GIS-Based Susceptibility Mapping and Zonation of Debris Flows Caused by Wenchuan Earthquake

Debris flow susceptibility zonation (DBSZ) is necessary for disaster management and planning development activities in mountainous regions. This paper presents the results of a pilot study for assessing debris-flow hazards using geographic information system (GIS) techniques. The debris flow caused by earthquake in Wenchuan County was identified on the basis of remote sensing images interpretation and field investigation. In this paper, the debris flow nominal susceptibility factor method has been applied for DBSZ mapping in Wenchuan county. Relevant thematic maps representing various factors (e.g., lithology, fracture belts, earthquake magnitude, slope, aspect, relative relief, form factor, drainage areas) that are related to debris flow activity, have been generated using remote sensing and GIS techniques. The debris-flow susceptibility index of these factors above is calculated. The overall debris-flow hazard at a particular watershed may be assessed according to all DH indexes. They are classified as the very high, high, moderate and low hazard zones.