Last week, Central France and Northern Italy were battered by severe rainfall, which resulted in devastating floods that caused widespread damage.
Utilising our Earth Observation expertise, we have quickly produced a series of flood extent maps that can be used to visualise the impact on urban areas and affected populations. These have been produced using data from ESA’s Sentinel 1 satellite and have been collated into an interactive web map of the affected areas using Google Earth Engine. Mallon colleague, Dara McGovern, was responsible for creating the following images.
Mapping Floods with ESA’s Sentinel 1 Satellite
Mapping flooding following heavy rainfall can be challenging as cloud cover can obscure the affected areas, making it hard to gain an accurate picture of what is happening on the ground. This is where data captured from the Sentinel 1 satellite offers a key advantage.
Sentinel 1 observes the Earth using Synthetic Aperture Radar (SAR). This has become a standard and reliable method for determining the extent of major floods as SAR can penetrate cloud cover, operate in any weather condition and provide timely and crucial information. Sentinel 1 SAR uses C–band microwaves emitted from the satellite to reconstruct the target landscapes or objects.
Creating a flood extent is achieved by using a change detection approach on Sentinel 1 data. Additional datasets were intersected with the derived flood extent layer to assess the number of potentially exposed people, affected cropland, and urban areas.
Below we have created some visualisations of the affected areas.
France
Loire River – Before Radar/SAR img
Loire River – After Radar/SAR img
Loire River – Flood extents mapped
Lyon
Saône River
Italy
Oglio River
