湘江干流四大家鱼产卵期生态水文情势变化分析

Analysis on changes of eco-hydrological regime during spawning period of four major Chinese carps in Xiangjiang River

产卵期是鱼类生命周期最重要的环节,对生态水文、水力条件有着特殊的要求。以湘江常宁张河铺至衡阳云集四大家鱼产卵场为研究区域,以涉及研究区域的近尾洲和大源渡日调节型电站蓄水时间作为时间节点,采用IHA-RVA法(生态水文指标变动范围法)对归阳(1961~2015年)、衡阳(1959~2015年)两水文站四大家鱼产卵期(4~7月)水文序列进行分析,得出日调节型电站蓄水前后四大家鱼产卵期生态水文指标变异度。结果表明:(1)通过Mann-Kendall趋势检验法得出产卵场4月流量呈下降趋势;(2)日调节电站蓄水使得库区产卵期(4~7月)月均流速整体降低,库区中部月均流速高度改变,库区尾部月均流速低度改变;(3)产卵期库区中部1,3,7,30 d及90 d最小流速值,30,90 d最大流速值减少且高度改变,库区尾部30,90 d最大流速值减少且高度改变;(4)库区中部流速低脉冲次数升高,改变度为74.79%;库区尾部产卵期水位的低脉冲特征已基本消失。

The spawning period is the most important part in a fish life cycle, which has special requirements for the ecological hydrological and hydraulic conditions.This paper took the four major Chinese carps spawning ground as the research area, from Zhanghepu reach of Changning to Yunji reach of Hengyang in Xiangjiang River, and takes the water storage time of two daily regulating power stations, Jinweizhou and Dayuandu in the study reach as a time node.The IHA-RVA method(ecological hydrology index change range method)was used to analyze the hydrological sequence of the four major Chinese carps spawning periods(April to July)at the two hydrological stations of Guiyang(1961~2015)and Hengyang(1959~2015).The variation degree of the ecological and hydrological indicators during the spawning period before and after the water storage of the daily regulating power stations was obtained.The results showed that:(1) the flow in the spawning ground in April showed a decreasing trend through the Mann-Kendall trend test;(2) water storage of the power stations made the average monthly velocity decrease in general during the spawning period(April to July)in the reservoir area, especially the average monthly velocity in the middle of the reservoir area changed significantly, and the average monthly velocity in the tail reservoir area changed little;(3) in the middle of the reservoir during spawning period, the minimum velocity values of 1 d, 3 d, 7 d, 30d and 90d, and the maximum velocity values of 30d and 90d decreased significantly, and in tail reservoir area the maximum velocity values of 30d and 90d also decreased largely;(4) in the middle of the reservoir area, the frequency of low pulse flow rate increased with change degree of 74.79%;the low pulse characteristics of water level in the reservoir end during spawning period have disappeared.