A Framework for Estimating Global River Discharge From the Surface Water and Ocean Topography Satellite Mission

Michael Durand, Colin J. Gleason, Tamlin M. Pavelsky, Renato Prata de Moraes Frasson, Michael Turmon, Cédric H. David, Elizabeth H. Altenau, Nikki Tebaldi, Kevin Larnier, Jerome Monnier, Pierre Olivier Malaterre, Hind Oubanas, George H. Allen, Brian Astifan, Craig Brinkerhoff, Paul D. Bates, David Bjerklie, Stephen Coss, Robert Dudley, Luciana FenoglioPierre André Garambois, Augusto Getirana, Peirong Lin, Steven A. Margulis, Pascal Matte, J. Toby Minear, Aggrey Muhebwa, Ming Pan, Daniel Peters, Ryan Riggs, Md Safat Sikder, Travis Simmons, Cassie Stuurman, Jay Taneja, Angelica Tarpanelli, Kerstin Schulze, Mohammad J. Tourian, Jida Wang

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish (US)
Article numbere2021WR031614
JournalWater Resources Research
Issue number4
StatePublished - Apr 2023
Externally publishedYes


  • discharge
  • hydrology
  • inverse problem
  • remote sensing
  • SWOT mission

ASJC Scopus subject areas

  • Water Science and Technology


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