The paper takes the example of Jiuzhai Valley (Shuzheng Scenic Spots), a World Natural Heritage, to analysis Jiuzhai Valley natural disaster (debris flows) risk level. This paper calculates the speed, quantity and impact force of debris flows under 6 scenarios of storms, 20-year return period, 50-year return period, 100-year return period, 200-year return period, 500-year return period and 1,000-year return period; using Participatory GIS to make survey over residents in Shuzheng Scenic Spots, classify the structure and serving years of different buildings, and set up vulnerability relationship between debris flow and buildings in the village under 6 different scenarios; roughly learning the property and building conditions of each household and calculating potential losses that 6 scenarios may respectively cause to the village; carrying out overall analysis of disaster prevention costs and benefits targeted at the local acceptable risks and raising measures for natural disaster prevention in Jiuzhai Valley.
