The Role of Aeolian Transport Processes in the Intertidal Zone on Sediment Exchange Between Marine and Aeolian Coastal Zones.

Abstract

Coastal dunes are generally dynamic due to a combination of marine and aeolian sediment transport processes. The growth of coastal dunes is generally governed by wind driven sediment transport. Quantifying and predicting aeolian sediment transport processes is a scientific and practical challenge. This is caused by the uncertainties in the relative importance of the transport capacity of the wind and the availability of sediment (or sediment supply). Especially sediment supply has recently been hypothesized to be of governing importance but no quantitative knowledge is available yet. The intertidal zone adds further complexity since sediment supply is likely influenced by alternating marine and aeolian processes on the tide timescale. However, while sediment availability is likely to vary along the coastal zone, no measurements of sediment supply and availability has been successful in the past.

In this study we use detailed measurements of wind driven erosion and sedimentation in the intertidal and supra-tidal coastal zone to quantify sediment supply for aeolian sediment transport and associated dune growth. During the 6 weeks SEDEX2 field campaign, a RIEGL 200VZ laser scanner is used to collect high resolution topographic data with 15-minute intervals during several tidal cycles. The data reveals the small but significant erosion in the intertidal zone due to wind driven processes within a tidal cycle for the first time. At the same time the small but significant sedimentation at the dry beach and dunes is measured on the tidal timescale. These data are essential in understanding sediment exchange between marine and aeolian zones and the growth of coastal dunes.