Do salt marshes survive sea level rise? Modelling wave action, morphodynamics and vegetation dynamics

Journal article (2018)

Authors

S.N. Best IHE Delft Institute for Water Education
M. van der Wegen Deltares, IHE Delft Institute for Water Education
J Dijkstra Deltares
P. Willemsen University of Twente, Deltares, Universiteit Utrecht, NIOZ Royal Netherlands Institute for Sea Research
Bas W. Borsje Board Young Waddenacademie, University of Twente
D. Roelvink IHE Delft Institute for Water Education, Deltares, Coastal Engineering - CEG
Research Group
Coastal Engineering (CEG) (TU Delft)
Waves Salt marshes Mudflats Bio-geomorphology Mud-morphodynamics Sea level rise (SLR)
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Published Date

01-11-2018

Language

English

Faculty

Civil Engineering & Geosciences

Department

Hydraulic Engineering

Research Group

Coastal Engineering

Abstract

This paper aims to fundamentally assess the resilience of salt marsh-mudflat systems under sea level rise. We applied an open-source schematized 2D area model (Delft3D) that couples intertidal flow, wave-action, sediment transport, geomorphological development with a population dynamics approach including temporal and spatial growth of vegetation and bio-accumulation. Wave-action maintains a high sediment concentration on the mudflat while the tidal motion transports the sediments within the vegetated marsh areas during flood. The marsh-mudflat system attained dynamic equilibrium within 120 years. Sediment deposition and bio-accumulation within the marsh make the system initially resilient to sea level rise scenarios. However, after 50–60 years the marsh system starts to drown with vegetated-levees being the last surviving features. Biomass accumulation and sediment supply are critical determinants for the marsh drowning rate and survival. Our model methodology can be applied to assess the resilience of vegetated coast lines and combined engineering solutions for long-term sustainability.