Meanders and Increased Flow Resistance - Impacts on Flooding in Coastal and Estuarine Systems

This study combines observations from New England tidal channels with numerical modeling (the Regional Ocean Modeling System, ROMS) to study the hydrodynamic drag in coastal and estuarine systems. The existence of complex topographic features, such as channel meanders, can lead to significantly increased flow resistance. The drag coefficient based quadratic velocity is used to quantify the flow resistance, which can be increased by a factor of 5 in meanders compared to straight channels. The increased drag leads to faster tidal amplitude decay, increased tidal phase lag, and decreased coastal flooding potential. Meander restoration can therefore serve as a nature-based solution for flooding mitigation, in the context of climate change, sea level rise, and more frequent coastal storm events.

Reference(s):

Bo, T., Ralston, D. K., & Geyer, W. R. (2023). Sources of drag in estuarine meanders: momentum redistribution, bottom stress enhancement, and bend-scale form drag. Journal of Physical Oceanography, 53(7), 1629-1650.

Bo, T., Ralston, D. K., Kranenburg, W. M., Geyer, W. R., & Traykovski, P. (2021). High and variable drag in a sinuous estuary with intermittent stratification. Journal of Geophysical Research: Oceans, 126(10), e2021JC017327.

Bo, T. & Ralston, D. K. (2020). Flow separation and increased drag coefficient in estuarine channels with curvature. Journal of Geophysical Research: Oceans, 125(10), e2020JC016267.