The Foundation And Application Of Typhoon Storm Surge Intensity Grade Model

Storm surge is an enormous natural disaster phenomenon which comes from the sea; it refers to the phenomenon of abnormal rise and fall of surface and the mountainous waves caused by the strong wind and the radical change of air pressure of intense synoptic system such as tropical cyclones, extra tropical cyclone, fulminant cyclone. If storm surge superposes astronomical tide, especially the huge astronomical tide and the high tide, it would make its affected sea area water level rise sharply, the seawall is ruined , and even the inland submersed by the seawater, consequently it results in a catastrophe.China is a continental country, but also a maritime nation, good natural conditions of China's economic prosperity and social development is provided by being close to the sea. 70 percent of medium-sized cities and 50 percent of the national economic income distribution in the coastal areas, it formed a situation that coastland driven the development of the mainland, but the oceanic disaster condition and even wreck the coastal areas of economic construction and social development. In our country, the annual direct economic losses caused by the oceanic disaster such as the storm surge, storm waves, severe sea ice, sea fog and strong wind at sea is roughly 0.5 billions, and about 500 people were killed. Of all economic losses, storm surge nearby the coast damaged most severely. Storm surge disaster has become the greatest marine disaster in China. Therefore, it is essential and necessary for against and reduces the disaster of coastal areas to research and explore the mechanism of typhoon surge of disaster, forecast the typhoon surge and the degree of disaster timely and accurately.In order to reduce the losses of people's lives and property due to the storm surge disaster, from the 20th century 50's, the world's major coastal country have set up a system of observation, warning and forecasting about storm surge, launched a storm surge forecasting services. From the 60's, the Chinese workers took up with the research of storm surge theory and its forecasting the methods , has set up and perfect stepwise the storm surge theory successively, and explores the potential avenue of studying and calculating the storm surge start from the reciprocity of the ocean and the atmosphere. They had made a successful numeric simulation for the storm surge of various sea areas of China's coastland.At present, the domestic and overseas forecasting for storm surge disaster mainly according to the increasing water forecast value of the period affected by the typhoon and then forecasting the highest tide, then carries on the comparison with this tide level value and the local warning water level value,, if the highest tide point will be reached or above the warning level value, then consider the storm surge disasters will happen and promulgate storm surge disaster forecast or warning. Otherwise, consider that the storm surge disaster will not happen.To further improve the moisture-resistance and disaster reduction of the marine ,and reduce the losses caused by disasters, the issue standing on the principle of maximum entropy , apply Poisson-maximum entropy compound extreme value distribution model to the intensity of typhoon storm surge disaster classification, the model to restrict the known information at the same time to maintain information on the biggest unknown uncertainties, and contains more than one of the parameters determined, so the theory has a wide adaptability. By the analysis of the wave height factor corresponding to the storm surge, and compared to the traditional distribution the model can effectively avoid the priori and human factors when we conducted analysis of the probability characteristics. It is relatively stable and can overcome the shortcomings of the traditional methods in the situation of lack of observed material.This paper hope for searching for the forecasting methods of typhoon surge disaster by analysis the existing materials of marine disasters and other materials, and use it as a breakthrough point, to find the reason of the disaster and way of forecasting ,in the hope of describing the intensity of storm and the size of the disaster accurately, and warning storm surge which may occur in the future in advance accurately on the basis of the existing samples, then can help the authorities deploy the moisture-resistance and disaster reduction in a timely , appropriate and effective way.