Predicting Dominance of Sand Transport by Waves, Tides, and Their Interactions on Sandy Continental Shelves

Waves and tidal currents resuspend transport shelf sediments, influencing sediment distributions bedform morphology with implications for various disciplines including benthic habitats, marine operations, spatial planning. Shelf-scale assessments of wave-tide-dominance sand tend not to fully include wave-tide interactions, which nonlinearly enhance bed shear stress apparent roughness, change the current profile, modulate wave forcing, can dominate net transport. Assessment contribution interactions requires computationally/labor intensive coupled numerical modeling, making comparison between regions or climate conditions challenging. Using Northwest European Shelf, we show dominant forcing mode potential magnitude is predictable from readily available, uncoupled wave, tide, morphological data in a computationally efficient manner using k-Nearest Neighbor algorithm. Shelf areas exhibit different modes similar exceedance conditions, related differences depth, grain size, tide range, exposure. Wave-tide across most energetic combined conditions. Meso-macrotidal tide-dominance while shallow, fine-grained, microtidal wave-dominance over statistically representative year, dominating extensively >30 m depth. Sediment strongly affects seabed morphology. Sand geometry varies significantly predicted dominance classes increased length asymmetry, decreased height, increasing wave-dominance. This approach efficiently indicates where simple noninteractive processes may be sufficient modeling transport, enables interregional comparisons sensitivity testing changing applications globally.