Site-specific debris flow vulnerability assessment

Abstract

Debris flow vulnerability is the potential maximum losses in people, property and materials due to potential debris flow damaging phenomenon for a specified area and during a reference period, which is measured on a scale of 0 (0%) to 1 (100%). Debris flow vulnerability is related to the huge and complex socioeconomic and environmental system, which is mainly classified into two categories of property and population. The property index includes the assets of building, transportation infrastructure, lifeline, personal property, and land resources. Site-specific debris flow vulnerability is a complex-function of the property index. The population index includes the age, education level, wealth situation, natural growth rate of population, and population density. Site-specific debris flow vulnerability is a sum-production-function of the property index. Monetary unit is used to measure the property value, while the value of person may not be simply measured by money. Thus the property index and population index with different units cannot be directly added. In this paper, the transformation functions have successfully provided identical scale and dimensionless expression for both the indexes of property and of population, which make the vulnerability possibly to be expressed synthetically as the sum of the values of property and population. Mathematically debris flow vulnerability is computed by the square root of the half sum of the transformed values of property index and population index.