Quantifying Tidal Dune Morphodynamics at the Laboratory Scale: A Combined Measuring and Modelling Approach

Understanding the morphodynamics of tidal dunes is essential for improving predictions of sediment transport and seabed evolution in coastal and estuarine environments. This study advances our understanding through a combined experimental and numerical investigation into the short-term morphodynamic evolution of laboratory-scale tidal dunes under controlled conditions.

Building on earlier flume experiments examining hydrodynamic interactions of reversing currents with fixed-bottom, sand-coated asymmetric compound dunes, we incorporated a cm-thick layer of unimodal sediment over the rigid dune models to simulate mobile-bed conditions. High-resolution Particle Image Velocimetry (PIV) was employed to capture detailed spatial and temporal dynamics of turbulent flows and the concurrent evolution of dune surfaces.

Complementary numerical modelling utilised the oceanographic circulation model CROCO, incorporating its non-hydrostatic solver and the USGS sediment transport module. The lab-scale model application was calibrated and validated against the laboratory measurements, demonstrating exceptional agreement in the short-term evolution of dune morphology. Key findings include the accurate replication of observed boundary layer dynamics, sediment transport mechanisms, and morphodynamic changes under reversing tidal currents. These experiments establish a solid benchmark for validating non-hydrostatic models of tidal dune morphodynamics.

This work underscores the transformative potential of integrating detailed physical experiments with advanced numerical models to refine our predictive capabilities for morphodynamic processes in tidal environments. The insights gained are particularly significant for coastal engineering and seabed mobility studies, with direct applications to the design and optimisation of offshore wind farm infrastructures.