Summary

The VIIRS Floodwater Fraction Map Products Web App is a tool that displays daily flood extents covering the entire CONUS derived from the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the joint NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi-NPP) satellite. The map products in the Web App are updated daily and include both the daily products as well as a post-processed 5-day composite flood extent.

Data Sources

Visible Infrared Imaging Radiometer Suite (VIIRS)

Web Application

VIIRS Floodwater Fraction Map Products

Methodology

The web app shows two products- the Daily product, the Five-Day Composite, and the VIIRS / ABI joint product.

The Daily product is produced by a collaborative effort from NOAA Joint Polar Satellite System (JPSS), George Mason University, and the Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison. The daily product is based on VIIRS satellite imagery shows flood extent as a percentage of water extent detected in each 375-meter pixel. Several advanced algorithms are used to determine this water fraction, including a water detection algorithm, a cloud shadow removal algorithm, and a terrain shadow removal algorithm. The final product shows a  water fraction percentage (1-100%) that indicates the coverage of the pixel that contains water. Higher percentages indicate more water and thus flooding. Below is an example of the daily product, where darker reds show greater flooding in California in the winter of 2017.

 

 

 

 

 

 

 

 

 

 

 

(source: NOAA JPSS)

The Five-Day Composite product is created daily by the modeling group within the FEMA Geospatial Response Team using the Daily product. This composite flood extent saves the max water fraction percentages over a moving window of 5 days to improve obscuration due to cloud cover. Values are binary so the map output shows only red pixels where at least 40% of the pixel was covered with water during the five-day moving window.

Below is an image was taken from the web application that shows red pixels where flooding has been detected along the North Carolina coast as Hurricane Florence made landfall in September of 2018.

 

 

 

 

 

 

 

 

 

 

The VIIRS / ABI Joint product blends the flood detection results from all the GOES-16/ABI,  Suomi-NPP/VIIRS and NOAA-20/VIIRS flood maps during a day. It is based on the VIIRS 375-m flood  maps, and uses the 1-km ABI clear-sky detection results to fill the gaps of clouds and cloud shadows in the VIIRS maps. Thus, it shows the flood extent under the maximal clear-sky coverage derived by the satellites during the daytime. In the maps, flood water fractions (open water percentage in a VIIRS 375-m pixel or an ABI 1-km pixel)  are represented in colors from light green to red. Warmer color means more flooding.

Access & Use Information

Public: This dataset is intended for public access and use.

Downloads & Resources

Download VIIRS data

Contact

FEMA Mapping and Analysis Center

Madeline Jones

Credit:

NOAA JPSS Program Office

George Mason University

Space Science and Engineering Center at the University of Wisconsin-Madison

References

The VIIRS Flood Detection Map Quick Guide can be found here.

More information about Flood detection using SNPP/VIIRS can be found here.

Updated on October 10, 2019