重庆小南海枢纽运用后坝下游近坝段水位变化研究

为了分析小南海枢纽运用后坝下游近坝段河道水位的变化特性,基于物理模型试验和一维泥沙数学模型计算,研究了小南海枢纽运用初期和运用20 a末,不同特征流量条件下,坝下游近坝段河道水位的变化过程,以及引起水位变化的主要原因。研究表明:小南海枢纽运用后,坝下游约4 km河段范围内,水位较建坝前有不同程度下降,坝下游0.4 km处水位最大下降约1.47 m,出现在枢纽运用初期的枯水流量时;坝下游4 km以下河段水位,在枢纽运用初期下降甚少, 随着三峡水库运行年限增加,库区泥沙淤积增多,水位逐渐高出初期水位,在枢纽运用20 a末,坝下游8.2 km处水位较初期水位最大升高约0.6 m;引起坝下游近坝段河道水位变化的主要原因是施工期坝下游河床的开挖和三峡水库调度及泥沙淤积。

Fluctuation of Water Level in the Downstream River Course Near Dam after Operation of Xiaonanhai Hydropower Project in Chongqing

Through physical model and one-dimensional mathematical model,we analysed the water level variation under different characteristic discharges and the causes of the variation in the downstream river course near Xiao-nanhai Hydropower Station in its initial operation stage and at the end of 20-year operation.The modeling results show that after the operation of Xiaonanhai station,water level decreased in the range 4km downstream of the dam compared with the natural status,the maximum decrease (1 .47m)happened at 0.4km downstream from the dam during dry season in the initial operation stage.In the initial stage,no obvious water level drawdown happened in the downstream of the 4km range,but with the accumulated sedimentation in Three Gorges Reservoir (TGR),wa-ter level will rise higher than that in the initial stage.After 20 years of operation,the maximum increase (0.6m) of water level (compared with that in initial stage)happened at the position 8.2km downstream of the Xiaonanhai dam.The downstream river bed excavation in construction period and the sedimentation with TGR operation are both main causes of water level changing in the river course near Xiaonanhai Dam.