本文通过长江口实测氯度与流量和潮位资料的相关分析,预估了未来河口水质的变化。计算表明,当大通站下泄流量不足13×10³m³/s时,未来东线调水及海平面上升,将使长江口南支河段水质严重恶化;三峡水库建成后,枯季1-3月增加下泄水量虽可抵消东线调水的影响,但在水库蓄水的10月遇枯水年分,水质将大幅度下降。

Water pollution by salt water intrusion is primary influence factor of water quality in the Changjiang Estuary, and its intensity is mainly controlled by river discharge and tidal level in the estuary. The construction of the projects of water transfer from south to north and the Changjiang Gorges Reservoir will change the discharge of the Changjiang River, meanwhile, global climatic warming will cause relative sea-level rise of 0.5-1.0m in this region in the middle of next century. By correlative analysis of discharge, tidal level and chlorinity. the distance of salt water intrusion etc., the changes of water quality in the South Branch of the Changjiang Estuary in future have been estimated by the changes of discharge and tidal level. As a result, serious harm will appear in dry season of dry year of discharge less than 13×10³m³/s at Datong station. The construction of the Changjiang Gorges Reservoir will improve water quality of the Changjiang Estuary to some extent from Jan. to Mar., but it will aggravate water pollution of the estuary in October of dry year. When discharge more than 15×10³m³/s at Datong station, the effects of the changes of discharge and tidal level in future on water quality of the estuary is very small.