ESTIMASI SEDIMENTASI WADUK BERDASARKAN EROSI LAHAN Studi Kasus Bendungan Batujai

Abstract

Batujai Reservoir is located in Central Lombok Regency. It is used to supply the demand for irrigation water and power generation. The development of the upstream area of the reservoir causes a high rate of soil erosion, which in turn triggers the problem of silting up the Batujai reservoir due to the high rate of sedimentation. This study intends to determine the contribution of soil erosion to sedimentation that occurs in the Batujai Reservoir and the direction of land rehabilitation for conservation following the conditions of the Batujai Reservoir watershed so that it can provide useful information for dam preservation. Soil erosion was calculated using the USLE method, so secondary data according to USLE parameters were needed, such as rain data, land use data, soil type data, and topographic data. The amount of sedimentation in the reservoir is calculated based on the bathymetry map of the bottom of the reservoir as measured by the echo-sounding technique. The sedimentation rate in this reservoir is based on the last measurements in 2017. The results showed that the contribution of soil erosion upstream of the Batujai reservoir was 109.974,078 tons/ha/year. With the Trap Efficiency sediment value of 0.094 %, the sediment that entered the Batujai reservoir for 35 years was 1,200,000 m3. From the results of the analysis, it is estimated that the useful life of the Batujai Dam is around 5 years and 10 months, namely in 2021 in June.