秋季香溪河库湾水体冲淡时间分布特征的成因

针对三峡水库支流库湾的秋季水华问题,以香溪河库湾为研究对象,选取2009和2010两年的9月1日—11月30日作为研究时段,通过建立三维水动力模型,探讨了香溪河库湾水体冲淡时间分布特征及其成因.研究结果表明,在汛末蓄水期,香溪河库湾水体冲淡时间较长的区域均出现在中游,且随着汛末库水位抬高,库湾各层水体冲淡时间最大值均随着增长;因9月三峡库区干流水体主要由中、底层倒灌进入库湾,使得库湾中下游至下游区域表层水体冲淡时间最长,且随着中、底层倒灌持续时间增长,河口附近表层水体冲淡时间较中、底层的差值也有所增长;在支流上游和中上游区域,水体在蓄水期绝大部分时间的流动方式表现为由库湾底层流向干流,使得该区域底层水体冲淡时间较表、中层的短.研究结果可为三峡水库支流库湾秋季水华问题的防治提供借鉴.

Causes of distribution characteristic of flushing time of Xiangxi bay in autumn

For the problem of algal bloom of tributaries of the Three Gorges Reservoir in autumn, 3D hydrodynamic model, based on the background of the Xiangxi River was set up to explore the flushing time distribution and its causes during Sep.1 to Nov.30. Results show that in the storage period of the Three Gorges Reservoir, the areas of longer flushing time mainly focus on the middle of tributary embayment of the Xiangxi River, and the maximum of flushing time at every layer of tributary embayment increases as the water level rises at the end of flood season; in the following middle and lower area of tributary embayment, flushing time of the surface layer is the longest owing to trunk stream decanted into the tributary embayment from the middle and bottom layers, and the difference of flushing time between the surface and middle and bottom layers nearby tributary embayment estuary increases with the duration of trunk stream intrusion increasing. In the upstream and middle and upper areas, the flow direction is from the bottom of the tributary embayment to trunk stream within most of the time of this period, so flushing time at the bottom of this area is shorter than that at the surface and middle layers. The results can provide a reference for preventing and controlling the fall blooms problems of tributaries embayment of the Three Gorges Reservoir.