Four-Dimensional Investigation of Gravel Beach Ridge Accretion and 50 Years of Beach Recharge at Dungeness, UK, Using Historic Images, GPR and Lidar (HIGL)

Lucy Buck,Maria Inggrid,Charlie S Bristow

doi:10.3390/app112110219

Lucy Buck, Maria Inggrid + Show 1 more

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https://doi.org/10.3390/app112110219

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Abstract

Dungeness is a cuspate foreland on the south coast of England that is the largest shingle feature in Europe and includes hundreds of beach ridges. It is also the location of two nuclear power stations that were constructed in the 1960s. The dominant southwest waves cause longshore drift from west to east, eroding the southwest side of Dungeness, accompanied by accretion on the east side. A record of this eastward movement and sediment accretion is preserved by the shingle beach ridges. The power stations are located on the eroding southwestern side of the ness, and a system of beach recharge has been used to move shingle from the downdrift, east-facing shore to the updrift, southwest-facing shore to protect the power stations from coastal erosion. We use a novel combination of historic images, ground-penetrating radar (GPR), and Lidar (HIGL) to investigate accretion and beach ridges at Dungeness during the past 80 years. We report changes in accretion along the coast and use GPR to determine the thickness of beach gravels. The amount of accretion, represented by the width of the backshore, decreases downdrift from south to north. The number of beach ridges preserved also decreases from south to north. By combining the shingle thickness from GPR with elevation data from Lidar surveys and records of beach accretion measured from aerial images, we estimate the volume and mass of gravel that has accumulated at Dungeness. Historic rates of beach accretion are similar to recent rates, suggesting that the 55 years of beach recharge have had little impact on the longer-term accretion downdrift.

Highlights

Dungeness is a prominent cuspate foreland on the south coast of England that is around 25 km wide and projects almost 10 km into the English Channel (Figure 1)
Number beach ridges decreased from south the section studied, we found that the number of beach ridges decreased from south to north (Figure north (Figure 4)
The beach ridges are underlain by seaward inclined reflections from beachface progrades, and the thickness of the shingle decreases from south to north

Summary

Introduction

Dungeness is a prominent cuspate foreland on the south coast of England that is around 25 km wide and projects almost 10 km into the English Channel (Figure 1). It is reported to be the largest coastal shingle feature in Europe [1]. The shape of the foreland has evolved through the late Holocene, as it has prograded southwards into the Channel [2]. Shingle ridges on the surface of the foreland record these changes in the morphology of the ness and have been mapped by [3] and [4]. The positions of the shorelines at Dungeness, as shown by historic maps from 1617 and 1800, are used to assess historic changes in the shoreline [3]. The 1617 map drawn by Poker was used by [3] to represent the shoreline in

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