructure and drainage systems are caused by flooding. Data used for this study were meteorological (rainfall) data, drainage systems dimensions, digital elevation model (DEM). Determining the peak discharge by the rational method using land-use, rainfall intensity and the catchment area of internal all sub-catchments and also the upstream catchment inflow by SCS (CN). These results show, that 78.9% of the drainage systems are not adequate to carry the design flood based on intensity with a return period of 10 years. The other problems lack well-connected and sufficient drainage lines, solid wastes were directly disposed into the storm drainage system and insufficient slope provides which results in decreasing the efficiency of the system. Most drainage systems perform severely degraded are at Farma academy school 54.3%, at new bus station 44.181%, at Malka Oda Hospital 61.6%, at Alelu market 46.5% and Alelu primary School 56.2% were severely degraded
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    HYDRAULIC PERFORMANCE ASSESSMENT OF STORM WATER DRAINAGE SYSTEMS OF DEJEN TOWN USING STORM WATER MANAGEMENT MODEL
    (Hawassa University, 2021-10-17) BEKALU ZELALEM TILAHUN
    Stormwater drainage problem is a major challenge facing most of the Cities and Towns of the world including Cities and Towns in Ethiopia. As Dejen Town has stormwater drainage problems, this study was conducted to assess the current performance of the Town, to estimate and predict flood amount, and to design drainage structure for a design period of 10-years to solve such problems. To do this, first meteorological data such as rainfall data of the study area from (1987-2018), drainage line, and plan of the Town was collected from concerning bodies, and field survey of the study area was done to measure the drainage canal dimensions, and Global Position System of the Junctions. Then missing rainfall data was filled; data consistency was checked and analyzed using Microsoft-excel. Assessment of the current drainage condition of the study area was performed and the current drainage capacity of existing structures was calculated using measured canal dimensions by Manning’s formula. Nevertheless, most of the existing drainage structures were inadequate to dispose runoff to the outfall area and most drainage structures in study area were poor. The goodness of fit test indicates General Pareto distribution fits for flood frequency analysis and Intensity-Duration- Frequency curve was developed by using this distribution method. By using rainfall intensity calculated from the developed Intensity Duration-Frequency curve, the amount of peak discharges were estimated by the rational formula for each sub-catchments for a 10-years design period. Then, Storm Water Management Model was applied for the prediction of discharge in each sub-catchment. The Storm Water Management Model output indicated that the discharge resulted from the sub-catchments was greater than the existing capacity in most sub-catchment. This implies in most of the canals, Junctions, and outfalls the flood level was greater than the designed water level, and over-flooding occurs at drainage canals and most of the junctions were over flooded. To solve these problems the following mitigations were recommended; construction of additional drainage structures with proper dimension especially for secondary roadsides with no drainage structures, design and construction of well connected structures, adopting the culture of clearing sediment and periodic repairing of drainage structures before total failure.