A Regime‐State Framework for Morphodynamic Modeling of Seabed Roughness

Abstract Seabed roughness in the dynamic near‐shore environment is continuously modified by interplay of physical and biological processes including bedform morphodynamics bioturbation. We introduce a novel regime‐state framework to determine dominant modifier seabed based on observed or estimated forcing, which are classified critical Shields parameter wave mobility thresholds. The applied set field observations containing time‐lapse sonar imagery ripple growth, decay, rate decay varies both processes. sensitive oscillatory forcing magnitude direction relative relict orientation time‐evolving height. found two distinct episodes ripples decayed 20%–30% within 4–5 days. Ripple models did not agree up following same time period. By varying using time‐dependent diffusion coefficient determined mechanism, resulted better agreement observations. Benthic megafauna also shown create roughness, excavating dense fields (>1 pit/m 2 ) pits (≤84 cm diameter) that acoustic comparable 8–12 high ripples. spatiotemporal variability megafaunal pit formation suggests diffusion‐based bioturbation adequate require additional parameterization mechanistically model. presented this study serves as for future investigations modeling morphodynamics, bioturbation, roughness.