managing
flood risk
Summary Report June 2012
Tamar Catchment
Flood Management Plan
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June 2012
Environment Agency
Tamar Catchment Flood Management Plan
1
Introduction
I am pleased to introduce our summary of the Tamar Catchment
Flood Management Plan (CFMP). This CFMP gives an overview of
the flood risk in the Tamar catchment and sets out our preferred
plan for sustainable flood risk management over the next 50 to 100
years.
The Tamar CFMP is one of 77 CFMPs for England and
Wales. Through the CFMPs, we have assessed inland
flood risk across all of England and Wales for the first
time. The CFMP considers all types of inland flooding,
from rivers, ground water, surface water and tidal
flooding, but not flooding directly from the sea (coastal
flooding), which is covered by Shoreline Management
Plans (SMPs). Our coverage of surface and ground
water is however limited due to a lack of available
information.
The role of CFMPs is to establish flood risk management
policies which will deliver sustainable flood risk
management for the long term. This is essential if we
are to make the right investment decisions for the
future and to help prepare ourselves effectively for the
impact of climate change. We will use CFMPs to help us
target our limited resources where the risks are
greatest.
This CFMP identifies flood risk management policies to
assist all key decision makers in the catchment. It was
produced through a wide consultation and appraisal
process, however it is only the first step towards an
integrated approach to Flood Risk Management. As we
all work together to achieve our objectives, we must
monitor and listen to each others progress, discuss
what has been achieved and consider where we may
need to review parts of the CFMP.
Flooding within the Tamar catchment can be attributed
to flooding from the rivers, estuaries, surface water run-
off and drainage systems. Previous incidents include
flooding in Launceston in December 1979, widespread
flooding in October 2000 and a dramatic event in
Canworthy Water in August 2004. While the numbers of
properties at risk across the Tamar catchment may be
relatively low compared with other areas of the country,
the risk to life, and community disruption caused by
flooding, can be just as significant.
We cannot reduce flood risk on our own, we will
therefore work closely with all our partners to improve
the co-ordination of flood risk activities and agree the
most effective way to manage flood risk in the future.
We have worked with others including Plymouth City
Council, Natural England, South West Water and the
National Farmers Union to develop this plan.
This is a summary of the main CFMP document, if you
need to see the full document an electronic version can
be obtained by emailing
enquiries@environment-agency.gov.uk
or alternatively paper copies can be viewed at any of
our offices in South West Region.
Richard Cresswell
South West Regional Director
2
Environment Agency
Tamar Catchment Flood Management Plan
The purpose of a CFMP in managing flood risk
3
Catchment overview
4
Current and future flood risk
6
Future direction for flood risk management
10
Sub-areas
1
Upper Tamar sub-area
12
2
Tidal Central sub-area
13
3
Plymouth sub-area
14
4
East Tamar sub-area
16
5
Central Tamar sub-area
18
6
West Tamar sub-area
20
Map of CFMP policies
21
Contents
Environment Agency
Tamar Catchment Flood Management Plan
3
The purpose of a CFMP
in managing flood risk
CFMPs help us to understand the
scale and extent of flooding now and
in the future, and set policies for
managing flood risk within the
catchment. CFMPs should be used to
inform planning and decision
making by key stakeholders such as:
• the Environment Agency, who will
use the plan to guide decisions
on investment in further plans,
projects or actions;
• Regional Assemblies and local
authorities who can use the plan
to inform spatial planning
activities and emergency
planning;
• Internal Drainage Boards (IDB),
water companies and other
utilities to help plan their
activities in the wider context of
the catchment;
• transportation planners;
• land owners, farmers and land
managers that manage and
operate land for agriculture,
conservation and amenity
purposes;
• the public and businesses to
enhance their understanding of
flood risk and how it will be
managed.
Figure 1. The relationship between CFMPs, delivery plans, projects and actions
CFMPs aim to promote more
sustainable approaches to
managing flood risk. The policies
identified in the CFMP will be
delivered through a combination of
different approaches. Together with
our partners, we will implement
these approaches through a range
of delivery plans, projects and
actions.
The relationship between the CFMP,
delivery plans, strategies, projects
and actions is shown in Figure 1.
Policy planning
• CFMPs and Shoreline Management Plans.
• Action plans define requirement for delivery
plans, projects and actions.
