三峡水库汛期水沙异步特性及沙峰输移时间研究

以三峡水库运用以来2003—2018年库区主要测站的水沙数据为基础,对上游来沙入库时刻水沙异步特性进行了统计分析,讨论了不同水位级情况下典型场次洪水过程中沙峰输移时间与不同影响因素之间的关系,并利用回归分析法得到了拟合程度较好的沙峰输移时间回归公式。结果表明:洪峰流量>30 000 m³/s的40场典型洪水过程,入库时刻沙峰超前、同步、滞后洪峰的场次比例分别为42.5%、42.5%、15%;金沙江下游向家坝等梯级水库蓄水运用后,沙峰在三峡库区的传播时间明显增长。由于水库不同运用时期汛期坝前水位变化范围不同,采用了分水位级的方式对库区沙峰输移时间与不同影响因素的相关性进行讨论,进而使用逐步回归的方法分别建立了拟合效果较好的沙峰传播时间公式,可为水库沙峰调度提供技术支撑。

Water-Sediment Asynchrony and Transport Time of Sand Peak in Flood Season of Three Gorges Reservoir

The basic laws of water-sediment asynchrony in the reservoir area at sediment incoming moment were statistically analyzed based on the water-sediment data from main monitoring stations of the Three Gorges Reservoir in 2003-2018. The duration of sand peak transport affected by various factors during typical floods under different water levels was discussed. The regression formula for the transport time of sand peak with a good degree of fitting was also obtained via regression analysis. Results revealed that among 40 typical flood processes with peak discharge greater than 30,000 m³/s, the floods with sand peak arriving earlier than flood peak, sand peak arriving synchronously with flood peak, and sand peak lagging behind flood peak accounted for 42.5%, 42.5%, and 15%, respectively. After the operation of Xiangjiaba and other cascade reservoirs on the lower reaches of the Jinsha River, the propagation of sand peaks in the reservoir area elongated apparently. In view of the different ranges of water level fluctuation in front of dam during flood season, the rating and grouping of water level was considered to analyze the correlation between sand peak transport time and different influencing factors; furthermore, stepwise regression was adopted to establish the formula of sand peak propagation time with good fitting effect. The research results offer technical support for the sand peak dispatching of reservoirs.