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A framework for estimating global river discharge from the Surface Water and Ocean Topography satellite mission

March 27, 2023

The Surface Water and Ocean Topography (SWOT) mission will vastly expand measurements of global rivers, providing critical new data sets for both gaged and ungaged basins. SWOT discharge products (available approximately 1 year after launch) will provide discharge for all river that reaches wider than 100 m. In this paper, we describe how SWOT discharge produced and archived by the US and French space agencies will be computed from measurements of river water surface elevation, width, and slope and ancillary data, along with expected discharge accuracy. We present for the first time a complete estimate of the SWOT discharge uncertainty budget, with separate terms for random (standard error) and systematic (bias) uncertainty components in river discharge time series. We expect that discharge uncertainty will be less than 30% for two-thirds of global reaches and will be dominated by bias. Separate river discharge estimates will combine both SWOT and in situ data; these “gage-constrained” discharge estimates can be expected to have lower systematic uncertainty. Temporal variations in river discharge time series will be dominated by random error and are expected to be estimated within 15% for nearly all reaches, allowing accurate inference of event flow dynamics globally, including in ungaged basins. We believe this level of accuracy lays the groundwork for SWOT to enable breakthroughs in global hydrologic science.

Publication Year 2023
Title A framework for estimating global river discharge from the Surface Water and Ocean Topography satellite mission
DOI 10.1029/2021WR031614
Authors Michael Durand, Colin Gleason, Tamlin Pavelsky, Renato Frasson, Michael Turmon, Cedric H. David, Elizabeth Altenau, Nikki Tebaldi, Kevin Larnier, Jerome Monnier, Pierre Olivier Malaterre, Hind Oubanas, George Allen, Brian Astifan, Craig Brinkerhoff, Paul Bates, David M. Bjerklie, Stephen Coss, Robert W. Dudley, Luciana Fengolio, Pierre-Andre Garambois, Augusto Getirana, Peirong Lin, Steven A. Margulis, Pascal Matte, J.Toby Minear, Aggrey Muhebwa, Ming Pan, Daniel L. Peters, Ryan Riggs, Md Safat Sikder, Travis Simmons, Cassie Stuurman, Jay Taneja, Angelica Tarpanelli, Kerstin Schulze, Mohammad Tourian, Jida Wang
Publication Type Article
Publication Subtype Journal Article
Series Title Water Resources Research
Index ID 70251080
Record Source USGS Publications Warehouse
USGS Organization New England Water Science Center