Water Resource
Permanent URI for this collectionhttps://etd.hu.edu.et/handle/123456789/71
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Item ASSESSMENT OF STORMWATER DRAINAGE SYSTEM IN HAWELA TULA SUBCITY, HAWASSA CITY(Hawassa University, 2023-10-28) SINTAYEHU BETISO BERASAThe major goal of this study was to evaluate Tula Town's current storm water drainage system and to provide ideas or engineering solutions that would be able to resolve the current issues. Storm Water Management Model (SWMM), which is a dynamic rainfall runoff simulation model widely applied for urban drainage, was chosen for assessing the triggering factors as well. Due to insufficient drainage network infrastructure and a rise in urban pavement on most urban sub-catchments, this problem developed. The Rainfall depths of sixteen years (2006-2021) of Tula meteorology station were obtained from National Metrological Agency. An intensity duration frequency curve for different return periods (2, 5, 10, 25, 50, 100yrs) formulated by Log person type III distribution method was used as an input for the model due to its slightly better coefficient of determination than other method. The study made use of the SWMM5.2 model and the low impact development control. The calibration and validation of the SWMM5.2 model well-done and its performance was tested by the goodness of fit using the coefficient of determination (R2 ) =0.98, the Nash –Sutcliffe coefficient (NSE) =0.91, and Relative error (RE) =24.13%. The simulated area of the study subdivide to two outlets of the total area of sub-catchment is 70.55ha joint to drainage system infrastructure of 37 nodes, 48 channels, by SWMM 5.2 model. According to the model's results, more than 50% of drainage infrastructure is flooded. At the outfall, total sub catchment runoff has an average flow of 6.0785m3 /s, a maximum flow of 11.39m3 /s, and an overall volume of 222.228*103 m 3 as predicted by the SWMM5.2 model. The town's ongoing drainage issue is helped by the varied implementation of low impact development techniques. In general, the Tula Town urban drainage system evaluation infrastructure overflow studied and regulated for the problem occurred using the best alternative mitigation measures by enhanced low impact development management for all study sitesItem PERFORMANCE ASSESSMENT OF URBAN DRAINAGE SYSTEMS OF ALETA-CHUKO TOWN(Hawassa University, 2022-08-12) MEBIRATU MENGISTUAs 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 recommendedItem HYDRAULIC PERFORMANCE EVALUATION OF URBAN DRAINAGE SYSTEM AND PROPOSED MITIGATION MEASURES: A CASE STUDY AT KOFE KEBELE IN DILLA TOWN(Hawassa University, 2023-10-23)This thesis aims to provide a comprehensive evaluation of the hydraulic performance of an urban drainage system and propose effective mitigation measures to address the negative impact of flooding in Kofe Kebele of Dilla town using the Stormwater Management Model (SWMM) 5.1. The study area covers 180 hectares of land; it has three outlets, the catchment is classified into 34 sub-catchments, and the drainage system has 144 junction nodes and 191 conduit links. Flow routing was computed using kinematic waves and Green-Ampt was used for the infiltration model. Rainfall data for Dilla were obtained from the National Meteorological Agency and twenty-five years of data were used (1997–2021). The normal ratio method was used to fill in missing data. A double mass curve was used to check consistency, outlier identification was performed to check for higher and lower outliers, and rainfall frequency analysis and frequency distribution fitting were performed to evaluate the goodness of fit. A goodness-of-fit test was performed, and it was found that Gumbel, or GEV (I), has a good fitness value, and IDF curves were developed based on the ERA standard. A 25-year return period was used as the design storm. The United States Environmental Protection Agency’s Storm Water Management Model (EPA SWMM 5.1) and the Geographic Information Systems (ArcGIS) tool were used to model and analyze stormwater characteristics. recorded water levels and velocities were used to calibrate and validate the EPA SWMM 5.1 model. Three conduits were selected for calibration and validation. The results obtained for the calibration of the performance indicator of the Nash-Sutcliffe efficiency (NSE) for each conduit (C78, C97, and C184) were 0.87, 0.91, and 0.85, respectively, and for the coefficient of determination (R2 ) were 0.75, 0.84, and 0.77, respectively. The other indicator considered was the relative error, where the errors were 8.3%, 4%, and 7%. Referring to the validation, the performance of the model for Nash Sutcliffe efficiency (NSE) for the aforementioned conduits was 0.91, 0.88, and 0.88, respectively; it was 0.88, 0.99, and 0.78 for the coefficient of determination (R2 ), with a relative error of 3.7%. These results show that the model has a good performance and can perform the analysis for the study area. Low-impact development (LID) techniques were investigated based on land use and land cover conditions to sustainably solve the flooding problem. From various LID alternatives, three LID techniques were chosen based on site conditions: bioretention cells, infiltration trenches, and rain barrels. The simulation results indicated that the combination of bioretention cells, infiltration trenches, and rain barrels had a better capacity to minimize runoff. This study suggests using low-impact development (LID) to address flooding issues in a sustainable manner.