Understanding the coastal variability at Norte beach, Portugal

ABSTRACT Silva, A.N., Taborda, R., Antunes, C., Catalão, J. and Duarte, J. 2013. Understanding the coastal variability at Norte beach, Portugal Norte beach stands in a coastal stretch fully exposed to the high energetic North Atlantic wave regime. The beach is located updrift of the Nazaré submarine canyon head, a sedimentary sink that captures the southward directed longshore drift. Systematic monitoring of Norte beach has been conducted by a coastal video monitoring system since 2008. A total of 31 monthly coastlines were extracted and analyzed in the period between December 2008 and May 2012. Results show a rare high seasonal coastline variability which exceeds 160 m in the southward sector (adjacent to the headland) and 70 m at the central and north sectors. These coastline variations are related with modifications in the planform beach configuration: beach oscillates between a straight (generally from June to August) and an arcuate configuration (during the remaining months of the year). Results suggest that Norte beach variability depends mainly on longshore drift gradients rather than with cross-shore sedimentary transfers. The intense wave refraction over the canyon head, associated with the westerly swell waves, generates a sedimentary convergence at the centre of the beach promoting the increase of the beach curvature, while, northern and/or short waves (more frequent in summer) tend to linearize the beach. This work contributed with valuable information about the sedimentary dynamics of the Norte beach and showed that this site is a suitable candidate to evaluate longshore drift from shoreline changes.

[1]  Ana Silva,et al.  COSMOS: A lightweight coastal video monitoring system , 2012, Comput. Geosci..

[2]  Robert A. Holman,et al.  Extreme value statistics for wave run-up on a natural beach , 1986 .

[3]  Raúl Medina,et al.  The CoastView project: Developing video-derived Coastal State Indicators in support of coastal zone management , 2007 .

[4]  P. Ciavola,et al.  An Integrated Study of Shoreline Variability Using GIS andARGUS Techniques , 2022 .

[5]  R. Holman,et al.  The history and technical capabilities of Argus , 2007 .

[6]  George M. Watts,et al.  A STUDY OF SAND MOVEMENT AT SOUTH LAKE WORTH INLET FLORIDA , 1953 .

[7]  Hilary F. Stockdon,et al.  Empirical parameterization of setup, swash, and runup , 2006 .

[8]  Peter Nielsen,et al.  Wave setup and runup: An integrated approach , 1989 .

[9]  Stefan Aarninkhof,et al.  A critical review of the CoastView project: Recent and future developments in coastal management video systems , 2007 .

[10]  Edward B. Thornton,et al.  Wave set-up on a natural beach , 1981 .

[11]  David A. Huntley,et al.  The Evaluation of Large Scale (km) Intertidal Beach Morphology on a Macrotidal Beach Using Video Images , 1998 .

[12]  T. Baldock,et al.  Probability distributions for wave runup on beaches , 2010 .

[13]  Robert A. Holman,et al.  Quantification of nearshore morphology based on video imaging , 2004 .

[14]  Paul D. Komar,et al.  Beach Processes and Sedimentation , 1976 .

[15]  Lavinio Gualdesi,et al.  Rapid environmental assessment in the nearshore , 2008 .

[16]  Ian L Turner,et al.  A video-based technique for mapping intertidal beach bathymetry , 2003 .

[17]  G. Dodet,et al.  Wave climate variability in the North-East Atlantic Ocean over the last six decades , 2010 .

[18]  R. Dean,et al.  Shoreline variability via empirical orthogonal function analysis: Part I temporal and spatial characteristics , 2007 .

[19]  Nathaniel G. Plant,et al.  Intertidal beach profile estimation using video images , 1997 .