Analysis of the saltwater intrusion in the Changjiang estuary during the flood season in extreme drought year

Based on the hourly discharge records at the Datong station and the measured data of hydrology and salinity in the Changjiang estuary during the flood season in the extreme drought 2006 coinciding with the operation of the large hydropower engineering, the characteristics of the saltwater intrusion and the changes of the freshwater caused by the saltwater intrusion are discussed. The results show that: (1) During the extreme drought year, the intensity of both the saltwater intrusion in the north branch and the inverse intrusion into the South Branch is strengthened in the period of the spring tide, especially in Oct. 2006, which resuls from the absence of the freshwater in the river segments of Chenghang reservoir and Baogang reservoir; (2) The main way of inversed intrusion of the saltwater in the north branch goes clearly via the north channel of Baimaosha into the south branch, and the diluted water in the Changjiang River evidently from the south channel of Baimaosha to the south branch. The flowing water from these different ways meets in the back of the Baimaosha and extends over the region of the Wusong inlet; and (3) because the region of the Wusong inlet is affected by the action of the saltwater intrusion from the north passage and the south passage, freshwater resource can be found there. However, the seaward segment of the Wusong inlet is covered by the high saltwater body.