Detecting water-surface superelevation in meandering rivers using Surface Water and Ocean Topography (SWOT) satellite data

Accurate data on curvature-induced water-surface superelevation are important for understanding complex patterns of fluid motion in meandering rivers. Nevertheless, superelevation has been studied primarily in the laboratory because field measurements are difficult to obtain. This study assesses whether the Surface Water and Ocean Topography (SWOT) satellite can detect superelevation in meander bends. Plots of lateral water-surface slope (LWS) reveal distinct superelevation in two sets of Mississippi-River bends. As expected, the magnitude and direction of LWS are strongly correlated with channel curvature. Superelevation can also be detected on comparatively narrow Wabash-River bends, but levels of noise are more pronounced than for the Mississippi bends. Mean flow velocities estimated from LWS based on theoretical considerations agree closely with gauge-based estimates (+7 to 35%). These findings confirm that SWOT data can be used to reliably detect superelevation in large river bends, providing the basis for global assessments of hydrodynamics in large meandering rivers.