Research On Flood Risk And Insurance Of Xunjiang Flood Control Reserve In The Pearl River Basin

Flood disasters are characterized by high frequency of occurrence,strong destructiveness and wide range of influence.Under the background of global warming,the rate of water circulation will accelerate,and the frequency and intensity of floods will increase significantly.In addition,with the rapid advancement of urbanization,human activities have led to drastic changes in the land use of the underlying surface,which will further increase flood losses.Therefore,a comprehensive and systematic research on flood risk and insurance can provide decision support for scientific and efficient flood risk management.This paper takes the Xunjiang Protected Area in the Pearl River Basin as the research object,establishes a hydrodynamic model to simulate the flood evolution process,integrates multiple risk factors to assess the flood risk,constructs a submerged water depth-loss function to determine the insurance rate,and puts forward a proposal for medium and high risk areas.An optimization model of disaster bearing costs for residents considering flood insurance.Below are key research findings:(1)The HEC-RAS model was established to simulate the flood evolution process in the study area;the SDWI water body index method was used to extract the Sentinel-1 satellite remote sensing water body map to verify the reliability of the hydrodynamic model.The results show that:compared with satellite remote sensing water bodies,the HEC-RAS hydrodynamic model has an average hit rate of 0.80,an average false alarm rate of 0.28,and a good simulation accuracy;from 1997 to 2017,the Xunjiang Flood Control Protection Area had the largest submerged area in 1998,reached 590.34 km2,and the minimum was 187.46 km2 in 2011;the annual maximum peak flow and submerged area showed a downward trend before 2011,and then began to increase slightly,which is worthy of vigilance.(2)Considering factors such as inundation characteristics,population,and socio-economic time-varying risk of flood was calculated by integrating the above three risk factors,and the variable projection importance(VIP)criterion attribution identifies the main drivers of risk.The results show that:from 1997 to 2017,the flood risk in the study area showed a downward trend in areas above 88%,while the exposure and vulnerability showed an upward trend in areas above 65%and 82%,respectively;the medium and high risk areas accounted for 5.20%of the total area of the study area.%,mainly concentrated in areas such as Huancheng Town,Changzhou Town,Datang Street and Xiaying Town;in the past 20 years,the flood risks of different levels showed an intensifying trend.An upward trend;in the middle and high risk areas of the Xunjiang Flood Control Protection Area,the increase in water depth,GDP,and night lights over time are the main factors leading to increased flood risk.(3)The flood loss was calculated using the water depth-loss function,and the capital asset pricing model(CAPM)was used to carry out the research on the flood insurance rate;considering the flood insurance,an optimization model of the disaster bearing cost of residents was established,and the genetic algorithm(GA)was used to optimize the Residents expect the lowest disaster bearing cost.The results show that the expected annual flood loss in the study area is 2.221 billion yuan,and the average insurance premium rate is 2.85%.Before optimization,it was reduced by 46.4%;the willingness to purchase insurance in different regions is quite different,and the willingness to purchase insurance in severely disaster-stricken areas is low;the average government subsidy for insurance purchases in the Xunjiang flood protection zone is 62.2%,and the average post-disaster rescue ratio is 2.94%;research The total planned expenditure of the district government is 511 million yuan,accounting for 0.36%of the region’s total GDP;the total expected compensation amount of flood insurance is 588 million yuan.