Wirral Local Flood Risk Management Strategy - Geosmart ...
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Wirral Local Flood Risk Management
Strategy
Part 1
WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
Contents
Part 1
1. Introduction
2. National Context for Flood Risk Management
3. Local Context for Flood Risk Management
4. Local Objectives for Strategy
5. Risk Management Authorities
6. Lead Local Flood Authority (LLFA) Structure, Governance and Local Partnerships
7. Local Flood and Coastal Erosion Risk
7.1 Current Local Flood and Coastal Erosion Risk
7.2 Current Local Flood and Coastal Erosion Risk Management
7.3 Current Management of Local Flooding Issues
7.4 Future Local Flood and Coastal Erosion Risk
7.4.1 Local Flood Risk Management Guiding Principles
7.4.2 Spatial Planning (including consents and SuDS)
7.4.3 New work
7.4.4 Maintenance
7.4.5 Asset register
7.4.6 Resilience, Response and Recovery
8 Investigations
9 Communications
10 Funding
11 Skills (needs, gaps and succession planning)
12 SEA
13 Programme & Proposed Future Flood Risk Investigations
14 Local Flood Risk Management Action Plan
15 Definitions
Part 2
Appendices
WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
Part 1
1.0 Introduction
1.1 The Wirral
The Wirral Peninsula is set between the River Dee and the River Mersey, extending into Liverpool
Bay and the Irish Sea and overlooking both the Welsh Hills and the Liverpool skyline. It has a rich
cultural and maritime heritage with a legacy of picturesque country villages, medieval hamlets and
buildings, a wide variety of private and municipal golf courses, including the world famous Links
course, Royal Liverpool Golf Club and a number of operating ports and 25 miles of unspoilt coastline
with three of the five recommended good beaches in the North West. It has a well-connected
transport system, with both rail and motorway links to the main national networks. It is also home to
several protected coastland parks, preserving some of the finest coastal scenery in Britain. There is
also an unusual array of wildlife, from migratory birds to colonies of grey seals.
1.2 Wirral Council
Wirral Council as a Unitary Authority is the Lead Local Flood Authority (LLFA) for the Wirral borough
area and undertakes the flood and coastal erosion risk management functions as described in
sections 4 & 5 of Part 1 of the Flood and Water Management Act 2010 (FWMA). It is also the
Highway and Planning Authority; the Land Drainage body, in accordance with the Land Drainage Act
1991 and the Coastal Defence operating authority, although both are operated under permissive
powers and as such Wirral Council is not obliged to carry out any flood and coastal defence works at
present. Wirral has developed a policy statement on Local Flood Risk Management, which is detailed
in Appendix 1 of Part 2 of this document.
2.0 National Context for Flood Risk Management
The FWMA placed a requirement for the Environment Agency (EA) to develop a National Strategy for
Flood and Coastal Erosion Risk Management in England. This strategy, which was subsequently
approved by the Secretary of State and Parliament, provides a framework for the work of all LLFA’s.
The National Strategy sets out the long-term objectives for managing flood and coastal erosion risks
and the measures to achieve them. It sets the context for and informs on the production of local flood
risk management strategies by the LLFA. These local strategies in turn provide the framework for the
delivery of local improvements needed to help communities to manage local flood risk. They also aim
to encourage more effective risk management by enabling people, communities, business and the
public sector to work together.
WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
3.0 Local Context for Flood Risk Management
3.1 General
Following the 2007 summer floods, Sir Michael Pitt published his review of the response by the
responsible parties, setting out 92 recommendations to be addressed. Government accepted these
recommendations and announced its intention to introduce a Floods & Water Bill in order to respond
to them. This resulted in The Flood & Water Management Act (2010). It created clearer roles and
responsibilities and instilled a more risk based approach. There was a new lead function for local
authorities in managing flood risk, following on from their role as the LLFA created following The
Flood Risk Regulations (2009) that transposed the EU Floods Directive into UK law.
The Act included a number of measures and responsibilities for the LLFA, which included the
production of a Local Flood Risk Management Strategy (LFRMS) under Section 9. Effect of national
and local strategies: England - (1) A lead local flood authority for an area in England must develop,
maintain, apply and monitor a strategy for local flood risk management in its area (a “local flood risk
management strategy”).
Details of Legislative and other Flood Risk Context are set out in Appendix 2 of Part 2 of this
document
4.0 Local Objectives for Strategy
Wirral Council as the LLFA will work with its partners, other flood risk management authorities,
individuals, communities and organisations to reduce the threat of flooding and coastal erosion. It will
achieve this through the aims and objectives as set out in this strategy.
4.1 Aims and Objectives of the Local Strategy
The aim of the local strategy is to ensure that the overall context of the National Strategy is met
through Wirral’s management of local flood and coastal erosion risk.
The Council will, through its flood and coastal erosion activities, manage the local risk to people and
their property through the objectives set out below.
• Understand the local risks of flooding and coastal erosion, working together with partners,
other risk management authorities, organisations and the community to identify the causes
and put in place long-term plans to manage these risks and make sure that other plans take
account of them;
• Ensure that the guiding principles for sustainable development are applied and inappropriate
development is avoided in existing and future areas at risk of flood and coastal erosion while
elsewhere, carefully managing other land to avoid increasing the risks;
• Where financially viable, build, maintain and improve local flood and coastal erosion
management infrastructure and systems to mitigate or reduce the likelihood of harm to people
and damage to the economy; environment (natural, historic, built and social) and society as a
whole.
• Increase public awareness of the effects of climate change and the implications for an
increase in flood risk, engage with people specifically at risk of flooding, to encourage them to
WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
take action to manage and/or mitigate the risks that they face and to make their property more
resilient; .
• Support and assist those bodies responsible for improving the detection, forecasting and
issue of warnings of flooding. Plan for and co-ordinate a rapid response to flood emergencies
and promote faster recovery from flooding.
