Programme OS4g Risk management 1
Flash flood risk management in real time for assistance to coordinators
Author(s): Emma Haziza, Michel Desbordes
Keyword(s): Risk, flash
flood, decision, public safety, multi disciplinary approch
Session: OS4g Risk management 1
The borders of the
Mediterranean are exposed to a hazard which is considered today as one of the most destructive in the world, taking
into account human loss : the victims of flash flood.
Flash floods are characterized by a very fast spatial and timing
dynamic. A good example of that is la Vaison la Romaine in 1992. The water level in the channel rose from twenty
centimetres up to ten meters in a period of four hours. To face this situation, administrative services work together to
manage that risk in real time. They activate a series of alerts that are specified in regulatory laws.
In France, the
principal coordinator is the Prefet of the department. That person decisions dictate the series of events that will
initiate measures to reduce territorial vulnerability (evacuating people, closing roads, etc).
The most recent events
in the Mediterranean area (Languedoc-Roussillon, Bouches du Rhône, Var, etc) these last years (Nîmes, 1988 ;
Vaison la Romaine, 1992 ; Aude, 1999 ; Gard, 2002, 2005, Hérault 2003, 2005), and the experience we gained
from these (MEDD, 2003, 2005) have allowed us to observe that we are increasingly more susceptible to their
These observations highlight the need of a multi disciplinary approach for handling aid and assistance in
these situations (Haziza, 2007)
The objective of this article is to highlight the difficult task of the person who
makes the decisions, taking into account the short allowable response period when this situation (of a high spatial and
timing dynamic) occurs.
Monitoring the crisis management from the 5th to the 9th of September in the department
of Herault will allow us to understand the decisions that have been made to significantly reduce the vulnerability of
the hazard exposed area.
Therefore, from hydro meteorological forecast to field data, this analysis will allow to
clarify the scope of the crisis managers in the decision making process and the key factors after the alert is raised.
Specifically this analysis will highlight the aggravating factors required to optimize the decisions made.