[PDF]Flooding in Gardens-How to cope with excess water in the garden

IS YOUR GARDEN THREA

Two million homes in England and Wales
are at risk of flooding from rivers or the
sea.The Environment Agency is
responsible for flood defence, warning
and communications to the people living
in these properties.

You can find out if you are at risk by
calling Floodline on 0645 988 1188 or

visiting the Environment Agency's website
at www.environment-agency.gov.uk/flood.

If your home is at risk, there are simple
steps you can take to lessen the distress
and expense it may cause to you and
your family. Even if your home itself is not flooded, floodwater can cause havoc in
the garden, destroying years of dedicated effort and costly planting and landscaping.
This guide shows how you can plan your garden to withstand the worst ravages of
flooding and how to restore it if the worst happens.




FLOODING. You cant always prevent it, you can prepare for it



In England and W ales the Environment Agency operates a flood warning service in
areas at risk of flooding from rivers or the sea. If flooding is forecast, warnings are issued
through the media or direct to people at home or work using a set of four
easily recognised codes.



Flood
Watch



Flooding possible. Be aware! Be prepared! Watch out!



Flood
Warning



Flooding expected affecting homes, businesses
and main roads. Act now!



Severe

Flood

Warning




Severe flooding expected. Imminent danger to life and
property.Act now!

An all-clear will be issued when flood watches or
warnings are no longer in force. Floodwater levels
receding. C heck all is safe to return. Seek advice.



Contents



Preparing for a flood
If floods are imminent
After a flood



2
4
5




Restoring your garden 6

W hat to do with your plants 7

M inimising future flood damage 8

Flood-resistant planting 10

Vegetables, lawns and wildlife 12

The Environment Agency and Gardening W hich? 13



Preparing for a flood



Why flooding is a problem

In autumn 2000, Britain experienced some
of the heaviest rainfall in years, leading to
severe and widespread flooding.A further
outbreak of flooding in autumn 2001 had
even more impact than the previous year's
floods in some areas.

In the worst affected places, gardens were
completely devastated by the direct impact
of the floods; others became overgrown
and neglected as people moved out of
their homes for months. Frequently,
gardens were used as temporary parking
spaces for caravans housing flood victims.
Long after the water levels subsided,
gardeners found that plants had suffered
damage from the storms and waterlogging.

Scientists are predicting that climate
change will lead to more frequent floods
in the future. Although flooding is a natural
event that can't be prevented, you can be
prepared for it. Follow the advice in this
booklet to protect the plants and hard
landscaping in your garden when floods
are forecast, and take action now to
reduce further damage if you live in
a flood risk area.After the floods have
passed, use our guide to help you return
your garden to its former glory.

This booklet explains how to cope with
unexpected flooding from overflowing
rivers or canals, run-off from agricultural
or industrial land, and water from the sea
or estuaries reaching low-lying coastal
areas. Some of the advice in the section on
drainage applies equally well to situations
where there is groundwater flooding
(when an already high water table in
poorly draining soil rises above ground
level following heavy rainfall).



Before a flood

•Call Floodline on 0845 988 1188 for
free information, including a factsheet
pack, a Flood D irectory about the
warning service in your area and
a handy guide on how to flood-proof
your home.

• Keep a list of useful telephone numbers
to hand - your local authority,
emergency services, insurance company
and Floodline.

•Talk to your family, friends and
neighbours about what you would do,
and prepare a flood plan together.
Discuss what you might need in the
event of a flood.

Make up a flood kit. Include a torch,
blankets, a portable radio, important
personal documents stored in closed
polythene bags and waterproof clothing
including rubber gloves and boots. Store
the kit in a place safe from floodwater.
Buy or make sandbags to block patio
and garden doors and airbricks.

Insu rance

Your household insurance policy will
usually cover damage to outbuildings,
garages and sheds. It does not generally
cover storm or flood damage to gates,
fences, hedges, garden plants, containers
or ornaments unless you have taken out
an extension to your household policy.



H



Using sandbags & floodboards

Keep a stock of unfilled hessian or plastic
sandbags, sand, a shovel, bricks, blocks of
wood, nails and a saw in the shed. In an
emergency, make sandbags from old
pillowcases, empty compost bags or
black plastic sacks.These can be filled
with sand or earth.

•Two people are needed to fill sandbags:
one to hold the bag open, one to fill.
Wear gloves when handling sand, as it
is abrasive. Take care when lifting
heavy bags.

