Sedimentation Analysis in the Tambakboyo Retention Basin Using the USLE Method and Eco Sounder Measurements to Support the Optimization of Water Availability

Abstract

The Tambakboyo Dam has been operated for more than 10 years, resulting in increased sedimentation and reduced storage capacity from 400,000 m3 to 300,285 m3. Therefore, to support the optimization of water availability, the age of the reservoir needs to be known. This research analyzes the volume of sediment in the Tambakboyo Reservoir to determine the effective age of the reservoir by estimating the rate of erosion that occurs. The USLE method is used to determine the rate of erosion that occurs in the Tambakboyo Dam catchment area and bathymetry measurements are used to determine the volume of reservoir sediment directly. Using the USLE method, the DTA erosion rate was 13,864 tonnes/ha/year, while direct echo sounding measurements were 11,254 tonnes/ha/year. The remaining age of the reservoir based on the USLE method is 23.02 years, while direct measurements reach 28.359 years. So it can be concluded that the erosion rate in the Tambakboyo watershed is included in the very light erosion category, however the SDR results comparing sediment entering the reservoir with sediment calculated using the USLE method show that sediment control is still not effective.