Enabling Exploration of Earth's Water Cycle: Moving the needle on SWOT discharge accuracy through ground-breaking advances

Principle Investigator: Michael Durand (Ohio State University​)

Co-Investigator(s): Steve Coss

Collaborator(s): Colin Gleason, Jida Wang

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The successful launch of the Surface Water and Ocean Topography (SWOT) mission opens a new era in characterizing global surface water hydrology. River discharge is a critical indicator of upstream hydrological processes, used to monitor freshwater resources. Rivers are poorly observed globally, however, precluding observational constraint on how the water cycle is changing in a warming world. Satellite remote sensing of river discharge has helped to address the problem of poor global river discharge observation, but prior to SWOT, estimation in ungauged basins has had limited impact, largely in part to accuracy limitations. SWOT provides the means to take global discharge remote sensing to another level in its accuracy. Once it achieves its target accuracy, SWOT discharge enables a new look at global hydrologic questions, such as the sensitivity of the water cycle to climate change, and applications such as monitoring of streamflow in ungaged basins.

We here propose a two-part project. First, we will manage the effort to truly move the needle on SWOT discharge accuracy, coordinating the efforts within the Discharge Algorithm Working Group to prioritize and test algorithm improvements. This will involve 1) assessing and improving flow laws, the relationships that connect SWOT measurements to river discharge, 2) improving estimation of the flow law parameters via coordinating efforts, 3) further improving the “integrator” algorithm that combines information across river sub-basins. Second, we will conduct a novel study using SWOT discharge to compute a new estimate of sensitivity of global streamflow to climate change at higher resolution.