Integrating Lateral Contributions Along River Reaches to Improve SWOT Discharge EstimatesBeighley, E., Zhao, Y., Feng, D., Fisher, C.K., Raoufi, R., Durand, M.T., David, C.H., Lee, H., Boone, A.A., and Cretaux, J-F. (13-Dec-16)Understanding the potential impacts of climate and land cover change at continental to global scales with a sufficient resolution for community scale planning and management requires an improved representation of the hydrologic cycle that is possible based on existing measurement networks and current Earth system models. The Surface Water and Ocean Topography (SWOT) mission, scheduled to launch in 2021, has the potential to address this challenge by providing measurements of water surface elevation, slope and extent for rivers wider than roughly 50-100 meters at a temporal sampling frequency ranging from days to weeks. The global uniformity and space/time resolution of the proposed SWOT measurements will enable hydrologic discovery, model advancements and new applications addressing the above challenges that are not currently possible or likely even conceivable.
One derived data product planned for the SWOT mission is river discharge. Although there are several discharge algorithms that perform well for a range of conditions, this effort is focused on the MetroMan discharge algorithm. For example, in MetroMan, lateral inflow assumptions have been shown to impact performance. Here, the role of lateral inflows on discharge estimate performance is investigated. Preliminary results are presented for the Ohio River Basin. Lateral inflows are quantified for SWOT-observable river reaches using surface and subsurface runoff from North American Land Data Assimilation System (NLDAS) and lateral routing in the Hillslope River Routing (HRR) model. Frequency distributions for the fraction of reach-averaged discharge resulting from lateral inflow are presented. Future efforts will integrate lateral inflow characteristics into the MetroMan discharge algorithm and quantify the potential value of SWOT measurement in flood insurance applications.