Author(s): Dian Sisinggih; Fahmi Hidayat; Sri Wahyuni
Linked Author(s): Fahmi Hidayat
Keywords: Reservoir lifetime; Sediment flushing; Trap efficiency; Capacity-inflow ratio
Abstract: Sedimentation has always been a great threat to the useful life of reservoirs in the Brantas river basin. Flushing is one of the preferable techniques used to enhance the useful life of reservoir due to its advantages in removing a high amount of deposited sediment. This paper highlights the proposed method to assess the interval flushing periods and morphological evolution of Wlingi reservoir after Mt. Kelud eruption in 2014. The recent reservoir bathymetry data was used to analyze the amount of flushed sediment. The useful life may be computed by determining the number of years required for each incremental loss of reservoir capacity using the relation between trap efficiency of reservoir and capacity-inflow ratio. The estimated volume of flushed sediment was about 1.02 x 10^6 m^3 during a single flushing event and the depth of eroded sediment was varied up to 3 meters. By assuming the constant inflow of sediment then it takes 2.78 years to fulfill its dead storage. It can be thus concluded that the effective interval flushing period of Wlingi reservoir should be no more than 2 years to recover reservoir capacity and to prolong its lifetime. The finding of this study could be practically implemented in Wlingi Reservoir.
Year: 2018