5.0 Risk Management Authorities
Details of the Risk Management Authorities within the Wirral Area are detailed in
Appendix 3 of Part 2 of this Document
6.0 LLFA Structure, Governance and Local Partnerships
6.1 The Wirral Flood Management Partnership
In 2008, in response to the Pitt review and recommendations, Wirral’s Streetscene & Transportation
Overview & Scrutiny approved the establishment of a cross-party Elected Members Steering Group,
which met regularly with the cross-departmental Officers Flood Group which was also established in
2008 following a local flooding incident.
The present Wirral Flood Group is a combination of these two groups, plus representatives from the
EA, UU, WW, Wirral NHS and the Emergency Services. The partnership relationship has been
strengthened by re-branding as the Wirral Flood Management Partnership Group, together with the
introduction of agreed Terms of Reference that all partners have signed up to. This group reported
annually to the Overview & Scrutiny Committee and more recently to its replacement, the
Regeneration & Environment Policy & Performance Committee on flood risk management
undertaken during the previous year and sets out its actions/targets for the next
In addition, an operational sub-group, made up of Council Officers and representatives from the EA,
UU and WW, has been established to deal with the day-to-day flooding and flood risk issues, it meets
bi-monthly or as required and reports to the Flood Management Partnership Group 6 monthly
meetings. The Governance and Partnership Arrangements structure is detailed below in Figure 2Chief Executive Officer
Regeneration &
Environment Policy &
Performance Committee
Cabinet Member
Environment & Conservative Party
Sustainability Strategic Director Strategic Director of
Regeneration & Transformation & Lead Elected Member
(Portfolio Holder) Environment Resources
Assistant Chief
Executive / Head of
Environment Agency
Emergency Universal &
Infrastructure Services Lib Dem Party Lead
Strategic Services Head of Environment & Head of Elected Member
Regulation Regeneration
Sewerage - Strategic
UU Labour Party Lead
WW Senior Manager Building Control Planning- Develop. Elected Member
Highways Manager Control Manager
Health, Safety & Resilience
Operations Manager
(Chairman Flood Management
Environment Agency
Partnership)
Operational
Highway Asset Forward Planning Head of Legal &
Manager Manager Member Services
Sewerage - Operational
UU WW
FCERM Lead Officer &
Legal & Member
Chairman Operational
Flood Group Services Lead
Communications Emergency Planning Planning - Forward Planning - Development
Climate Change Control Lead
Lead Highway Assets, Coastal Planning Lead
Officer
& Drainage Team Leader
Figure 2. Governance and Partnership Arrangements
(Members of Flood Management Partnership and
Operational Flood Group in shaded boxes)WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
6.2 Other Partnerships for Consultation
The Council has existing arrangements for community consultation via its Local Strategic
Partnership, Local Constituency Committee’s, Wirral Youth Engagement, and Wirral Voluntary and
Community Services Network.
The Local Strategic Partnership Assembly is a non-statutory, non-executive body bringing together
representatives of the public, private, voluntary and community sectors. Consultation with the Local
Strategic Partnership reaches senior Council managers, key local public service providers and
designated local champions for subjects such as housing, health and social care, access and
mobility, and crime and disorder.
The Council also currently operates four Local Constituency Committee’s, which is one of the key
ways that Wirral Council engages with local people; and gives them an opportunity to shape services
in their area and give feedback in connection with Council Plans, Policies and Strategies.
Wirral Youth Engagement through The Executive Youth Board and Youth Forums are a more recent
addition to the Council’s consultation network, working alongside the Local Constituency Committees
to address a traditionally “hard-to-reach” group. They allow young people to raise their concerns and
shape local services.
Consultation through the Wirral Voluntary and Community Services Network (WVCSN), which
operates outside the Council and, work with local community groups and voluntary organisations
which provide services locally. They have the potential to reach over 400 member organisations
across Wirral. However, WVCSN representatives also form a significant part of the Local Strategic
Partnership.
7.0 Local Flood and Coastal Erosion Risk
7.1 Current Local Flood and Coastal Erosion Risk
Local flood and coastal erosion risk means flood risk from:-
• the sea;
• groundwater;
• rivers and ordinary watercourses which includes a lake or pond or other area of water which
flows into an ordinary watercourse; and
• surface runoff.
Wirral is potentially vulnerable to flooding from several sources:
• Coastal/Tidal
• Fluvial from rivers / watercourses
• Groundwater
• Pluvial or surface water
• Sewer
• Man made structures
• Climate changeWIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
Coastal / Tidal flooding can be caused by river or sea defences being overtopped, usually caused by
a combination of low pressure and high tide. However, where defences are not overtopped or
exceeded, tidal flooding can also be caused by spray overtopping.
Fluvial flooding from rivers and watercourses occurs as a result of flows in a river /watercourse
exceeding their capacity. This type of flooding may result from overtopping and / or breaching of flood
defences following heavy rainfall and / or melting snow, which causes abnormally high water levels. It
can also be caused by debris build up which can ultimately block them or any screens located on
them.
Groundwater flooding results when the natural water table within the underlying strata rises to ground
level. This can result from reductions in water abstraction, or following extended periods of sustained
rainfall. The areas most at risk can be low-lying areas or where the ground water table is at a
naturally shallow level.
Pluvial or surface water flooding is usually, but not exclusively, as a result of intense rainfall that
exceeds the capacity of the installed drainage system, this often leads to flooding of the public
highway. Typically this type of flooding is very localised and has short lead-times, making it difficult to
predict. It can occur where no watercourse exists. The problem and severity of ‘pluvial’ flooding can
be exacerbated by: topography, drainage system capacity and surfaces with low permeability.
