三峡水库不同运用情景对四大家鱼繁殖水动力学影响

三峡工程的修建及其调度运用,改变了库区的水动力条件.四大家鱼的栖息、繁殖也因水文条件的变化而发生改变.本研究采用Mike 11商业软件,基于三峡库区622个河道断面,分天然、三峡水库156 m和175 m蓄水调控等3种情景,分别模拟了1997-2003年库区来水条件下的库区水流状态.在2002-2003年库区云阳断面四大家鱼卵、苗观测基础上,推算了库区2002-2003年四大家鱼产卵场的分布,分析了三峡水库运用对产卵场水动力条件影响.在前人对四大家鱼鱼卵水力学特性实验研究的基础上,讨论了三峡水库不同运用情景下四大家鱼卵能否在库区内有足够的漂程和漂流时间的问题.结果表明.三峡水库156 m蓄水调控方式对于库区产卵场已经产生影响,主要是5月份涨水流量小于8 000 m3/s时,家鱼卵在库区没有足够的漂程和漂流时间;三峡水库175 m蓄水运用方式影响较大,影响时期主要集中在6月中旬前,四大家鱼卵在库区内没有足够的漂程和漂流时间.6月中旬后,156 m、175 m两种运用方式对于重庆产卵场四大家鱼产卵生态水文条件影响较小,四大家鱼卵在库区内有足够的漂程和漂流时间.

Hydrodynamic Effect of Different Regulation Scenarios for Three Gorges Reservoir on Four Major Chinese Carps Spawning

Following the construction and operation of the Three Gorges Dam (TGD), hydrodynamic conditions in impoundment zone have been altered, so will the spawning and habitat surroundings of the four major Chinese carps be changed. Considering 622 river sections, the daily discharge during 1997-2003, natural daily water level and two assumed processes extracted from TGD regulation scheme in Sandouping site in three simulated scenes, were simulated with commercial software Mike 11. According to growth period of spawns or fries captured in Yunyang Section in 2002-2003, four spawning sites of the four major Chinese carps from Zhutuo Section to Yunyang Section were ascertained based on the hydrodynamic analysis, as agrees with previous studies. Based on previous experiments on spawn hydrodynamics, problems of whether spawns of the four major Chinese carps may with safety floatation time and distance become swimming fries are discussed. The results show that, when TGD regulation scheme with 156 m water level is carried out, hydraulic process in three of four spawning sites is not suitable for spawning of the four major Chinese carps. For the fourth spawning site in Chongqing city, though there is no alternation in hydraulic process, if swelling discharge in May is less than 8 000 m3/s, there will be no enough time and distance for spawn growth. If TGD regulation scheme with 175 m water level is carried out, there will be no enough time and distance for spawn growth before the mid of June for the four spawning sites. After the mid of June, the hydraulic process will not be much affected for the fourth spawning site in Chongqing city for two TGD regulation schemes, and there will be enough time and distance for spawn growth.