黄河口清水沟河道的冲淤过程与模拟

Erosion and aggradation processes and calculation method for the Qingshuigou channel on the Yellow River Delta

为揭示黄河口清水沟河道长时段的冲淤演变规律并建立其冲淤计算方法,分析了清水沟1976—2015年的时空冲淤演变过程,采用河床演变的滞后响应模型,考虑河口来水来沙及河道延伸与蚀退的影响,建立了清水沟累计冲淤量的计算方法。结果表明:1976—1980年改道初期清水沟改道点上游先冲后淤,改道点下游淤滩塑槽,淤积量随着下游河道展宽而增加,1980年后改道点上、下游河道冲淤过程趋于一致;受水沙条件等因素影响,1980—1986年清水沟主槽冲刷展宽,之后主槽淤积萎缩;1996年清八改汊和2002年小浪底水库"调水调沙"原型试验以来,河道转淤为冲,2002年后河道冲刷速率随时间指数衰减;河床演变的滞后响应模型可计算清水沟长时段的冲淤过程,该方法可为预测未来清水沟冲淤演变趋势提供科学参考。

The spatial and temporal evolution characteristics of the Qingshuigou channel during 1976—2015 were comprehensively analyzed to investigate the long-term evolution process of the channel. A calculation method for the erosion and aggradation volumes at the Qingshuigou channel was proposed on the basis of Delayed Response Model and by considering the effects of water and sediment conditions and channel extension and retreat. Results showed that the channel reaches at the upstream of the avulsion point were eroded and then aggraded during 1976—1980. Meanwhile,the sediment deposited at the downstream channel reaches and the deposition volume increased in the downstream direction as the channel and floodplain widened. The evolution of the upstream and downstream channel reaches became in-phase after 1980. Influenced by the water and sediment conditions and other factors,the channel was eroded during1980—1986 and aggraded during 1986—1995. Erosion occurred again due to the artificial water diversion in 1996 and the implementation of water and sediment regulation scheme. The erosion rates decayed exponentially with time after2002. The proposed method could accurately calculate the erosion/aggradation volume of the channel for a long time period,and it might be used to predict channel evolution in the near future.