How tides and waves enhance aeolian sediment transport at the sand motor mega-nourishment

Abstract

Expanding knowledge concerning the close entanglement between subtidal and subaerial processes in coastal environments initiated the development of the open-source Windsurf modeling framework that enables us to simulate
multi-fraction sediment transport due to subtidal and subaerial processes simultaneously. The Windsurf framework couples separate model cores for subtidal morphodynamics related to waves and currents and storms and aeolian
sediment transport. The Windsurf framework bridges three gaps in our ability to model long-term coastal morphodynamics: differences in time scales, land/water boundary and differences in meshes.
The Windsurf framework is applied to the Sand Motor mega-nourishment. The Sand Motor is virtually permanentlyexposed to tides, waves and wind and is consequently highly dynamic. In order to understand the complex
morphological behavior of the Sand Motor, it is vital to take both subtidal and subaerial processes into account. The ultimate aim of this study is to identify governing processes in aeolian sediment transport estimates in coastal environments and improve the accuracy of long-term coastal morphodynamic modeling.
At the Sand Motor beach armoring occurs on the dry beach. In contrast to the dry beach, no armor layer can be established in the intertidal zone due to periodic flooding. Consequently, during low tide non-armored intertidal beaches are susceptible for wind erosion and, although moist, may provide a larger aeolian sediment supply than the vast dry beach areas. Hence, subtidal processes significantly influence the subaerial morphology and both need to be accounted for to understand the long-term aeolian morphodynamic behavior of the Sand Motor.