灾害系统:灾害群、灾害链、灾害遭遇

Disaster system: disaster cluster,disaster chain and disaster compound

根据灾害系统的结构与功能特征的复杂性,将灾害系统中的多灾种情形分成三大类:灾害群、灾害链以及灾害遭遇。灾害群是指灾害在空间上的群聚和时间上的群发,各致灾因子之间不存在成因上的联系性,可依据多灾种风险评估模型对其进行评价;灾害链则表现为类似多米诺骨牌的现象,各致灾因子之间具有成因上的联系性,其风险可通过转移概率风险评估模型进行评估;灾害遭遇表现为各致灾因子之间的相互碰头现象,其风险可通过组合概率风险模型进行评估。狭义上的多灾种仅指致灾因子在空间上群聚或群发。灾害群的致灾程度是各单一致灾因子的总和,对某一地区来讲,灾害群聚或群发,都会使区域总体致灾加重;灾害链与灾害遭遇的致灾强度大大超过其关联的各单一致灾因子的总和,其中灾害链的致灾强度具有累加效应,而灾害遭遇的致灾强度具有叠加效应。灾害累加与叠加都可明显放大致灾的程度,形成巨灾风险。

Based on the structure and function complexity of the disaster system,the multiple hazards in the disaster system can be classified into disaster cluster,disaster chain and disaster compound. A disaster cluster refers to hazards clustering in space and time without any linkage. Its risk can be evaluated by the multi-hazards risk model.A disaster chain represents hazards that have causal relationship like dominoes. Its risk can be evaluated by the transfer probability risk model. A disaster compound implies different hazards confronting with each other. Its risk can be evaluated by the combination probability risk model. Broadly speaking, multi-hazards include the complexity of natural disaster system,however,in narrow sense,it only refers to the disaster cluster. The severity of a disaster cluster is the summarization of every single hazard. Spatial coexistence and temporal cooccurrence will amplify the disaster severity in a specific area. The disaster intensity of disaster chain and disaster compound is much stronger than simple addition of all related hazards. The hazard severities of disaster chain and disaster compound have an accumulating effect and multiplying effect separately,and accumulating and multiplying effects can significantly enlarge the hazard severity and induce a catastrophe.