Risk Assessment Of Storm Surge Disasters Based On GIS Technology

Under the background of global warming and sea levels rising, marine disasters are increasing. Long and winding coastline along with the special location which is both in tropical and temperate zones, China has become one of the hardest hits by the storm surge disasters, resulting in significant economic losses and casualties. So it is needed to assess the risk of storm surge disasters, and to develop effective measures, in order to further enhance the ability of disaster prevention and mitigation, to defense and resistance storm surge disasters and reduce losses, and finally to realize the goal of sustainable development.In this paper, the domestic and foreign research progress of storm surge disasters are well studied. Based on the previous research results and the risk assessment theory of storm surge disasters, it is put forward that the risk assessment object should be the ecosystem consists of the natural environment and the human social and economic system. Besides, the basic process of the risk assessment of storm surge disasters is built up and contains three parts which are risk identification, risk analysis and regionalization and risk management.Combined with the characteristics of storm surge disasters, the job of the risk analysis, which is the most important part of the risk assessment, has been done by constructing the evaluation model based on the Pressure-State-Response model. The indicators in the model are selected from natural, social and economic factors under the scientific, comprehensive, representative, operational and different scales principles. Also, the standardized method is chosen for index standardization and the improved analytic hierarchy process is determined to calculate the weight of the index. Eventually, the risk of storm surge disasters of the study area is analyzed by calculating the comprehensive index using the weighted sum method.Taking Dinghai District in Zhoushan as an example, the overview of the natural geography, society and economy is presented in this paper along with the analysis of the characteristics of the storm surge and the historical condition of the tide disaster. It is learned that on the one hand, this region belongs to the island hilly topography and is easy to be affected by the typhoon which have high possibility to trigger the storm surge disaster. On the other hand, with the rapid social and economic development, the marine industry has gradually become the important supporting industry. Therefore it is of great importance to reduce the loss that is caused by the storm surge disaster in this area by assessing the risk. In this paper, the DEM data, the remote sensing data and the other social and economic data are collected and processed with the use of ArcGIS and ENVI, and all be converted to the raster data which is resampled to 100 m X 100 m. Then the relative risks of different regions in the study area is obtained using the grid calculator and the grid based risk zoning map of storm surge disasters in Dinghai District is made as a result. Along with the evaluation result based on the administrative unit, it can be found that the risk is high in the coastal area and is low in the center of islands where there are low mountains and are covered by woodland with less population. In addition, the risk in Beichan Country and Changguo Street are relatively high for different reason. The former is for its low ground level and the latter is for its dense populations. However, the risk can also be reduced by the high disaster prevention and mitigation capacity, take Cezi Country and Lincheng Street as an example. In the end, some useful measures to reduce the risk of storm surge disasters are proposed as suggestions for the local government from three aspects which are controlling the pressure, repairing the state and improving the response.