Estimation of Sedimentation of Koka Hydropower Reservoir Using Bathymetric Survey Awash Basin, Ethiopia
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Date
2023-11
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Addis Ababa University
Abstract
Reservoir sedimentation is a serious problem globally as it significantly reduces the original capacity of reservoirs and affects irrigation, hydroelectric power generation, drinking water supply, flood control, and other recreational activities.
Sediment capture through reservoirs is a major concern for Ethiopians, who have many large natural and artificial reservoirs. This study was conducted in Koka reservoir in Oromia region Upper Awash basin with the objectives of estimating reservoir sedimentation and life of Koka hydropower reservoirs using bathymetric survey.
To estimate reservoirs sediment deposition comparison of initial reservoirs capacity, and present capacity of the reservoir that was obtained by bathymetry survey developing of TIN surface and analyzing volume of reservoirs using Surfer, and ArcGIS 10.8 Software’s were essential .
According to the current bathymetric survey, the capacity of Koka Reservoir has been reduced from 1850 Mm3 in 1960(during first impounding) to 1049.9 Mm3 in 2023.
The result showed that Koka reservoirs have lost 43.2% of its total capacity due to sedimentation in 63 years of operation period. The total amount of sedimentation was estimated to be 800.1 Mm3 with in an annual rate of loss of reservoir 12.7 Mm3/year.
The study indicated that the dead storage volume has been totally lost and 577.1 Mm3 of the live storage zones are occupied by sediments this shows that the live storage zones have been losing 34.6 % of its storage capacity after 63 years of operation.
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Keywords
Bathymetry, Koka Hydropower, Reservoir Sedimentation, Storage Capacity