Abstract: The drought events happen in the Changjiang River basin with increasing frequency in recent years due to the global climate change. There was a drought event at the middle and lower reaches of the Changjiang River in the late spring and early summer of 2011, resulting in the river discharge at Datong station in April, May and June of 2011 decrease 33.4%, 50.6% and 50.3%, respectively, compared with the corresponding monthly mean values. The observation data indicated that in the April salinity at Chongxi hydrological station exceeded 0.45 (standard of drink water) in the most measured time, the saltwater spilling over from the North Branch took about 2 days and 3~5 days from Chongxi hydrological station to Nanmen and Baogang reservoir, respectively, the not suitable water intake time was 2 and 4 days at Baogang reservoir, 5 and 4 days at Qingcaosha reservoir. In the middle and late May, it was still occurred by high saline water at Yonglongsha in the North Branch, it reached 7 days that salinity exceeded the drink water standard at Chongxi hydrological station, the not suitable water intake time was 8 days at Qingcaosha reservoir. During the observed 5 tidal periods from 4 to 7 in June (middle tide after spring tide), salinity near Dongfenxisha reservoir water intake was higher than 0.45 in about half observation time, was lower than 0.45 near Chenhang reservoir and Qingcaosha reservoir water intakes, but increased gradually with time, indicating that the salt there come from the saltwater spilled over from the North Branch. The saltwater intrusion in the Chnagjiang River Estuary happens generally in December and next January to March, and vanishes in April to June with the increasing river discharge. The drought event induced by climate change enhanced the saltwater intrusion and influenced severely the safety of water intake in the Changjiang River estuary in the not period of saltwater intrusion.

Key words: Changjiang River Estuary, climate change, drought event, saltwater intrusion, in-situ observation