Coastal Vulnerability Assessment using geoindicators: case study of Rio Grande do Sul coastline

Abstract Geoindicators are means adopted for the measurement of geological processes and phenomena that occur at or near the Earth's surface and vary significantly over periods of 100 years or less. These tools have focused on assessing geological impacts and risks over the last three decades. However, the use of geoindicators is not widely known and has not been as greatly exploited as have most environmental indicators. The objective of this study is to contribute to the diffusion of information about and the application of geoindicators. We have defined, in terms of geoindicators, parameters and aspects of coastal environments that are commonly studied or monitored. The geoindicators proposed were designed for assessing coastal physical vulnerability in the case of the coastal beaches of Rio Grande do Sul, Brazil. Four geoindicators were defined and tested: the height and morpho-ecological state of the foredunes, shoreline position, and washout concentrations. An additional sócio-environmental indicator was included, sanitary quality. These indicators were brought together to constitute a Physical Vulnerability Index that represented seven locations along the coastline assessed. In addition, the indicators and Index values were used to generate a cartographic map that could be understood by the public and used by decision makers.