Page - 279 - in Book of Full Papers - Symposium Hydro Engineering

300,000 m3 up to 1.2 million m3 of sediment per year that may tackle the issue of riverbed degradation at the downstream part of the reservoir, which is currently the riverbed degradation is happened approx. 2 to 8 m caused by rapid illegal sand mining. However flushing implementation should consider the availability of water so it cannot be done every year. Keywords: Wlingi Dam, flushing, dredging, sedimentation. 2. INTRODUCTION Wlingi Dam was completed in 1977 with a total catchment area of 2,890 km2, located in Blitar, East Java, Indonesia. It has gross reservoir capacity 24.0 million m3 and effective capacity 5.20 million m3. The dam was built as the after bay of Sutami Hydro Electric Power Plant (HEPP) and has benefits: - Controlling flood discharge from 2,824 - 2,370 m3/sec. - Providing water for irrigation 17,50 m3/s to Lodagung irrigation area of 15,132 Ha (in Blitar and Tulungagung). - Generating HEPP with installed capacity 2 x 27 MW, producing energy 164.980 million KWh / year. - Fisheries and tourism. Due to its location in the downstream part of Kelud Volcano (one of the most active volcanoes in Java island), cause a huge sediment supply to the reservoir. Combined with land degradation in the upper area of its catchment, sedimentation become the main issue of water resources management in Wlingi dam. To overcome the above issues, some measurements has been conducted such as conservation, dredging, flushing, and preparing sabo dam and check dam in the upstream. Flushing and dredging with riverine disposal that hydraulically pumped the sediment into the downstream of the dam. The purpose of the study is to know the effectiveness of the management sediment through flushing, dredging with spoil bank disposal, dredging with riverine disposal to channel below. Knowing the effectiveness of this sediment management is expected to increase the lifetime of the reservoir. 279