Environmental Engineering Reference
In-Depth Information
drives the protection of existing wetlands and
restoration of lost habitats (Rupp 2009).
These policy drivers and targets for coastal
habitat creation provide clear national and in-
ternational strategic rationale(s) for managed
realignment; perhaps the most quantifiable, and
hence probably clearest, rationale for continuing
such projects is demonstrated in the UK by the
shortfall that exists between the amount of hab-
itat created so far and the habitat extent targets
that have been set. Against the targets set out
above, the realignment and RTE projects com-
pleted by 2009 have created 1330 ha of new
habitat. A third of this area (450 ha) was for
project-specific compensation and therefore does
not represent restoration, while the remaining
two-thirds (880 ha) was for nature conservation,
biodiversity enhancement, coastal squeeze com-
pensation as well as flood defence enhancement
(Rupp-Armstrong et al. 2008) and these collec-
tively contribute to a restoration target. To illus-
trate the contribution that has been, and can be
made, to habitat creation targets specifically
by managed realignments, these 1330 ha were
created by 44 projects of which 33 were realign-
ments delivering 94% of the habitat area while
the remaining 11 projects were smaller-scale
RTEs contributing 6%.
Although a national and international strategic
rationale for implementing these schemes exists,
the dichotomy faced by coastal managers who
seek to implement them is one of how to balance
the need to protect assets that are currently behind
defences, be they farmland, property or infrastruc-
ture, with the need to give the shoreline sufficient
space to respond to the changing conditions and
so maintain a healthy suite of habitats within the
transition from sea to land. This conflict between
the costs of land protection and the value of the
land has a long history, with the debate shifting
according to prevailing social and economic pri-
orities. Soft coastlines have always changed but
the idea of seeking to fix them and/or claim new
land to create new agricultural land relatively
cheaply was clearly prevalent from the 14th to
20th centuries. In the 20th century, however,
priorities shifted several times. The 1909-1912
one example, Andrews et al. (2000) concluded that
90% of the intertidal area has been lost to land
claim on the Humber Estuary and, consequently,
that 99% of the storage potential for carbon in the
estuary has also been lost.
The need for managed realignment schemes is
often driven by, or at least supported by, a range
of national and international legislative and pol-
icy drivers. In Europe, the EU Habitats Directive
requires compensation to be provided, ideally as
close as possible to the area of loss, where devel-
opments or strategies are deemed to affect the
integrity of internationally designated Natura
2000 sites and Ramsar wetlands. This can in-
clude compensation for coastal defence manage-
ment plans where these contribute to ongoing
deterioration through coastal squeeze. Another
international policy driver for the offsetting
historic and ongoing coastal habitat losses is
Biodiversity Action Planning (BAP), for which
objectives for the restoration of saltmarsh, mud-
flat and saline lagoon habitats have been iden-
tified in response to the 1992 Rio Convention on
Biological Diversity (CBD). For example, the UK
government has BAP targets for saltmarsh and
mudflat creation that add up to 600 ha per year
combined (UKBAP 2006), with an additional
target to create a further 3600 ha by 2015 to offset
historic losses.
In the UK there are also targets that seek to
restore coastal habitats within nationally desig-
nated Sites of Special Scientific Interest (SSSIs) to
a favourable conservation status, and one current
target is to restore 95% of SSSIs to this status by
2010. Also, the creation of new habitats will con-
tribute to improving the status of estuaries under
the European Water Framework Directive (WFD)
through the enlargement of the intertidal zone
per se, and the subsequent increased abundance
of angiosperms (i.e. seed-bearing saltmarsh) and
the likely improvement of conditions for fish
populations.
In the USA comparable legal drivers exist in-
cluding theCleanWaterAct (1968), which requires
compensatory mitigation for harmful discharges
intowetlands, and theCoastalWetlands Planning,
Protection and Restoration Act (1990), which
