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三峡工程运用后,受上游来沙减少及水库拦沙影响,下泄沙量急剧减少,坝下游宜枝河段发生显著冲刷,平滩河槽形态也相应调整。由于宜昌及宜都河段在河型、河床组成上略有不同,且不同断面的河槽形态沿程变化较大,故采用基于河段平均的方法,分别计算了这两河段2002-2013年的平滩河槽形态参数。计算结果表明:研究时段内两河段的平滩河宽总体变化很小;但宜昌段平滩水深约增加1.3m,而宜都段平均冲深达2.9m;两河段的平滩面积均呈持续增加趋势。在此基础上,建立了河段尺度的平滩河槽形态参数与前5年平均的汛期水流冲刷强度之间的经验关系,用于预测该河段平滩河槽形态的调整趋势。
After the Three Gorges Project is put into operation, due to the decrease of sediment in the upper reaches and the influence of sediment storage in the reservoir, the amount of discharged sediment drastically decreases and the Yi River section downstream of the dam has a significant erosion, and the shape of the Pingtan channel has also been adjusted accordingly. As the Yichang and Yidu sections are slightly different in river type and riverbed composition, and the channel sections in different sections vary widely along the river sections, the method based on the average of the river sections is used to calculate the average length of the river sections from 2002 to 2013 Of the flat beach channel shape parameters. The calculation results show that the overall width of the Pingtan River in the two sections is small during the study period, but the water level of the flat beach increases about 1.3m in Yichang section and 2.9 meters in Yidu section; Continue to increase the trend. On this basis, the empirical relationship between the shape parameters of the Pingtan channel on the river scale and the average flood intensity during the flood season in the first 5 years is established, which is used to predict the trend of adjustment of the Pingtan channel.