6 - Flood risk management: Risk cartography for objective negotiations

Summary

ABSTRACT

Flood damage in France and Europe in recent years has shown that there is still a long way to cope with this problem. It seems that the conceptualization of the risk by dividing it between a socioeconomical dimension (vulnerability) and a hydrologicalhydraulic dimension (hazard) is a promising means of investigation. Moreover, recent hydrological synthetic models, called flow-duration-frequency models, allow one to propose quantification of these two parameters of risk, that is, vulnerability and hazard. Estimating its spatial characteristics is very useful in the process of objective negotiation where land use managers take into account flood risk and socially acceptable risk. Representative maps, such as those proposed by the “inondabilité” model, can be forwarded to decision makers in order to help them use hydrological and hydraulic results in a more efficient way. These new concepts and methods should improve risk mitigation and lead to better acceptability of the risk level in the potentially flooded area.

INTRODUCTION

Extreme floods have been particularly numerous in France in the recent past. They caused severe economic and human damage. Among disastrous recent floods were those of Vaison la Romaine (1992), Corsica (1993) and Camargue area (1994), north and west of France (1994 and 1995), Var (1994), and so on. These events showed that flood risk management, and especially land use management in flood plains, is not sufficient to cope with the problem.

A risk policy should be based on three different aspects, as shown in Figure 6.1: these are prevention in the phase of land use management, flood forecasting and crisis management, and individual risk culture to improve citizen reactions to flood risk (Gilard and Givone 1993).