Coastal flood risk assessments: spatial and temporal biases
Résumé
The vulnerability of coastal populations increases because of sea level rise as a result of
climate change. This trend is also due to a phenomenon of risk production related to
urbanization in flooding areas. This research analyzes vulnerability of French coastal area
inhabitants to coastal flooding from their personal risk assessments. More precisely, this
study focuses on spatial optimism bias (“things are better here than there”) and temporal
pessimism bias (“things will get worse in the future”) in the assessment of coastal flooding.
This study is based on an interdisciplinary methodology (combining geography and
environmental psychology approaches) and it uses several tools. First, personal risk
assessments on current and expected (in 25 and 100 years) coastal flooding phenomena
from 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 produced
personal mapping of coastal flooding areas at their town level. Those participatory maps
were compared to official mapping of flooding areas. Third, spatial data were collected and
analyzed using GIS software (where is the respondent’s house located?, is the respondent’s
house located inside a flooding area according to official mapping?, are there any coastal
protections near the respondent’s house?). In addition to variables such as personal risk
experience or personal risk knowledge, we hypothesize that the spatial data have an
incidence on personal assessments of coastal flood risk and help to understand the spatial
and temporal biases in those personal assessments.