Spatiotemporal exposure of daily and residential mobility facing flash floods: proposition for a methodology based on scales
Echelle spatiale et temporelle de l'exposition des mobilités quotidiennes et résidentielles face aux crues rapides : proposition d'une méthodologie fondée sur les échelles
Résumé
This contribution exposes a project called MobiClimEx funded by the French Research Agency (ANR). It focuses on the question of mobility facing the recurrence of extreme precipitations and floods, enhanced with climate change, particularly in Mediterranean area. Mobility is addressed both in its short terms aspects at the event scale (daily mobility) and in long terms at the biographic scale (residential mobility). The aim of this project is to develop an interdisciplinary approach addressing both physical and social dynamics involved at different levels (dimensions) and for different scales (spatial and temporal, but also jurisdictional or institutional). The main point is to define how a relevant combination of scales allows handling all the dimensions. The proposed methodology is tested on a field case (the Gard Department), located in the South-East of France, particularly prone to flash floods. This region was exposed to particularly strong events in 1958, 1988, 2002, 2005, 2008 and 2014. The first question that we ask is: can we observe/distinguish an impact of flash floods on short and long term mobility? It has been already showed that daily mobility, and especially drivers, are particularly exposed to flash floods (Ruin et al, 2008 ). Furthermore, we know through previous works on mobility that residential choices have a strong impact on the daily mobility in general. Can we conclude that certain residential choices increase daily mobility exposure to flash floods? Furthermore, can we observe an influence of floods on land-use policies and residential choices? How do the flooded areas evolve after an event? What does that mean to live in flood prone areas? Based on rebuilt past events observed on field, we assess the problems posed by maintaining the current social and climatic dynamics in the future. Beyond the presentation of the proposed exercise on mobility, this contribution aims also at exploring scales and concepts allowing analyzing cycles of adaptations in land use or in political regulations. Finally, the proposed methodology aims at understanding the socio-hydro-meteorological dynamics leading to high impact events in the past, in order to build, with stakeholders, scenarios able to imagine future dynamics.