• Protect large areas of sheet glass in
patio doors by placing sandbags,



plywood or metal sheeting outside
doors and window frames. Weak or
damaged banks and retaining walls can
be shored up with sandbags.

•Greenhouse doors can also be
protected with floodboards. Even if
you cannot create a complete seal,
the boards will reduce the amount
of floodwater entering the building.

•After the flood has passed, remove
sandbags and debris piled up against
airbricks in buildings to allow free
air circulation.



Positioning
sandbags

U




Using boardsto
prevent floodwater
entry to property
and gardens




Tuck flaps under Board




H



If floodsare imminent

In the garden

• Unplug any exterior electrical
connections such as outdoor lighting
and pond pumps and filters. Direct-
drive pumps can remain submerged in
water but bring low-level equipment
indoors if possible.

•Check that non-return valves are
fitted on outdoor taps.Turn off the
water supply to the garden.

•Weigh down manhole covers with
sandbags or heavy objects. If they lift
up during a flood, the drain may be left
open which could create a hazard.

• Move free-standing items such as pots,
dustbins, rotary driers, statues,
obelisks, furniture and play equipment
to a sheltered location or weigh them
down in situ with sandbags.

• Move small containers to higher ground,
or onto strong, stable structures such
as a brick-built barbecue, heavy picnic
table or built-in greenhouse staging.

•Tie in climbing plants.

•Check tree ties are secure on newly
planted trees.

•Anchor fruit cages and coldframes
against storm damage or dismantle
them if time permits.Take up cloches
and bean supports and store them in
a safe place.

•Take valuable objects (or those of
sentimental value) indoors, or move
them to a higher place in the garden.
Move treasured border plants to raised
beds, plant stands or heavy containers.

• Peg netting securely over ponds to save
plants and fish from being swept away.




Shed and greenhouse

• Move powered machinery indoors or
raise it on pallets.

• Empty petrol mowers. Keep all
paperwork relating to machinery
filed indoors.

• Lock gardening tools away.

• Remove any chemicals, fertilisers,
pesticides, oils, paints and petrol and
lock them away safely indoors. If left
outside, they could be swept into the
floodwater and pollute watercourses.

•C lose off the flow valves on gas
cylinders in the greenhouse and unplug
all electrical equipment. Remove low-
level electric heaters and grow-lights.
Check that wind braces and anchors
on the greenhouse are secure and
close vents and windows. Protect
greenhouse bases with sandbags.

• Move small containers, bags of compost,
watering cans etc, onto greenhouse
benching. Harvest any crops that can be
ripened indoors, such as tomatoes.



After a flood



Mark the high water level on outside
walls for reference. This will also act as
a reminder when replanting. If you are
making an insurance claim, do not throw
anything away until you have been told
that you may. If in doubt, take photographs
or video footage of damaged items.

Water levels may fluctuate for several
weeks, depending on rainfall and drainage
conditions. Check weather reports and call
Floodline on 0845 988 1188 for the latest
flood warnings. Wait to start repairs until
you are sure that the floods are over.

Health and safety

Wear rubber boots and disposable rubber
gloves when working outside, as
floodwater may be polluted with oil,
chemicals, and untreated sewage. Cover
any open wounds with waterproof
plasters. If you are not inoculated against
tetanus, contact your local health centre.

Keep off flooded lawns and borders as far
as possible. Keep out of fast-flowing water
or deep still water, and be aware that
standing water may contain mud, broken
glass or lumps of debris.Young children,
pregnant women, the elderly and anyone
with a weakened immune system should
stay away from flooded areas altogether.

If crossing standing water, move slowly
and carefully and use a stick to check for
holes, dislodged manhole covers and sharp
objects. nee water levels have returned
to normal, lawns, paths and patios may
remain slippery from sediment. Give hard
surfaces a thorough hose down and allow
them to dry before resuming normal use.

Check outdoor buildings and structures by
examining roofs, walls, fencing, doors and
windows for any changes. Flooding may
also have damaged soil-retaining walls and



eroded banks or terracing.You may need
to contact a professional who can assess
any structural damage.

Limit the time spent working in damp,
wooden buildings, as moulds can worsen
chest complaints.Although the risk of
illness is minimal, if you accidentally
swallow floodwater and feel unwell,
contact your doctor.

You may find mice or rats, stray cats or
dogs, or homeless wildlife sheltering in
your garden after a flood. Contact your
local authority's pest control officer or
dog warden, the RSPCA,or your local
W ildlife Trust if you need help.

