Page - 313 - in Book of Full Papers - Symposium Hydro Engineering

4. CONCLUSION AND RECOMMENDATION 4.1. CONCLUSION Sedimentation is a problem faced by almost all the reservoirs in the world. High sedimentation rate which would threaten the sustainability of the reservoir function and shorten the useful life of the reservoir. Sengguruh reservoir has lost almost 75% of the effective storage since the dam was completed in 1988. To overcome the problem of sedimentation in Sengguruh reservoir some efforts has been conducted sediment management, consist of conservation in the upstream of Brantas River watershed, construction of sediment controlling infrastructure, and sediment dredging. Non-structural efforts such as empowerment and public education have also been carried out. Dredging work in Sengguruh Dam using the dredger has been conducted since 2001. Starting in 2016 the development of dredging work has been done by (a) combination of 2 dredging types using available dredgers and additional heavy equipment (amphibious excavators) to take out sediment which located at positions could not be done by dredgers (dry- wet excavation), (b) installation of booster pump and floating pipe as support of the dredgers, (c) modification of dredger ladder, (d) management of spoilbank by re-arrange of hauling and reloading cycles, and accelerate sediment material drying by installing vertical-horizontal drainage. This dredging method gives the benefit that the dredging of sediment can be implemented more effectively and efficiently to ensure high hydropower production, maintain effective storage capacity and prolong age of reservoir with of course considering environmental aspect around the area. More importantly, it can be done near the hydropower intake because the sediment is increasingly moving forward to the dam. 4.2. RECOMMENDATION Need to do a more study on the characteristics and processes of sedimentation in Sengguruh reservoir so that the management of sediment through dredging work could be done more effectively and efficiently. Environmental management need to be studied further to minimize the impact. 5. ACKNOWLEDGEMENTS The authors thank to Jasa Tirta I Public Corporation, the River Basin Organization in Brantas, Bengawan Solo, Jratunseluna, Serayu Bogowonto and Toba Asahan River basins in Indonesia for providing data used in this paper. 313