Sewer flooding both foul and surface water, can occur as a result of heavy rainfall overloading
sewers or failure of a sewer due to collapse or debris build up.
Man-made structure flooding can result from the failure of canals, reservoirs, and other man-made
structures along with problems caused by the failure of pumping stations, water mains and industrial
activity.
7.1.1 Historical Significant Local Flood Risk
In order to identify if there had been any historical local significant flood risk, it was necessary to
define what was to be considered as a locally significant flooding incident. Wirral MBC, along with
other Councils on Merseyside, agreed this as flooding that affected 20 people (or approximately 8
houses) or 1 critical service, within a 1 km square area.
Although flooding was found to have occurred at a number of locations across the borough, only two
recent incidents met the locally significant flooding criteria. However, records from a number of
sources suggest that surface water flooding has occurred following a number of previous either high
intensity storm events or extended periods of heavy rain and until recently had only affected a small
number of properties internally. The majority of the recorded flooding in the past was mainly external
to the property, or restricted to the highway, open space and farmland.
7.1.2 Future Significant Local Flood Risk
The Government, drawing on information from existing surface water flood risk maps, identified
locations across the UK, where local flood risk is significant and where these locations are clustered
together they have been identified as Indicative Flood Risk Areas.
The above criteria did not identify any indicative flood risk areas within the Wirral.WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
However, although no indicative flood risk areas were identified, it was established that a number of
locations existed that could be at risk from future flooding that would affect possibly 23000 properties
following a 1in 200 year rainfall event across the Wirral, although there is only a 0.5% chance of it
occurring in any one year.
7.1.3 Climate Change
Recent changes in climate, particularly in the North West have included: -
• average mean temperatures rising by about 2.65°C over the last century
• the 1990s being globally the warmest decade in the last century with 1998 being the hottest
year on record
• seasonal rainfall has varied by as much as 15% from the average in the last 30 years
• decreases in summer rainfall during the last century of up to 20%
• increases in high intensity winter rainfall having been experienced since the 1960s
• increases in flooding of some major rivers in the region in the last few decades
• sea levels around Liverpool having risen by about 6cm in the last 50 years and 10cm over the
last 100 years.
Predicted changes which may affect the climate of the UK include:-
• Warming in the North West, which will increase mean winter temperatures between 1 and 3°C
and in summer between 2.6 and 4.1°C by the 2050’s. While by the 2080’s summer mean
temperatures across the North West may have risen between 2 and 5.9°C.
• More warming in summer and autumn than in winter and spring.
• Winters will become wetter than at present by up to 26%, whilst summers will most likely
become drier.
• This contrast between winter and summer climate will increase with time. Winters will become
wetter and summers drier.
• Sea level rises of up to 30cm by the 2050’s and 80cm by the 2090’s (these are specifically
based on latest climate change guidance from EA in 2011).
The predicted changes are generally based on the Governments own UK Climate Impacts and the
most recent predictions from the UK Climate Projections 2009 (UKCP09), which has produced a
series of potential climate change scenarios based on differing global emission rates from low to
high. There are a large number of uncertainties associated with predicting the outcome of these
scenarios, which create limitations on the accuracy of the predictions.
The Wirral Climate Change Group is a local forum supported by Wirral Council’s Sustainability Unit,
which co-ordinates action on climate change in Wirral. The group is working on the development of a
replacement climate change strategy for Wirral 2014-19.
There are clearly a large number of potential consequences of climate change with differing degrees
of likelihood associated with them. Wirral will ensure that it is as prepared as possible, within the
resource constraints placed on it, to respond to the challenges posed by extreme weather events, in-
line with Government guidance.WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
7.2 Current Local Flood and Coastal Erosion Risk Management
7.2.1 Coastal Erosion and Tidal Flood Risk
Coastal erosion is a natural process caused by wind and wave action wearing away the land, such as
the foreshore or cliffs. Where tidal currents, wind and waves, cause the land to be worn away and
removes sediment which is not replenished, then erosion occurs. Erosion of foreshores can happen
slowly over time; however, lowering beach levels can increase the risk of failure of coastal defence
structures, while erosion at the base or toe of a cliff can cause instabilities, which become
immediately apparent.
Coastal erosion and tidal flood risk is managed through the Council’s responsibilities for coastal
defence.
A strategic approach is adopted for Flood and Coastal Erosion Risk Management (FCERM) at Wirral.
The strategic hierarchy comprises Shoreline Management Plans (SMPs), followed by Strategy Plans
and finally detailed scheme appraisal. Each of these stages becomes progressively more detailed
and site specific, leading ultimately, provided sufficient funds are identified, to the implementation of a
management scheme that is considered appropriate for a specific length of coastline.
The current North West England and North Wales Shoreline Management Plan (SMP2), was
adopted by Wirral Council in September 2010 and defines a preferred shoreline management policy
for each Policy Unit defined along the Wirral Frontage
Whilst the SMP identifies what policy should be adopted for future coastal defence management, the
emerging Wirral Coastal Strategy identifies how the policies would most appropriately be
implemented, based on a more detailed understanding of coastal processes applying, flood and
coastal erosion risks faced by coastal communities, environmental impacts and the economic
justification for different future coastal management scenarios.
Wirral Council is an active member of the North West and North Wales Coastal Group, leading on the
sub-cell 11a SMP production in 2010. Membership together with collaborative working between
members of the Coastal Groups reinforces the strategic approach taken towards FCERM.
Wirral Council is the major owner of the 42km of sea and river frontage between its boundaries on
the Dee and Mersey Estuaries, whilst most of this frontage is artificially defended to reduce flood and
coastal erosion risk no major works have been undertaken on the Wirral since 2001, with the
exception of the reconstruction of the West Kirby Marine Lake Outer Wall in 2008. There has
however been on-going revenue expenditure on the maintenance of existing coastal defence assets.
