China is one of the countries that is most seriously affected by storm surges. In recent years, storm surges in coastal areas of China have caused huge economic losses and a large number of human casualties. Knowledge of the inundation range and water depth of storm surges under different typhoon intensities could assist predisaster risk assessment and making evacuation plans, as well as provide decision support for responding to storm surges. Taking Pingyang County in Zhejiang Province as a case study area, parameters including typhoon tracks, radius of maximum wind speed, astronomical tide, and upstream flood runoff were determined for different typhoon intensities. Numerical simulations were conducted using these parameters to investigate the inundation range and water depth distribution of storm surges in Pingyang County considering the impact of seawall collapse under five different intensity scenarios (corresponding to minimum central pressure values equal to 915, 925, 935, 945, and 965 hPa). The inundated area ranged from 103.51 to 233.16 km² for the most intense typhoon. The proposed method could be easily adopted in various coastal counties and serves as an effective tool for decision-making in storm surge disaster risk reduction practices.

Storm surges represent a prominent and significant natural hazard in the coastal areas of China and cause substantial human and economic losses. We investigated historical storm surge events in these areas to assess the distribution of associated hazards and to construct a storm surge hazard index. The tide-gauge data from 83 observational stations along the Chinese coast were collected, and the assessment was based on two indicators, namely the storm surge height and the exceeded water warning level of these events. Further, we conducted a vulnerability assessment of coastal counties in China using population and economic distribution data. Thereafter, the distribution of storm surge hazards and vulnerability levels was considered, and we determined the county-level risk of storm surges covering 219 coastal counties in China. The findings revealed substantial spatial variations therein, with high-risk areas in terms of the population and economic effects of such surges accounting for 25.1% (55/219) and 27.4% (60/219) of all coastal counties, respectively. These results provide preliminary insight into storm surge risks in China and have implications for the prevention and mitigation of storm surges for central government.

The warning water level is the default water level at which storm surges may occur along a coast and indicates a stage of alert. This level forms the basis for storm-surge forecasting, and prewarning is an important reference for governments and aids in the decision-making process for storm-surge prevention and disaster risk mitigation. The warning water level has four categories (blue, yellow, orange, and red) based on water level observational data. Taking into account the actual defense capability of the shore, we determined the warning water level by comprehensively analyzing factors, including the high water level at the typical return period of each shore section, wave exposure degree and defense capability of storm-surge protection facilities, and the shore-section importance level. Here, we proposed a quantitative method for determining the warning water level, and the application of this method was introduced by determining the warning water level at the shore section of Zhifu District (Yantai City, Shandong Province, China) as an example. We analyzed the spatial distribution characteristics of the warning water levels for 259 shore sections along the coast and revealed their current marine disaster prevention capabilities. Our findings provide a valid direction for determining future warning water levels and a reliable scientific reference for redetermining warning water levels in coastal areas while improving marine disaster prevention and protection capabilities.