You can find rapid flood maps that estimate the affected areas where flooding occurs. These maps can help you stay safe and aware during a crisis. Learn more about Google SOS Alerts.
Where we get the data
We use satellite data from sources like Copernicus Sentinel-1 satellites from the European Space Agency. This satellite produces a Synthetic Aperture Radar(SAR) image that our algorithms use to calculate the flooded area.
When the map gets updated
We update flood maps when a new satellite image is available. After an image is taken, it takes several hours until it’s in our systems. It can also take several days to produce a satellite image that we can use. If our latest available image is older than 72 hours, we usually stop showing it until there’s a new image available.
Map accuracy
It’s difficult to recognize flooded and non-flooded areas from a satellite image so there may sometimes be errors. For example, maps may not be able to show flooding in dense woods or urban areas. For an average image, we estimate that about 80% of the suggested flooded area is accurate. Areas that aren't marked as flooded aren't predicted to be safe since we are unable to show maps in dense woods and urban areas.
A map is unavailable
In some cases, you may not find a flood map. Sometimes there isn’t a satellite image available or the image doesn’t generate a qualified map.