A programme of regular inspection and monitoring is also in place and the output from these
activities has informed and been fully considered during the production of the Wirral Coastal
Strategy.WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
7.2.2.1 Main Rivers
The Environment Agency maintains 97km of main rivers and any associated flood defences within
the Wirral catchment. These are:-
• Dibbinsdale Brook
• Dibbinsdale Brook Tributary
• Clatter Brook
• Storeton Brook
• Prenton Brook
• River Fender
• Newton Brook (Mersey)
• Greasby Brook
• Carr Drain
• Perimeter Drain
• Arrowe Brook
• The Birket
• Birket Old Courses
The Environment Agency has a prioritised programme of regular maintenance on all its main rivers,
which includes inspections, litter and debris removal, desilting, strimming, flailing and weed
treatment. However, they have identified that with the changing financial climate it is likely that this
may need to be reviewed annually, with the likelihood that maintenance reductions will be necessary.
Where these main rivers pass into culverts under the public highway Wirral Council, as the Highway
Authority, has inspection and maintenance responsibilities.
7.2.2.2 Ordinary Watercourses
In addition to these ‘Main Rivers’ there is a network of ordinary watercourses for which Wirral Council
is the relevant operating authority and it has been agreed with the Environment Agency that there are
5.04km of ‘critical ordinary watercourses’ of which 3.89km are culverted and although these are non-
main river they are critical due to their potential to put large numbers of people and property at risk of
flooding. As the LLFA for the Wirral area, the Council is now also responsible for consenting and
enforcement of certain works to these ordinary watercourses.
No planned maintenance of watercourses is undertaken at present, although in urban areas where
flood risk may be more critical, problems are more easily recognised and acted on. Even where
Wirral has riparian owner responsibilities, no extensive planned maintenance is undertaken.
Additionally, in the past, due to the resource implications, no investigation of flooding problems that
related purely to ordinary watercourses had been carried out. This has resulted in there being very
little knowledge or understanding of the land drainage flooding issues.
Outside the urban areas, these watercourses are generally not deemed critical and flood risk could
be minimised by the proper exercise of maintenance by the owners. However, again where they pass
into culverts under the public highway Wirral Council, as the Highway Authority, has maintenance
responsibilities. Where these culverts are large enough to be considered as a highway bridgingWIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
structure (usually a span greater than 1.5m), then they are visually inspected bi-annually, while every
5 years a more detailed structural assessment is undertaken.
It is likely that some of these highway culverts are protected by debris screens but no detailed
records of the location and condition are held at present.
7.2.3 Groundwater
The Environment Agency Areas Susceptible to Ground Water Flooding Map (AStGWF) suggests that
the coastal fringes to the east and northeast together with the northwest of the Wirral could be
susceptible to groundwater flooding.
However, the production of these maps was based on limited geological information and does not
take account of groundwater rebound following reductions in water abstraction. In addition, the maps
show 1km grid squares where geological and hydrogeological conditions show that groundwater
might emerge but it is likely that only isolated locations within the overall susceptible area are actually
likely to suffer the consequence of groundwater flooding.
Figure 4 below taken from Wirral’s Preliminary Flood Risk Assessment shows the Environment
Agency AStGWF Map for the Wirral.
Figure 4 Environment Agency AStGWF Map for the Wirral
No records were identified of known groundwater flooding within the Wirral thus it is not possible to
conclude if any past groundwater flooding had had any significant effect on existing recorded surface
water flooding. However, it is possible that the future requirement to deal with surface water by theWIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
adoption of SuDS could possibly lead to groundwater and land drainage flooding becoming more
widespread.
Groundwater does affect the operation of the three Mersey tunnels (2 road and 1 rail) and continuous
pumping is undertaken at present by the operator.
7.2.4 Pluvial or Surface Water
At present the Council’s limited resources are directed primarily at dealing with flood risk related to
the public highway through the annual pre-emptive cleansing of gullies and associated assets, minor
repairs and improvements and the investigation of flooding incidents particularly where a relationship
with the public highway is suspected.
Where new highway drainage systems are provided they are designed not to flood in a 1in 100 year
rainfall event + a 20% increase in capacity for climate change.
7.2.5 Sewer
The majority of the public sewerage system in the Wirral is owned and maintained by United Utilities,
however the southwest corner of the Borough, around Heswall, is the responsibility of Dwyr Cymru
(Welsh Water). Much of the highway drainage system within the Wirral discharges into these public
sewers and during high intensity storm events or extended periods of heavy rain the public sewerage
system often becomes overloaded resulting in both surface water and foul flooding of the highway
and property.
A register of reported sewage flooding incidents is held by both United Utilities and Welsh Water; and
are utilised to identify locations where sewer capacity improvements are necessary and would
provide economical local benefits. Both produce 5-yearly investment plans identifying those locations
that will benefit from improvements over that period.
In addition they undertake both planned and reactive maintenance on their sewerage assets to
reduce flood risk. However, any new sewers or upsizing that is undertaken are designed to ensure no
flooding in a 1in 30year rainfall event while taking account of climate change and urban creep.
7.2.6 Man-made Structures
The failure of man-made structures can lead to flooding which can have no relationship with rainfall
events. The failure of canals, reservoirs, pumping stations, water mains and the infrastructure at
industrial sites can lead to flooding. The responsibility to maintain these where they occur in the
Wirral rests with a number of public and private organisations. As they are identified the flood risk will
be assessed and the flood risk management authority with responsibility will be notified.
7.2.7 Climate Change
Wirral has been attempting to mitigate climate change through behavioural changes and by reducing
its carbon emissions thus reducing its carbon footprint, for example through initiatives such as energy
management to reduce consumption, recycling and green transport initiatives. There has also been
work on adapting to climate change where possible through for example, changes in how theWIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
Planning Department deals with inappropriate developments in flood risk areas or by protecting
existing assets. Opportunities to reduce surface water discharging from new development is also
utilised where possible.
