Effectivity of underwater dam for reducing reservoir sedimentation, case study: Cipanundaan reservoir, West Java, Indonesia

Abstract

As one of dam priority in Indonesia, Cipanundaan dam faced severe problem related to the sedimentation. The sedimentation in Cipanundaan derived from both soil erosion and landslide (earth slide and earth flow) along the river. Based on analysis, total potential sediment reached until 137,819 m3, which is shortened the dam lifespan only for 10 years. This research is conducted the effectivity of application of underwater dam in order to maintain intake system. Three underwater dams are constructed for controlling 8 mm/year of sedimentation from both erosion and translational landslide. The numerical modelling used ANSEDIM program to develop surface sediment elevation in reservoir. The result showed the infrastructure is succesfully suspending sediment enter the system, thus, the dam has a longer lifetime. The research revealed that application of three underwater dams will reduce 2.5 times of sediment volume, increase up to 6 times of effective volume and extend the dam's lifetime until 250% from existing condition. This outcome will be helpful to planner, engineers and managers for better managing of reservoir sedimentation and water resources.