Browsing by Author "Melaku, Wendachew"

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    Assessment of River Bank Overtopping Problem (In case of Sedie River, Abbay basin, Ethiopia)
    (Addis Ababa University, 2020-06) Melaku, Wendachew; Daniel, Fikreselassie (PhD)
    Flood forecasting is an important mechanism to prevent and manage the consequences of flood damage problem on agricultural areas. This study focuses on assessment of Sedie river flooding problem by preparing flood inundation map for different return periods. Different models including hydraulic model HEC Ras, hydrological model HEC HMS with integration of ArcGIS, HEC GEOHMS and Ras Mapper tools used for conducting this study. Primary data, surveyed river cross section and secondary data’s such as rainfall, stream flow, DEM, Land use / land cover and Soil type data’s collected and used for the study. Totally around 8 years of observed flow data 5 years (1996-2000) for calibration and 3 years (2001-2003) for validation used. After the analysis of the data it was found that HEC HMS calibration and validation result was good and the performance of the model checked with the coefficient of determination and Nash-Sutcliffe with good result of 0.84 and 0.83 for calibration, 0.74 and 0.73 for validation respectively. Due to the unavailability of observed water level and rating curves in the study area the HEC RAS model calibration and validation result compared qualitatively and relatively good result obtained. The calibrated manning roughness for the left and right bank obtained 0.035 and 0.025 for the main channel of the river. The flood inundation map prepared by using Ras Mapper tool and different flood inundation map results for different return periods obtained. The flood inundation map shows that for especially 50yr and 100yr return periods the flood damages 177.22 ha and 280.78 ha farming areas respectively. Therefore in order to mitigate this damages structural and nonstructural measures recommended depending upon the severe of damage at each stations.