| Sediment replenishment is a technique employed to prevent sediment deficiency in riverbeds. The distribution of sediment in a riverbed is affected by the volume of replenished sediment, in addition to the flood discharge. We examine the effects of flood discharge on the riverbed material distributions by analyzing a case of sediment replenishment in the Futase Dam in Saitama Prefecture, Japan. Specifically, we compared data from 2003 to 2013 on the annual volume of flushed sediment (Sf), the annual maximum flood discharge (Qmax), and the proportion of particles less than 100 mm in diameter (P<100mm). Results showed that the annual P<100mm at the downstream site may decrease following heavy flooding (i.e., Qmax reaches a ten-year high) possibly as a result of fine particles on the riverbed being carried away by flood water. Alternatively, the area covered by the replenishing sediment may be limited when Qmax is at a ten-year low. Thus, in the case of the Futase Dam, a moderate degree of flooding may facilitate sediment transport at the downstream reach and distribute fine particles on the riverbed. |
