Browsing by Author "David, Cedric H."

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    Extending global river gauge records using satellite observations
    Riggs, Ryan M.; Allen, George H.; Wang, Jida; Pavelsky, Tamlin M.; Gleason, Colin J.; David, Cedric H.; Durand, Michael (IOP, 2023-05-26)
    Long-term, continuous, and real-time streamflow records are essential for understanding and managing freshwater resources. However, we find that 37% of publicly available global gauge records (N = 45 837) are discontinuous and 77% of gauge records do not contain real-time data. Historical periods of social upheaval are associated with declines in gauge data availability. Using river width observations from Landsat and Sentinel-2 satellites, we fill in missing records at 2168 gauge locations worldwide with more than 275 000 daily discharge estimates. This task is accomplished with a river width-based rating curve technique that optimizes measurement location and rating function (median relative bias = 1.4%, median Kling-Gupta efficiency = 0.46). The rating curves presented here can be used to generate near real-time discharge measurements as new satellite images are acquired, improving our capabilities for monitoring and managing river resources.
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    A Framework for Estimating Global River Discharge From the Surface Water and Ocean Topography Satellite Mission
    Durand, Michael; Gleason, Colin J.; Pavelsky, Tamlin M.; Frasson, Renato Prata de Moraes D. M.; Turmon, Michael; David, Cedric H.; Altenau, Elizabeth H.; Tebaldi, Nikki; Larnier, Kevin; Monnier, Jerome; Malaterre, Pierre Olivier; Oubanas, Hind; Allen, George H.; Astifan, Brian; Brinkerhoff, Craig; Bates, Paul D.; Bjerklie, David; Coss, Stephen; Dudley, Robert; Fenoglio, Luciana; Garambois, Pierre-Andre; Getirana, Augusto; Lin, Peirong; Margulis, Steven A.; Matte, Pascal; Minear, J. Toby; Muhebwa, Aggrey; Pan, Ming; Peters, Daniel; Riggs, Ryan; Sikder, Md Safat; Simmons, Travis; Stuurman, Cassie; Taneja, Jay; Tarpanelli, Angelica; Schulze, Kerstin; Tourian, Mohammad J.; Wang, Jida (American Geophysical Union, 2023-04-06)
    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.