Assessment of Flood and its Damage on Agricultural Yields in Vulnerable Areas of Upper Awash, Ejere Woreda, West Shewa, Oromia Regional State, Ethiopia
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Date
2026-01-01
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Addis Ababa University
Abstract
Floods are recurring natural events that can have both negative and positive consequences: however, their adverse impacts on agricultural activities particularly in areas with inadequate
risk management are often devastating. Flooding in upper Awash River region has been a persistent problem for agricultural fields over an extended period. Therefore, attention should
be focused on risk assessment, as well as on accurately analyzing and quantifying the flood occurrences. The objective of this research is to quantify and evaluate the impact of flood
damage on wheat and barley yields in Bolengo kebele, Ejere woreda, Oromia regional state, Ethiopia. The area is frequently affected by flooding from the upper Awash River basin. Data
on crop average, seasonal yields, flood levels, and community participation in the flood management were collected from woreda office, field observation, and focus group discussions.
Historical streamflow data was obtained from the Hombole station, the tributary of Awash River, which was recorded between 1999 and 2022. Floodplain mapping near the Awash
River was developed based on the peak flow of the river for different return periods using the HEC-RAS model, the ArcGIS tool for spatial processing and HEC-GeoRAS to link ArcGIS
with HEC-RAS. The basic assumptions in statistical flood frequency analysis include the independence and stationarity of the data series and that the data originated from the same
distribution. Homogeneity and stationarity test at different significant level were conducted using Wald-Wolfowitz and Mann-Whitney methods. These tests confirmed that the flow data
are independent, homogeneous, stationarity and no outliers at the 5% significant level. Flood quantile estimates were computed from return periods of 2, 5, 50, 100, and 500 years, with
the discharge value ranging from 38.93 to 99.22m3/sec. The corresponding floodplain area was found in the range of 87.6 to 147 hectares, resulting in crop losses of 1,489.2 to 2,512.6
quintals of wheat and barley, respectively. The flood inundation map of the area indicated that the downstream parts of the cultivated land are more vulnerable to flooding. The most
affected areas are located close to the awash main course. The results indicated a critical need for a flood risk management strategies both structural and non-structural to mitigate the
economic impact of recurrent floods on agricultural land in the area.
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Keywords
Flood Damage, Hydrological modelling, Upper Awash River Basin, Bolengo kebele.