Note: Some plans may not be led by us – we may identify the
need and encourage their development.
Policy delivery plans (see note)
• Influence spatial planning to reduce risk and
restore floodplains.
• Prepare for and manage floods (including local
Flood Warning plans).
• Managing assets.
• Water level management plans.
• Land management and habitat creation.
• Surface water management plans.
Projects and actions
• Make sure our spending delivers the best
possible outcomes.
• Focus on risk based targets, for example numbers
of households at risk.
4
Environment Agency
Tamar Catchment Flood Management Plan
The Tamar catchment lies between
the East Cornwall, North Devon and
South Devon CFMP areas. It drains
an area of 1,800 square kilometres
(700 square miles). The River Tamar
meets the sea at Plymouth Sound,
with the Tamar estuary extending
approximately 22km inland to
Gunnislake.
The topography of the Tamar
catchment is varied. The main
upland areas are west Dartmoor and
east Bodmin moor, from which the
Thrushel, Lyd, Tavy, Walkham, Plym,
Yealm, Ottery, Kensey and Inny rivers
spring. The remainder of the
catchment is made up of rolling
farmland, valleys and heaths. The
River Tamar itself originates from the
far northern part of the catchment, in
the hills close to the North Devon
coast. Annual rainfall ranges from
more than 2,000mm (80in) on the
edge of Dartmoor to less than
1,000mm (40in) on the coastal
Catchment overview
lowlands. The England and Wales
average is 920mm (36in).
Granites make the upper catchment
relatively impervious which in turn
leads to the flashy nature of rivers
and their tributaries, often resulting
in water levels rising rapidly in a
short time. The lower areas have
sandstones and mudstones overlain
with alluvial silts and clays and
terrace deposits from rivers and sea.
The Tamar catchment is
environmentally rich with many
important environmental locations,
and some quality river systems. The
area has a rich mining heritage with
the western edge of the catchment
included in the Cornish mining World
Heritage site. There are three Areas
of Outstanding Natural Beauty, five
Special Areas of Conservation (SAC),
one Special Protection Area (SPA), 61
Sites of Special Scientific Interest
(SSSIs) and 880 Scheduled
Monuments.
Most of the catchment is rural, with
only four per cent being urbanised.
However the principal urban centre is
Plymouth, which is the most
populous city in Devon and Cornwall.
Tavistock and Launceston are the
other major settlements within the
catchment, along with Saltash,
Plympton and Plymstock (which are
all within the housing market area of
Plymouth). Just over 341,000 people
live in the Tamar catchment. Over
250,000 of these are in the Plymouth
area.
Granites make the upper catchment
relatively impervious which in turn
leads to the flashy nature of rivers
and their tributaries, often resulting
in water levels rising rapidly in a
short time.
Environment Agency
Tamar Catchment Flood Management Plan
5
Map 1. Location and extent of the Tamar CFMP area
© Crown Copyright. Environment Agency 100026380.
Legend
Tamar CFMP
Urban areas
Main rivers
Railway
Motorway
Camelford
Launceston
Tavistock
Bodmin
Callington
Horrabridge
Liskeard
Plymouth
Ivybridge
0 4 8 12
16
Kilometres
Okehampton
Bude
Great
Torrington
N
➜
Flooding from the River
Kensey at Newport in
Launceston in 1980
6
Environment Agency
Tamar Catchment Flood Management Plan
Current and future flood risk
There is a recorded history of
flooding within the Tamar catchment
that dates back to the 19th Century.
This is from a range of sources:
rivers, the estuaries, surface water
run-off and sewer systems.
More recent flooding incidents
include Launceston in December
1979, widespread flooding in
October 2000 and extreme flooding
in August 2004 at Canworthy Water.
The estuaries contribute to flood risk
in the Tamar catchment, making
flooding from the rivers worse when
high tides coincide with high
rainfall. For example, in February
1974, very high tides in the Tamar
estuary caused areas of Calstock,
Cargreen, Morwellham, and
Millbrook to flood.
While the numbers of properties at
risk across the Tamar catchment may
be relatively low compared with
other areas of the country, the risk to
life, and community disruption
caused by flooding can be just as
great.
There are flood alleviation schemes
throughout the catchment that
reduce this flood risk. Over 90km of
defences provide varying levels of
protection.
