Gis and Social Vulnerability Analysis

Abstract

Vulnerability to natural hazards is spatially variable, and these variations are not necessarily in direct proportion to physical risk. Other variables come into play, including those related to the nature of the hazard, in this case flash floods, and those related to socioeconomic and land use variables, and all of these might be influenced by political decision-making. These data can be incorporated as separate data layers in a Geographic Information System, thus facilitating analysis of spatial patterns as well as providing the basis for determining measures of vulnerability; a number of methods have been developed. These methods take into account probability of occurrence, indices of the spatial extent, and characteristics of the community at risk. Community is sometimes defined by spatial boundaries and other times by characteristics such as age or mobility, and the proportion or absolute number of people and amount of property at risk. Despite these advances, little work has been done to evaluate methods of defining and depicting social vulnerability. This is addressed by testing three methods in a case study community. 2. Introduction Areas are considered at risk to flash flooding because of their physical location. However, even communities with similar physical situations can have different levels of vulnerability as a result of social, political, and economic differences. Indeed, portions ofthe community can be differentially vulnerable. Thus, vulnerability can be defined in a number of ways, two of which are susceptibility to damage from an event and ability to recover from the impacts of an event. The first is related to physical characteristics of an area that make it more or less damage prone, including such variables as size of the watershed, relief, and soil types. Susceptibility to damage is also related to building 37 E. Grunt/est and J. Handmer (eds.), Coping with Flash Floods, 37-48.