Coastal erosion in NW Spain: Recent patterns under extreme storm wave events

German Flor-Blanco, Javier Alcántara-Carrió, DWT Jackson, German Flor, C. Flores-Soriano

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18 Citations (Scopus)
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Abstract

Coastal dunes are sensitive to both anthropic and natural processes of erosion. In this study, we analyse the geomorphic changes in 15 dune-fringed coastlines of Asturias (NW Spain) for the period 1992 to 2014 to determine specific drivers of erosion. Coastline migration patterns were obtained using geospatial analysis of vertical aerial images and field surveys. The annual and maximum wave energy, maximum significant wave height, duration and number of storm events were determined for each climatic year by using available wave data from both recordedbuoy data (1997–2014) and the WAM numerical model (1956–2015). The study shows that since 2006, coastline retreat has significantly accelerated along the Asturias coast. In particular, severe erosion of sandy beaches and dunes occurred in 2013/14, reaching up to 40 m of coastline retreat and destroying numerous ports and seafront promenades. Increased frequency of unusually strong storm waves, with significant wave height (Hs) exceeding 9 m, together with an unusual 5° westward variation from the mode in offshore wave approach direction during these storms, appear to be the main catalysts in heightened erosion capacity of storm waves in the 2013/14 period. This resulted in the removal of small dune areas and a severe recession in the easternmost part of the largest (natural) dune fields in the region. Under these stormy periods, foredunes and climbing dunes developed notably pronounced escarpments and blowouts, with sand subsequently relocatedinto the foreshore and backshore zones. This study demonstrated that increased frequency in powerful storm events (Hs > 9 m) and an alteration in storm approach direction, can lead to significantly enhanced erosion of dune coastlines, even along those that are modally-attuned to high energy events.
Original languageEnglish
Article number107767
Pages (from-to)1-17
Number of pages17
JournalGeomorphology
Volume387
Early online date19 May 2021
DOIs
Publication statusPublished - 15 Aug 2021

Bibliographical note

Funding Information:
Wave data bases from Estaca de Bares and Cabo de Pe?as buoys, as well as from WAM numerical model, have been supplied by Puertos del Estado (Spanish Government). Aerial photographs and orthophotographs have been supplied by the Cartography Service of the Principado de Asturias and the Instituto Geogr?fico Nacional (IGN) of Spain. The digital elevation model has been provided by the Cartography Service of the Principado de Asturias (SITMA). The authors also thank the Cluster of Energy, Environment and Climate Change and to the Marine Observatory of the University of Oviedo for providing the Cudillero buoy data. In addition, we would like to thank the invaluable help of Monica Cardo with several graphics and the scientific reviewers have been helpful in improving the manuscript. This work is a contribution to UNESCO IGCP Project 639 ?Sea Level Change from Minutes to Millennia?.

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

  • Coastal dunes
  • Coastline retreat
  • Climate change
  • Storm frequency
  • Storm approach angle

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