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Temporal and spatial variations in recession rates and sediment release from soft rock cliffs, Suffolk coast, UK

Brooks, Susan M. and Spencer, T. (2010) Temporal and spatial variations in recession rates and sediment release from soft rock cliffs, Suffolk coast, UK. Geomorphology 124 (1-2), pp. 26-41. ISSN 0169-555X.

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Official URL: http://dx.doi.org/10.1016/j.geomorph.2010.08.005

Abstract

High rates of coastal retreat characterise the weakly cemented Plio-Pleistocene rocks and sediments which form much of the cliffed coastline of East Anglia, southern North Sea. The accurate establishment of sediment losses from these cliffs has a regional significance as these sediments are important in maintaining beaches and nearshore bank systems and in feeding nearshore sediment transport pathways. However, the high spatial and temporal variability of cliff failure processes in such materials necessitates fine-scale integration of alongshore variations in cliff retreat over a series of well-established time periods to accurately define cliffline recession rates and sediment volume inputs to the nearshore system. This study applied the DSAS (Digital Shoreline Analysis System) within the GIS software package ArcMap to digitised, georeferenced positions of former shorelines, obtained from historic maps and aerial photographs (after 1992), for the sections of Benacre–Southwold and Dunwich–Minsmere on the Suffolk coast of East Anglia, UK; transects were cast every 10 m alongshore, producing very high spatial resolution upon which to assess shoreline retreat (over 1000 transects along 11 km of shoreline). Long-term (1883–2008) mean shoreline retreat rates varied between 2.3–3.5 m a− 1 (Benacre–Southwold) and 0.9 m a− 1 (Dunwich–Minsmere). For six cliffed subunits within these larger coastal sections, spatial variations in cliffline recession rates for shorter time intervals (at ca. 20-year intervals) within this longer (125 year) period were established. The combination of recession rates with photogrammetric methods of obtaining cliff top elevation at the same spatial resolution, available using aerial photographs and digital terrain models, along with cliff sediment composition, allowed the calculation of sediment volumetric inputs from cliff retreat in the period 1992–2008. Re-assessment of the magnitude and location of sediment inputs into the nearshore zone, their interaction with regional sediment transport and the growth of inshore bank systems, as well as the implications for contemporary and near-future coastal management strategies are discussed with reference to this section of the Suffolk coast.

Item Type: Article
Keyword(s) / Subject(s): Digital Shoreline Analysis System (DSAS), shoreline retreat, NextMap, sediment release, ArcMap, coastal management
School or Research Centre: Birkbeck Schools and Research Centres > School of Social Sciences, History and Philosophy > Geography, Environment and Development Studies
Depositing User: Administrator
Date Deposited: 26 Jul 2011 09:44
Last Modified: 17 Apr 2013 12:21
URI: http://eprints.bbk.ac.uk/id/eprint/3851

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