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Finding a home for fluvial geomorphology in EIA in the UK
Fluvial geomorphology is the scientific study of
landforms associated with river channels and the
sediment transport processes forming them. Rivers
are inherently dynamic systems, influenced by a wide
range of natural and human factors affecting flow
and sediment loadings. Geomorphological impacts
can occur at local, reach and catchment scales and
vary over geological and recent timescales.
Accounting for natural geomorphology in river
projects can help reduce adverse ecological and
aesthetic impacts, and in some cases can offer
improvements to the baseline which is often already
degraded by human activities. In this way
geomorphology is a sustainable link between river
engineering
and
the
wider
environment.
Consideration of fluvial geomorphology during the
feasibility, planning and design stages of a river
project can offer reduced future maintenance costs,
help prevent costly repairs, and ensure a longer life
span for new or modified assets.
Geomorphological assessments consider existing
channel morphology (shape), fluvial processes
(interactions between water and sediment) and
sediment regime (i.e. the tendency of a reach is to
either erode, deposit, transfer or exchange
sediment). Assessments are made of how these
characteristics change in response to component
activities of a development. The Environmental
Impact Assessment (EIA) Regulations require a
description of the aspects of the environment likely to
be significantly affected. As water is a key
consideration in EIA, it would not be unreasonable to
assume that fluvial geomorphology should feature in
EIAs, particularly where the scoping process
identifies it as a valid issue to be incorporated.
However this is most likely to be the case where
there is a requirement placed by the Regulator or
where geomorphologists are consulted to advise a
project (both relatively recent developments).
Currently
in
England
and
Wales,
fluvial
geomorphology is frequently mentioned in EIA via a
wider regulatory requirement to demonstrate
compliance with the Water Framework Directive
(WFD). Each responsible UK regulatory body has an
impending requirement to achieve Good Ecological
Status for all water bodies by 2015. In water bodies
where this is technologically or financially unfeasible,
there are a further two deadlines of 2021 and 2027.
Geomorphology (described as hydromorphology) is
one of three parameters contributing to the overall
Ecological Status, the other two being biological and
physico-chemical.
Two key questions remain: how should fluvial
geomorphology be considered in EIA, and where
should the outcomes be reported?
In
the
authors’
experience
when
fluvial
geomorphology and WFD compliance assessments
are undertaken and reported in an Environmental
Statement, they frequently form a component of
“Water
Environment”
chapters,
alongside
assessments of water quality, hydrology and/or flood
risk. This can sometimes make an already
comprehensive chapter somewhat unwieldy. Matters
can be more complicated on projects in England and
Wales by an absence of accepted guidance on how
to assess for WFD compliance as part of an EIA.
With few guiding principles yet established,
assessors currently have to rely largely on their own
professional judgement and experience.
One approach within the Jacobs national
geomorphology team has been to produce a
standalone WFD compliance assessment, presented
as a separate chapter to the Water Environment,
detailing how a development potentially impacts on
biological, hydromorphological and physico-chemical
aspects. However a compliance assessment focuses
on how changes to the various WFD assessment
parameters could impact on ecology and has not
therefore been routinely considered the future risk
and sustainability aspects of development activities
in terms of geomorphology.
A more holistic approach used by Jacobs is to
include a more detailed geomorphological and
physico-chemical assessment within the Water
Environment chapter, with biological elements
reported separately within the Ecology chapter. WFD
compliance is then dealt with as a succinct appendix
to the Environmental Statement, drawing on key
points within these two chapters. This solution
provides a number of reporting efficiencies in terms
of responding to the need to consider fluvial
geomorphology in both EIA and WFD terms. This
approach also makes it easier to draw out
geomorphological issues to input to the design of
river projects, thus further mitigating environmental
impacts and increasing project sustainability.
It is recognised that consideration of fluvial
geomorphology in EIA remains an evolving area for
England and Wales. By way of contrast in Scotland it
is now an explicit consideration of all relevant
development activities.
By contrast in England and Wales such changes to
status are assessed more subjectively. Although
MIMAS involves a form of streamlined fluvial
geomorphology assessment, limitations exist on how
certain types of modifications are accounted for, and
there is a residual risk of being over-prescriptive
where the field survey of morphological alterations
remains subjective. The science of fluvial
geomorphology provides a key link between
understanding environmental impacts (e.g. ecology,
habitats and WFD status) and reducing environment
risk to developments, thus potentially improving their
sustainability and longevity. So regardless of how
fluvial geomorphology impacts are reported, it is
important that this discipline is considered throughout
the planning, design and assessment of
development projects wherever works impact the
fluvial environment.
Ellie Phillips and Alison Flynn are both Senior
Geomorphologists in Jacobs, March 2015.
To undertake any ‘in’ or ‘near’ channel works,
developers
in
Scotland
must
demonstrate
compliance with the Controlled Activities Regulations
(CAR), derived from the WFD. For substantial works,
a CAR licence must be obtained from the Scottish
Environment
Protection
Agency
(SEPA)
to
demonstrate that geomorphology and its impacts
have been fully considered and mitigated. CAR
licences are usually obtained after an EIA and allow
impacts and mitigation to be considered further.
In Scotland, fluvial geomorphology is also
fundamental to WFD Ecological Status where it is
used as a surrogate for ecological assessment.
SEPA has developed a tool called MIMAS
(Morphological Impact Assessment System) which
determines the degree of modification to natural river
morphology and relates this to Ecological Status. As
a result, impacts of new channel modifications or
improvements can be assessed using MIMAS and
directly related to improvement or deterioration to
Ecological Status.
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