Institute of Technology

Permanent URI for this communityhttps://etd.hu.edu.et/handle/123456789/66

The Institute of Technology focuses on education, research, and innovation in engineering, technology, and applied sciences to support sustainable development.

Browse

Has files: YesSubject: search.filters.subject.HEC-GeoRAS

Search Results

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    HYDRAULIC MODELING AND FLOOD MAPPING OF HAROSHA RIVER WITH HEC-RAS AND HEC-GeoRAS MODELS IN TIGRAY, ETHIOPIA
    (Hawassa University, 2017-10-27) MULUGETA TAREKE ABEBE
    The Harosha river catchment is found in Tigray region in Raya Valley. This study area is surrounded by Waja and Tumuga catchment in the south and Harosha, Limeat and Harle catchment in the North and also it is the upper south part of the Raya valley catchment. The area is also dominated by undulating terrain with relatively steep to moderately steep and flatter slopes in the downstream of the catchment. Harosha flood plain has been vulnerable to high flooding from rainfall during rainy season. Also the main causes of these damages are land use changes from years to years and the main objective of this study is to estimate peak flood for various return period and prepare flood inundation mapping that can be used as decision support system for future intervention. The data used for this study was annual daily maximum rainfall, DEM, land use land cover map, and soil map and the flood frequency analysis of annual maximum daily rainfall was analyzed. The SCS rain fall-runoff method, HEC-RAS, HEC-GeoRAS and ArcGIS environment are used to determine the peak flood for different return periods. The simulation result for return period of 5, 10, 25, 50 and 100 year floods magnitude are 347.4, 383.7, 420.8, 443.6 and 463.1m 3 /s respectively. The maximum flood hazard and flow depth maps for a return periods of 5, 10, 25, 50 and 100 year are 84.6 and 3.36; 86.1 and 3.84; 86.9 and 4.35; 87.1 and 4.91; and 87.7 hectare and 5.89 m respectively with a maximum velocity of 4.6 m/s.
  • No Thumbnail Available
    Item
    ASSESSMENT OF THE RUN OF THE RIVER HYDROPOWER POTENTIAL AT THE DOWN STREAM OF KOKA DAM AND FORECASTING THE LEVEL OF FLOODING AT SELECTED SITE (CASE STUDY OF AWASH RIVER BASIN, ETHIOPIA)
    (Hawassa University, 2023-10-26) ASHENAFI AYZA ASELE
    Energy demand is increasing exponentially. This is because of rapid population growth, urbanization, the higher standards of living, industrial and agricultural expansion. Nevertheless, the available energy supply is not reliable due to sedimentation problem. So, it is advisable to use the nearby available natural resources (i.e. river and suitable topography) for potential assessments without adverse effect to cope with increasing and diversified energy demands. This study aims to investigate the assessment of river run of hydropower potential at 50km downstream of Koka Dam. To achieve the goal, Stream flow data were collected from 1991-2016 and height information was quantified from contour map and 3D spatial analyst tool in ArcGIS. Initially, the study was identified three possible potential sites and from these sites; site one was selected as the most prioritized site using MCDA method. The study included the Flood level forecasting at mostly prioritized site for further precaution using HEC-GeoRAS for preprocessing of geometric data and HEC-RAS for post processing of hydraulic modeling. Following the aforementioned model, methods and data the study computed the theoretical power at site one was (8981kw and 4197kw), technical power was (6960kw and 3253kw) and the annual energy output was (60.9GWh/year and 28GWh/year) are the maximum and minimum power at Q30 and Q95 respectively. The most preferred site had dependable flow of 19.71m3/s and is occur 95% of the year and the design flow was 42.17m3/s and is occur 30% of the year. The flood inundation area and the maximum flood depth at mostly prioritized river station 1100 where the study starts head measurement (i.e. upstream full reservoir level) and around 1km upstream of R.S. 1100 (i.e. at R.S.2050) were (145.79m 2 , 4.96m) and (204.09m 2 , 5.62m) respectively for 100 year return period. The validation of spatial information for site one tested were 0.71 for RMSE and hydraulic model performance for R.S.1100 and R.S.2050 were (0.7, -8.29 and 0.97) and (0.83, 5.92 and 0.96) for ENS, PBIAS and R for return period of 100 year and show the applicability of the model was good. To encapsulate we can get the site at 50km downstream of Koka Dam that have the capacity to produce annual energy of 60.9GWh/year. Consequently, it is possible to minimize the problem of highly increased and diversified electric demands at the target area. Hence, it is recommended that the government at national as well as local level or any other agency should look over it in detail and finding to implement thorough investigation of the area
  • No Thumbnail Available
    Item
    DAM BREACH ANALYSIS AND FLOOD INUNDATION MAPPING FOR GIDABO DAM
    (Hawassa University, 2019-03-15) FIRAOL BEFEKADU GELETA
