气候变化和水利工程对丹江口大坝下游水文情势的影响

Effects of climate change and water conservancy projects on hydrological regime downstream of Danjiangkou Dam

采用变化范围法划分不同影响期,并对丹江口下游的黄家港站1965-2017年水文情势的变化趋势进行评估。结果表明:丹江口大坝蓄水使下游河道枯水期的流量增加,丰水期和平水期的流量减少;气候变化引起的降雨减少使各月份的月中值流量和年极大值流量减少,低流量脉冲次数增加;梯级大坝的修建使黄家港水文站受回水影响,月中值流量和年极小值流量增加,发生时间提前。受南水北调中线工程调水影响,月中值流量和年极小值流量大幅度减少,高/低流量脉冲次数增加。不同时期影响造成汉江中下游水文情势的波动,并影响了汉江中下游水生态系统的稳定性。

In this study,the hydrological trend of the Huangjiagang hydro-station downstream of Danjiangkou from 1965 to 2017 was evaluated by RVA method via dividing different influence periods.The results show that the impoundment of the Danjiangkou Dam can increase the discharge in dry seasons while decrease the discharge in flood and normal seasons in the downstream.The decrease of rainfall caused by climate change leads to the decrease of the monthly mean flow and the annual maximum discharge,but the occurrence of low flow pulse is increased.The backwater of the cascade dams increases the monthly mean flow and the annual minimum discharge with earlier occurrence.The Middle Route of the South-to-North Water Transfer Project substantially reduces the monthly mean flow and the annual minimum discharge with an increase of both low and high flow pulse.The hydrological regime fluctuation in the middle and lower reaches of the Hanjiang River is induced by the different influencing periods,which affects the stability of aquatic ecosystems.