Electricity

Following a flood, turn off the electricity
supply to the garden. Do not use any
appliance that has been affected until it,
and the power supply, have been checked
out by a competent electrician.

Waste collection

Flood debris and other waste is classified
as 'controlled waste' as it may contain
small amounts of chemicals, oil, solvents
and sewage. Local authorities sometimes
provide skips for the disposal of flood
waste, or can give advice on where to
get them. therwise, specialist waste
management firms can advise (see
Yellow Pages or www.yell.com).

D ispose of wet sandbags, affected bags of
compost and fertiliser, sand from children's
sand pits and bark chippings covering play
areas. Clear mud and leaves blocking
drains and gutters.

If a lot of mud or silt has piled up on both
sides of a wall, remove it gradually from
both sides to avoid overloading one side,
which could cause damage.



Restoring your garden



Brick and wooden structures

Hose down and scrub mud from
rendered and brick walls. Brick or block
walls will gradually dry out naturally,
though this may take many months.
Efflorescence, a white bloom, is caused
by soluble salts within the clay being
transported to the surface of wet bricks:
it will stop appearing when the wall has
dried and can then be removed with
a bristle brush. Green algae and moss
can be removed with a stiff brush and
the wall washed down with disinfectant.

Brickwork, especially old bricks, may
suffer damage from the pressure of the
floodwater. In particular, if a hard frost
follows a flood, bricks may shrink or crack
as they dry. Make a note of any cracking
and fill it once the brick has completely
dried out, then repoint the brickwork.
More serious cracking and buckling may
have weakened the wall and damaged
parts should be repaired or, if necessary,
rebuilt by a reliable contractor.

Fences, gates, pergolas and other wooden
structures can suffer damage if in
prolonged contact with water. C heck for
loose planks, panels and rotting posts and
replace them with wood that has been
pressure-treated with timber preservative.

In greenhouses and outbuildings, wooden
window frames may jam when wet and
warp as they dry.This may lead to flaking
paint. C heck for signs of rot, and repair
and treat the timber. nee dry, the frames
can be repainted. pen vents in the
greenhouse once the weather improves
and remove and destroy any damaged or
diseased pot plants. Wash down glass and
benching with disinfectant.

Check wooden furniture and play
equipment for loose nails, rot and fungal



growths. Clean with detergent, and leave
to dry, then treat with a fungal inhibitor.

Soil and borders

As the floods recede, make a note of
low-lying areas in the garden to help with
replanning later. If you have hired a pump
to clear water from your house, check
whether you can use it out of doors as it
will greatly speed up the drainage process.

Sodden soil can lead to shallow rooting,
making plants unstable and prone to
drought in dry spells. It also encourages
slugs and snails and fungal diseases such
as phytophthora, which kills plant roots.
Deep digging can loosen soil compacted
by flooding, but wait until it dries out.
Turn over the earth to the depth of your
spade and avoid bringing heavy subsoil to
the surface. Try not to tread directly on
sodden soil.W here possible, work from
boards to avoid compaction, or place
stepping stones among borders.

There is nothing practical you can
do to counteract the effects of salt left
by seawater flooding, though it will
disperse in time. Precious plants can
be lifted, the soil washed off, then
replanted in containers. Raised beds
made from uncontaminated soil are
a longer-term solution.

Ponds

In general, most aquatic life can cope with
freshwater flooding. Depending on the
location, you may well find that fish have
not swum away, but remained in their
flooded pond, surviving strong currents
by burrowing into the mud. Sea water is
more likely to cause fatalities among the
fish population. Most aquatic plants,
however, are dormant in autumn and
winter, and should recover by the
following spring.



What to do with your plants



Perennials

Most plants will survive a few days'
immersion in water, but the roots need
oxygen and will begin to die if left in cold,
waterlogged soil, especially if you have
been flooded by salt water. Rescue your
most valuable plants. Gently fork them
out of the soil, wash silt and debris from
the roots and foliage, then heel them in
in a drier part of the garden, or pot up
small plants in containers with fresh
compost until they can be planted out.
Digging a shallow trench around
vulnerable plants will help drain water
away from their crowns. Lightly forking
around larger shrubs and trees will help
to break up any surface compaction and
relieve local drainage problems.

If there are obvious signs of dieback, such
as browning leaves, check the viability of
stems or branches by removing a sliver
of bark. n living stems, the bark will be
firm, the underside green and the wood
beneath green or white and moist. n
dead stems, the bark will either be soft
and shiny, or dry and tough, the underside
will be brown or black, and the wood
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