长江与鄱阳湖水文关系及其演变的定量分析

Quantitative study on hydrology relationship between the Yangtze River and Poyang Lake and its changes

鄱阳湖蓄水受到自身流域来水和长江流量的双重影响,利用长江汉口和鄱阳湖星子水文监测资料,统计分析后得到长江与鄱阳湖量化的水文关系:(1)如果汉口流量小于15 000 m^3/s,长江对鄱阳湖出流影响不明显,鄱阳湖基本上自由出流,湖水位变幅较大。(2)如果汉口流量超过18 000 m^3/s,长江对鄱阳湖出流顶托作用明显,汉口流量越大,顶托越显著,因顶托而滞蓄在湖盆的水量可达31.9%~81.4%。(3)如果星子水位10.5~16.5 m且汉口流量大于20 000 m^3/s,出现长江向鄱阳湖倒灌的可能性较大;星子水位低于8 m或鄱阳湖主汛期一般不会发生倒灌。2000年以后鄱阳湖与长江水文关系发生了一些变化,主要表现在长江对鄱阳湖出流顶托作用弱化,鄱阳湖枯水期提前并延长,湖水位日涨落幅度增大。定量研究这些关系,对于鄱阳湖水资源利用、水环境和水生态保护具有重要作用。

The storage in the Poyang Lake is affected by runoff from the watershed itself and the YangtzeRiver flow. The hydrological relationship between the Yangtze River and Poyang Lake is obtained by statisti-cal analysis of hydrological monitoring data from Hankou and Xingzi stations, representing Yangtze and Poy-ang respectively.（1）When the flow of Hankou is less than 15,000 m3/s, the impact of the Yangtze Riveron the outflow of the Poyang Lake is not obvious, and the outflow from the lake is mainly free to go outwith larger rang of stage in the lake.（2）When the flow of Hankou exceeds 18,000 m3/s, the retarding roleof the Yangtze is becoming significant to the outflow from Poyang, storing 31.9% ~ 81.4% of inflow in thelake.（3）When the water level at Xingzi is between 10.5-16.5 m and the flow of Hankou is more than20,000 m3/s, the floodwater may flow from the Yangtze into the Poyang Lake. However, such phenomenamay not occur when the water level at Xingzi is lower than 8 m. Some changes have taken place in the re-lations between Poyang and Yangtze since 2000, which are mainly shown in weakening the retarding effectof the Yangtze River on the outflow of Poyang Lake, bringing forward and prolonging the dry season of thelake and magnifying the daily fluctuation amplitude of water level in the lake. Quantitative study of these re-lationships is of great importance to utilize water resources and to protect water environment and aquaticecology in the Poyang Lake.