Overview of the current flood risk
Today, this accounts for over 2,750
properties across the catchment at
potential risk of flooding from rivers
and the tide (excluding those behind
defences).
Also at risk are the police station at
Tavistock, the A30 and A374, the
mainline railway in at least three
locations, two schools, a nursery and
a health centre.
Furthermore, some designated
environmental sites are within the
floodplain or may be affected by
actions. These include Culm
Grasslands SAC and Dartmoor SAC,
and SSSIs such as Dunsdon Farm,
Otter Valley, Kernick and Ottery
Meadows, and Grimscott and
Lymsworthy Meadows.
What is at risk?
‘… More than three-quarters
being the heaviest shower I have
ever witnessed; the whole of the
lower part of the town
(Plymouth) was flooded.’
1871
Table 2. Critical infrastructure at risk:
7 electricity substations, 14 railway lines, 17 A roads, 1 water treatment works
Number of properties at risk
Locations
>1,000
Plymouth
500 to 1,000
None
100 to 500
Plympton, Tavistock, Launceston
50 to 100
None
25 to 50
Plymstock, Bridestowe, Saltash
Environment Agency
Tamar Catchment Flood Management Plan
7
Map 2. Flood risk to property in a 1% annual probability river flood, ignoring current flood defences
© Crown Copyright. Environment Agency 100026380.
Legend
Properties with a 1%
chance of flooding
25 - 50
51 - 100
101 - 500
501 - 1,000
1,001 - 1,500
Tamar CFMP
Main rivers
Launceston
Tavistock
Plymouth
Plympton
0 4 8 12
16
Kilometres
Plymstock
Bridestowe
Saltash
N
Table 1. Locations of towns and villages with 25 or more properties at risk in a 1% annual probability flood
8
Environment Agency
Tamar Catchment Flood Management Plan
How we currently manage the risk
• Flood risk mapping – A major part
of the programme is Flood Zone
Improvements and Hazard
Mapping. This is focused on
improving the mapping at high-
risk locations.
• Managing development – Our
development control team
supports the planning process by
ensuring that new developments
have the appropriate flood risk
assessments and follow PPS25
(Government Planning Policy
Statement on Flood Risk).
• Flood warning – a multi-media
warning service called Floodline
Warnings Direct provides targeted
warnings to people via different
media methods, including
telephone, email and SMS text
messaging. We also provide a
public access telephone service
called Floodline that people can
ring to check if there is a flood
warning for their area. Major
Incident Plans are in place for
Launceston and Plympton and for
tidal flooding at the Barbican,
Plymouth.
• Flood defence schemes – We
have flood defence schemes at
Canworthy Water, Cawsand,
Gunnislake and Calstock,
Launceston, Notter Bridge,
Bathpool, Millbrook, Plympton,
Plymouth, Tavistock, Horrabridge,
Walkhampton, Yealmbridge and
Yealmpton.
• Maintenance – We maintain
channels and defences.
The distribution of potential flood
risk from rivers and tides is
illustrated in Map 2 for a flood with a
1% annual probability (0.5% for
tides) of occurring or being
exceeded.
The greatest concentration of
properties at risk of flooding is at
Plymouth and Plympton. Here some
1,510 properties are at risk from
river and tidal flooding. This is set to
increase due to rising sea levels.
Tavistock and Launceston have the
next highest concentrations in
property at risk with some 270 and
110 properties at risk respectively.
In addition to these locations, there
are risks of surface water flooding,
which can be deep and fast flowing,
across much of the catchment.
However, further studies following
on from the CFMP are needed by us
and our partners to quantify this
potential risk.
Where is the risk?
➜
Minor roads near Launceston
impassable due to flooding
Environment Agency
Tamar Catchment Flood Management Plan
9
The impact of climate change and future flood risk
We have considered a range of
factors that could influence flood risk
over the next 100 years to find out
how flood risks could change in the
Tamar catchment. We have found
that climate change has the greatest
influence on future flood risk,
increasing flooding from rivers and
the sea, as well as from sewers.
Land management also contributes,
because of the rural nature of the
catchment.
Urban development could affect
flood risk in a small number of
locations, including Plymouth,
Tavistock and Launceston.
