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Post-Event: May 1 to July 1, 2026<\/span><\/p>

Pre-Event: July 18, 2026<\/span><\/p>

Date of Next Image:<\/span><\/p>

Dec 11, 2025<\/span><\/span><\/p>

Summary:<\/span><\/p>

We developed a rapid-response workflow to map flooded areas during this emergency event using multi-temporal Sentinel-1 SAR data. Sentinel-1\u2019s SAR backscatter characteristics are particularly effective for detecting surface water: water surfaces typically exhibit low backscatter, whereas non-water areas show higher backscatter. Leveraging this physical property, we distinguished between water and non-water surfaces from both pre- and post-flood observations.<\/span><\/p>

To highlight flood-induced surface changes, we computed the differenced co-polarized VV backscatter (dVV = VV_post \u2013 VV_pre). This change detection technique enhances the visibility of newly inundated areas. We then applied a simple threshold to the dVV image to separate flooded from non-flooded areas.<\/span><\/p>

Suggested Use:<\/span><\/p>

The final output is a binary raster product, where pixels with a value of 1 represent flooded areas (dark blue color).<\/span><\/p>

A permanent water body layer and a binary layer incorporating land cover are also included.<\/span><\/p>

Satellite/Sensor:<\/span><\/p>

Sentinel-1 /Synthetic Aperture Radar (SAR)<\/span><\/p>

Resolution:<\/span><\/p>

10 meters<\/span><\/p>

Credits:<\/span><\/p>

Dr. Khuong H. Tran (Khuong.tran@nasa.gov)<\/span><\/p>

Esri REST Endpoint:<\/span><\/p>

See URL section on right side of page<\/span><\/p>

WMS Endpoint:<\/span><\/p>

https://maps.disasters.nasa.gov/ags03/services/NM_FIre_202506/sentinel1_flood/MapServer/WMSServe<\/span><\/p>

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