水库三角洲河道输沙之研究

水库进口附近三角洲河道之水流系近似均匀流，并非真正之均匀流。三角洲河道动床之自我调整作用，因水库水位之回水影响，其输沙特性有异于明渠均匀流，传统上，将明渠均匀流平衡条件之下输沙公式应用于估算的三角洲河道之输沙能力，似有其不稳定性。本研究进行一系列水流区输沙试验，并纳入文献「１０」Ｈｏｔｃｈｋｉｓｓ之试验数据一并分析。

A Study on Sediment Transport in Reservoir Delta Channel

The flow occurring in a delta channel at the reservoir entrance is a near uniform flow, not a uniform flow in essence. The sediment transport resulted from self adjustment of the channel bed due to backwater effects differs from that occurring in a uniform flow. Conventional assumption of uniform flow conditions has been made to estimate the sediment transport capacity in a delta channel, and the reliability of the estimates remains uncertain. This study conducted a series of sediment transport experiments in a laboratory flume with flows falling within the lower flow regime. Sediment transport analysis has been performed on the test results along with the test data taken by Hotchkiss(1989).Experimental results indicate that the sediment transport capacity in a delta channel exceeds that estimated under the assumption of uniform flow as a result of self adjustment of the channel bed caused by backwater effects. Both Engelund Hansen formula and Parker formula well underestimate the sediment transport capacity in a delta channel. This study suggests an empirical formula, based on the experimental channel, to estimate the sediment transport capacity in a reservoir delta channel.