长江中游四大家鱼发江生态水文因子分析及生态水文目标确定

Study on the eco-hydrological factors and flow regime requirement on spawning of four major Chinese carps in the middle reaches of Yangtze River

基于长江中游四大家鱼发江量历次调查数据，采用宜昌站作为长江中游水文情势变化分析的控制站，基于其1900，2004年共105年的日径流资料，采用每年5～6月涨水过程数、总涨水日数、平均每次涨水过程日数等3项生态水文指标。分析了四大家鱼发江量与3项生态水文因子的变化关系，认为产卵场所处江段每年5～6月的总涨水日数是决定家鱼苗发江量多寡的一个重要环境因子。根据IHA方法，对宜昌站105年来的生态水文指标分析表明，长江宜昌站生态水文过程的改变并不明显，5～6月总涨水日数变化趋势不显著，显示长江中游影响四大家鱼苗发江量的生态流量过程改变不明显，与前人得出的葛洲坝枢纽修建后四大家鱼的产卵条件和卵苗江汛规律没有变化这一认识一致。但是，随着三峡水库的运行，下游河道的生态环境流量过程会有较大改变，本文建议三峡水库的调控以保障长江中游每年5～6月的总涨水日数维持在22．1±7．2范围内为生态水文目标，即可从生态环境流量过程方面补偿水利工程对中游四大家鱼鱼苗发江量的影响。

The four famous freshwater fishes, i.e. black carp （ Mylopharyngodon piceus）, grass carp （ Ctenopharyngodon idellus ）, silver carp （ Hypophthalmichthys molitrix ） and big head （ Aristichthys mobilis） are the main fishes in Yangtze River. On the basis of four surveies on the four major Chinese carps in 1960s, 1970s, 1980s and 1990s, data of the spawning amount in Yidu reach and Jianli reach were available. These reaches are located below Yichan gauge station 40km and 210km respectively in the middle reaches of Yangtze River. Daily discharges from 1900 to 2004 in Yichan gauge station were adopted as references discharge for the above two studied target reaches. Three eco-hydrological factors, such as, number of discharge rise events, total days with discharge rise （DDS） and average DDS for discharge rise process during May and June were extracted and used to build a relationship with spawning amount of the four major Chinese carps during the same period. It was found, the relationship between total DDS and spawning amount is significant in Yidu reach, other relationships are slight. So, the total DDS plays an important role in spawning amount in the middle reach of Yangtze River. Analysis also tells that the total DDS during May and June does not show significant trend in the past 105 years. This implies that the spawning condition on eco-discharge for the four major Chinese carps has been relatively stable during the past 105 years. However, after the Three Gorge Project（TGP） is built, the flow regime would be altered and not suited for spawning. So, based on RVA method, total DDS of 22.1 ± 7.2 days during May and June should be guaranteed. This should be regarded as the flow regime requirement for the regulation of TGP.