Abstract:

Risk assessment of debris flow hazard in settlement sites is the basis for accurately forecasting and predicting disasters and reckoning damages and losses. With the help of GIS, a total of 9 factors in the fields of geologic structure, topography, hydrometeorology and human activities were selected for use in analysis of  influencing factors and risk assessment of debris flow hazards in Panxi region, with the analytic hierarchy process, and the assessments were verified for the accuracy against conditions of the sites where actual debris flows occurred. Based on spatialization of the population data of Panxi region, potential risks of debris flow hazards in the settlement sites were analyzed. Results show that the distribution of the areas extremely high and high in risk is mainly affected by fault in the west of the region, and by river more than by fault in the middle and south of the region, and by the three factors of fault, slope and elevation, more than by river in the northwest and northeast of the region. In 84.10% of the areas rated to be extremely high, high and medium in risk in the risk assessment actual debris flow hazard did occur, affecting about 72.48% of the population. Areas extremely high in risk are generally distributed in the vicinity of a fault, areas high in risk are in the periphery of the former, areas moderate in risk areas are relatively far away from a fault, and areas low in risk are in the eastern and western parts of the study areas where no faults are found.

Key words: debris flow, risk assessment, analytic hierarchy process, settlement site