Search

A risk assessment for storm surge disasters can provide scientific support for coastal management as well as marine disaster prevention and mitigation. By taking the Wenchang City of Hainan Province as a pilot area, a risk assessment approach for typhoon-induced storm surge disasters is introduced in detail in this article. First, a numerical simulation system for storm surge inundation is developed, which is applied for the simulation and calculation of the probable maximum storm surge in Wenchang, and the obtained inundation areas and depths are used to assess the storm surge hazard. Then, the data of land use and disaster-bearing bodies are used to classify and assess the vulnerability of Wenchang. Finally, by taking the community as unit, the risk assessment for typhoon-induced storm surge affecting Wenchang is performed by combining the assessment results of both hazard and vulnerability, thereby obtaining a level map of risk distribution. The results show that there are risks of typhoon-induced storm surge in most of the coastal areas of Wenchang, especially for its northeast and east coastal areas, where the risks reach Levels I–II. This approach can be conveniently applied to risk assessments of storm surge in other coastal areas. Note that this approach focuses on the current risk of typhoon-induced storm surge in coastal areas, and further studies will be conducted on the assessment methods for the potential risk.

Understanding of the offshore wind wave status plays a guiding role in surrounding marine engineering constructions, marine traffic, sea farming, etc. Further study is beneficial to marine economy development, as well as to the academic value of wave theory. This paper primarily introduces the deduction of new wind wave growth relations. Firstly, a new relation formula between wave steepness and wave age was deduced by combining the 3/2 power law developed by Toba with the nonlinear dispersion relation deduced by Li, and by ignoring the effect of water depth. And when the higher-order term was ignored, the relation formula can be simplified as that based on linear dispersion. Secondly, based on the combination of this new relation formula with the significant wave energy balance equation, new wind wave growth relation formulae including the wave non-linear dispersion effect were deduced. When the deduced growth relation formulae were applied in offshore area of Jiangsu incorporating with Mitsuyasu’s empirical formula about the open sea fetch and wind speed, accurate open sea wave parameters of Jiangsu can be formulated by only considering one parameter, such as wind speed. Overall, as this methodology avoided the uncertainty about the fetch of open ocean and operation error during the calculation process, results gained from this report had higher accuracy than other published formulae, and results were validated by NCEP reanalyzing data of Jiangsu offshore area and other researches.

For providing a better shelter condition, it is necessary to build a breakwater in Zhongzui Bay. In order to know whether mooring area meets the requirement after engineering construction and compare the mooring area between solid breakwater and permeable breakwater, a numerical simulation method is used in the sheltering harbor of Zhongzui Bay. The used Mild-slope equation which describes wave refraction, diffraction and reflection, considers the steep slope bottom and effect of energy dissipation. It has been validated to fit for simulating wave transformation in the coastal zone. Under extreme high water level and design high water level, wave fields in the calculation area of three wave types in three different return periods are simulated by using this method respectively. In addition, wave height in front of breakwater can be provided. Then the wave parameters and the mooring area of two occasions, with and without breakwater, are gained in calculation area. Based on these results, some conclusions are presented in the end.Copyright © 2007 by ASME