海平面上升对钱塘江河口盐水入侵影响的预测研究

Predicting the impact of sea level rise on saltwater intrusion in the Qiantang Estuary

海平面上升会对河口地区盐水入侵和物质输运造成一定影响,尤其将对饮用水安全造成威胁,因此海平面上升问题越发受到人们的关注.为研究水源地对海平面上升的响应,防范未来可能出现的盐水入侵危害,本文基于FVCOM模式建立了钱塘江河口三维潮流盐度数值模型,并在此基础上通过一系列数值试验分析未来海平面上升(SLR)对河口盐水入侵的影响.结果表明,海平面上升使得河口盐度整体有所增大,盐水入侵距离增加,且小潮期增幅更加明显,在相对海平面分别上升0.3、0.6和1.0m情况下,大潮期盐水入侵距离分别增加1.1、2.2和6.0km,盐度最大增幅发生在七堡附近,量值分别达到0.17、0.32和0.49;小潮期入侵距离则分别增加2.8、5.9和9.8km,盐度最大增幅发生在盐官附近,量值分别达到0.38、0.80和1.22.海平面上升也会引起各取水口盐度和超标时间的增加,在相对海平面上升0.3~1.0m时,南星桥至珊瑚沙3个取水口平均盐度增值分别为0.1~0.3、0.1~0.3和0.1~0.2,最长连续超标时间增值分别为1.0~4.1、0.5~1.6和0.1~0.2d.

Sea level rise was greatly concerned by society with its effects on saltwater intrusion and material transport in estuaries, which threaten drinking water supplies. In order to study the response of drinking water source to sea level rise, and prevent potential disasters in the future, a 3D numerical model for tidal flow and salinity was built based on the unstructured model FVCOM, and then applied to assess the impact of future sea level rise（SLR） on saltwater intrusion in the Qiantang Estuary through a series of numerical simulation. The results indicated that the sea level rise can cause substantial increase of salinity and the magnitude was higher during neap tide than during spring tide. The salinity intrusion moved farther upstream by 1.1, 2.2 and 6.0km, respectively, for the SLRs of 0.3, 0.6 and 1.0m during spring tide, while 2.8, 5.9 and 9.8km during neap tide. The maximum increase of salinity rised near Qibao station, and the values reached 0.17, 0.32 and 0.49 respectively during spring tide, while, the maximum increase of salinity occurred near Yanguan station, and the magnitude reached 0.38, 0.80 and 1.22 during neap tide. When the relative sea level rise was in 0.3~1.0m, the increase of average salinity at three water intakes from Nanxingqiao to Shanhusha were 0.1~0.3, 0.1~0.3 and 0.1~0.2, the increase of maximum excessive salinity time were 1.0~4.1, 0.5~1.6 and 0.1~0.2 d respectively.