The long-term existence of dam structures significantly modified the river\nchannel. In accordance with a drastic increase of low-head dams under consideration\nfor removal in recent years, it is important to predict the effects of\nlow-head dam removal from the modified river channel by the low-head dam\nconstruction. This study intends to investigate the long-term channel evolution\nprocess following low-head construction and removal and to find out the\ninfluential parameters (sediment diameter, river bed slope, dam height) for\nthose channel evolution by two-dimensional numerical simulation model.\nFollowing the low-head dam construction, sediment deposition rates in upstream\nof the low-head dam are varied with the influential parameters. The\nsediment deposition rates and sandbar formation with riparian vegetation\nsettlement on sandbars have significantly affected for channel evolution following\nlow-head dam removal. Especially the knickpoint formation and the\ntypes of vegetation (grass type and tree type) on the sandbars are critical factors\nfor channel evolution following low-head dam removal. Through the\nnumerical simulation results of low-head dam construction (50 years) and\nlow-head dam removal (50 years), it is identified that the modified river\nchannel by low-head dam may not be easily restored to pre-dam conditions\nfollowing its removal especially in river geomorphology and riparian vegetation.\nConsequently, this study found that the reversibility following low-head\ndam construction and removal depends on the sediment deposition rates in\nupstream of the low-head dam.
Loading....