三峡工程运行前后荆江三口水文情势的变化

基于1980～2015年荆江三口五站逐日流量数据,采用IHA指标体系分析度量三峡工程运行前后荆江三口水文情势的变化。除新江口和弥陀寺在枯水期1～3月有小幅增长外,三口各站点月均流量值均减小,汛期下降幅度较大。最大日流量值持续下降,但2003年后变化趋势相对平缓。沙道观和管家铺站断流天数显著上升,各站流量变化率明显降低。荆江三口水文情势变化受长江干流径流量减少、径流过程改变以及干流与口门河段河道冲淤不一致的共同影响,对长江中游四大家鱼种群以及洞庭湖苔草草洲的发展产生一定负面作用。

Hydrological Regime Changes in the Three Outlets of Jingjiang River Before and After the Operation of the Three Gorges Project

Using mean daily discharge data from 1980 to 2015, effects of the Three Gorges Dam on hydrological situation of the Three Outlets were measured based on indicators of hydrologic alteration. Except for a slight increase in Xinjiangkou station and Mituoshi station from January to March, mean monthly flow showed a significant downward trend in the five hydrological stations of Three Outlets, and decreased more in flood season. The maximum daily flow showed an significant downward trend for all hydrological stations in the past decades, but the trend was relatively stable after 2003. Number of days for Shadaoguan station and Guanjiapu station draught-up increased significantly, and the rate of flow change was obviously reduced for all hydrological stations. Hydrologic regime change for the Three Outlets was influenced by its own channel evolution, runoff reduction and runoff process change of the Yangtze River, had some negative effects on the Four Major Chinese Carp populations and the Carex meadow development of Dongting Lake.