Development in Plymouth in
particular may be significant with
investment and re-generation efforts
in existing waterfront areas. In
addition, a new town is planned at
Sherford, to the north-east of
Plymstock. As with all new
development, the new town of
Sherford will need to be
implemented in accordance with
PPS25 to ensure that flood risks are
not increased.
The following future scenario has
been used in the Tamar CFMP.
• 20% increase in peak flow in all
watercourses due to climate
change.
• a total sea level rise of 900mm by
2100 due to climate change.
• 7% increase in river flows due to
land use change.
• 4% increase in river flows in
certain locations due to urban
development.
0
500
1000
1500
2000
2500
Plymouth
Plympton
Tavistock
Launceston
Plymstock
Bridestowe
Current
Future
Number of
Pr
oper
tie
s
at
Flood Ri
sk
Figure 2. Current and future (2100) flood risk to property from a 1% annual
probability river flood, ignoring current flood defences
In the future we expect flood extents
to increase slightly but this is limited
in most places by the topography of
the catchment. However flood
depths are likely to increase. This
means that more people and
property will be affected more
frequently by flooding in the future.
Plymouth is expected to see the
greatest flood risk in the future (see
Figure 2).
10
Environment Agency
Tamar Catchment Flood Management Plan
Approaches in each sub-area
We have divided the Tamar catchment into six distinct
sub-areas which have similar physical characteristics,
sources of flooding and level of risk. We have identified
the most appropriate approach to managing flood risk for
each of the sub-areas and allocated one of six generic
flood risk management policies, shown in Table 2.
To select the most appropriate policy, the plan has
considered how social, economic and environmental
objectives are affected by flood risk management
activities under each policy option.
Map 3. Tamar sub-areas
Bude
Fowey
Bodmin
Totnes
Saltash
Plympton
Plymouth
Liskeard
Polzeath
Delabole
Torpoint
Ivybridge
Camelford
Plymstock
St Blazey
Tavistock
Ashburton
Callington
St Austell
Launceston
Okehampton
Mevagissey
Wadebridge
Kingsbridge
Horrabridge
Lostwithiel
St Columb Road
Great Torrington
Gunnislake
Tywardreath
© Crown Copyright. Environment Agency 100026380.
0
4
8
12
16
Kilometres
N
Legend
Tamar CFMP
Sub-area
Upper Tamar (Policy 6)
Tidal Central (Policy 6)
Plymouth Area (Policy 5)
East Tamar (Policy 4)
Central Tamar (Policy 3)
West Tamar (Policy 3)
1
2
3
4
5
6
7
8
9
Future direction for
flood risk management
➜
A farmer tries to reach a bullock in floods at Polson Bridge,
Launceston in October 2000
Environment Agency
Tamar Catchment Flood Management Plan
11
Policy 1
Areas of little or no flood risk where we will continue to monitor and advise
This policy will tend to be applied in those areas where there are very few properties at risk of flooding.
It reflects a commitment to work with the natural flood processes as far as possible.
Policy 2
Areas of low to moderate flood risk where we can generally reduce existing flood risk management actions
This policy will tend to be applied where the overall level of risk to people and property is low to moderate.
It may no longer be value for money to focus on continuing current levels of maintenance of existing defences
if we can use resources to reduce risk where there are more people at higher risk. We would therefore review
the flood risk management actions being taken so that they are proportionate to the level of risk.
Policy 3
Areas of low to moderate flood risk where we are generally managing existing flood risk effectively
This policy will tend to be applied where the risks are currently appropriately managed and where the risk of
flooding is not expected to increase significantly in the future. However, we keep our approach under review,
looking for improvements and responding to new challenges or information as they emerge. We may review
our approach to managing flood defences and other flood risk management actions, to ensure that we are
managing efficiently and taking the best approach to managing flood risk in the longer term.
Policy 4
Areas of low, moderate or high flood risk where we are already managing the flood risk effectively but where we
may need to take further actions to keep pace with climate change
This policy will tend to be applied where the risks are currently deemed to be appropriately-managed, but
where the risk of flooding is expected to significantly rise in the future. In this case we would need to do more
in the future to contain what would otherwise be increasing risk. Taking further action to reduce risk will require
further appraisal to assess whether there are socially and environmentally sustainable, technically viable and
economically justified options.
Policy 5
Areas of moderate to high flood risk where we can generally take further action to reduce flood risk
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.
