A Novel Approach to Mapping Ebb-Tidal Delta Morphodynamics and Stratigraphy

44 Pages Posted: 15 Oct 2021 Last revised: 30 Mar 2022

See all articles by Stuart Pearson

Stuart Pearson

Deltares; Delft University of Technology

Edwin Elias

Deltares

Bram van Prooijen

Delft University of Technology

Helena van der Vegt

Deltares

Ad van der Spek

Deltares

Zheng Bing Wang

Deltares

Abstract

Ebb tidal deltas (ETDs) are highly dynamic features of sandy coastal systems, and coastal management concerns (e.g., nourishment and navigation) present a pressing need to better describe and quantify their evolution.  Here we propose two techniques for leveraging the availability of high-resolution bathymetric surveys to generate new insights into the dynamics and preservation potential of ebb-tidal deltas. The first technique is conformal mapping to polar coordinates, using Ameland ebb-tidal delta in the Netherlands as a case study.  Since the delta tends to evolve in a clockwise direction around the inlet, this approach provides an improved quantification and visualization of the morphodynamic behaviour. We clearly illustrate the sediment bypassing process and repeated migration of channels and shoals across the inlet from updrift to downdrift coasts. Secondly, we generate a decadal scale (1975-2021) stratigraphic model from the differences between successive bathymetries. This stratigraphy showcases the delta's depositional behaviour through space and time, and provides a modern analogue for prehistoric ebb-tidal deltas. During the surveyed period, inlet fills form the largest and most stable deposits, while the downdrift swash platform is the most stable structure over longer periods. Together, these approaches provide new perspectives on ebb-tidal delta dynamics and preservation potential which are readily applicable to other sites with detailed bathymetric data. These findings are valuable at annual to decadal timescales for coastal management (e.g., for planning sand nourishments) and also at much longer timescales for interpreting stratigraphy in ancient rock records.

Keywords: ebb tidal delta, Morphodynamics, stratigraphy, conformal mapping

Suggested Citation

Pearson, Stuart and Pearson, Stuart and Elias, Edwin and van Prooijen, Bram and van der Vegt, Helena and van der Spek, Ad and Wang, Zheng Bing, A Novel Approach to Mapping Ebb-Tidal Delta Morphodynamics and Stratigraphy. Available at SSRN: https://ssrn.com/abstract=3943525

Stuart Pearson (Contact Author)

Deltares ( email )

Rotterdamseweg
Delft
Netherlands

Delft University of Technology ( email )

Stevinweg 1
Stevinweg 1
Delft, 2628 CN
Netherlands

Edwin Elias

Deltares ( email )

Rotterdamseweg
Delft
Netherlands

Bram Van Prooijen

Delft University of Technology ( email )

Stevinweg 1
Stevinweg 1
Delft, 2628 CN
Netherlands

Helena Van der Vegt

Deltares ( email )

Rotterdamseweg
Delft
Netherlands

Ad Van der Spek

Deltares ( email )

Rotterdamseweg
Delft
Netherlands

Zheng Bing Wang

Deltares ( email )

Rotterdamseweg
Delft
Netherlands

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