The University of Southampton
University of Southampton Institutional Repository

Masked shoreline erosion at large spatial scales as a collective effect of beach nourishment

Masked shoreline erosion at large spatial scales as a collective effect of beach nourishment
Masked shoreline erosion at large spatial scales as a collective effect of beach nourishment
Sea‐level rise along the low‐lying coasts of the world's passive continental margins should, on average, drive net shoreline retreat over large spatial scales (>102 km). A variety of natural physical factors can influence trends of shoreline erosion and accretion, but trends in recent rates of shoreline change along the U.S. Atlantic Coast reflect an especially puzzling increase in accretion, not erosion. A plausible explanation for the apparent disconnect between environmental forcing and shoreline response along the U.S. Atlantic Coast is the application, since the 1960s, of beach nourishment as the predominant form of mitigation against chronic coastal erosion. Using U.S. Geological Survey shoreline records from 1830–2007 spanning more than 2500 km of the U.S. Atlantic Coast, we calculate a mean rate of shoreline change, prior to 1960, of ‐55 cm/yr (a negative rate denotes erosion). After 1960, the mean rate reverses to approximately +5 cm/yr, indicating widespread apparent accretion despite steady (and, in some places, accelerated) sea‐level rise over the same period. Cumulative sediment input from decades of beach nourishment projects may have sufficiently altered shoreline position to mask "true" rates of shoreline change. Our analysis suggests that long‐term rates of shoreline change typically used to assess coastal hazard may be systematically underestimated. We also suggest that the overall effect of beach nourishment along of the U.S. Atlantic Coast is extensive enough to constitute a quantitative signature of coastal geoengineering, and may serve as a bellwether for nourishment‐dominated shorelines elsewhere in the world.
2328-4277
1-11
Armstrong, Scott B.
83514fef-1710-4477-9e75-64425b2022b1
Lazarus, Eli
642a3cdb-0d25-48b1-8ab8-8d1d72daca6e
Armstrong, Scott B.
83514fef-1710-4477-9e75-64425b2022b1
Lazarus, Eli
642a3cdb-0d25-48b1-8ab8-8d1d72daca6e

Armstrong, Scott B. and Lazarus, Eli (2019) Masked shoreline erosion at large spatial scales as a collective effect of beach nourishment. Earth's Future, 1-11. (doi:10.1029/2018EF001070).

Record type: Article

Abstract

Sea‐level rise along the low‐lying coasts of the world's passive continental margins should, on average, drive net shoreline retreat over large spatial scales (>102 km). A variety of natural physical factors can influence trends of shoreline erosion and accretion, but trends in recent rates of shoreline change along the U.S. Atlantic Coast reflect an especially puzzling increase in accretion, not erosion. A plausible explanation for the apparent disconnect between environmental forcing and shoreline response along the U.S. Atlantic Coast is the application, since the 1960s, of beach nourishment as the predominant form of mitigation against chronic coastal erosion. Using U.S. Geological Survey shoreline records from 1830–2007 spanning more than 2500 km of the U.S. Atlantic Coast, we calculate a mean rate of shoreline change, prior to 1960, of ‐55 cm/yr (a negative rate denotes erosion). After 1960, the mean rate reverses to approximately +5 cm/yr, indicating widespread apparent accretion despite steady (and, in some places, accelerated) sea‐level rise over the same period. Cumulative sediment input from decades of beach nourishment projects may have sufficiently altered shoreline position to mask "true" rates of shoreline change. Our analysis suggests that long‐term rates of shoreline change typically used to assess coastal hazard may be systematically underestimated. We also suggest that the overall effect of beach nourishment along of the U.S. Atlantic Coast is extensive enough to constitute a quantitative signature of coastal geoengineering, and may serve as a bellwether for nourishment‐dominated shorelines elsewhere in the world.

Text
Armstrong et al 2019 Earth's Future - Accepted Manuscript
Available under License Creative Commons Attribution.
Download (1MB)
Text
Armstrong et al 2019 Earth's Future - Version of Record
Available under License Creative Commons Attribution.
Download (1MB)

More information

Accepted/In Press date: 15 January 2019
e-pub ahead of print date: 18 January 2019
Published date: 8 February 2019

Identifiers

Local EPrints ID: 427693
URI: https://eprints.soton.ac.uk/id/eprint/427693
ISSN: 2328-4277
PURE UUID: 654b6053-cbcd-4cb5-847f-077b4515235e
ORCID for Eli Lazarus: ORCID iD orcid.org/0000-0003-2404-9661

Catalogue record

Date deposited: 25 Jan 2019 17:30
Last modified: 20 Jul 2019 00:28

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×