水库调度影响下中华鲟产卵场的水动力特征

三峡工程试验性蓄水于2010年成功蓄至175 m,开始逐渐进入正常运行期.在此背景下,分析近年来三峡-葛洲坝实际联合调度运行对坝下中华鲟产卵场水动力时空特征的影响,对加深理解中华鲟产卵适应性对水利工程调控的动态响应有重要意义.针对葛洲坝至宜昌江段的中华鲟产卵场建立了三维水动力模型,以出现2次鲟鱼产卵繁殖的2011年产卵日为代表性工况,开展了水利工程调度运行影响下的产卵场短期水动力特征模拟研究.研究表明:对鲟鱼自然繁殖起直接作用的河段底层流场较规则稳定,但在水流交汇处和地形突变处会出现局部紊乱变化;上、下产卵区的流速为0.8~1.4 m/s,在大江电厂与二江电厂下游均有流速较大的分布区,流速最大值出现在二江电厂泄水处下游;适宜中华鲟繁殖的流速范围出现在大江下游导流墙尾段至江心隔流堤前段1/3处与江心隔流堤尾端至下游约700 m内.

Short-term hydrodynamic features of Chinese sturgeon spawning ground under reservoir regulation conditions

The water level of Three Gorges Reservoir(TGR)reached to 175 meters in 2010, indicating this hydropower project had started its normal operation. Chinese sturgeon spawning ground is located at downstream of Gezhouba reservoir immediately and the water level of the ground is affected by regulation of both reservoirs. Since hydrodynamics in the ground can play a crucial role in multiplication of Chinese sturgeon, effects of regulation of both reservoirs on the hydrodynamic characteristics of Chinese sturgeon spawning ground are investigated to explore its suitability for reservoir regulation of a hydraulic project. A three-dimensional hydrodynamic model is built for the Chinese sturgeon spawning ground from Gezhouba to Yichang reach. The short-term hydrodynamic characteristics of the spawning ground are studied by simulation method at two water levels at which two spawning events were observed in 2011. It is shown that the bottom layer flow, which is directly related to multiplication of Chinese sturgeon, is smooth and stable, but there is local turbulence in two streams mixing regions and in bumpy areas of the bed. The stream velocity is varied from 0.8 to 1.4 m/s; a higher velocity is observed in the downstream of Dajiang Power Station and Erjiang Power Station, but the highest velocity is found in the downstream of at Erjiang Power Station. The fluid domains with a stream velocity suitable for Chinese sturgeon spawning are ranged respectively from the end of the training levee in the downstream of Dajiang Power Station to the first 1/3 portion of the central separation levee in the river, and from the end of the central separation levee to 700 m extension in the downstream of the separation levee.