http://ir.bdu.edu.et/handle/123456789/10239 2001-01-13T05:52:03Z 2001-01-13T05:52:03Z Zemene, Abebaw Tsega http://ir.bdu.edu.et/handle/123456789/16636 2025-03-18T06:19:13Z 2024-06-01T00:00:00Z

ASSESSMENT OF THE CAUSE OF FAILURE DIVERSION WEIRS IN COMMUNITY-MANAGED SMALL SCALE IRRIGATION SCHEMES IN ARIB WATERSHED, AMHARA REGION, ETHIOPIA Zemene, Abebaw Tsega Many diversion head-works for irrigation have been designed and constructed in the past few years. Some of them are performing successfully, but some of the schemes have failed. So, it is important to deal with the assessment of the causes of failure diversion weirs and identify the main design parameters implemented for irrigation. In this work, the existing design practices, failure causes, and failure mechanisms in the four Community-Managed Small-Scale Irrigation (SSI) diversion weirs in the Arib Watershed, North Gojjam Zone, Amhara Region, Ethiopia, have been assessed. To identify and characterize the existing irrigation schemes, field observation and measurements, group discussions, interviews, and questionnaires were used, and the data was analyzed by SPSS statistical software. Arc-GIS 10.7 was applied to delineate the watershed of the study area; peak discharge was estimated by the Soil conservation system (SCS); and the HEC-HMS was used for building the hydrologic models. Peak rainfall from Bahir Dar metrological station analyzed for feature 50 years return by using Gumbel distribution method was 148.46mm. The analysis resulted the river peak design flood was 217.7m3/s and 202.9m3/s computed by HEC-HMS and SCS-CN method respectively. The main constraint parameters that contributed to the failure of the irrigation schemes, including planning, institutional, social, operational, and economic, have been assessed. The main problems observed in the diversion schemes are sedimentation at the head-works and canals, damage to intakes and sluice gates, clogging of intakes, and damage to distribution systems. Some of the problems recognized at the institutional, social, and operational levels are due to a lack of adequate community participation, the absence of Water Users Associations (WUA), proper handing over, a lack of training and maintenance, and evaluation and monitoring issues. The study suggests rehabilitation measures for the failed SSI schemes. The results of the study will help the SSI schemes perform better and more efficiently to increase agricultural productivity in the study region, as well as other small-scale irrigation schemes in our country. Key words: Weir failure, HEC-HMS, design parameter, Arib Watershed, SCS, Hydrologic, Hydraulic

2024-06-01T00:00:00Z YOHANES, BELACHEW ABEBE http://ir.bdu.edu.et/handle/123456789/16635 2025-03-18T06:17:44Z 2024-07-01T00:00:00Z

ASSESSMENT OF IRRIGATION PERFORMANCE ON COMMUNITY MANAGED IRRIGATION PROJECT IN THE CASE OF WURKO SCHEME YOHANES, BELACHEW ABEBE Even if almost 70% of the water used worldwide is applied for crop irrigation, to meet global food demand, irrigation systems structural design, management, and maintenance have been inadequate. Therefore, the study assesses the efficiency of Wurko small-scale irrigation scheme in Lake Tana Sub-Basin, Blue Nile Basin, Ethiopia. Of the 85 ha designed command area, 61 ha was active during the study season. In this finding, a single irrigation season (December to June) of the year 2024 has been taken into consideration, based on 22 years of metrological data (2000–2021). Field observations, discharge measurements in the canals, measurements of water applied to the field, household survey and examination of moisture contents of the soil before and after irrigation, determination of soil physical properties were the primary data whereas climatic data, agronomic data, yields, command and cropped areas, and report of other documents are used as secondary data. The data are analyzed using the CROPWAT 8.0. The findings of the internal performance indicators were 77.51%, 70%, and 53.56% for conveyance, application, and overall efficiencies, respectively. The results of the external performance indicators, relative water supply, relative irrigation supply, water delivery capacity, irrigation ratio, and the sustainability of an irrigated, output per cropped and command area ,output per irrigation supply and water consumed were, in that order, 1.55, 1.62, 1.24, 0.72,0.9, 14637 US$/ha, 10504 US$/ha, 14.15 US$/m3, and 2.69 US$/ m3, respectively. According to those external performance indicator figures, there is a limited supply of water, the real command area has shrunk by 28.2% from its original plan, and some of the initially installed structures are starting to fail. The overall performance is generally regarded as a good performance. As a result, for water users association to carry out its duties, the right organizational structure, plan monitoring, and capacity building must be in place. Keywords: Blue Nile, Wurko, Irrigation, CROPWAT, efficiency

2024-07-01T00:00:00Z Yesyt, Tsegaye Tamirate http://ir.bdu.edu.et/handle/123456789/16634 2025-03-18T06:15:32Z 2024-11-01T00:00:00Z

