Impact assessment of reservoir desiltation measures for downstream riverbed migration in climate change: A case study in northern Taiwan

Typhoon Aere in 2004 induced severe sedimentation and loss of storage capacity the Shihmen Reservoir northern Taiwan. The resulting dramatic increase turbidity water seriously affected supply. To effectively maintain stability supply reservoir’s capacity, government Taiwan began to plan construct a series improvement measures, such as sediment flushing tunnel, JhongJhuang Bank-Side Reservoir, Amuping Desilting Tunnel. However, previous studies only focused on impact tunnel Tunnel downstream riverbed, did not consider possibility increasing discharge after completion Reservoir. In addition, climate change will cause intensity extreme rainfall enormously future. That extra challenge existing flood prevention facilities. Therefore, this study considered that used dynamical downscaling typhoon data under RCP 8.5 scenario explore riverbed migration main channels Dahan Tamsui Rivers We rainfall–runoff model Hydrologic Modeling System simulate runoff, hydraulic transport CCHE1D holistically events consequent river scouring deposition behaviors. Our results showed projected peak during late 21st century (2075 2099) be at least 50% higher than baseline (1979 2003) period. terms prevention, potential overbank flooding area, trend long-term dominated by degradation (-0.489 ± 0.743 m) measures have limited (0.011 0.094 Rivers. After operation is expected ratio 70% floods, it excessive may affect