A large proportion of the UK coast is currently suffering from
erosion (17% in the UK; 30% in England; 23% in Wales; 20% in
Northern Ireland; 12% in Scotland). Almost two-thirds of the
intertidal profiles in England and Wales have steepened over the
past hundred years, a process which is particularly prevalent on
coasts protected by hard engineering structures (this represents
46% of England's coastline; 28% of Wales; 20% of Northern Ireland
and 7% Scotland). Both coastal erosion and steepening of intertidal
profiles effects are expected to increase in the future due to the
effects of climate change, especially sea-level rise and changes to
the wave conditions.
The natural response of coastal systems to sea-level rise is to
migrate landward according to the roll-over model, through erosion
of the lower part of the nearshore profile and deposition on the
upper part. This process is accompanied by the onshore transport of
sediment. The roll-over model is applicable to estuaries, barriers
and tidal flats, and the rate of coastal recession is likely to
increase with the rate of sea-level rise. Rocky coasts (hard and
soft) are erosional coasts and retreat even under stable sea-level
conditions. Their retreat rates are expected to increase as a
result of sea-level rise and increased storminess, but along
soft-rock coasts, the introduction of cliff material into the
nearshore zone may slow down local erosion rates through the
formation of beaches. Human activities, such as land reclamation,
the building of hard coastal defences and the construction of
jetties and marinas significantly impair the ability of coastal
systems to respond naturally to changes in the forcing by
restricting the free movement of coastal sediments.
It is very important to consider, however, that the coastal
response to sea-level rise is very much determined by site-specific
factors. These include relative sea-level history, Isostasy is the
Equilibrium in the earth's crust such that the forces tending to
elevate landmasses balance the forces tending to depress
landmasses.isostatic land-level change, solid and drift
geology, wave/tide conditions, longshore sediment transport, human
impacts and the interactions between different coastal systems.
More often than not, it is these site-specific factors that
determine the coastal response, rather than a global change in sea
level or a regional change in wave climate. Therefore any
predictions of coastal response due to climate change will have a
low confidence, unless a detailed study is conducted and long-term
coastal change data are available.
