Download Strategic Flood Risk Assessment (SFRA)

West Berkshire Council
West Berkshire Planning Strategy
Strategic Flood Risk Assessment (SFRA)
Introduction
Draft Planning Policy Statement 25: Development and Flood Risk, requires local planning authorities to prepare a
strategic flood risk assessment (SFRA) in consultation with the Environment Agency to “determine the variation of
flood risk across and from their area as the basis for preparing appropriate policies for flood risk management for
these areas”.
There are various forms of flooding which all present various levels of risk. As our climate changes the frequency,
patterns and severity of flooding will change. Flooding can occur from rivers, the sea, from land, groundwater,
sewers, reservoirs, canals and other artificial sources (Draft PPS25).
For West Berkshire Council the issue of flood risk has been considered throughout the preparation of the West
Berkshire Planning Strategy. Knowledge of the areas liable to flooding as indicated by the Environment Agency,
the types of flooding, the risk they present and how climate may affect these, has assisted in understanding
restrictions on development potential both in developing the spatial policies, development management policies
and throughout the Sustainability Appraisal / Strategic Environmental Assessment process.
The spatial strategy for West Berkshire
The West Berkshire Planning Strategy (WBPS) is a spatial planning framework for the District. It includes a
spatial vision, objectives and a spatial strategy which set out the planning approach for the next ten to twenty
years. The document has looked at the high level strategic issues and options for the District and this is reflected
in the high level strategic flood risk assessment undertaken.
The spatial strategy is based on three broad geographical areas first identified in the Local Transport Plan, these
are:
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Urban area – Newbury and Thatcham
Eastern urban area (e.g. Purley, Tilehurst and Calcot)
Rural West Berkshire
For a map showing the Environment Agency flood zones 2 and 3 within and beyond the District boundary please
refer to Chapter 2 of the WBPS. Further detail can be found on the maps on the Environment Agency’s website at
www.environment-agency.gov.uk/flood.
Urban area
These areas are primarily affected by flooding from the River Kennet, River Lambourn, River Enborne, the
Kennet and Avon Canal, and various lakes. The WBPS identifies Newbury as the principal focus for new
development over the next ten years, including some expansion beyond the existing built up area. Development
in Thatcham is to be generally restrained initially.
Eastern urban area
In the Purley area the District boundary with South Oxfordshire runs along the River Thames. The Calcot and
Theale areas are affected by the Kennet and Avon Canal, River Kennet, Holy Brook and Foudry Brook.
Numerous lakes are also in this area. In the eastern urban area development will be primarily on previously
developed land within the settlements in order to conserve the AONB and the areas liable to flood in the valley of
the River Kennet. The area to the south of Calcot and north of the M4 motorway is affected by the Holy Brook,
River Kennet, Kennet and Avon Canal, Foudry Brook and several lakes. Much of this area is within flood zone 3,
as indicated by the Environment Agency, which has a 1% or above chance of flooding each year and is generally
understood to be the floodplain. Part of this area is also classed as functional flood plain (zone 3c, PPG25). This
area is known to flood and is considered by the Environment Agency to be a high risk zone flood plain area.
Rural West Berkshire
The countryside will be conserved and will only be suitable for limited development.
Mitigation
The knowledge of flooding from rivers and other bodies of water has influenced the spatial planning approach for
West Berkshire in the West Berkshire Planning Strategy.
Flood risk is one of the many considerations for development proposals. Where there is a known risk of flooding,
from any type of flooding, proposals will be expected to mitigate the effects.
The West Berkshire Planning Strategy is not site specific, therefore the SFRA is not able to identify mitigation
measures required. Development proposals that come forward from the West Berkshire Planning Strategy will
need to carefully consider how they may negate the impact of development to any increase in flood risk. The
Development Management policies within the West Berkshire Planning Strategy will expect all developments to
address flood risk in accordance with PPG25 (and emerging PPS25), and this approach is supported by the
guidance given in ‘Quality Design – West Berkshire’ Supplementary Planning Document Series.
In June 2006 the Council adopted the ‘Quality Design – West Berkshire’ Supplementary Planning Document
Series. Part 4 of this series, titled ‘Sustainable Design Techniques’ encourages the inclusion of Sustainable
Urban Drainage Systems in all new developments including residential and commercial, large and small.
Other documents that will form part of the Local Development Framework will need to carefully consider the
possible implications for all types of flooding.
Climate Change
Much of the power we use comes from the burning of fossil fuels which releases emissions such as carbon
dioxide into the atmosphere. In the UK, annual emissions of carbon dioxide are equivalent to 9 tonnes, compared
to USA of 20 tonnes and India of 1 tonne. By reducing the amount of carbon we burn we can slow down the rate
of climate change.
Our climate is changing and the impacts of this are uncertain however research strongly suggests that we will see
more heavy rainfall days in the future in the UK than we currently get and subsequently the risk of flooding will
increase.
Climate change will increase flood risk as more intense rainfall will increase peak river flow. In the summer, dry
soils are unable to absorb heavy rainfall fast enough and this results in sever localised flooding. Winter soils will
tend to be wetter on average and will similarly be unable to absorb heavy rainfall fast enough. These changes in
rainfall duration and intensity will have direct implications on river flooding, local flash flooding and we could see
areas not previously flooded experiencing flooding for the first time.
The Department for Communities and Local Government is developing a Planning Policy Statement on climate
change.
Development of the SFRA
Draft PPS25 requires a SFRA to either form part of the Sustainability Appraisal of Local Development
Documents, or to be used to inform it, and this in turn will inform the sequential approach to flood risk in the
development allocation and development control process.
In the development of the spatial policies in the WBPS close consideration was given to the extent of the areas
liable to flood, as identified by the Environment Agency, and the amount of predicted greenfield land required to
deliver the District’s housing requirements.
The Council will consider the issues of flooding in more detail when work starts on the forthcoming Housing Site
Allocations DPD and the options for housing sites. As such a detailed SFRA will need to be developed for that
DPD.
In line with guidance set out in draft PPS25, any sites being considered under the Housing Site Allocations DPD
which are within flood zones 2 or 3 should be subject to a sequential test before being considered further. Where
a site does not conform with the sequential test the draft guidance states that the exception test should then be
applied. Development under the exception test will only be justified where it is necessary to meet the wider aims
of sustainable development.