An Introduction to the VIIRS 3-D Flood Products

Abstract:

Near real-time flood maps from Suomi-NPP& NOAA-20/VIIRS (Visible Infrared Imaging Radiometer Suite) have been applied in flood operations for river forecasting, disaster monitoring and relief efforts by river forecasters and decision-makers. However, the moderate spatial resolution at 375m only allows these maps to provide limited inundation details. To derive more information from the VIIRS imagery, a downscaling model has been developed to generate the VIIRS 3-D flood products by using the 375-m VIIRS floodwater fraction product and the 30-m SRTM/DEM. These VIIRS 3-D flood products include the VIIRS 375-m floodwater surface levels, 30-m floodwater extent and 30-m floodwater depth, which not only provide the floodwater with much richer inundation details horizontally, but also show the vertical distribution of floodwater. Validation analysis with high-resolution satellite images shows the downscaled VIIRS flood extent is highly consistent to the results from Landsat-8 OLI, Sentinel-2 and SAR images. Gauge heights are also used to validate the downscaled VIIRS 375-m floodwater surface level products and the results are quite promising. Considering the VIIRS imagery is available twice a day in mid-low latitudes, the downscaled VIIRS 3-D flood products show great advantages in flood mapping in comparison to the high-resolution satellite imagery such as Landsat-8 OLI and so on, which are with revisit intervals varying from 5 to 16 days. The 3-D products also derive continuous distribution of floodwater surface levels along rivers rather than the scattering gauge observations.