珠江口磨刀门水道咸潮入侵下区域供水风险评估与预警要素研究

<p indent="0mm">As the center of gravity of global population and economic and social development, estuary coastal areas are highly susceptible to saltwater intrusion phenomena during the dry season due to the weakening of upstream runoff and estuary tides, causing significant impacts on regional water supply security and social stability. In this study, an integrated risk assessment model coupling the simulation of saltwater intrusion, the local reservoir emergency storage dispatch, and the regional water supply security index (SI) is developed using the Modaomen waterway of the Pearl River Estuary, where Guangdong, Hong Kong, and Macao are located, as an example. We quantitatively assessed the regional water supply risk under different degrees of saltwater intrusion by combining the current (2023) water supply capacity of the Zhuhai-Macao water supply system and the long-time series natural runoff data from 1979 to 2019, and explored the water supply risk warning levels and corresponding thresholds in terms of upstream runoff, the probability of water withdrawals from major intakes, and the fullness of the local reservoirs. The results show that, due to the serious impact of the saltwater intrusion, the water storage of the local reservoirs in Zhuhai will experience a significant drop in the dry seasons of 1989, 1998, 2003, 2004, and 2005, with the SI value continuing to be below 0.2 for a number of days, and thus face a particularly significant water supply risk. Based on the historical frequency of the SI, the risk warning level of the salty tide in the Modaomen waterway is classified as 4 levels: blue, yellow, orange, and red. The combined flow rate <sc>(2500 m³/s)</sc> of the upstream Wuzhou and Shijiao stations, the average chance of water withdrawals from the major intakes (0.6/0.3/0.1), and the average fullness rate of the local reservoirs (0.8/0.5/0.2) are taken as the warning indicators. When the average chance of water withdrawals from the major intakes is less than 0.1 and the average fullness rate of the local reservoirs is less than 0.2, it corresponds to a particularly significant water supply risk and a red warning level. In the future, the chance of water withdrawals from the major intakes and the fullness rate of local reservoirs can be considered as key controlling indicators, providing a scientific decision-making basis for responding to the saltwater invasion and safeguarding regional water supply security at the stages of actual monitoring, real-time assessment and dynamic adjustment.