Signifikansi Skenario Pembangunan Check Dam Dalam Menahan Laju Sedimentasi Di Waduk Sempor

Abstract

Recently, several reservoirs in Indonesia are in critical condition. Sempor is one of reservoir which is also in critical condition, where based on measurement data of sedimentation in Sempor Reservoir 1994 that the total catchment volume reduction due to sedimentation was 12.04 million m 3 in the period of 16 years (from 1978 to 1994) or 752,500 m 3 /year. It will give bad impact for all parties, including the increased risk of flooding, reduction in irrigated land area and interrupt operation of hydroelectric power. This high sedimentation rate is expected to be suppressed by constructing of check dam in Sampang and Kedungwringin river that flow into Sempor Reservoir. The calculation of significance to see how much the influence of check dam that will be built in suppressing sedimentation rate was calculated using regression equation which is the relationship between river discharge with sediment discharge and Meyer-Peter and Muller's equation. Microsoft Excel was used in analysis of data. The results showed that check dam scenario in the second and third order of main river can reduce sedimentation rate 19,587,04 m 3 /year and 60,319,79 m 3 /year (9,6% and 29,6% from the potency of flowing sediment). The rate of sedimentation after the scenario was still upper than the limit of tolerance 12.878 m 3 /year.