Policy 6
Areas of low to moderate flood risk where we will take action with others to store water or manage run-off in
locations that provide overall flood risk reduction or environmental benefits
This policy will tend to be applied where there may be opportunities in some locations to reduce flood risk
locally or more widely in a catchment by storing water or managing run-off. The policy has been applied to
an area (where the potential to apply the policy exists), but would only be implemented in specific locations
within the area, after more detailed appraisal and consultation.
Table 3. Policy options
12
Environment Agency
Tamar Catchment Flood Management Plan
Upper Tamar
Sub-area 1
The issues in this
sub-area
The steeper rivers in this area react
fast to localised rainfall and
produce rapid increases in river
flows. This affects the settlements
of Holsworthy, Bridgerule,
Bridestowe, Northcott Hamlet and
Canworthy Water. When combined
with areas of restricted natural
floodplain, fast flows build up at
these constrictions and cause
severe localised flooding.
The 1% annual probability flood
affects approximately 90 properties,
a church and limited areas of
environmental importance. It is
estimated that in the future, by
2100, an additional 20 properties
could lie within the 1% annual
probability flood extent. This is
mainly due to the impacts of
climate change.
Our key partners are:
West Devon District Council
Torridge District Council
Devon County Council
Cornwall Council
Dartmoor National Park
National Farmers Union
South West Forestry
The vision and
preferred policy
Policy Option 6 - we will take action
with others to store water or
manage run-off in locations that
provide overall flood risk reduction
or environmental benefits.
This will reduce flood risk in
settlements and reduce the level of
risk in downstream areas. In
addition, this policy would benefit
the geomorphological processes of
the catchment and the natural
environment. Care must be taken to
ensure that actions do not result in
the disturbance to various SSSI and
SAC habitats and features.
Actions should concentrate on
floodplain attenuation
(connectivity) measures to benefit
the catchment downstream. Land
management measures to minimise
run-off should also be targeted.
Proposed actions
to implement the
preferred policy
• Complete Systems Asset
Management Plans for existing
defences at the Tamar, Deer and
Claw confluence. Consider the
potential to re-establish
floodplain and create wetland
habitat to reduce peak flows
downstream. Explore the
possibilities for flood attenuation
at Roadford Reservoir to reduce
peak flows at Lifton and Tinhay.
• Continue with work to identify
rapid response catchments.
• Increase awareness of landowner
responsibility regarding land
ownership, maintenance and
surface water flooding across the
dispersed, isolated communities.
• Investigate the potential for
creating wetland habitat and
flood storage in existing
floodplains. For instance,
upstream of Canworthy Water.
• Increase woodland and forest
cover by diversifying farming and
involving the community in
promoting the development of
woodland on upper catchment
slopes.
Land use planners should designate
floodplains and wetland areas as
functional floodplain in order to
maximise their storage potential
and reduce risks downstream. This
will also avoid introduction of
further constrictions to flood flows.
Environment Agency
Tamar Catchment Flood Management Plan
13
Our key partners are:
West Devon District Council
South Hams District Council
Cornwall Council
Devon County Council
Natural England
South West Forestry
Landowners
National Farmers Union
Tidal Central
The issues in this
sub-area
Tidal Central covers the lower
section of the River Tamar. It
includes the villages of Calstock,
Morwellham and Bere Ferrers, as
well as part of Gunnislake.
At Morwellham flooding is largely a
result of high flows in the River
Tamar. At Calstock it is due to a
combination of heavy rainfall and
high tides. Above Gunnislake the
River Tamar flows within an incised
valley that naturally limits
floodplain storage and confines the
flow of floodwater. Inundation can
also occur at periods of very high
spring tides.
There are several incidents of
surface water flooding recorded
across the area.
The 1% annual probability fluvial
flood (and 0.5% tidal) affects
approximately 50 properties. There
is one electricity substation at risk.
The number of properties at risk in
the future, as a result of the impact
of climate change has not yet been
assessed.
The vision and
preferred policy
Policy Option 6 - we will take action
with others to store water or
manage run-off in locations that
provide overall flood risk reduction
or environmental benefits.
The chosen policy will play an
important role in absorbing the
impacts of sea level rise.
We would intend to review the
capabilities of existing defences at
locations such as Morwellham and
Calstock, to ensure we can maintain
flood risk at an acceptable level.
