2015-2017年枯季长江河口青草沙水库盐水入侵分析

摘要 本文基于2015-2017年1-3月青草沙水库上闸口和下闸口实测盐度资料，结合实测大通径流量、崇明东滩风况、堡镇水文站水位和崇西水文站盐度，分析最近3年1-3月青草沙水库盐水入侵频次和来源.在青草沙水库取水口，2015、2016和2017年1-3月共发生盐水入侵频次分别为3次、1次和1次.2016和2017年枯季各仅发生1次盐水入侵，与径流量显著偏大有关.在这3年1-3月青草沙水库取水口共发生的5次盐水入侵中，仅1次来自北支盐水倒灌，盐水从崇西水文站到青草沙水库取水口时间约为3 d；4次源自北港下游盐水正面入侵，潮型为小潮或小潮后中潮，在一般北风下强度弱，在强北风作用下盐度显著增强.从最近3年青草沙水库取水口盐水入侵情况看，北港下游正面盐水入侵频次明显增加，在小潮期间遇到强北风作用会导致较严重的正面盐水入侵.
Abstract：Based on the measured salinity at the upper and lower water gate of Qingcaosha reservoir from January to Match from 2015 to 2017, and combined the measured river discharge at Datong station, wind at weather station at Chongming eastern shoal, water level at Baozhen hydrologic station and salinity at Chongxi hydrologic station, the frequency and source of saltwater intrusion at the water intake of Qingcaosha reservoir in the last three years were analyzed. The frequencies at the water intake of the reservoir from January to March in 2015, 2016 and 2017 were three, one and one of saltwater intrusion, respectively. Only one time of saltwater intrusion in the dry season of 2016 and 2017 occurred due to the higher river discharge. Among the total five times of saltwater intrusion happened at the water intake from January to March in the last three years, only one of saltwater source was from upstream, i.e., the saltwater-spilling-over from the North Branch into the South Branch, which took about 3 days for the saltwater moving from the Chongxi hydrologic station to the water intake of the reservoir; Four times of saltwater source were from downstream, i.e., the saltwater intrusion through the North Channel, which appeared in neap tide or medium tide after neap tide, was weaker under general wind speed, and was stronger under strong north wind. In view of the saltwater intrusion at the water intake of Qingcaosha reservoir in the last three years, the frequencies of saltwater intrusion coming from the downstream of the North Channel were increased distinctly, and the saltwater intrusion would be severe if strong north wind occurs in neap tide.