Abstract:

As an important part of hail disaster risk research，regionalization of hail disaster has a significant effect for formulating regional countermeasure on disaster mitigation and prevention. Assessment of hail disaster risk is the precondition and foundation of the hail disaster risks regionalization. Anhui Province where hail disasters are frequent was taken as an example. In this province hail disasters frequently occur April to September，and are coincident to main growing stages of cotton，which is one of the main economic crops in this province. Although its short duration time，small influence scope and strong abruptness，hail poses a grave threat to cotton farming. This influence mainly manifests in the following five aspects：breaking leaves and stem of cotton，knocking cotton bolls，battering growing point and causing total destruction. Therefore，it is very important to study the influence of hail disaster to cotton and to map the zonation of risk for secure production of cotton. Based on the regional disaster system theory and hail disaster risk assessment database of cotton，risk analysis is taken and atlas of risk assessment was compiled from four dimensions respectively—sensibility of environment，hazard of hail，vulnerability of cotton and risk of hail. Among them，with hail disaster magnitude index （H） and loss rate of cotton （L） ，which are obtained with the method of statistical inference and comprehensive index measure，hail disaster risk of cotton was carried out based on constructed model for calculating annual loss rate of cotton hail：Sa=∑〖DD（〗n〖〗i=1〖DD）〗Si－∏〖DD（〗n〖〗i=1〖DD）〗Si=1－∏〖DD（〗n〖〗i=1〖DD）〗（1－Si）. Then cotton hail risk zoning of Anhui Province was complete with multimethod，such as GIS technology，method of “topdown” and “bottomup”，cluster analysis and reference of remote sensing images. Zoning indexes include assessment result of disasterforming environment sensibility，topography and landform，frequency of hail falling，proportion of cotton planting，regionalization result of single factor，and result of risk assessment. Finally risk regionalization maps of hail disaster for cotton of Anhui Province were mapped with GIS. Anhui Province could be regionalized to 3 regions （HuaiBei plain，Jianghuai region and mountain area of South Anhui），10 subregions and 22 units. The southeast of Huaibei plain，west of Huaibei plain and Yanjiang plain were main planting areas of cotton. Sensibility，hazard and vulnerability were all high in those areas. So those areas were key districts to attention for cotton production and hail disaster management. In this paper three & onedimensional risk regionalization methods，combined with multitechnology and multimethod，were presented. This research could provide scientific bases for hail disaster risk management，disaster prevention and mitigation. It also offers an efficient method for other regions and disasters.