Population Evacuation: Assessing Biophysical Risk and Social Vulnerability to Floods

Abstract:

A relatively new topic of environmental hazards research revolves around vulnerability to disasters. These studies focused separately on biophysical and social vulnerability perspectives. Only recently, community-based vulnerability studies have become common because of the recognition that combining social and biophysical components is important and practical (Cutter, et al., 2000; Cutter, et al., 2003; Turner, et al., 2003). Researchers have modeled vulnerability to analyze its spatial variation (Montz, Cross, and Cutter, 2006). This study aimed at developing a technical framework for community-based vulnerability to the specific hazards of floods. Developing a technical framework in this research used a “vulnerability of place” method (Hebb & Mortsch, 2007). The data reduction technique used was Principal Components Analysis (PCA) which allows for each variable to explain part of the vulnerability. The case study was on flooding in the Tennessee River Basin. The initial run with all 46 variables produced 13 components that explained 69.77% of the variance. Because of the relative homogeneity across the county (i.e., land use and soil types most vulnerable to flooding being located away from heavily populated areas) biophysical variables became less important in this region in creating overall risk scores. This is made all the more obvious by the number of social variables (17) compared to the number of biophysical variables (8) in the final components. The lowest risk block groups are located within the cities: central Florence, central, and central Madison. The highest risk block groups are in rural areas covered predominately with pasture and agricultural land or forests. They also lie near or within the 100 year floodplain.