Abstract
AbstractWaves and tidal currents resuspend and transport shelf sediments, influencing sediment distributions and bedform morphology with implications for various disciplines including benthic habitats, marine operations, and marine spatial planning. Shelf‐scale assessments of wave‐tide‐dominance of sand transport tend not to fully include wave‐tide interactions, which nonlinearly enhance bed shear stress and apparent roughness, change the current profile, modulate wave forcing, and can dominate net sand transport. Assessment of the contribution of wave‐tide interactions to net sand transport requires computationally/labor intensive coupled numerical modeling, making comparison between regions or climate conditions challenging. Using the Northwest European Shelf, we show the dominant forcing mode and potential magnitude of net sand transport is predictable from readily available, uncoupled wave, tide, and morphological data in a computationally efficient manner using a k‐Nearest Neighbor algorithm. Shelf areas exhibit different dominant forcing modes for similar wave exceedance conditions, related to differences in depth, grain size, tide range, and wave exposure. Wave‐tide interactions dominate across most areas in energetic combined conditions. Meso‐macrotidal areas exhibit tide‐dominance while shallow, fine‐grained, microtidal regions show wave‐dominance over a statistically representative year, with wave‐tide interactions dominating extensively >30 m depth. Sediment transport mode strongly affects seabed morphology. Sand wave geometry varies significantly between predicted dominance classes with increased wave length and asymmetry, and decreased height, for increasing wave‐dominance. This approach efficiently indicates where simple noninteractive wave and tide processes may be sufficient for modeling sediment transport, and enables efficient interregional comparisons and sensitivity testing to changing climate conditions with applications globally.
Highlights
Residual sediment transport patterns influence the transport and fate of continental shelf sediments, influencing sediment distributions and morphological evolution (Harris & Collins, 1991; King et al, 2019; Leonardi & Plater, 2017; Pingree & Griffiths, 1979; Pingree & Le Cann, 1989; Stride, 1963; van der Molen, 2002; Xu et al, 2016; Zhang et al, 2016)
Using the Northwest European Shelf, we show the dominant forcing mode and potential magnitude of net sand transport is predictable from readily available, uncoupled wave, tide, and morphological data in a computationally efficient manner using a k-Nearest Neighbor algorithm
The Northwest European continental shelf (Figure 1) was selected for this study due to a combination of ready availability of environmental and morphological variables covering the entire continental shelf area, referred to as “shelf scale” data (Graham et al, 2018; O’Dea et al, 2012; Tonani et al, 2019; Tonani & Saulter, 2020; Wilson et al, 2018), a highly varied tidal regime ranging from macrotidal to microtidal (Pingree & Griffiths, 1979), a varied wave climate ranging from regions exposed to a potential 7000 km fetch dominated by long-period swell waves (e.g., Celtic Shelf; Collins, 1987; Draper, 1967; Scott et al, 2016) to regions sheltered from the Atlantic swell and dominated by wind-waves (e.g., Netherlands Shelf; van der Molen, 2002)
Summary
Residual (net) sediment transport patterns influence the transport and fate of continental shelf sediments, influencing sediment distributions and morphological evolution (Harris & Collins, 1991; King et al, 2019; Leonardi & Plater, 2017; Pingree & Griffiths, 1979; Pingree & Le Cann, 1989; Stride, 1963; van der Molen, 2002; Xu et al, 2016; Zhang et al, 2016). Waves and tidal currents result in resuspension and transport of shelf sediments (Carter & Heath, 1975; Pattiaratchi & Collins, 1988; Thompson et al, 2019), influencing KING ET AL. The relative impact of wave and tidal forcing influences sand wave morphology and migration rates (Campmans et al, 2018a, 2018b; Damen et al, 2018a, 2018b; Van Dijk & Kleinhans, 2005), causing potential disturbance and affecting the distribution of benthic communities (Damveld et al, 2018, 2020; Harris, 2014). Predictive habitat suitability modeling requires an understanding of physical disturbance regimes and knowledge of the dominant drivers of sand transport at the shelf scale is important (Harris, 2014)
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