Implementation of a Unique Real Time Flash Flood Forecasting System in Martinique

In France and specially in the Caribbean islands, the serious damage caused in urban areas by the recent flash floods showed the importance of efficient and adapted reactions of the municipality. Faced with a flash flood crisis, decisions should be taken, based on the current information available, which is often very limited due to the lack of time to obtain, manage and analyse it.

Therefore, the Conseil Général of Martinique decided to develop an operational, integrated and innovative tool SDAC (Système Départemental d’Alerte de Crues) to be able to forecast and manage urban flooding in real time. The modeling system is based on predicted precipitations from rain gages (radar imaging will be integrated soon), a rainfall-runoff model, a hydraulic model developed for urban area and a risk definition representing the flood importance.

This innovative system has been initially implemented on four watersheds of the island in 1999, including the Lezarde basin particularly vulnerable to floods that induce important damages on the road system as well as on the economic activities of the island (airport, commercial center…). In 2005, the system was significantly improved and innovative steps were taken to reach different objectives: (i) to improve the robustness and precision of the flood forecast (ii) to improve the alert system for small watersheds (iii) to represent in detail the flooding zones in the urban areas using GIS (iv) to insure alert message reception that allows prevention action and (v) to make the forecasting data and maps available on internet for public information.,

The system is currently operational and very promising since the results prove the significant advancement obtained when combining the growing computer power and the increasing urban hydrological knowledge.

The next step in 2009 is to include the radar data and the sea level data in real time in order to (i) enhance the anticipation of rainfall that can produce flood and (ii) take into account the sea level hydraulic constraint that could be significant for some basins during a big storm.