Debris Flow Risk Mapping Based on GIS and Extenics

Abstract. Debris flow, a very dangerous natural disaster, frequently occurs in mountainous areas of Sichuan province. China. Here, we applied the extenics method, which is normally used in single debris flow risk assessment, towards a large-scale debris flow risk assessment for the first time, and built the classical matter elements and joint domain matter elements for assessment of the debris flow risks in Sichuan province. Eight factors, including relative elevation, slope, rock hardness, rainfall, gully density, vegetation coverage, occurrences of historical debris flow and historical earthquake occurrences were selected for debris flow assessment by using geographic information system technology and weight analysis approach. Based on the risk assessment, the debris flow risk map was generated. Results indicate that areas with high risk and very high risk accounted for 21.32 % and 14.35 % of the whole province, respectively. 76 % of the verification points fall within the moderate, high and very high risk areas, suggesting high accuracy of extenics method in large-scale assessment areas. Thus, the Geographic Information System (GIS) and extenics based methods could provide a strong support for debris flow management in the region.