半干旱区极端强降雨灾害链损失快速评估方法——以甘肃岷县“5·10”特大山洪泥石流灾害为例

Rapid-assessing Methods of Loss in Extremely Heavy Rainfall Disaster Chain in Semiarid Region——A Case Study on a Flash Flood Debris Flow in Minxian County,Gansu Province

通过对半干旱地区极端强降雨灾害链的研究,构建了基于流域单元、综合多源信息的极端强降雨灾害链损失快速评估方法。其中,流域评估单元的选择、遥感解译与灾害信息员实地调查的房屋易损性判定准则、综合损失的灾害链损失评估思路等是该方法的主要特点。甘肃岷县"5·10"特大山洪泥石流灾害房屋损失评估误差小于15%,基本满足应急救助决策的需要。建立多源数据条件下的洪涝灾害实物量毁损快速评估体系,可提升灾害应急救助效率。

Less attention was paid to the extremely heavy rainfall disaster chain in semiarid regions in the previous researches. Under climate change, the frequency and intensity of extremely heavy rainfall in semiarid areas in Chi- na was in an obvious increase trend in recent decades. It is important to develop a methodology of rapid assessment of damage and loss （RADL） in an extremely heavy rainfall so as to enhance the capability of preventing the disas- ters in semiarid areas. In this paper, a method was developed to assess the damage and loss in an extremely heavy rainfall disaster chain, especially in flash flood and debris flow disaster chains based on multi-source data and infor- mation, including the real-time precipitation, inundated area derived from remote sensing image interpretation re- sults, social and economic infiJrmation of the study area, etc. Three points should be emphasized in the framework of this method： （1） The assessment unit of the RADL was the combination of watershed unit and GRID unit, in which the watershed unit included the second-level watersheds in the study area, and the spatial resolution of GRID unit was decided by the social and economic information （e. g. population density） ; （2） The home vulnerability curve was an important factor to implement the RADL. In this paper, a home vulnerability matrix was established based on the real-time filed survey of disaster information collectors at village scale due to the lack of vulnerability curve at that time; （3） From the perspective of final damage and loss in the extremely heavy rainfall disaster chain （including flash flood and debris flow） , the method was a comprehensive framework to implement the RADL. The study results could provide a scientific basis for the establishment of rapid assessment system of physical damage and loss induced by flood and debris flow disasters.