广东暴雨洪涝灾害损失定量评估

广东暴雨强度大、范围广、季节长,造成的灾害重、影响大。为合理、定量地评估广东暴雨洪涝过程强度及其损失,基于1994—2018年广东致灾暴雨过程和相应灾情资料,构建了广东暴雨过程综合强度评估模型和灾情指数模型,并采用百分位数法进行暴雨强度和灾情等级划分,以第60、第80、第90和第95百分位数为临界阈值,分别将致灾暴雨过程强度和灾情划分为弱(1级)、较弱(2级)、中等(3级)、较强(4级)、强(5级)和微灾、小灾、中灾、大灾、巨灾5个等级,进而分析了不同强度等级暴雨过程可能造成的人口、农作物、房屋和经济等承灾体损失。结果表明:(1)1994—2018年间,广东各等级致灾暴雨过程主要出现在4—9月的汛期,5—7月尤其多,要特别注意防御;(2)致灾暴雨过程强度等级与各类承灾体灾情指数存在显著正相关关系:随暴雨强度的增强,倒塌房屋数呈指数增长,受灾人口、死亡人数、农作物受灾面积和直接经济损失呈线性增长;(3)平均而言,当暴雨强度达到强(5级)等级时,受灾人口、死亡人数、农作物受灾面积、倒塌房屋数和直接经济损失标准分别约为187.19万人、22人、10.52×10^4 hm^2、1.12万间和13.07亿元。

Quantitative assessment of disaster loss caused by rainstorms and floods in Guangdong

Rainstorms in Guangdong have the characteristics of high intensity,wide range and long season,causing severe flood disasters and great impacts.In order to make rational and quantitative assessment on the intensity and loss caused by rainstorms and floods in Guangdong,a comprehensive intensity assessment model and disaster index model were constructed and proposed in this study,based on analysis of the rainstorm events and their corresponding loss data in Guangdong from 1994 to 2018.By using the 60^th,80^th,90^th and 95^th percentiles as critical thresholds,the rainstorm events were classified into five categories,namely,Ⅰ(week),Ⅱ(relatively week),Ⅲ(medium),Ⅳ(relatively strong),and Ⅴ(strong)according to their intensity.They were also categorized as micro disaster,small disaster,medium disaster,major disaster,and catastrophe according to their severity in terms of disaster loss.The possible losses of population,crops,houses and economy caused by rainstorm events of different categories were then analyzed.The results indicated that:(1)During 1994—2018,the rainstorm events with different categories in Guangdong mainly occurred in the flood season,i.e.from April to September,especially from May to July.(2)The intensity of the rainstorm events had a significant positive correlation with the disaster index of various hazard-bearing bodies.With increasing intensity of the rainstorm events,the number of collapsed houses increased exponentially,while the number of people affected,the number of deaths,affected areas of crops and direct economic losses all increased linearly.(3)When the intensity of the rainstorm events reached up to category Ⅴ(strong),the averaged values of the number of people affected,the number of deaths,affected areas of crops,the number of collapsed houses and direct economic losses are 1871900 people,22 people,105200 hectares,112 thousand rooms and 1.307 billion Yuan,respectively.