7.3 Current Management of Local Flooding Issues
7.3.1 General
Although a recurring problem throughout the Borough, flooding in Wirral had until recently, tended to
take place mostly on an isolated incident basis. However, a number of extreme rainfall and coastal
storm surge events have occurred, as detailed below.
• In August 2011, a 1 in 461 year rainfall event affecting the Heswall and Wallasey/New
Brighton areas with over 30 properties affected by internal flooding.
• August 13th 2012, a 1 in 30 year rainfall event affected the whole Borough and 46 properties
suffered some form of internal flooding.
• August 15th 2012, a 1 in 12 year event affected the whole Borough and some 26 properties
were affected by internal flooding.
• August 29th 2012, a 1 in 20 year rainfall event, led to 10 properties across the Borough
suffering some form of internal flooding.
• September 24/25th 2012, a 1 in 25 year rainfall event led to widespread flooding and road
closures although only 1 property reported internal flooding.
• December 5th 2013, a low-pressure induced surge caused already high tide levels to
increase by over 1.2m. Wave action raised water levels even higher and the westerly winds of
force 8, gusting to force 10 led to defences being overtopped at West Kirby, Hoylake and
Meols. 4 Commercial and 8 residential properties were flooded and although some minimal
damage was caused to coastal defences there was significant damage to other council
assets, private property and private defences. In addition, at New Brighton flooding caused by
overtopping, vertically reflected waves and wind blown wave spray across the flood
containment defences led to 19 businesses and 4 domestic properties being flooded.
Localised flooding can also occur as a consequence of a lack of maintenance, capacity issues or that
no drainage exists at all.
Flooding from public sewers is a continuing problem affecting most areas but to varying degrees and
both UU and WW, although tackling the problem, prioritise the flooding such that internal flooding of
property is the highest priority for funding while highway and external property flooding is considered
a lower priority. However it is likely that through resolving internal property flooding by increasing the
public sewer capacity, benefits to the system as a whole accrue.
In the early 2000’s the Council carried out an assessment of the flood risk from ordinary
watercourses based on historical flooding information coupled with the Environment Agency’s
indicative flood plain maps. It was satisfied at the time of the assessment that there were minimal
risks to human health, the social and economic welfare of individuals and communities,
infrastructure, and the environment (including cultural heritage), created by the flood risk from these
ordinary watercourses. However, following the recent flooding incidents this has been reviewed and
will continue to be reviewed on a regular basis as detailed knowledge on the drainage network is
collated. The localised ordinary watercourse flooding locations are listed below and now include
Rigby Drive and Lloyd Drive, Greasby, which have been added to this list following the review.WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
• Clatterbridge Hospital
• Croft Drive east, Caldy
• Column Road, Caldy
• Brimstage Road, Brimstage
• Brimstage Road, Brackenwood
• Target Road, Heswall
• Arrowe Park Road, Upton
• Arrowe Brook Road/Arrowe Brook Lane, Greasby
• The Great Culvert (this is owned and maintained by others)
• Rigby Drive/Lloyd Drive, Greasby
Council Officers regularly meet with operational representatives of the EA, UU and WW to discuss
flooding issues and identify how, by co-ordinating maintenance and improvement works, flooding and
flood risk can be resolved or at least reduced. These partnerships will be developed and extended, to
include the sharing/exchange of information, which will be essential for the development and
implementation of both the national and local flood risk management strategies.
A list of historical flood locations has been developed and this is reviewed regularly and updated.
Locations that have received remedial works are archived but stay on the list for record purposes. At
present there is no specific funding to deal with flooding issues.
7.3.2 Flood Warning
The EA has for many years produced mapping identifying areas at risk of flooding from rivers or the
sea. These “Indicative Flood Plain Maps” have formed the basis of Flood Warning Areas, used by the
EA to warn residents of possible flooding events. The method of warning for Wirral’s two Flood
Warning Areas (FWAs) (Tides in Merseyside and Cheshire, and Wirral Flood Watch Catchment) was
indirect via general reports on local media. The Indicative Flood Plain Maps are also used with regard
to planning policy and development control. The present Planning Policy Guidance: Development
and Flood Risk (PPG25) has identified constraints for development based on 1% risk of flooding for
river and 0.5% risk of flooding for tidal in any one year. PPG25 also contains guidance for
development in areas at 0.1% risk of either type of flooding. The areas at risk are defined from the
EA’s Indicative Flood Plain mapping
In 2004 the EA identified Wirral as an area where it could provide a direct flood warning service to
properties at risk of tidal and / or fluvial flooding. The FWAs introduced by the EA did not include any
of the areas at risk of flooding from the Critical Ordinary Watercourses identified in the Council’s
Policy Statement on Flood and Coastal Defence. There has been a 34% take up of the flood warning
within the Wirral and of the properties receiving direct flood warnings, 17% are in flood warning areas
with no history of flooding.
Following the coastal flooding in December 2013 the Environment Agency introduced a targeted
Flood Warning Area for New Brighton specifically around Marine Point, it undertook to improve take
up of the existing Flood Warning Area at West Kirby and rebranded its Flood Alerts for the Dee
Estuary and north Wirral to make the locations more familiar to Wirral residents. The new Flood
Alerts were both subsets of existing larger alerts but it was hoped that by making them specific it
would then make the alert more timely and accurate targeting only the specific area at risk. These
new areas are:-WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
• Irish Sea from Hilbre Island to Heswall - Areas at risk include land from Hilbre Island and
along the coast from West Kirby to Heswall.
• Irish Sea from Hoylake to New Brighton - Areas at risk include land at the head of the Wirral
from Hoylake to New Brighton and including parts of Leasowe and Wallasey.
