A macroscale analysis of coastal steepening around the coast of England and Wales

Abstract

Coastal steepening potentially presents an array of management issues in the form of financial implications of sea defence degradation, increased risk posed to the hinterland as wave attenuation is reduced, 'coastal squeeze' and statutory requirements in the light of the Habitats Directive. The extent to which coastal steepening has occurred throughout England and Wales has been investigated through use of a GIS and dataset based on historical Ordnance Survey map information. Data were collected along 1084 selected profile lines, positioned so as to be geomorphologically representative of the coast. Features recorded from each map year included the positions of mean high water (MHW) and mean low water (MLW), the relative movements of which infer changing intertidal gradients. The results presented in this paper are on a subject and scale not previously published. It is revealed that 61% of the coastline studied has experienced a tendency towards steepening. Of the remainder, 33% has flattened, and 6% has experienced no rotational movement. This tendency towards steepening has been the dominant movement on each of the west, south, and east coasts.

The role of geodiversity in delivering ecosystem services and benefits in Scotland

“…If such rates continue into the future then they will have matched the latest projections from UKCP09 which show an expected net regional sea-level rise of between 5 and 7mm/yr in Scotland over in the next few decades, outstripping rates seen in the last 7000 years (Rennie & Hansom 2011). The resulting effects are likely to be exacerbated by continued sediment deficit (Hansom 2001), coastal steepening (Taylor et al 2004), fluctuating levels of storminess and the presence of 'hard' coastal defences.…”

Coastal use accelerated the regional sea-level rise

“…coi.gov.cn). The cases in the UK have also shown that use of seawalls and embankments can exacerbate the steepening process of coasts by halting the landward movement of high tide, which has resulted in an intertidal squeeze and ultimately the changes in beach profiles would accelerate the tidal range (Taylor et al, 2004;Jackson and McIlvenny, 2011). In addition, the possible funneling effects in confined spaces in the Bohai Sea due to excessive groundwater depletion may also lead to loss of accommodation space in unhardened coastlines (Taniguchi et al, 2008).…”

Shoreline response of eroding soft cliffs due to hard defences

“…The remaining defended coast will continue to develop artificial headlands at their boundaries and lead to shoreline steepening (Taylor et al, 2004) and greater wave attack, already noted at some defended towns, for example Cromer and Overstrand in Norfolk (Craig Smith, 1973;Ward, 1922). Climate change and sea-level rise will worsen the situation.…”

“…However, this was only a short term solution as the problem of increased erosion was moved down-drift (Silvester and Hsu, 1997). Defences have contributed to shoreline steepening (Taylor et al, 2004) leading to deeper water, increased wave attack and the outflanking of the protection. Subsequently along UK softcliffed coasts this has resulted in the formation of a number of artificial headlands which require additional or stronger protection than when they were first constructed (Brown and Barton, 2007;Valentin, 1954).…”