Enhanced Circular Subregion Method in Typhoon Hazard Analysis

AbstractThe coastal region of China suffers from severe typhoons. Hazard mitigation and risk management require a good estimation of the typhoon wind speed. In this study, an enhanced circular subregion method (CSM) is proposed. The efforts are mainly made in three aspects. First, a new treatment is developed to model the observed central pressure difference better. Second, the appropriate size for the enhanced CSM is discussed. Studies indicate that 500 km is appropriate. Third, Nataf transformation is introduced to incorporate the correlations among typhoon key parameters in wind hazard estimation. The enhanced CSM combined with a typhoon wind field model is used to assess the typhoon hazard for nine cities located in the coastal region of mainland China. Results show the design wind speeds predicted by traditional CSM are lower than those by the enhanced CSM for nine cities with an averaged difference of 4.3% for 50-year and 4.9% for 100-year return periods. The maximum difference was 6.1% in Fuzhou for 100-year return periods. Results also show the consideration of correlations among typhoon key parameters results in a change of the design wind speed at less than 2% for nine cities. Note that the consideration of correlations may not be neglected in other countries.