Measuring The Value Of Coastal Wetland For Typhoon Protection:A Case Study Of China

Frequent natural disasters such as typhoons,floods,and storm threaten seriously the life safety and property security in the coastal zone with high density of population and economic activities.Coastal wetlands can reduce the damaging effects of typhoon on coastal communities by reducing the wind speed,decreasing the water level and flow rate of flood,and absorbing storm energy during Typhoon process.The drastically shrinking of coastal wetland area resulted from human activities is due to not placing proper value on them.It is very important to measure the value of coastal wetland for Typhoon protection and integrate these information into coastal wetland management.This thesis developed a model to assess the value coastal wetland in Typhoon protection based on the systemic study on the typhoon disaster factors and typhon protection mechanism of wetland,and using the multidiscipline theories and methodologies,including environmental economics,econometrics,ArcGIS and MATLAB.The maginal value,total value and average value of wentland in China's coastal provinces(Hainan province,Guangxi province,Guangdong province,Fujian province,Zhejiang province and Shanghai)were evaluated by employing the established model.The main achievements of the dissertation were as follows:1)The study establishes theoretical regression model of typhoon disaster based on the systematic analysis of the factors affecting typhoon disasters(wind speed,precipitation during typhoon,and the spatial distribution of wetland and propert in the Typhoon swath)and typhoon protection mechanism of coastal wetland,A regression model was developed in this study using 47 major Typhoon hit China since 2000 with the natural log of damage per unit GDP in the Typhoon swath as the dependent variable and the natural logs of wind speed,rain fall,terrestrial wetland area and intertidal wetland area in the swath as the independent variables.The results of the overall model test and the significance test of the single variables show that the regression model was highly significant.The adjustet R-squared of the regression model is equal to 0.708 which indicates that the model can explain over 70%of the change of relative damage of typhoon.The correlation between the predicted value and the observed value is 0.846,and the predicted value has a good linear fitting relationship with the observed value.2)The study establishes the marginal value assessment model of typhoon protection from coastal wetland according to the established regression model and the marginal value of typhoon protection was evaluated.The results show that a loss of 1 km2 wetland in the model corresponded to an average RMB 3.70 million increases in typhoon damage from specific typhoon,with the lowest loss is RMB 55,000(typhoon 0807 Kalmaegi)and the highest is RMB 15.60 million(typhoon 0413 Rananim).The results show that the marginal value of wetland for typhoon protection is non-normal distributions.The marginal value of the typhoon protection service for each typhoon is affected by the wind value,coastal wetland area and the GDP in the typhoon swath.3)This study estimated the marginal,annual total value and average value of coastal wetland for Typhoon of each coastal city using above the relationship and taking into account the annual probability of hits by typhoon of varying intensities(Tropical Depression,Tropical storm,Severe tropical storm,typhoon,Strong Typhoon and Super Typhoon).The results show that the mean marginal value of typhoon protection services in the typhoon area is RMB 3.14 million/km2(the maximum and minimum values are RMB 20.456 million/km2 and RMB 5.73 million/km2,respectively)at city scale.The average value of wetland for typhoon protection services is 3.83 RMB/m2.The highest the average value is in Shenzhen City(21.75 RMB/m2),and the lowest in Changjiang City(0.03 RMB/m2).The results also show that the total value of wetlands for typhoon protection is RMB 34.78 billion per year in China,that is,coastal wetland can reduce RMB 34.78 billion economic losses resulted from Typhoon per year.The highest total value is in Wenzhou City are higher(RMB 2.90 billion per year),the lowest in Changjiang(RMB 9 million per year).4)The study estimates the value of typhoon disaster protection in grid scale wetland,and obtains the spatial distribution of typhoon protection value in lkmxlkm resolution.In the 1km×1km grid scale,the wetland typhoon value is between 0 and RMB 282.04 million/km2.The correlation between the total value of typhoon protection services calculated at lkm×1km scale and that at city scale is 0.8016,which indicates that our resulted is robust.In this paper,the data used in wetland area,gross domestic product(GDP)and typhoon path are more intuitive than previous research.The method established in this study not only can be used to assess the value of coastal wetland for protection at current situation,but also can be used to predict the change of economic loss resulted from Typhoon witch the change of area of wetland and GDP.Therefore,the resulted results of this paper,together with values of other ecosystem services provided by the coastal wetland can inform the development of strategy restoring and preserving coastal wetland.