Study On Spatiotempral Variation Characteristics And Regulation Of Flood Vulnerability In Wanjiang Region

The flood disaster is one of the most serious natural disasters of threatening mankind,which seriously interferes with the order of economic and social development.The extreme precipitation occurs frequently in Wanjiang area of Anhui Province,and the risk of flooding is rather high.The research on the flood vulnerability in Wanjiang region aims at reducing the risk of flood disaster and improving the capability of disaster prevention,mitigation and resistance.In this paper,the research progress,representative models and basic methods of flood hazard vulnerability studies at home and abroad have been summarized.The specific contents include the construction of vulnerability index system,extreme precipitation in flood season,temporal and spatial changes of vulnerability in Wanjiang region,early warning of vulnerability and the corresponding regulation etc.Firstly,based on statistical yearbooks,national meteorological data,NDVI,GIS extracted data,under the guidance of the principle of operationality,integrity,accessibility,scientificity,and adapting to local conditions etc.,37 most representative indicators have been selected,and the index system for vulnerability assessment in the Wanjiang area has been constructed by using the DPSIR model and the principal component analysis method as well.Then POT sampling,MK trend test and wavelet analysis are used to study the temporal and spatial evolution characteristics of extreme precipitation during flood season in Wanjiang region.Finally,through random forest modeling,the vulnerability index is empowered,and the GIS technology and the percentile method would be used to analyze the evolution characteristics of the vulnerability index.The vulnerability of the flood disaster in Wanjiang region can be divided into five levels: high,sub-high,intermediate,low and poor,and the temporal and spatial variation characteristics of vulnerability in Wanjiang region have been dynamically analyzed and evaluated.Subsequently the change of vulnerability alert could be predicted,and the flood hazard vulnerability control measures would be proposed.The research results are as follows:(1)From May to September,the risk of floods caused by extreme precipitation in Wanjiang region increased first and then decreased.It was at the highest risk of flood disaster in August,and at the lowest in May and September.Judging from the trend value of extreme precipitation indicators,it showed a decreasing change in May and September and an increasing trend in June,July and August.(2)From 1960 to 2016,the extreme precipitation in flood seasons of Wanjiang region generally increased from north to south,and it also showed an upward trend,especially in Chaohu lake and its east region,the intensity of extreme precipitation increased significantly,and the disaster-causing factors were greatly enhanced,thus the risk of flood disaster went up quickly and highly.While in the northern area of Chuzhou and the southwestern area of Xuancheng the extreme precipitation was declining,though the change was not so obvious.(3)In 2003,2005,2006,2007,and 2008,there was more precipitation in the north and less precipitation in the south.In other years,there were more precipitation in the south and less in the north.This kind of distribution affects the vulnerability distribution greatly.However,the vulnerability distribution of flood disaster in Wanjiang area has been basically consistent with the distribution of extreme precipitation.(4)In 2003 and the years from 2005 to 2008,the overall vulnerability of the north was comparatively high,and in the south it was relatively low.In 2009 and 2016,the overall vulnerability was higher in the south and less vulnerable in the north;From 2010 to 2015,on the whole it was not high at all.;The area of high vulnerability reached the largest in both 2005 and 2016.The regions of different vulnerability levels were mutually transformed,and the number of areas with high and sub-high vulnerability was generally decreasing;while the areas with intermediate,low and poor vulnerability were generally increasing.Besides,the vulnerability of flood disasters in Wanjiang Region was on the rise slightly.(5)Seven kinds of vulnerability simulation control scenarios were preset,and the positive indicators were up 5% in different scenarios and the negative indicator is lowered by 5% to simulate vulnerability.It was found that scenario 6 and scenario 7 were more practical and operational,so the indicators contained in these two scenarios would be mainly adjusted and controlled,like total fiscal revenue,flood control farmland area,highway density,per capita expenditure on agriculture,forestry and water affairs,agricultural irrigation and drainage machinery,hospital beds per 100,000 people,soil erosion control area,agricultural irrigation and drainage machinery,waterlogging area,timber harvesting,per 100,000 rural employees,per capita residential and industrial land,and per capita other lands.(6)It was recommended to strengthen the construction of engineering and non-engineering measures,continuously improve the legal system for flood control and disaster prevention,optimize the emergency plan for flood,develop the insurance industry for flood disaster,improve the work efficiency of management department of flood control,and raise the awareness of flood prevention among broad masses,so that the vulnerability level of flood could be effectively reduced,the safety of people’s life and property would be guaranteed,and the economic and social development of the Wanjiang region would be finally promoted.