ABSTRACT: Modelling the effect of wind angle and beach geometry on sediment delivery to coastal dunes.

CGRG Bibliography of Canadian Geomorphology
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Abstract

Spatial models that explicitly link micro-scale process mechanics to macro-scale landform response are a rare but essential component of our understanding of geomorphic process-response interactions. This paper outlines a geometric framework that may serve as the foundation for future efforts leading toward more general and practically useful models of aeolian sediment transport across beaches and sand delivery to coastal dunes. Three key elements (beach geometry, wind approach angle, the fetch effect) are considered in conjunction with an unspecified equilibrium transport model, and their interaction, given prescribed initial conditions, leads to predictable outcomes regarding the spatial distribution of sediment erosion, transport, and delivery across the dune line. A novel component of the model is explicit consideration of alongshore bounding features (e.g., jetties, groins, headlands, river mouths, tidal inlets) that act as sediment sinks and thereby influence the mass transport rate under oblique winds. Computer simulations demonstrate that there is a tradeoff between enhanced transport (due to the fetch effect) and reduced transport (due to the cosine effect) as wind approach angle varies, and that the geomorphic manifestation of this tradeoff is uneven alongshore growth of dunes. The specific nature of non-uniform dune fields in the real world can be investigated by incorporating long-term wind climatologies into the modelling framework.

Bibliography of Canadian Geomorphology