Groundwater arsenic (As) contamination affects millions of people in South Asia. In this paper, we propose a composite vulnerability framework to identify, for mitigation, the population who are at the highest risk of suffering adverse impacts from exposure to As and warrant mitigation measures. Bihar, India, which was selected for the case study, has large areas with As concentrations far exceeding the upper limits of acceptable level of As in drinking water. Drawing on the existing social science research, we identify a host of socioeconomic and demographic variables, in addition to As concentration in groundwater, which compound a community's vulnerability to the adverse effects of As. The result is a "composite vulnerability index,'' which consists of biophysical, socioeconomic, and demographic factors that collectively determine a community's overall vulnerability to As. Additionally, using geographic information systems (GIS), we represent the composite vulnerability index visually through a set of maps, which highlight the interaction between different community characteristics to generate unique community vulnerability profiles. In summary, this paper outlines a systematic approach to understanding vulnerability to groundwater As, as both social and natural construct, which can be applied to different geographic areas, and to improving decision making and planning pertaining to diverse environmental problems.
