Rainfall Intensities Simulation Based On Boundary Model And Rainfall Risk Analysis Of Typhoon

Disasters losses induced by landing typhoon are often caused by heavy rainfall,and torrential rains from typhoon have posed a serious threat to human life and properties.In this paper,we study the rainfall intensities and long-term rainfall risk from typhoons.A parametric typhoon rainfall model is proposed to predict the rainfall intensities and analyze long-term rainfall risk.More precisely:Firstly,we extend the two-component typhoon boundary layer model to three-component by introducing vertical wind velocity in Yan Meng’s model.Then we propose a three-component moving typhoon boundary layer model,which is Modified Yan Meng,Smith(MYS)model,and vertical and radial wind velocity profiles are analyzed by numerical simulations.By referencing the results of MM5,the modified model makes the predication of radial wind velocity and vertical wind velocity more accurate,and the result of tangentia l wind velocity is close to the original model.Furthermore,based on the MYS model,by integrating the previous research results,we propose a simple parametric rainfall model from typhoon,which is Modified Yan Meng,Smith Rainfall(MYSR)model.Considering the effects of the sloping angle of the wall and the azimuthal redistribution,we modify the MYSR model and propose a simple algorithm for calculating the daily rainfall using hourly rainfall.We study the simulation of Typhoon No.0515 Khanun and Typhoon No.0513 Talim by using MYSR model,respectively.The simulation of Typhoon Khanun is better than the simulation of Typhoon Talim.The simulation of the rainfall from Typhoon Talim on the first day is relatively good,and the simulation on the third is not so satisfactory with the typhoon heading inland.With the above cases,we analyse the causes of the deviations and point out the shortcomings of our model.Finally,simulations are performed at Shenzhen city,taking Shenzhen as the center of a circle,with radius of 250 km.The optimal probability distributi on of the typhoon parameters is made in the region.Based on the Monte Carlo model,and the typhoon attenuation model,we obtain the intensity of landed typhoon.Taking the straight-line path of typhoon in the area,simulations are performed with 857 storms,in about 285 years,simulated at the site.Applying MYSR model and extreme probability model,the 10-yr,20-yr,50-yr,100-yr and 200-yr return period extreme rainfall are obtained.By comparing with “Tropical Cyclone Atlas”,the above result of 50-yr return period is reliable.