Approach to Mutil- objectives Assessment for Urban Tor r ent Hazard
城市山洪灾害多目标评估方法探讨

This paper focuses on the problems of urban torrent hazard in the recent years and reviews the current study status and future research work about assessment of urban torrent hazard. According to torrent - breeding environment, triggering factors, social and economic situation of flooded area, this research formed a GIS based technical methodological system, which is shown as following: collect data →establish database of spatial attribute →choose the system of assessed indexes→analyze forecasting estimation→torrent hazard assessment and risk zonation. Based on this, an integrated methodology for urban torrent risk assessment is approached. Procedure of the methodology for torrent hazard zonation in the flooded area, urban vulnerability analysis, loss evaluation and risk assessment, torrent hazard zonation on the alluvial fan are created via geomorhologic method and the numerical simulation method. Detailed land cover information was derived by using the high resolution satellite imagery and then we evaluated the vulnerability values on different land - use features. Based on a GIS statistical and analytical tool, urban torrent loss and risk for urban area is evaluated. These assessments can be used for torrent mitigation by identifying hazard areas, allowing for avoidance through zoning or other land use policy decision. In addition, residents who live in torrent areas need risk information for evacuation and flood control.