A new perspective on meso-scale shoreline dynamics through data-driven analysis

D.E Reeve,J Horrillo-Caraballo,H Karunarathna,S Pan

doi:10.1016/j.geomorph.2019.04.033

D.E Reeve, J Horrillo-Caraballo + Show 2 more

Open Access

https://doi.org/10.1016/j.geomorph.2019.04.033

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Journal: Geomorphology	Publication Date: Jun 3, 2019
Citations: 7	License type: cc-by

Affiliation: Swansea University, University of Wales

Abstract

The twin ambits of climate change and coastal development have raised public awareness of shoreline management. Simultaneously, they have highlighted a gap in our understanding of sediment transport and morphodynamic processes at time and space scales appropriate for shoreline management purposes. Here, we analyse an exceptional set of beach surveys gathered over a period of twenty-two years along the Suffolk coast, eastern UK, that extends over approximately 80 km to investigate the meso-scale shoreline variations. The surveys have been made biannually along fixed transects spaced at approximately 1 km intervals as part of a strategic monitoring exercise undertaken by the coastal authorities to assist in shoreline management planning. Changes in beach volume, foreshore slope and shoreline position have been computed to investigate both spatial and temporal changes. The analysis reveals some distinct responses to the physical processes of tides and waves, anthropogenic interventions and geological controls. Neither a clear relationship between the presence of sea defences and beach response nor an ordered regional-scale shoreline movement are evident. Temporal variations in beach volumes and position provide a similarly complex picture with recessionary, accretionary and stable behaviour all apparent within the study site. There is evidence of quasi-cyclic behaviour at some locations as well as a reduction in variability over time-scales beyond approximately five years.

Highlights

Our shorelines are an inherently dynamic place where waves and tides provide the driving mechanism to move sediment, changing the shape of the surface of the nearshore and foreshore
Results are discussed in a ‘dimensional’ order; that is first positional changes, beach volume changes, and the coastal trends classification which relies on position and gradient changes
We conclude that the majority of the Suffolk beaches are not exhibiting the phenomenon of coastal squeeze at meso scales;

Summary

Introduction

Our shorelines are an inherently dynamic place where waves and tides provide the driving mechanism to move sediment, changing the shape of the surface of the nearshore and foreshore. These correspond respectively and approximately to: sand ripples to small coastal schemes; individual coastal schemes; shoreline management planning; and continental and geological changes These scales map quite neatly onto different categories of model that are available for predicting shoreline response to tides and waves, with some well-known exceptions detailed below. At the very largest scales empirical models that describe the profile or plan-shape of the shoreline under equilibrium conditions are available (e.g. Silvester and Hsu, 1997; Moreno and Kraus, 1999; Bruun, 1962, 1983, 1989; Dean, 1977, 1991; Rosati et al, 2013) These have been used at synoptic scale to design coast and flood protection schemes, (Fleming and Hamer, 2000). Between these two extremes there is a knowledge gap and a plethora of modelling approaches, (Hanson et al, 2003; Nicholls et al, 2015)

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