Bedforms in macrotidal estuaries and deltas are distinguished from those in rivers and oceans due to the tidally-driven water depth variations and the varying hydrodynamic processes resulting from the interaction between tidal and fluvial flows. The relations between hydrodynamics, sediment transport, and bedform morphology in these estuaries are complex, but research on the morphodynamics of bedforms in such environments is s...

Estimates of bed roughness used for predictions of sediment transport are usually derived either from simple scalars of the physical roughness (i.e., ripple height or grain size) or from the hydrodynamic roughness length (Zo) based upon velocity gradient estimates in the benthic boundary layer. Neither parameter accounts for irregular bed features. This study re-evaluates the relation between hydrodynamic roughness and physica...