The policy can also support the
improvement and expansion of
existing wetland areas and
designated sites.
Proposed actions
to implement the
preferred policy
• Develop System Asset
Management Plans that will
reduce our level of maintenance
and will utilise the floodplains
more effectively.
• Investigate the possibility of
creating flood storage areas for
fluvial waters linking existing
limited floodplains within the
estuary.
• Investigate potential for wetland
habitat creation through the
expansion of existing SSSI areas
and other appropriate wetland
areas within the Tamar estuary.
• Produce detailed studies for
Morwellham, Gunnislake and
Calstock to review capabilities of
current defences to cope with
combined high fluvial flow and
spring tides.
• Review urban drainage capacity
at Metherell and look at
improving conveyance at times of
high flows to reduce and prevent
out of bank flows.
Land use planners should designate
floodplains and wetland areas as
functional floodplain to protect and
enhance their storage potential.
Sub-area 2
14
Environment Agency
Tamar Catchment Flood Management Plan
Plymouth Area
Sub-area 3
The issues in this
sub-area
The Plymouth Area covers sections
of the Plymouth Sound, Tamar and
Plym estuaries, and includes the
City of Plymouth.
The City of Plymouth contains by far
the largest number of properties
within the Tamar catchment. The
city forms an important part of the
South West’s Regional Spatial
Strategy in providing new homes in
the future. Much of this
development may be around, or
adjacent to, the waterside areas.
Some of these areas of the city are
in the floodplain of the Tamar and
Plym estuaries. Infrastructure
around the city such as the A374
and mainline railway is also at risk.
Our key partners are:
Plymouth City Council
Cornwall Council
South Hams District Council
Devon County Council
South West Water
Network Rail
Natural England
It is estimated that, for the sub-area
as a whole, 1,600 properties are at
risk of flooding within the fluvial 1%
(and tidal 0.5%) annual probability
flood area. The defences at these
and other areas affected by flooding
are regularly maintained and are in
good condition although a residual
flood risk remains. Approximately
500 properties are protected by
defence schemes at the Barbican
and Plympton.
Surface water and sewer flooding
occurs due to surface water volumes
exceeding urban drainage system
capacity.
The number of properties at risk is
expected to increase to 2,800 by
2100 as a result of the impacts of
climate change and proposed
development planned within the
catchment.
The vision and
preferred policy
Policy Option 5 - we can generally
take further action to reduce flood
risk.
This policy will support
sustainability objectives by
reducing the future increase in flood
risks to the urban environment
whilst avoiding significant adverse
impacts on the environment. The
benefits are most significant in
relation to the economy of the
urban centres.
Objectives relating to
geomorphology, biodiversity, and
landscape may be met, but this
depends on the response used to
manage flood risk. However, it is
envisaged that sensitive and
appropriate approaches to
managing flood risk (through
incorporation of environmental
constraints during detailed
appraisal and design) could be
developed that do not cause
adverse impacts in the long term.
Environment Agency
Tamar Catchment Flood Management Plan
15
Proposed actions to implement the preferred policy
• Develop System Asset Management Plans to help reduce flood risk and investigate the need for, and
where necessary implement, Surface Water Management Plans for problem areas in Plymouth and
Plympton.
• Produce detailed studies for Plymouth, Plympton, Plymstock, Tamerton Foliot, Saltash and Turnchapel to
review flow capacities, obstructions to high flows and to investigate upstream attenuation.
• Use programmes to raise and maintain awareness of flood risk and self-help measures.
• Ensure development conforms to PPS25 and identify opportunities through the implementation of PPS25
to work with developers to reduce flood risk elsewhere in Plymouth area.
• Investigate adaptation measures for the mainline railway and the A374 road against increased flooding
due to climate change.
• Investigate opportunities to create green corridors alongside the rivers.
• Investigate opportunities for managed realignment to restore intertidal habitat along Plymouth waterfront
and estuaries.
• Continue with work to identify rapid response catchments.
• Review urban drainage capacity within Plymouth, Plympton and other major urban areas. Implement
findings and provide recommendations.
• Implement strategies for flood risk management of the mine site identified at Plympton to assess the
potential pollution risk from flooding.
