中文摘要：

通过对三峡库区中部典型支流朱衣河与干流界面水动力参数、河口流场强度与特征的分析,计算了干支流水体交换通量,进而探讨水库运行各个时期干支流水体交换情况及其对库区水环境的影响。结果表明,朱衣河河口水体具有双向流动特性,水库运行各个时期干支流交界面进出水体分布不同,流速差异显著;不同季节与水库运行期河口流场相应表现出上下分层、左右分布,以及进出流量差异显著等特征;尽管朱衣河河口净流量较小（全年大部分时期小于100 m^3/s）,然而双向水流结构的存在致使水体有效交换量相对显著（约为净流量的5-10倍）。根据朱衣河实测数据及相关资料,初步推算了库区干流水体参与干支流水体交换的比例,得出全年平均交换率为204%,1月份最高,达343%。

英文摘要：

Through analyzing the hydrodynamic parameters, the intensity and characteristics of the estuarine flow field at the interface of the mainstream and the tributary of Zhuyi River, a typical tributary in the central area of Three Gorges Reservoir, the flux of water exchange between the mainstream and tributary is calculated. On the basis of the calculation results, the water exchange in different impoundment periods and the influences on the water environment of the reservoir are discussed. The results show that the flow at Zhuyi estuary is bidirectional;the distribution patterns of the inward and outward flow varies in different periods and so does the flow velocity;the estuary flow features in layered distribution and left-and-right distribution with significant difference between inflow and outflow flux;despite the small net water flux, mostly below 100 m^3/s, the effective water exchange volume （ about 5 to 10 times of the net flux） is relatively significant due to bidirectional flow structure . According to the measured data and the related information, the proportion of mainstream participating in the water exchange is estimated prelimi-narily. The annual average proportion is 204 % with the highest of 343 % in January.