This dataset supports the analysis conducted in the study "Did Official Flood Maps Work in Hurricane Helene? Systematic Evaluation of Official Flood Maps with Ground-truth Observations." It includes: (1) camera-based ground-truth flood extent data from Hurricane Helene in Pinellas County, Florida; (2) official flood maps from FEMA, FDEM, and Fathom; (3) population exposure and flood map performance metrics at the census block group level; (4) auxiliary datasets such as land cover and high-resolution population grids; and (5) Python scripts for calculating the Social Vulnerability Index (SoVI). The data enable spatial validation of flood risk models and investigation of socio-spatial disparities in flood map accuracy.

Date of Images:Syn-Event: 2024-09-26 23:38:04 (UTC) or 7:38 PM EDTPre-Event: 2024-09-14 23:37:54 (UTC) or 7:38 PM EDTSummary:The Advanced Rapid Imaging and Analysis (ARIA) and Observational Products for End-Users from Remote Sensing Analysis (OPERA) teams at NASA's Jet Propulsion Laboratory and California Institute of Technology derived the surface water extent maps using the OPERA Dynamic Surface Water eXtent from Sentinel-1 (DSWx-S1) products. The results posted here are preliminary and unvalidated results, primarily intended to aid the field response and people who want to have a rough first look at the water extent. The ARIA-share website has always focused on posting preliminary results as fast as possible for disaster response.OPERA DSWx-S1The OPERA DSWx-S1 data identifies surface water and inundated vegetation. We provide the Water (WTR) and the Binary Water (BWTR) layers. Images are provided from 1) September 14, 2024 and 2) September 26, 2024. Each image consists of multiple MGRS tiles that were merged together for a composite image saved as a GeoTIFF file.ARIA/OPERA water change map derived from OPERA DSWx-S1The ARIA/OPERA water change map is derived from two OPERA DSWx-S1 Binary Water (BWTR) images taken on September 14, 2024 and September 26, 2024. The BTWR combines inundated vegetation and open water into a single water class.These maps depict areas of new water detection (or loss). The change map includes values of: (0) indicate no change between images, (1) absence of water pre-event, presence of water syn-event, and (-1) presence of water pre-event, absence of water syn-event. Satellite/Sensor:Synthetic Aperture Radar (SAR) instrument on European Space Agency's (ESA) Sentinel-1A satellite was used for both the September 14 and September 26 images.Resolution:30 metersThe DSWx-S1 products have these flags:250 (light gray) and 251 (dark gray) represent HAND and layover/shadow masks, respectively.HAND mask (light gray, value 250) delineates regions where the terrain's elevation exceeds a specified threshold relative to the height above the nearest drainage point, indicating areas less likely to be subject to direct inundation. Layover/shadow mask (dark gray, value 251) identifies zones that are either occluded by topographic features taller than the surrounding landscape (layover) or are not illuminated by the radar signal due to obstruction by these elevated features (shadow), leading to potential data voids in SAR imagery.OPERA DSWx-S1 data availabilityThe post-processed products are available to download at https://aria-share.jpl.nasa.gov/20240926-Hurricane_Helene/DSWx/. The OPERA DSWx-S1 products have been in production since September 2024, are freely distributed to the public via NASA's Physical Oceanography Distributed Active Archive Center (PO.DAAC), and can be downloaded through NASA's Earthdata search. For more information about the OPERA project and other products, visit https://www.jpl.nasa.gov/go/opera.For more information about the Dynamic Surface Water eXtent product suite, please refer to the DSWx Product page: https://www.jpl.nasa.gov/go/opera/products/dswx-product-suiteFor more information about the Caltech-JPL ARIA project, visit https://aria.jpl.nasa.govFor more information about the JPL OPERA project, visit https://www.jpl.nasa.gov/go/opera/Suggested UseDSWx-S1The OPERA DSWx-S1 products classifies the OPERA Radiometric Terrain Corrected SAR backscatter from Sentinel-1 (RTC-S1) input imagery into: not water, water, and inundated vegetation