三峡水库运用后长江中下游枯水位变化成因研究

Study on the mechanism of lower water level in middle and lower reaches of the Yangtze River after impounding of the Three Gorges Reservoir

研究河流枯水位及极低水位变化对河流安全和高效利用具有重要意义。采用实测资料分析的方法,对三峡水库蓄水运用以来长江中下游河段的枯水位变化趋势及成因进行研究。结果表明,三峡水库蓄水运用以来,长江中游河段枯水位出现累计性下降,其中以荆江河段最为显著。2019年宜昌以下长江干流段更是出现三峡水库蓄水以来最为严重的极低水位情况。成因分析表明,枯水位累积性下降主要与枯水河槽冲刷有关,而极低水位出现主要是受枯水河槽冲刷和支流来水减少影响。其中,沙市站极低水位是枯水河槽严重冲刷下切所致;螺山站、汉口站的极低水位是枯水河槽冲刷下切和支流来水偏少共同导致的结果,大通站极低水位主要是受支流来水严重偏枯的影响。

Based on the observed data,the processes and mechanism of lower water level in the middle and lower reaches of the Yangtze River after impounding of the Three Gorges Reservoir are studied.The result shows that the lower water level of the middle reaches of the Yangtze River has decreased cumulatively,especially in the Jingjiang Reach.There was the lowest water level phenomenon downstream of the Yichang City in Yangtze River in 2019.According to analysis,the cumulative decrease of low water level is mainly related to the erosion of low-water-channel,and the lowest water level is mainly affected by the erosion of low-waterchannels and the reduction of branch flow.The lowest water level at Shashi Station is caused by severely erosion of the low-water-channel,and the lowest water levels at Luoshan and Hankou stations are the result of the erosion of the low-water-channel and the reduction of branch flow.The lowest water levels at the Datong Station were caused by the reduction of water flow in the Yangtze River.