Coastal flood risk assessments: spatial and temporal biases

Résumé En

The vulnerability of coastal populations increases because of sea level rise as a result ofclimate change. This trend is also due to a phenomenon of risk production related tourbanization in flooding areas. This research analyzes vulnerability of French coastal areainhabitants to coastal flooding from their personal risk assessments. More precisely, thisstudy focuses on spatial optimism bias (“things are better here than there”) and temporalpessimism bias (“things will get worse in the future”) in the assessment of coastal flooding.This study is based on an interdisciplinary methodology (combining geography andenvironmental psychology approaches) and it uses several tools. First, personal riskassessments on current and expected (in 25 and 100 years) coastal flooding phenomenafrom 342 inhabitants in four coastal cities in France (Barneville-Carteret in Manche, Saintes-Maries-de-la-Mer in Bouches-du-Rhône, Châtelaillon-Plage in Charente-Maritime, Sainte-Anne in Guadeloupe) were investigated at four spatial levels of assessment (home, town,country, the world) using a questionnaire survey. Second, respondents also producedpersonal mapping of coastal flooding areas at their town level. Those participatory mapswere compared to official mapping of flooding areas. Third, spatial data were collected andanalyzed using GIS software (where is the respondent’s house located?, is the respondent’shouse located inside a flooding area according to official mapping?, are there any coastalprotections near the respondent’s house?). In addition to variables such as personal riskexperience or personal risk knowledge, we hypothesize that the spatial data have anincidence on personal assessments of coastal flood risk and help to understand the spatialand temporal biases in those personal assessments.