Amplification of downstream flood stage due to damming of fine-grained rivers
Date
2022Author
Ma, Hongbo
Nittrouer, Jeffrey A (TTU)
Fu, Xudong
Parker, Gary
Zhang, Yuanfeng
Wang, Yuanjian
Wang, Yanjun
Lamb, Michael P
Cisneros, Julia
Best, Jim
Parsons, Daniel R
Wu, Baosheng
Metadata
Show full item recordAbstract
River dams provide many benefits, including flood control. However, due to constantly
evolving channel morphology, downstream conveyance of floodwaters following dam closure
is difficult to predict. Here, we test the hypothesis that the incised, enlarged channel
downstream of dams provides enhanced water conveyance, using a case study from the
lower Yellow River, China. We find that, although flood stage is lowered for small floods,
counterintuitively, flood stage downstream of a dam can be amplified for moderate and large
floods. This arises because bed incision is accompanied by sediment coarsening, which
facilitates development of large dunes that increase flow resistance and reduce velocity
relative to pre-dam conditions. Our findings indicate the underlying mechanism for such flood
amplification may occur in >80% of fine-grained rivers, and suggest the need to reconsider
flood control strategies in such rivers worldwide.