The EA warn by the most appropriate direct method, eg. phone, text or media broadcasts to
properties in the following areas:-
EA FWD Code FWD Name Properties
013FWCTDEE Irish Sea Hilbre Island to Heswall 50
013FWFME4 Arrowe Brook at Upton 21
013FSTTME3 Mersey Estuary at Woodside 107
013FWCTME1 Irish Sea from Hoylake to New Brighton 718
013FWFME7 River Birkett at Leasowe 1937
013FWFME6 River Birket at Meols 11
Irish Sea and Mersey Estuary from the Head of
013FWTTME8 4096
the Wirral to Runcorn
Figure 5 Wirral Flood Warning Area Statistics
7.3.3 Policy Statement on Flood and Coastal Defence
Wirral’s Flood and Coastal Defence Policy Statement is detailed in Appendix 1 of Part 2 of this
document and identifies that the Governments policy aim is to reduce the risk to people and the
developed and natural environment from flooding and coastal erosion by encouraging the provision
of technically, environmentally and economically sound and sustainable defence measures. Its
objectives in meeting this aim are:-
.
1 To encourage the provision of adequate and cost affective flood warning systems
2 To encourage the provision of adequate, economically, technically and environmentally sound
and sustainable flood and coastal defence measures
3 To discourage inappropriate development in areas at risk from flooding and coastal erosion.
7.3.4 Catchment Flood Management Plans
Wirral is spread across two Catchment Flood Management Plan (CFMP) areas, the Mersey Estuary,
and the Dee Estuary. The Mersey area has 12 actions associated with the local authority, 6 are high
priority and 6 medium and Wirral is the lead partner on 6 of these actions, while the Dee Estuary
CFMP has none relating to the Wirral.
The Mersey Estuary South catchment covers the rivers that drain into the River Mersey from the
Wirral peninsula. Two of the three main watercourses drain the Wirral catchment through the River
Birket and Dibbinsdale Brook. The third watercourse is Rivacre Brook, which is the southernmost of
the three main watercourses and flows into the Mersey near Ellesmere Port, and is not part of theWIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
Wirral catchment. There are no watercourses draining into the Dee Estuary from the Wirral, which
have associated flood risk.
Approximately two-thirds of the surface water flows generated within the Wirral discharges into the
River Birket and its tributaries. This ‘Main River’ flows into a large diameter culvert known locally as
‘The Great Culvert’. These flows are intercepted by an automatic, mechanically raked screen with a
bypass overflow should the screen blind or suffer a mechanical failure, which has lead to property
flooding in the past.
Downstream of this screen is a pumping station, operated by United Utilities that intercepts these
raked flows up to the stations maximum pumping capacity of 6m3/s, which are discharged into the
West Float Dock. Flows in excess of this pass forward into the downstream section of the ‘Great
Culvert which is designated as a public sewer and receives combined flows from the public sewerage
system. The ‘Great Culvert eventually discharges into the United Utilities WwTW at Shore Road,
Birkenhead. Flows in excess of the treatment capacity of the works are pumped directly into the River
Mersey via a storm pumping station with a capacity of 9.14m3/s.
The River Birket catchment was the subject of a flood risk study by the Environment Agency in 2006
and the results of this have been shared with Wirral. In addition a recent EA funded catchment
investigation has identified and mapped the surface water/land drainage catchments outfalling into it.
Further south, Dibbinsdale Brook drains the central area of the Wirral Peninsula, and its main
tributary is Clatter Brook. The catchment is mainly rural in the upper reaches, and heavily urbanised
in the lower reaches downstream from the confluence with Clatter Brook.
The aim of the CFMPs is to create a better environment through flood risk management. In
undertaking the actions there will be a need to consider the environmental responsibilities that apply
across all of the work, for example complying with legislation. Any activities undertaken to comply
with the actions will, therefore, need to meet the requirements of, for example, the Water Framework
Directive. In setting this plan and implementing actions, Wirral will ensure that it is maximising the
opportunities to meet its environmental responsibilities while reducing the flood risk.
The Mersey Estuary CFMP considers that the current flood risk management is adequate at present
while it may be necessary in the future to improve and extend this by changes to the level of
defences, flood forecasting and flood warning. In addition it recommends that there is no increase or
if possible a reduction in run-off from development and that an integrated urban drainage strategy is
developed with the EA and UU. These actions will be considered as an integral part of this flood risk
management strategy.
The Dee Estuary CFMP provides an overview of the proposed flood risk management at the
catchment scale for the next 50-100 years although the Wirral catchment is not considered to be
under any major risk.
The preferred policies for the Mersey Estuary Wirral Catchment would be:
Policy 5 : Areas of moderate to high flood risk, where we can generally take further action to
reduce flood risk, we will.WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
This policy will tend to be applied to those areas where the case for further action to reduce flood risk
is most compelling, for example, where there are many people at high risk, or where changes in the
environment have already increased risk. Taking further action to reduce risk will require additional
appraisal to assess whether there are socially and environmentally sustainable, technically viable
and economically justified options.
The table below taken from the Mersey Estuary CFMP shows the flood risk within the Wirral.
Catchme Communi Number Number of Relative Damage to Damage to Agricultural Damages
nt ty of Properties Hazard Residential Commercial (£k)
Properti at risk (1% (1% a.p.) Properties (£M) Properties (£M)
es at a.p.)
risk 10 1% 0.1 10 1% 0.1% 10% 1% 0.1%
(10% % % %
a.p.)
Mersey Wallasey, 289 4596 Medium 8 144 272 8 69 110 462 1270 1650
Estuary Bromboro
South ugh,
Ellesmere
Port
Irby,
Hoylake
Figure 6. Mersey Estuary CFMP Wirral Flood Risk
In addition, in order to achieve a sustainable approach to flood risk management and to ensure that
any improvements are not affected now or in the future, by, for example, inappropriate development.