with the masks such as layover/shadow mask and HAND mask. The WTR layer includes all classes. The BWTR layer merges water and inundated vegetation into a single water layer. Open water and inundated vegetation are represented in blue and green in WTR and blue in BWTR. Areas with masks are gray. The masks include the layover/shadow mask and HAND mask. Areas with no water detected are transparent. DSWx-S1 change mapThe ARIA/OPERA water extent change map classifies water extent into change/no change. Increased in water represented in blue, no change in water represented in transparent, decrease in water represented in red.RTC-S1OPERA Radiometric Terrain Corrected SAR backscatter from Sentinel-1 (RTC-S1) image was converted to a false color image. In this color scale, vegetated areas appear green, urban areas appear white/pink, calm water appears black, and rough water appears purple or magenta.” Credits:Sentinel-1 data were accessed through the Copernicus Open Hub and the Alaska Satellite Facility server. The product contains modified Copernicus Sentinel data (2024), processed by the European Space Agency and analyzed by the NASA-JPL/Caltech ARIA and OPERA team. NASA JPL-Caltech ARIA/OPERA Team==================Files:20240914_DSWx-S1_BWTR.tif: The September 14, 2024 binary water map is derived from the WTR layer as a union of water classes (open water and inundated vegetation) into a binary map indicating areas with and without water.20240926_DSWx-S1_BWTR.tif: The September 26, 2024 binary water map.20240926_DSWx-S1_WTR.tif: Masked interpreted water classification layer. This represents pixel-wise classification into one of three water classes (not water, open water and inundated vegetation), masks (HAND mask and layover/shadow mask), or no data classes. OPERA_DSWx-S1_BWTR_ChngMap_20240926-20240914_v2.tif: The ARIA/OPERA flood change map is derived from two OPERA DSWx-HLS images taken on September 14, 2024 and September 26, 2024. These maps depict areas of new water detection that is interpreted as flood. Track121_Florida_DSWx-S1-overview.png: An overview of the 20240926_DSWx-S1_WTR product with a satellite image background.These files have the same GeoTIFF format as the OPERA DSWx-S1 images described above and are in the UTM Zone 16N.

Dates of Images:Post-Event: October 12, October 10, October 7, October 5, October 2, September 27Pre-Event: September 20, September 22Date of Next Image:UnknownSummary:The True Color RGB composite provides a product of how the surface would look to the naked eye from space. The RGB is created using the red, green, and blue channels of the respective instrument.The Short Wave Infrared (SWIR) RGB is a product that is created using the SWIR, NIR, and Red channels of the respective instrument.The Color Infrared composite is created using the near-infrared, red, and green channels. The near-infrared gives the ability to see through thin clouds. Healthy vegetation is shown as red, water is in blue.Suggested Use:The True Color RGB provides a product of how the surface would look to the naked eye from space. The True Color RGB is produced using the 3 visible wavelength bands (red, green, and blue) from the respective sensor. Some minor atmospheric corrections have occurred.The Short Wave Infrared (SWIR) RGB is a product that can provides value in flood detection. Areas of water will appear blue, healthy green vegetation will appear as a bright green, urban areas in various shades of magenta, snow will appear as a bright blue/cyan, and bare soils being multicolor dependent on their makeup. Compare pre-event imagery to post-event imagery to identify potential flooding.A Color Infrared composite depicts healthy vegetation as red, water as blue. Some minor atmospheric corrections have occurred.Satellite/Sensor:MultiSpectral Instrument (MSI) on European Space Agency's (ESA) Copernicus Sentinel-2A/2B satellitesResolution:True Color: 10 metersCredits:NASA/MSFC, USGS, ESA CopernicusEsri REST Endpoint:See URL section on right side of pageWMS Endpoint:https://maps.disasters.nasa.gov/ags04/services/hurricane_helene_2024/sentinel2/MapServer/WMSServerData Download:https://maps.disasters.nasa.gov/download/gis_products/event_specific/2024/hurricane_helene_202409/sentinel2/