Flood risk mapping: from local to global

Figure 1. Flood risk mapping for Bujumbura, Burundi (central Africa) showing the number of times that each 30-meter pixel has been flooded in the last 40 years.

Floods have considerable impacts on people, economic activity, property and other assets, agriculture and the environment. Quantifying where floods have happened, how often and to what extent is crucial for managing risks through a variety of measures: reducing risks for example by designing flood defences; transferring risks through insurance and other financial instruments; mitigating risks through early warning of flood events.

We have been using the latest technologies in modelling, satellite remote sensing and data assimilation to map “everywhere and anywhere” from the local scales (street and block) to the global scale.

Figure 2. Annual maximum fractional flooded area for different 50-year return period (a flood with a 2% probability of occurrence) estimated from CaMa-Flood model simulations and GEV distribution statistical modelling.