南水北调工程实施后汉江水华发生可能性研究

南水北调中线工程对汉江中下游的生态与环境影响已有大量的研究成果，特别是对水华问题进行了更为深入的研究，但是其研究主要集中于仙桃至河口段，而沙洋以上河段还未进行过水华方面的研究工作。鉴于1998年及2003年两次发生的水华事件影响范围都达沙洋以上河段(已达湖北钟祥河段)，以及南水北调中线工程实施后汉江河道流量减小，流速降低，水环境容量降低，特别是兴隆枢纽回水区的壅水作用使其水体流速大幅下降(经计算小于0.3 m/s)，再加上汉江中下游水体中总氮、总磷含量普遍偏高，对兴隆枢纽回水区及襄樊市区段水华发生可能性分别应用加权灰关联度以及模糊数学中的隶属度概念进行了计算评价，得出结论为：在维持污染现状情况下兴隆枢纽回水区在枯水期(505.7 m\+3/s流量)具备水华事件发生的水文及营养物质条件；到2020年襄樊市区段也将具备水华事件发生的水文及营养物质条件。

PREDICTIONS ON WATER SOURCES AND ENVIRONMENT CARRYING ABILITY IN HANJIANG RIVER AFTER THE IMPLEMENTATION OF SOUTH TO NORTH WATER DIVERSION PROJECT--POSSIBILITIES OF ALGAL BLOOMING OCCURRENCE IN BACKWATER AREA IN XINGLONG HINGE AND XIANGFAN REACH OF THE HA

Extensive research has been carried out to evaluate the possible environmental effect of the south to north water diversion project in Hanjiang River, and algal blooms have been the focus of these studies,with most of them being related to the river reaches between Xiantao and its joint to the Yangtze River. However,little has been carried out in the reaches upper to Shayang. In consideration of two algal blooming events in 1998 and 2003 in reaches around Zhongxiang City of Hubei Province,the reduction of water flow and the increasing content of nutrients after the implementation of south to north water diversion project will cause the water velocity and the nutrient contents suitable for the occurrence of algal blooms in the backwater area in Xinglong hinge in the period of low water (505.7 m~3/s)as indicated by the weighed grey associate analysis and fuzzy mathematical analysis. In the year 2020,a similar result may be expected even in the Xiangfan reach of the Hanjiang River in lower water period.