It will be necessary to support and promote the following actions throughout all sub-catchments:
• Application of appropriate planning requirements and building regulations for proposed
developments under the National Planning Policy Framework (NPPF) and Part H of the
Building Regulations;
• Risk based approach to maintenance of drainage infrastructure;
• Increase the flood awareness and education for existing property owners/occupiers, including
the promotion of self help schemes such as ‘flood pact’ (an Environment Agency initiative).
• Encourage take-up of environmental stewardship schemes to improve land use management
and flood risk.
The Actions from the CFMPs are detailed in Appendix 5 and a diagrammatic representation of
the Wirral plan is shown in Appendix 6 of Part 2 of this document.
It is clear from the initial assessment of responsibility from the Lead Department that some actions
will be led by Environment & Regulation (Drainage) together with the involvement and support of
Regeneration (Planning), who act as lead for some actions. However, the involvement of the
Regeneration at all stages of the development and implementation will be critical. The timescales for
the implementation of actions has been set externally but Wirral will need to have made progress in
connection with them, despite a long timescale for completion.WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
7.3.5 Land Drainage Issues
As recommended by the Pitt review, Wirral will need to consider undertaking a more pre-emptive
view of the maintenance of the surface water system, in particular the clearing of strategic critical
watercourses although at present the exact locations and conditions of these are largely unknown. A
number of debris screens are believed to be located on some of the culverts beneath the public
highway but at present no regular cleaning is undertaken. The location of other critical culverts is
being investigated as the need to identify the flooding consequences to property and the travelling
public from any blockages or failures needs to be known. The mapping of the land drainage/surface
water catchments of the River Birket and part of the Dibbinsdale Brook has already been completed.
This has enabled the connection of urban surface water catchments with their river outfalls to be
established.
It would appear that even where Wirral has riparian responsibilities to maintain watercourses, this
has rarely been happening. This responsibility for maintenance is likely to occur at playing fields,
allotments, school premises and leased farmland. The future maintenance of all watercourses on a
regular basis by either the council or riparian owners, where these can be identified, will result in
additional storage capacity. However, it should be noted that the effect on the whole system of
regular maintenance needs to be considered as flooding problems downstream may occur due to
surface water draining more quickly.
Wirral at present has permissive powers under the Land Drainage Act 1991 but not a duty to carry
out works on ordinary watercourses. This can include improvements, general maintenance and
cleaning work; in addition the permissive powers enable the Council to take action against those who
are legally responsible to carry out such work but do not do so and in default carry out that work and
recharge the property. These are known as ‘Riparian Owners’ and are described in more detail
below.
The Council has never formally taken up these permissive powers as the process can be very
expensive and may involve a great deal of investigation. There is no specific budget for such work
and therefore any such problems have never been identified and recorded in any detail. However,
new responsibilities for local authorities within the Flood and Water Management Act will result in
more of these needing to be investigated although resolution will still be problematic.
The term ‘Riparian Owner’ describes anyone who owns a property where a watercourse bounds or
crosses it. Under common law they possess rights and responsibilities appertaining to that stretch of
watercourse, which may be an open watercourse, a culvert or pipe. Often property owners are
unaware of this responsibility particularly where the watercourse is underground. In addition, where a
watercourse is situated on a boundary between properties, it is normally presumed that a Riparian
Owner owns the land up to the centre-line of the watercourse, unless records exist to prove
otherwise, so both property owners would have riparian responsibilities.
A Riparian Owner is responsible for: -
• accepting water from the section of watercourse owned by their upstream neighbour and
transferring this, together with drainage from their own property, to their neighbour
downstream,WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
• carrying out, at his or her own expense, any necessary maintenance of the watercourse to the
satisfaction of the relevant Land Drainage Authority, which in the case of the non-main rivers
within the Wirral area is the Council.
As previously identified, the Council itself has riparian responsibilities to maintain watercourses
where it is the landowner and these are the responsibility of the Department that has ownership.
In addition, LLFA’s have led on ordinary watercourse consenting and enforcement, since April 2012,
following commencement of paragraphs 32-34 of Schedule 2 of the Flood and Water Management
Act 2010, which changed ordinary watercourse management by section 23 of the Land Drainage Act
1991 (LDA1991).
These regulatory powers, which have transferred from the Environment Agency to LLFA’s, enables
the control of certain activities that might have an adverse flooding impact. These include the erection
of milldams, weirs or other similar obstruction, culverting an ordinary watercourse, or alterations to an
existing culvert in a manner that would be likely to affect the flow of an ordinary watercourse, without
the consent in writing of the LLFA
7.3.6 Community Involvement
Involving and informing the local community concerning flood risk within Wirral is identified as a high
priority now and in the future and the necessary resources will need to be identified to support this
aim. The Wirral Flood Partnership has produced an information leaflet that gives residents
appropriate advice on what to do in the event of a flood, which will be made available, resources
permitting, at Wirral Council One-Stop-Shops and Libraries.
In addition, undertaking consultation with the various housing providers in Wirral would enable the
flood risk messages to reach a wider audience, increase the understanding of the local flood risk and
secure the prioritisation and response that these communities would wish to see in connection with
what are often localised problems that directly affect them.
The involvement of local communities in the funding of flood mitigation/prevention works will be
necessary in the future due to the limited amount of funding available nationally and locally. In
addition, it will not be economically, socially or environmentally feasible to permanently resolve all
flooding issues in the Wirral. As part of this Plan it is proposed to develop an investment strategy for
how the Council can work with other organisations and communities to raise further funds and
prioritise areas for further investigation and/or investment
7.4 Future Local Flood and Coastal Erosion Risk
7.4.1 Local Flood Risk Management Guiding Principles
For local flood and coastal erosion management to be viable and sustainable it will be necessary to
make difficult decisions on where risk management activities can and cannot be carried out. These
decisions, and the processes by which they are taken, will be guided by a number of high-level
principles.
