Physics Based Typhoon Multi-hazard Modeling And Hazard Analysis

Typhoon and its related natural hazards are severe challenges faced by most coastal countries or regions around the world.With the consturction and development of the“Belt and Road”,especially the“21^st-Century Maritime Silk Road”,the Chinese governments,multi-national corporations,construction enterprises,insurance and other related enterprises pay more attention to the typhoon hazards.Moreover,the impacts of typhoon hazards on other countries along the Maritime Silk Road has also gradually been incorporated into the risk management of Chinese enterprises.Therefore,based on the meteorology,atmospheric boundary layer theory,and hydrodynaics,studies of typhoon multi-hazard models of strong wind,rainfall and storm surge,and the development of hazard and risk assessment theory and methdology accordingly are of great theoretical and practical values.In the thesis,3-D numerical typhoon wind field models and their numerical solution methods are developed based on the equations of motion of the atmosphere in the boundary layer;a parametric typhoon rainfall model is built on the simulation of typhoon wind field by using the conservation of moisture flux,the Clausius-Clapeyron equation,the first law of thermodynamics,and the hydrodynamic equations;furhterly,based on the concurrent computation platform,a large-scale numerical typhoon storm surge simulation scheme for the entire offshore area of China is proposed by using the simulated typhoon wind field and typhoon atmospheric pressure field to drive the ADCIRC（Advanced Circulation Model）hydro-dynamic model.Finally,simulations and hazards analysis of typhoon strong wind,rainfall and storm surge of the Guangdong-Hong Kong-Macao Greater Bay Area are performed.The main contents are as follows:（1）Based on the Reynolds-averaged motion of equations of the atmosphere in boundary layer,the Louis boundary layer scheme,the Meng’s surface layer parameterization scheme and the nested grid technology,a nonlinear 3-D numerical typhoon wind field model in the terrain-following coordinate system is developed,which can consider the effects of various land cover and terrain.By comparing with the averaged vertical wind profiles,the H^*Wind data and the observed time series of wind speeds and directions,it is verified that this model can reasonably simulate the typhoon wind field structures at sea and land.（2）After simplifying the motion of equations of atmosphere by the scale analysis method,a simplified 3-D typhoon wind field model with high computational efficiency is established,which incorporates the horizontal advection,vertical advection and vertical diffusion processes.Then the effects of terrain and land cover is introduced into the wind field model by incorporat ing the equivalent surface roughness length into the drag coefficient C_d.It is found that the simulation results of the wind flied model are in good agreement with the WRF（Weather Research and Forecasting）model results,the H^*Wind data and the observed typhoon wind speeds and directions.（3）By using theories of the conservation moisture flux,the Clausius-Clapeyron equation and the first law of thermodynamics,a parametirc typhoon rainfall model is constructed.This rainfall model can consider the effects of typhoon atmosphere dynamics,topography,vortex stretching and wind shear.After comparing with the simulation results of WRF model and the observed hourly rainfall data in Zhejiang,Jiangsu and Shanghai area,it is found that this model can reasonab ly reproduce the accumulated typhoon rainfall.By comparing with the historical typhoon rainfall data,it is shown that the simulation results can reveal the statistical property of historical typhoon rainfalls fairly well.（4）Based on the ADCIRC hydro-dynamic model,by integrating the high precision GEBCO（General Bathymetric Chart of the Oceans）data,GSHHG（Global Self-consistent,Hierarchical,High-resolution Geography）coastline data and the tidal harmonic constants of TPXO9-altax,a typhoon storm surge simulation scheme for entire offshore area of China is proposed for concurrent computation platform.Storm surges caused by the synthetic typhoon events in ten thousand years are simulated.The sea level of storm surge of different return periods along the coast of China are obtained.Additionally,a refined typhoon storm surge model is constructed for the Guangdong-Hong Kong-Macao Greater Bay Area.This storm surge model is validated by comparing with the astronomical tide table data and the observed storm surge data at tide gauge stations around the Pearl River Estuary.Results show that this storm surge model can accurately reproduce the astronomical tides and typhoon storm surge processes.（5）From the Best Track Dataset and the typhoon events in one th ousand years generated by a full track typhoon synthetic model,a 114 historical typhoon event dataset and a 1738 synthetic typhoon event dataset affecting the Guangdong-Hong Kong-Macao Greater Bay Area are constructed respectively.Typhoon induced strong wind,heavy rainfall and storm surge are simulated for the typhoon events in two datasets separately,using the simplified 3-D typhoon wind field model,the parametirc typhoon rainfall model and the typhoon storm surge model.Typhoon hazard analysis of the strong wind,heavy rainfall and storm surge are alse studied by deriving the extreme parameters with different return periods.By comparing with the data in codes and literature,it shows that the extreme wind speeds simulated by the synthetic typhoon event dataset is consistent with the“Load code for the design of building structures”.It is also found that the west bank of the Pearl River Estuary is more vulnerable to typhoon storm surge than the east bank,due to the typhoon tracks moving from southeast to northwest.