Variations in storm-induced bed level dynamics across intertidal flats.

Area of Science:

• Coastal geomorphology
• Environmental fluid dynamics

Background:

• Intertidal flats exhibit complex morphodynamics influenced by varying hydrodynamic forces.
• Understanding these dynamics is crucial for predicting coastal evolution and ecological health.

Purpose of the Study:

• To investigate if storm events can alter the long-term morphological evolution of intertidal flats.
• To determine the contributions of various hydrodynamic factors (tidal flow, wind-driven flow, waves, water depth) to bed level changes.
• To analyze the impact of storm events on the spatiotemporal variations in intertidal flat morphodynamics.

Main Methods:

• Analysis of decades of bed level measurements from eight intertidal flats in the Netherlands.
• A 1-month intensive field campaign on a single intertidal flat to capture storm event hydrodynamics and morphodynamics.
• Measurement of post-storm recovery processes.

Main Results:

• Individual storm events can cause persistent morphological changes on intertidal flats, with magnitudes rivaling years of continuous evolution.
• The relative timing of hydrodynamic forcing processes, rather than solely their magnitudes, primarily controls the morphological impacts of events.
• Spatiotemporal variations in bed level dynamics are driven by inhomogeneous distributions of hydrodynamic forcing (including wind) and the local bed slope.

Conclusions:

• Storms are critical drivers of intertidal flat morphology, capable of significantly redirecting long-term evolution.
• The interplay and timing of different hydrodynamic forces are key to understanding event-driven morphodynamics.
• Future research should consider the under-explored role of wind and local topography in these processes.