Predicting marine and aeolian contributions to the Sand Engine's evolution using coupled modelling

Predicting marine and aeolian contributions to the Sand Engine's evolution using coupled modelling

van Westen, B. (TU Delft Hydraulic Engineering; Deltares)
Luijendijk, Arjen (TU Delft Coastal Engineering; Deltares)
de Vries, S. (TU Delft Coastal Engineering)
Cohn, Nicholas (U.S. Army Engineer Research and Development Center)
Leijnse, Tim W.B. (Deltares; Vrije Universiteit Amsterdam)
de Schipper, M.A. (TU Delft Coastal Engineering)

Hydraulic Engineering

2024

Quantitative predictions of marine and aeolian sediment transport in the nearshore–beach–dune system are important for designing Nature-Based Solutions (NBS) in coastal environments. To quantify the impact of the marine-aeolian interactions on shaping NBS, we present a framework coupling three existing process-based models: Delft3D Flexible Mesh, SWAN and AeoLiS. This framework facilitates the continuous exchange of bed levels, water levels and wave properties between numerical models focussing on the aeolian and marine domain. The coupled model is used to simulate the morphodynamic evolution of the Sand Engine mega-nourishment. Results display good agreement with the observed aeolian and marine volumetric developments, showing similar marine-driven erosion from the main peninsula and aeolian-driven infilling of the dune lake. To estimate the magnitude of the interactions between aeolian and marine processes, a comparison between the simulated morphological development by the coupled and stand-alone models was made. This comparison shows that aeolian sediment transport to the foredune, i.e. 214,000 m³ over 5 years, extracts sediment from the marine domain. As a result, the alongshore redistribution of sediment from the main peninsula by marine-driven processes decreased by 70,000 m³, representing 1.7% of the total marine-driven dispersion. From the aeolian perspective, marine-driven deposition and erosion reshape the cross-shore profile, controlling the supply-limited aeolian sediment transport and the magnitude of sediment deposition in the foredunes. In the region with persistent accretion along the Sand Engine's southern flank, a higher than average foredune deposition was predicted due to morphological development of the region where sediment is picked up by aeolian transport. Including these marine processes in the coupled model resulted in an increase of 1.3% in foredune growth in year 1 and up to 6.7% in year 5 along this accretive section. At the northern flank, where the developing lagoon and tidal channel provided increased shelter to the supratidal beach, predicted foredune deposition reduced up to −11.5% over the evaluation period. Our findings show that both aeolian and marine transports impact reshaping the nourished sand, where developments in one domain affect the other. The study findings echo that the interplay between aeolian- and marine-driven morphodynamics could play a relevant role when predicting sandy NBS.

AeoLiS
Coupled modelling
Delft3D Flexible Mesh
Mega nourishment
Morphodynamics
Numerical modelling

http://resolver.tudelft.nl/uuid:e75d53c4-0252-4890-aae5-052e378e6da7

https://doi.org/10.1016/j.coastaleng.2023.104444

0378-3839

Coastal Engineering, 188

Institutional Repository

journal article

© 2024 B. van Westen, Arjen Luijendijk, S. de Vries, Nicholas Cohn, Tim W.B. Leijnse, M.A. de Schipper