东线南水北调工程对长江口咸水入侵影响及对策

南水北调工程是长江流域继三峡工程后的又一重大工程，工程建成后对长江河口的环境与生态有何影响以及影响程度如何是众所关注的一个重要问题。南水北调是大规模的跨流域调水，有东，中，西线三种方案，它建成后必将对长江口的自然环境产生影响，这种影响可能涉及径流，泥沙，咸水入侵，岸滩冲淤，航道，水产，渔业和生态环境等诸多方面。根据有关初步设计资料及长江河口的流量和盐度等实测资料，用统计的方法对东线南水北调调水500，700和1000m^3/s后对长江口咸水入侵的影响进行了初步预测。为了减少其不利影响，还提出了采取加快实施北支整治工程，尽快建造新的避咸蓄淡水库，确定调水的控制流量和三峡工程提前蓄水等措施，供南水北调工程决策和设计部门参考。若参采取这些措施，南水北调对咸水入侵造成的负面影响是可以缓解或抵消的。

IMPACT OF SOUTH-NORTH WATER TRANSFER(EAST ROUTE) ON SALTWATER INTRUSION IN THE CHANGJIANG ESTUARY WITH CONSIDERATION OF ITS COUNTERMEASURES

The South-to-North Water Transfer(SNWT) is one of the major projects in the Yangtze River Basin followed by the Three-Gorge Project. It is of our great concerns how the SNWT project will have impacts on the environment and ecosystem of the Changjiang Estuary when it is finished. The SNWT projects, including East Route, Middle Route and West Route, transfer water in a large scale of multibasin. It is obvious that they will have much influences on the natural environment of the rivers estuary. The impacts may include aspects of river runoff, sediment, saltwater intrusion, waterway, shoal scouring and silting, aquaculture,fishery and ecosystem and so on.In this paper, we analyzed by statistic methods design of East Route Project and some observations on river discharge and salinity of the Changjiang Estuary. Based on this, we preliminarily accessed the impact of the SNWT on saltwater intrusion in the Changjiang Estuary when the river discharges of 500, 700 and 1 000 m 3/s were transferred, respectively. In order to decrease the negative impacts of the SNWT, some corresponding strategies were proposed. We should take actions to put the North Branch renovation engineering into practice as soon as possible, to build a new reservoir for avoiding saltwater and saving freshwater in the Changjiang Estuary, to determine the control discharge of transferring water by the SNWT as well as saving water by the Three-Gorge project beforehand. These strategies are referencial in making a strategy and for the design of SNWT. If these measures were taken, the negative Effects of saltwater intrusion in the Changjiang estuary resulted from the SNWT could be abated and/or counteracted.