Global River Width and Inundation Database from Sentinel-1 SAR Satellites
High resolution surface water maps and water body temporal dynamics are absent in many regions of the world. Still, the surface water inventories are crucial for water resources planning, water-bound transportation planning, and helping flood-prone communities prepare for and even prevent catastrophic flood events. Recent advancements of cloud based computing and machine learning algorithms enable near-real-time access and processing of satellite data and delivering surface water products to the research and applications communities. Most existing river width, inundations, and satellite-based streamflow databases are affected by cloudy or extreme meteorological conditions or coarser resolutions. Recent developments in SAR (Synthetic Aperture Radar) based satellites facilitate the generation of surface water products at unprecedented spatial/temporal resolutions.
We are using the Sentinel-1 SAR satellite data archive from 2015 to the present to create a global river width and surface water database at the reach scale. A modified version of the Sentinel-1 surface water mapping algorithm developed within the HydroSAR project lead by the University of Alaska Fairbanks and the NASA Alaska Satellite Facility (ASF) is used to map the surface water extent approximately every 36 days or better at 10m spatial resolution globally. This 10m water mask is fed to a workflow to quantify the river widths and surface water inundations in stream networks. We will soon be producing three data products based on our analysis:
- Effective river widths for the SWORD (SWOT A priori River Database) river reaches from 2015 to near real-time for the Sentinel-1 images.
- Pixel-level river widths for river center lines derived from Sentinel-1 images over time for river reaches.
- An inundation map for river reaches covering the entire globe assimilates satellite data with other low temporal frequency elevation datasets.
Additionally, we are linking our river width and inundation products using a cloud database in Amazon Web Services so that users can retrieve the river width/inundation time-series information over the web. Furthermore, our river width products will be available to use with other river geometry and historical streamflow discharge information to provide estimated river flow rates to enhance NASA SWOT mission time series. This presentation was given at the 2022 NASA ESDSWG Meeting (April 19-21, 2022).