Abstract. Estuarine saltwater intrusions are mainly controlled by
river discharge and tides. Unexpectedly, an extremely severe saltwater
intrusion event occurred in February 2014 in the Changjiang estuary under
normal river discharge conditions. This intrusion cut off the freshwater
input for 23 d into the Qingcaosha reservoir, which is the largest
estuarine reservoir in the world, creating a severe threat to water safety
in Shanghai. No similar catastrophic saltwater intrusion has occurred since
records of salinity in the estuary have been kept. During the event, a
persistent and strong northerly wind existed, with a maximum speed of 17.6 m s−1, lasting 9 d and coinciding with a distinct water level rise. Our study demonstrates that the extremely severe saltwater intrusion was caused by this northerly wind, which drove substantial landward net water transport to form a horizontal estuarine circulation that flowed into the northern channel and out of the southern channel. This landward net water transport overpowered the seaward-flowing river runoff and transported a
large volume of highly saline water into the northern channel. The mechanisms of this severe saltwater intrusion event, including the northerly wind,
residual water level rise, landward water transport and resulting horizontal circulation, etc., were systematically investigated.
IMPACTS OF DEEP WATERWAY PROJECT ON LOCAL CIRCULATIONS AND SALINITY IN THE CHANGJIANG ESTUARY, CHINA
