Proposal of Hazard Connectivity Index for debris flow disaster management

Abstract

The concept of connectivity and its index have been widely discussed and applied to environmental studies such as ecology, hydrology, geomorphology and hydrosedimentology. Supposing that this concept is very useful also in disaster risk management, we define the hazard connectivity associated to debris flows as the connectivity degree between the debris flow occurrence (trajectory) and the point of interest (location of house, person, and so on). Based on this definition, the Hazard Connectivity Index (HCI) associated to debris flow is proposed as: HCI = L/(x+L), where x is the shortest distance between the debris flow trajectory and the point of interest; and L is the runout distance of the debris flow or just mass movement. The HCI value varies from 0 to 1, being that its higher value indicates larger hazard condition. The HCI application to one case study showed that it can be useful in the analysis of the debris flow related hazard.