    This study presented the dam breach analysis and flood inundation mapping for Gidabo rock-fill embankment dam found in Southern part of Ethiopia. The geometrical data used for this study was extracted from the recently released ALOS PLASAR digital elevation model by Alaska Satellite Facility, which is having the spatial resolution of 12.5 by 12.5 meters. One dimensional unsteady flow simulation within HEC-RAS model was used to simulate dam breaching for both overtopping and piping failure scenarios. Dam breach parameters estimation was done for different empirical equations. Froehlich (2008) and Von Thun & Gillete methods was preferred since the results obtained for these methods are more approaches to the envelope curve developed for the historical dam failures for overtopping and piping failures, respectively. RAS mapper and ArcGIS tools was used to present the maps of spatial distribution of flood extent, flood depth and flood velocity, flood inundation, flood hazard maps of the study area. The breach parameters estimated for both overtopping and piping failure scenarios was provided the reasonable values. The maximum breach discharge simulated for overtopping and piping failure was obtained as 15,945.18 m3 /s and 14,904.18 m3 /s, respectively. Since the failure were tested for hydrologic failure and for normal water level condition, the magnitude of flood and the spatial distributions are obviously different. Developed inundation maps from this study could be possibly help as guidance for dam owners to develop the emergency action plan and for future expansion of irrigation project infrastructures, and other developmental activities around the downstream of the dam
  • No Thumbnail Available
    Item
    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
  • No Thumbnail Available
    Item
    HYDRAULIC MODELING AND FLOOD MAPPING OF HAROSHA RIVER WITH HEC-RAS AND HEC-GeoRAS MODELS IN TIGRAY, ETHIOPIA
    (Hawassa University, 2017-03-10) MULUGETA TAREKE ABEBE
    The Harosha river catchment is found in Tigray region in Raya Valley. This study area is surrounded by Waja and Tumuga catchment in the south and Harosha, Limeat and Harle catchment in the North and also it is the upper south part of the Raya valley catchment. The area is also dominated by undulating terrain with relatively steep to moderately steep and flatter slopes in the downstream of the catchment. Harosha flood plain has been vulnerable to high flooding from rainfall during rainy season. Also the main causes of these damages are land use changes from years to years and the main objective of this study is to estimate peak flood for various return period and prepare flood inundation mapping that can be used as decision support system for future intervention. The data used for this study was annual daily maximum rainfall, DEM, land use land cover map, and soil map and the flood frequency analysis of annual maximum daily rainfall was analyzed. The SCS rain fall-runoff method, HEC-RAS, HEC-GeoRAS and ArcGIS environment are used to determine the peak flood for different return periods. The simulation result for return period of 5, 10, 25, 50 and 100 year floods magnitude are 347.4, 383.7, 420.8, 443.6 and 463.1m 3 /s respectively. The maximum flood hazard and flow depth maps for a return periods of 5, 10, 25, 50 and 100 year are 84.6 and 3.36; 86.1 and 3.84; 86.9 and 4.35; 87.1 and 4.91; and 87.7 hectare and 5.89 m respectively with a maximum velocity of 4.6 m/s.
  • No Thumbnail Available
    Item
    FLOOD INUNDATION MAPPING AND HAZARD ASSESSMENT USING GIS AND HEC-RAS MODEL FOR BILATE RIVER FLOOD PLAIN, RIFT VALLEY, LAKE BASIN ETHIOPIA
    (Hawassa University, 2023-10-08) TIGIST ABERA
    Flood is a natural disaster that occurs suddenly which runs from hilly land to low land area of river banks when runoff exceeds the capacity of the natural or artificial water conveyance structures. Currently, the hazard of flood is common in some parts of Ethiopia including Bilate watershed and cause heart breaking losses in terms of property and even human life in flat river flood plains due to elevation difference and climatic factors. The main cause of flood disaster vulnerability is due to unavailability of proper River and watershed management. Hence, the intended aim of this research is to carryout inundation mapping and hazard assessment of Bilate River flood plain. The required data for this analysis were, Digital Elevation Model, stream flow data, soil type and land use land cover map. These data were collected from Ministry of Water, Irrigation and Electricity in legal request. Hydraulic Engineering Center- Geographic River Analysis System was used to prepare RAS import file for steady flow analysis on Hydraulic Engineering Center-River Analysis System. Stream flow data was checked for outlier and consistency at different significance level using Grubbs and Beck (G-B) test and double mass curve method respectively. For flood frequency analysis parameter estimation of worldwide used distribution functions was done by three important parameter estimation methods such as: method of moment, probability weight method and maximum likelihood method. Best fitted Pearson type distribution function was selected by linear moment (L-moment), D-index and correlation coefficient methods. The estimated peak floods in Bilate at Tena Bilate gauging station for 5, 10, 25,50, 100 and 500 years return periods were 153.2, 193.2, 273.6, 395.3 and 335.9 m3 /s respectively, at Guder station 140.89, 195.79, 217.64, 244.98, 270.33, and 323.86 m 3 /s respectively and at Wera were also 70.31,88.46,108.54, 121.9,134.17 and 159.78 m 3 /s respectively . Mapping of flood inundation was processed with inter connection of GIS extension tool HEC-GeoRAS and HEC-RAS software. The flood inundations for 5, 10, 25, 50,100 and 500 years return period were 16658, 16930,17207,17381,17531 and 17828ha respectively. Flood hazard map were prepared by reclassifying depth grid and its area bounding polygon. Also an assessment of hazard level was done with integrating flood causative agent land use land cover map with hazard map prepared after post-RAS processing. Area inundated at very sever to moderate hazard was ranges between 4% to 10.3% and around more than 72% was low hazard area. Hence, the result of the level of hazard indicates that there is significant potential of flood and the consequence risk on livelihood in study area in significant to sever level. It is recommended that, the watershed management party or any stakeholder, should use this research finding to take appropriate measure and reduce flood disaster in the future