Multi-Criteria Decision Making for the Assessment of Coastal Flood Vulnerability

In the last two decades, the population and economic growth of Caraguatatuba have been expressive in the Northeastern Coastline of Sao Paulo, especially in the Juqueriquere Watershed, which represents the major non-occupied plain of the region. However, there is a high rainfall at the site, which is also influenced by tidal effects, making it vulnerable to coastal floods. The main purpose of this study is to evaluate the watershed vulnerability to floods in a future scenario, by the use of Multi-Criteria Decision Making. The Compromise Programming method was used to analyze the eleven subbasins, according to the following criteria: distance from the coastline; slope; equivalent length; percentage of vegetative land cover in preservation areas surrounding rivers; altimetric level of the subbasin downstream; and, average CN (Curve Number) parameter increment, comparing the current and future scenarios. The CN parameter was achieved by the analysis of each subbasin soil hydrologic group and land use and cover. The current land use and cover map was obtained by the classification of satellite images and the future one, according to the zoning proposed by the City Master Plan. The results showed that due to the mild slope, closeness to the coastline and higher CN increment, the subbasins located on the plain mostly contributed to the increase of flood vulnerability.