16
Environment Agency
Tamar Catchment Flood Management Plan
East Tamar
Sub-area 4
The issues in this
sub-area
The steeper rivers in this sub-area
react quickly to localised rainfall,
producing rapid increases in flows
that affects settlements such as
Tavistock, Horrabridge,
Walkhampton and Dousland.
Exposed estuarine locations (Newton
Ferrers/Noss Mayo) can be subject to
tidal flooding when high tides
coincide with heavy rainfall. There is
also a history of surface water
flooding in Tavistock due to the
inadequacy of urban drainage
systems.
Our key partners are:
Devon County Council
West Devon District Council
South Hams District Council
Dartmoor National Park
Natural England
South West Water
It is estimated that 500 residential
properties, 3 electricity substations,
and a police station (in Tavistock) are
at risk of flooding from the 1%
annual probability flood.
Approximately 100 properties are
protected by defence schemes at
Dousland, Tavistock and
Walkhampton. The defences at these
settlements are regularly maintained
and are in good condition, although
a residual flood risk remains during
severe events.
In the future, Tavistock is expected to
see the greatest increase in the
number of properties at risk, with the
number increasing from 270 to 390.
The vision and
preferred policy
Policy Option 4 - we are already
managing the flood risk effectively,
but we may need to take further
actions to keep pace with climate
change.
The chosen policy was selected to
minimise potential social and
economic impacts from increased
flood risk in the future, whilst
avoiding potentially significant
environmental impacts.
Actions should concentrate on the
existing key settlements, but should
also include floodplain attenuation
(connectivity) measures to benefit
downstream areas.
Land management measures to
minimise run-off should also be
targeted.
Environment Agency
Tamar Catchment Flood Management Plan
17
Proposed actions to implement the preferred policy
• Develop System Asset Management Plans to help reduce flood risk.
• Undertake studies for flood risk problem areas such as Tavistock, Horrabridge, Walkhampton, Milton
Combe, Yealmpton, Wembury and Newton Ferrers to review flow capacities, possible obstructions to high
flows, and to investigate upstream attenuation.
• Continue with work to identify rapid response catchments.
• Support Local Authorities in the preparation of Local Development Framework Plans and associated
Strategic Flood Risk Assessments.
• Review urban drainage capacity within Tavistock particularly with regard to infill and new development to
find out where improvements can be made.
• Investigate the potential for creating flood storage areas in the upper parts of the catchment by creating
wetland habitat that are linked to existing floodplains, providing benefits to the lower parts of the
catchment including Tavistock.
• Review the possibility of more woodland and forest cover by diversifying farming and involving the
community in promoting the development of woodland.
• Raise and maintain awareness of flood risk and self-help measures.
• Increase awareness of landowner responsibility regarding maintenance and surface water flooding across
the dispersed and possibly isolated communities.
➜
The flooded River Yealm at Yeolmbridge in 1999
18
Environment Agency
Tamar Catchment Flood Management Plan
Central Tamar
Sub-area 5
The issues in this
sub-area
Central Tamar covers sections of the
Rivers Kensey, Ottery, Carey,
Thrushel, Lyd and Tamar. It includes
the town of Launceston which is
situated within the flood plain of the
River Kensey upstream of the
confluences of the Rivers Kensey and
Tamar.
Our key partners are:
Torridge District Council
West Devon District Council
Cornwall Council
Devon County Council
South West Water
Highways Agency
It is estimated that 140 properties
are at risk from the 1% annual
probability flood, with 100 of these
located in Launceston (as well as
other major infrastructure in the town
such as the A388) and 10 properties
in the villages of Lifton and Tinhay.
Flood defences reduce risks to 130
properties at Lifton/Tinhay, Luckett,
and Launceston (from both the River
Kensey and the Wooda Stream). The
defences at these settlements are
regularly maintained and are in good
condition though a residual flood
risk remains during severe events.
The number of properties at risk in
Launceston by 2100 will be in the
order of 125 as a result of the
impacts of climate change and
limited further development planned
within the catchment.
The vision and
preferred policy
Policy Option 3 - we are generally
managing existing flood risk
effectively.
There are a limited number of
economic and social assets at risk
of infrequent flooding in the long-
term. Whilst this policy will result in
the flood risk to these assets
increasing, the increased risk is not
considered to be significantly large
to justify increased levels of flood
risk management.
