402 / 2024-03-13 11:35:59

The Impact of Severe Drought on Freshwater Supply in Estuary and the Corresponding Strategies for Improving the Security of Freshwater Supply from a Basin Perspective--Taking the Yangtze River Basin and Yangtze River Estuary as Example

basin; drought; estuary; freshwater supply; the Yangtze River Basin and Estuary in China

Subtheme 1: Water-related Hazard and Risk Reduction > Topic 4: Integrated Response to Flood and Drought in River Basin

    Taking the Yangtze River Basin and Yangtze River Estuary in China as example, the impact of severe drought on freshwater supply in estuary and the corresponding strategies for improving the security of freshwater supply have been studied from the perspective of watershed.

    In the summer and autumn season of 2022, a historically drought event occurred in the Yangtze River Basin, it causes a sharp decrease of the Yangtze River’s discharge into the sea and so causes serious impact on the Yangtze River Estuary’s freshwater supply. In order to study the drought characteristics of the Yangtze River Basin and its impact on the water resource of the Yangtze River Estuary, the temporal and spatial distribution characteristics and evolution patterns of the drought event in the Yangtze River Basin in 2022 have been analyzed, based on multi-source satellite precipitation products and discharge data from major hydrological stations in the Yangtze River; and then the characteristics of saltwater intrusion in the Yangtze River Estuary under the 2022’s severe drought conditions have been studied; the numerical model of saltwater intrusion in the Yangtze River Estuary was established and validated to have good accuracy, then it was used to explore ways to improve the security of freshwater supply by the Yangtze River Basin under extreme drought conditions.

    The results showed that, the drought in the Yangtze River Basin in 2022 was gradually developing from upstream to downstream, with downstream drought being the most severe; the frequency of the drought occurring in July, August and September is about once every 25, 55, and 10 years respectively, while the frequency of the drought during autumn season (from July to September) is about once every 140 years; affected by this drought, the occurrence time of saltwater in the Yangtze River Estuary has been significantly advanced, with the longest duration of the Qingcaosha Reservoir’s saltwater reaching 98 days, which created a historical record; after about 4 days of increasing discharge at Datong hydrological station of the Yangtze River, the salinity of the Yangtze River Estuary began to decrease; but increasing the discharge at Datong hydrological station 7-8 days before the neap tide of the Yangtze River Estuary is proved to be the most effective and efficient way for reducing the saltwater intrusion of the Qingcaosha Reservoir in the Yangtze River Estuary.