1 Community focus and partnership working
2 A catchment and coastal “cell” based approach
3 Sustainability
4 Proportionate, risk-based approachesWIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
5 Multiple benefits
6 Beneficiaries should be encouraged to invest in risk management
7.4.1.1 Community Focus and Partnership working.
Wirral will work with other flood risk management authorities in partnership with communities to
understand the community perspective of flooding and coastal erosion, helping communities
understand and actively prepare for the risks, and encourage them to have direct involvement in
decision-making and risk management actions. The aim is to ensure that decision-making and
ownership of risk management measures are as local as possible but within a catchment or coastal
cell that ensures a fair allocation of funds and avoids the transfer of risk elsewhere without prior
agreement. Wirral will co-ordinate its consultations and the input of local bodies and communities
through its four local Neighbourhood Forum’s and public scrutiny and overview proceedings.
It will work closely with the Regional Flood and Coastal Committee (RFCCs) to consider how both the
costs and benefits of investment resulting from local flood risk management strategies should be
spread between geographical areas, communities and sectors. Involving those communities
identified as being at risk can help inform local decisions on what is needed and who should be
asked to contribute towards the costs of investment, so that costs and benefits are shared fairly.
Partnership working will also ensure that risk is managed in a co-ordinated way beyond authority
boundaries, for example across catchments or along the coast, with lead local flood authorities
working together collectively. By working in partnership with communities, Wirral will achieve a
clearer understanding of the issues, and be able to bring together those best placed to develop and
provide solutions.
The key aims will include the identification of synergies and efficiencies and ways of maximising
these, the development of better links with other related work, and the promotion of better sharing of
information and expertise
7.4.1.2 A Catchment and Coastal “Cell” based Approach
In understanding and managing flood and coastal risks locally, Wirral will ensure that it considers the
impact on other parts of the catchment or coast, to avoid passing risk on to others within the
catchment or along the coast without prior agreement. This catchment or coastal cell approach will
be a key aspect to managing risks at source and achieving wider benefits through better integrated
water management and increase the opportunity for developing new sources of funding as well as
pooling resources and expertise. The existing catchment flood management plans (CFMPs) and
shoreline management plans (SMPs) will support this approach.
7.4.1.3 Sustainability
Wirral will support local communities by managing flood and coastal erosion risks in ways that take
account of all impacts and the whole-life costs of any investment. The risk management solutions will
be forward-looking, taking account of potential risks that may arise in the future and being adaptable
to climate change. They will, where possible, also work with natural processes and aim to enhance
the environment. By adopting a more sustainable approach to the management of flood and coastal
erosion risks, Wirral aims to greatly improve the environmental condition of rivers, wetlands, coastal
areas, and the social and economic circumstances around and within the local settlements.WIRRAL LOCAL FLOOD RISK MANAGEMENT STRATEGY
PART 1 – DRAFT FOR CONSULTATION
Regeneration & Environment
7.4.1.4 Proportionate, risk-based approaches
It is not technically, economically or environmentally feasible to prevent flooding and coastal erosion
altogether. Therefore, Wirral’s risk-based management approach will target resources to those areas
where they will have the greatest benefit. These risk management measures will consider both the
probability over time of a flood or coastal erosion happening and the consequences that might arise if
it did. To do this the sources, pathways, receptors and consequences of risk need to be understood
and addressed as appropriate to manage all of the factors that combine to create risk. This approach
involves using a tiered assessment i.e. starting at a high, screening level and in stages becoming
more detailed to address the risks identified. It will seek to make risk management more
straightforward, removing unnecessary barriers while ensuring that legal and Government policy
requirements are met. All aspects of risk management will be carried out in a proportionate way that
reflects the size and complexity of the risk and society’s ability to manage it. Investment in managing
risk, and who pays for it, should reflect the benefits that result.
7.4.1.5 Multiple benefits
As well as reducing the risks to people and property, FCERM can bring significant economic,
environmental and social benefits. It can enhance and protect the built, rural and natural
environments, cultural heritage and biodiversity by preventing loss and damage to habitats and
heritage assets and reducing pollution. It can contribute to regeneration and income generation,
protect infrastructure and transport links, and contribute to economic growth. It is important that
communities are able to shape risk management actions to take account of local priorities, and that
this is supported, where appropriate, by local contributions to achieve additional benefits that might
not be possible otherwise. In all instances, Wirral’s flood and coastal risk management activities will
seek to avoid damaging the environment, including the historic environment, and wherever possible
work with natural processes; and always seek to provide environmental benefit, as required by the
Habitats, Birds and Water Framework Directives. This may include providing new habitats, which
may not be directly linked to FCERM schemes, to compensate for those that are lost as a result of
actions to protect people and property.
7.4.1.6 Beneficiaries should be encouraged to invest in risk management
When flood and coastal erosion risks are managed, the benefits achieved are in many cases
localised and lead to personal or private gain through the protection of specific individuals,
communities and businesses. However, they can also be public, through the reduction of future costs
to society arising from incident recovery. The Government have identified that as the private as well
as the public will benefit, then the costs should not fall to the general taxpayer alone. If costs are
borne by national budgets alone, the plans would be subject to national controls to ensure value for
money to the taxpayer, limiting the scope for local influence and hence there would be a lack of local
incentive to take sensible steps to reduce risk where possible, to avoid actions that might increase it,
or to keep the costs of risk management actions proportionate. Overall, the Government has
suggested that there will be the opportunity for significantly more risk management activity to take
place if alternative sources of funding can be secured in each area to reflect the local benefits that
would be delivered. Any local funding can be used to supplement the amounts available nationally to
ensure as many communities as possible can be protected.You can also read
