{ "documentInfo": { "Category": "", "Keywords": "202616_sentinel1_FloodDetection,MapServer", "Version": "3.5.0", "Comments": "Post-Event: May 1 to July 1, 2026Pre-Event: July 18, 2026Date of Next Image:Dec 11, 2025Summary: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.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.Suggested Use:The final output is a binary raster product, where pixels with a value of 1 represent flooded areas (dark blue color).A permanent water body layer and a binary layer incorporating land cover are also included.Satellite/Sensor:Sentinel-1 /Synthetic Aperture Radar (SAR)Resolution:10 metersCredits:Dr. Khuong H. Tran (Khuong.tran@nasa.gov)Esri REST Endpoint:See URL section on right side of pageWMS Endpoint:https://maps.disasters.nasa.gov/ags03/services/NM_FIre_202506/sentinel1_flood/MapServer/WMSServe", "AntialiasingMode": "Fast", "Title": "Map", "Author": "", "TextAntialiasingMode": "Force", "Subject": "Flood detection and impact assessment using Sentinel-1 Synthetic Aperture Radar for the Texas Floods July 2026" }, "maxImageWidth": 4096, "maxRecordCount": 2000, "description": "Post-Event: May 1 to July 1, 2026Pre-Event: July 18, 2026Date of Next Image:Dec 11, 2025Summary: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. 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Tran (Khuong.tran@nasa.gov)Esri REST Endpoint:See URL section on right side of pageWMS Endpoint:https://maps.disasters.nasa.gov/ags03/services/NM_FIre_202506/sentinel1_flood/MapServer/WMSServe", "datesInUnknownTimezone": false, "supportsQueryDomains": true, "units": "esriDecimalDegrees", "maxSelectionCount": 2000, "supportedImageFormatTypes": "PNG32,PNG24,PNG,JPG,DIB,TIFF,EMF,PS,PDF,GIF,SVG,SVGZ,BMP", "supportsClipping": true, "exportTilesAllowed": false, "maxImageHeight": 4096, "tables": [], "supportsDatumTransformation": true, "cimVersion": "3.6.0", "supportsQueryDataElements": true, "layers": [ { "subLayerIds": null, "maxScale": 0, "name": "Flooded Areas by Land Cover", "defaultVisibility": true, "id": 0, "minScale": 0, "supportsDynamicLegends": true, "type": "Raster Layer", "parentLayerId": -1 }, { "subLayerIds": null, "maxScale": 0, "name": "Flooded Areas", "defaultVisibility": false, "id": 1, "minScale": 0, "supportsDynamicLegends": true, "type": "Raster Layer", "parentLayerId": -1 }, { "subLayerIds": null, "maxScale": 0, "name": "Permanent Water", "defaultVisibility": false, "id": 2, "minScale": 0, "supportsDynamicLegends": true, "type": "Raster Layer", "parentLayerId": -1 } ], "mapName": "sentinel1_FloodDetection", "minScale": 0, "archivingInfo": {"supportsHistoricMoment": false}, "spatialReference": { "falseM": -100000, "xyTolerance": 8.983152841195215E-9, "mUnits": 10000, "zUnits": 10000, "latestWkid": 4326, "zTolerance": 0.001, "wkid": 4326, "xyUnits": 999999999.99999988, "mTolerance": 0.001, "falseX": -400, "falseY": -400, "falseZ": -100000 }, "fullExtent": { "ymin": 28.173567847693455, "xmin": -101.73176558829115, "ymax": 31.588782894859051, "xmax": -98.564934717184599, "spatialReference": { "falseM": -100000, "xyTolerance": 8.983152841195215E-9, "mUnits": 10000, "zUnits": 10000, "latestWkid": 4326, "zTolerance": 0.001, "wkid": 4326, "xyUnits": 999999999.99999988, "mTolerance": 0.001, "falseX": -400, "falseY": -400, "falseZ": -100000 } }, "supportedExtensions": "", "serviceItemId": "743afbe565bf4e5c80c99ec65aa5681d", "capabilities": "Query,Map,Data", "supportsDynamicLayers": true, "maxScale": 0, "singleFusedMapCache": false, "currentVersion": 12, "mapUnits": {"uwkid": 9102}, "referenceScale": 0, "supportsSpatialFilter": true, "supportedQueryFormats": "JSON, geoJSON, PBF", "initialExtent": { "ymin": 29.029327869440891, "xmin": -98.83528267848925, "ymax": 29.057047692530858, "xmax": -98.803067748952259, "spatialReference": { "falseM": -100000, "xyTolerance": 8.983152841195215E-9, "mUnits": 10000, "zUnits": 10000, "latestWkid": 4326, "zTolerance": 0.001, "wkid": 4326, "xyUnits": 999999999.99999988, "mTolerance": 0.001, "falseX": -400, "falseY": -400, "falseZ": -100000 } }, "serviceDescription": "

Dates of Images:<\/b><\/span><\/p>

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

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

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

Unknown<\/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:<\/b><\/span><\/p>

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

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

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

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

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

<\/span><\/p><\/div>", "copyrightText": "Dr. Khuong H. Tran (Khuong.tran@nasa.gov)", "supportsTimeRelation": true }