Groundwater pollution: a discussion about vulnerability, hazard and risk assessment

Three main stages in the development of groundwater pollution assessment since the 1970s are described. The first steps involved aquifer vulnerability assessment. In the second stage (from the late 1980s), three methodological approaches to risk assessment were developed. The latest stage (from the 1990s) has involved new technologies and approaches. At present, all three stages coexist, and their advantages and disadvantages are discussed. Experience highlights the need to account for the social vulnerability in risk assessment, particularly with respect to large cities in developing countries. Assessing groundwater pollution risk through an integrated approach appears to be the greatest challenge.