Actions in the Upper Tamar area
have the potential to reduce flood
risks in this area, which represents
a more effective response to flood
risk management as a whole.
The impacts of new development in
Launceston should be mitigated,
and overall flood risks reduced,
through the application of Planning
Policy Statement 25.
Environment Agency
Tamar Catchment Flood Management Plan
19
Proposed actions to implement the preferred policy
• Review existing channel maintenance and defences, and deliver System Asset Management Plans. In the
long term, review the effectiveness of existing flood risk management at Lifton, Tinhay and Gunnislake,
through the production of the plans.
• Investigate potential for creating wetland habitat by creating flood storage areas linked to existing
floodplains in the northern half of the area. This could be beneficial in reducing peak flows in this area
and downstream.
• Continue with programmes to raise and maintain awareness of flood risk and self-help measures.
• Continue with work to identify rapid response catchments.
• Support Local Authorities in the preparation of Local Development Framework Plans and associated
Strategic Flood Risk Assessments, including at least a level 2 assessment for development in
Launceston. Consider possible land use changes to less sensitive uses.
• Review existing flood risk in Launceston particularly with regard to infill and new development.
• Promote opportunities for the Environment Agency and the Highways Agency to work together to
implement Sustainable Drainage Systems.
20
Environment Agency
Tamar Catchment Flood Management Plan
West Tamar
Sub-area 6
The issues in this
sub-area
West Tamar covers the Rivers Inny
and Lynher and smaller rivers
draining to the Tamar. Flooding is
due to river, surface water, tidal and
tidal/wave action.
• River flooding is experienced
throughout the area with
overtopping of defences and
structure blockage leading to
excessive surface water flow.
This flooding can occur rapidly
and is often very localised.
• Exposed coastal locations
(Kingsand and Cawsand) and
estuarine locations (such as
Polbathic) experience tidal
flooding particularly at high
spring tides and have relatively
low standards of defence.
There are more than 270 properties
and one electricity substation at risk
of flooding. Of these, 16 properties
are defended by a scheme at
Millbrook. A section of the A374
between Polbathic and Sheviock is
also affected.
Our key partners are:
Cornwall Council
South West Water
The number of properties at risk is
not expected to increase by 2100.
The expected annual damages are
predicted to change very little by
2100 as a result of the impacts of
climate change and limited further
development planned within the
catchment.
The vision and
preferred policy
Policy Option 3 - we are generally
managing existing flood risk
effectively.
The chosen policy allows us to
undertake work such as System
Asset Management Plans to review
the existing defence regimes. It will
allow us to continue to manage the
flood risk into the future at locations
such as Altarnun and Millbrook -
accepting that there may be a slight
increase in flood risk in the longer
term but not committing large
expenditure to the development or
improvement of new flood defence
schemes.
This should provide benefits to
Plymouth by allowing more
resources to be concentrated in the
area of greater residential and
commercial development.
Additionally, the policy should avoid
adverse impacts upon
environmentally designated sites.
Proposed actions
to implement the
preferred policy
• Deliver System Asset
Management Plans based on
existing or alternative actions.
• Review flow capacities and
possible obstructions to high
flows at St Germans, Tideford,
and Polbathic.
• Continue to use programmes to
raise and maintain awareness of
flood risk and self-help
measures.
• Increase awareness of landowner
responsibility regarding
maintenance and surface water
flooding across the dispersed,
isolated communities within this
policy area.
• Continue with work to identify
rapid response catchments.
Environment Agency
Tamar Catchment Flood Management Plan
21
Map of CFMP policies
Map of the policies in the Tamar catchment
© Crown Copyright. Environment Agency 100026380.
Legend
Tamar CFMP
Main rivers
Urban areas
Preferred approach
Policy 1
Policy 2
Policy 3
Policy 4
Policy 5
Policy 6
Lostwithiel
Camelford
Launceston
Tavistock
Bodmin
Callington
Horrabridge
Liskeard
Plymouth
Ivybridge
Okehampton
Bude
Great
Torrington
0 4 8 12
16
Kilometres
Plympton
Plymstock
1
2
3
4
5
6
N
1
Upper Tamar
2
Tidal Central
3
Plymouth
4
East Tamar
5
Central Tamar
6
West Tamar
The sub-areas
GESW0612BWPV-E-E
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