IMPACT OF CLIMATE CHANGE ON GROUNDWATER RECHARGE IN GUMARA AND RIBB WATERSHEDS, ABBAY BASIN, ETHIOPIA. Yesyt, Tsegaye Tamirate Groundwater is an important water resource and needs more attention on its vulnerability to overexploitation, pollution and, especially, climate change. Studying impacts of climate change on groundwater recharge is important in the watershed to alleviate effects of climate change in groundwater recharge. In order to utilize the Groundwater resource properly and sustainably knowledge of the available groundwater and surface water resources and the capacity to use them is necessary. The aim of this study is to evaluate how climate change affect the groundwater recharge in the Blue Nile river basin of Gumara and Ribb watersheds. Bias corrected Global Climate Model (GCM) projection data set at Shared Socioeconomic Pathways (SSP4.5 and SSP8.5) were used for future groundwater recharge estimation at three time horizons (2030s, 2050s and 2090s) and base period of (1995-2014). The result of the Mann-Kendall trend test showed that mean annual minimum and maximum temperature are found to increase by (1.20c, 3.10c) and (2.80c, 4.80c) at SSP2-4.5 and SSP2-8.5 scenarios respectively, on 2090s from the baseline period. A hydrological model, (WetSpass-M) performance was assessed through manual calibration process, and R2 and NSE were obtained for the Gumara watershed (0.84, 0.83) during calibration and (0.83, 0.81) during validation respectively. During the calibration and validation process in Ribb watershed, R2 and NSE were (0.63, 0.61) and (0.62, 0.6) respectively. Even though consistent trend was not found in Rainfall, mean annual groundwater recharge of Gumara and Ribb watershed would reduce from (394.36 mm to 363.16mm, 358.40mm and 352.24mm) and from( 394.36 mm to 361.9mm,339.7 mm and 338.6mm) at SSP2-4.5 and SSP5-8.5 scenarios, on 2030s,2050s and 2090s from the baseline period respectively for Gumara watershed. Similarly, Ribb watershed would reduce from (420.71 mm to 390.15 mm, 383.76mm and 381.74mm) and from( 420.71 mm to 382.88 mm, 371.89mm and 367.98 mm) at SSP2-4.5 and SSP5-8.5 scenarios, on 2030s,2050s and 2090s from the baseline period respectively. Consequently, the study concluded that the groundwater recharge would reduce by 10.68% and 14.13% on 2090s from the baseline at SSP4.5 SSP8.5 scenarios respectively for Gumara watershed and 9.3% and 12.5% for Ribb watershed on 2090s from the baseline period at SSP4.5 and SSP8.5 scenarios respectively. Keywords: climate change; groundwater recharge; downscaling; WetSpass-M model.

2024-11-01T00:00:00Z YESHAMBEL, MULUALEM RETTA http://ir.bdu.edu.et/handle/123456789/16633 2025-03-18T06:10:40Z 2024-06-01T00:00:00Z

ASSESSMENT OF STORMWATER DRAINAGE SYSTEMS IN MERAWI TOWN USING SWMM YESHAMBEL, MULUALEM RETTA A drainage system’s performance reduces with time and degrades due to multiple factors. Street flooding and over-topping drainage systems were occurring in Merawi town. The objective of this study is to assess the performance of the drainage systems in Merawi town using the SWMM model. The SWMM model is one of the most popular models for urban flood planning and control. The digital map and pipeline network are used to set up SWMM work. The study employed both primary and secondary data collection. The sub-catchment characteristics and the storm sewer conduits are used to determine the parameters of the model. The simulated results indicate that the examined area would be flooded for 2, 5, 10, 25, 50, and 100-year return period precipitation. Hydrological and hydrodynamic modeling play a key role in the hydraulic, structural, and environmental impact assessment tasks in the urban drainage system. Climate change is one environmental threat that poses great challenges to the future development prospects of Merawi. The study used statistically downscaled daily data in 30-year intervals from the second generation of the Earth System Model (CanESM2) under two Representative Concentration Pathways (RCPs): RCP 4.5 and RCP 8.5 for two future time slices at 2040 and 2070. The projected annual minimum and maximum temperatures are expected to increase by 0.16°C, 0.99°C, 0.53°C, and 1.54°C in the 2040s and 2070s under the RCP4.5 scenario, respectively. Under RCP8.5, the annual minimum and maximum temperatures are expected to increase by 0.24°C, 1.72°C, 0.59°C, and 2.28°C in the 2040s and 2070s, respectively. Besides, the precipitation is expected to increase under intermediate and high emission scenarios by 0.236%, 0.681%, 0.846%, and 0.919% in the 2040s and 2070s, respectively. In both emission scenarios, the greatest changes in maximum temperature, and minimum temperature but non aristocratic changes in precipitation are predicted by the end of the century. According to the study, climate change would have been increased in the future, thus it should have brought an impact on the urban flood drainage system. Based on the research result we have recommended specific problems. Those are, LID to reduce runoff production. Continuous monitoring of the drainage facilities, proper dump site selection and solid waste management method is required. Keywords: stormwater drainage, SWMM, Runoff Generation, RCP scenario, LID

2024-06-01T00:00:00Z