Probability analysis of storm surge intensity and magnitude in China

Storm surge is one of the predominant natural threats to coastal communities. It occurs frequently and usually results in the most serious economic loss among all the natural hazards in China. The disaster induced by storm surge depends on various influencing factors such as the intensity, duration, and route of the passing typhoon, and thus a comprehensive understanding of natural coastal hazards is essential for the safe and sustainable development of the coastal area. Seawalls are the primary coastal protection facilities, and their protection standard can be established using return periods of the design tidal level (or water level) and design wave. But in China, the correlation between tidal level and wave, which is the parameter may enhance the interpretation of the actual storm process, isn't described in the existing design criterion. This paper proposes a new method to classify storm surge intensity based on PBGLD and PBLD. We illustrate this new method using observed tidal level and corresponding wave height series sampled from typhoon processes in the coastal area of Qingdao and Shenzhen, including the occurrence frequency of typhoon, and to make up the defects of the warning water level. A novel criterion is put forward to grade the intensity of typhoon-induced storm surge, and it forms the foundation to evaluate the storm surge intensity for seawall design. Study indicates that the new criterion gives an explicit notion in terms of joint probability that is easy to operate and fits well to the classification of the surge intensity. The proposed method of storm surge classification using new statistical model can be adopted as a reference approach in many coastal areas affected by typhoon. The data used here is limited, it is recommended that the calculation should only be used for reference, and more verification and improvement may be needed for broader application.