Risk Assessment Method And Application Of Typhoon Storm Surge Based On ADCIRC

In recent years, the risk assessment of typhoon storm surge disasters in coastal areas has become hotspots for international society and science frontier in academy. There are many research on assessment theories and methods in developed countries, some of which has been applied in different cities and achieved good effects. However, it is still an emerging field of research in China, which has not established a scientific, effective and simple system to demonstrate and extend. Based on analyzing the research advances of storm surge disasters both in domestic and foreign areas systematically, the empirical study using different methods is carried out in Taizhou City and Yuhuan County, where the storm surge disasters are severe in Zhejiang Province. This paper aims to build up a set of scientific and practical patterns in the risk assessment of storm surge disasters to cover the shortage of complexity in methods, heavy workloads, difficulty in data collection and insufficiency in data continuity.ADCIRC numerical model is introduced in this paper and applied to compute storm surge elevation in Taizhou City and storm surge inundation in Yuhuan County. The grid resolution is less than 200m in the coast of Taizhou City and 70-90m in Yuhuan county land. Considering the computation of inundation in Yuhuan County, the main 26 seawalls of Yuhuan County in grid have been set as one dimensional obstacle. Historical measured data are used to test the reliability of the model, which presents the relative error of maximum storm surge between observed and calculated is 5.4%, the relative error of highest tide level between observed and calculated is 8.0%, which shows the model calculation results are reliable preliminarily.Scenes of typhoon hazards has been constructed, which includes the research of storm surge in six different typhoon intensities in Taizhou City, based on processes varies from Hazard Assessment, Vulnerability Assessment, to Risk Assessment. Researchers mainly use mathematical statistics methods based on historical observation to do the research on hazard assessment of storm surge disasters in Chinese coastal cities. But both the timeliness and the results of assessments are not acceptable due to the short of observation. This paper uses numerical model to make compensation for the short of observation and uses probable maximum storm surge as the foundation of hazard assessment. In addition, society, economy, environment and anti-disaster ability are considered synthetically.16 evaluation factors are selected to reflect the vulnerability, which are easy to access, in order to build up the Vulnerability Indexes System of storm surge in Taizhou City and carry out the vulnerability analysis. Compared with previous studies, this method goes more deeply and thoroughly. The results show that the level for typhoon storm surge risk of Yuhuan, Jiaojiang, Sanmen, Luqiao and Linhai during typhoon intensity of 965 hPa, 945hPa,935hPa,935hPa and 915hPa respectively, are 1st grade, which is the highest level.Yuhuan County is selected as intensive area in this study, using maximum submerging depth as the basis of the risk assessment. Different from prior studies, seawalls are added in this paper which is critical for the computation of storm surge inundation. Besides, the paper indicates that most of vulnerability assessments ofbodies bearing disasters in intensive areas are quantitative evaluation mothods based on loss rate and intensity in previous work, which are widely used in foreign countries but not applicable to our national conditions. This paper adopts land use type as a basis of judgment to do the vulnerability assessment of bodies bearing disasters, which is simple, feasible and could reflect the vulnerability assessment more realistically and objectively. The results show that human active areas like streets, town centers are all high risk areas. The risk level of most coastal regions except the streets and town centers is 3rd grade, which is a medium risk level, most of which are bare lands, farmlands or shoals, few of which are villages or storage lands.In addition, the work keeps high significance by enriching and developing the theories and methods of storm surge assessments, the results also offer important case studies and demonstrations for the risk assessment of storm surge disasters with different spatial scales in the coastal areas in our country. Besides, most achievements in this aspect are based on different return periods, but this paper is based on different levels of typhoon intensity which is beneficial to the application in actual work and can cover the shortcomings of different return periods.