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Areas
at risk
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Speed
of flooding. Bank heights in
Central London are well below the
7 metre level so a storm surge large
enough to overwhelm the Barrier
will also exceed embankment walls.
The timescale will depend on a number
of factors like height of surge
and strength and persistence of
winds, but an estimate can be worked
out from tide tables.
In
normal circumstances, high water
on a spring tide takes roughly 20
minutes to travel from the Thames
Barrier to London Bridge and a further
30 minutes to reach Putney Bridge.
In other words, riverside Central
London could be inundated within
an hour of the Barrier overtopping.
Extent
of flooding. The amount of water
that pours into a particular area
will be governed by the severity
of the storm surge and by the height
of the embankment at that location.
Embankment
heights vary:
7.2
m alongside the Barrier
5.18-5.23 m on the Greenwich Peninsula
5.41 m between London Bridge and
Putney
5.54 m at Chiswick
Any
breach to the defences will increase
the rate and potential for damage.
Given the traffic and number of
moored vessels on the Thames, accidents
are almost inevitable.
London's underground rivers may
also contribute to the flooding,
particularly if there has been high
rainfall preceding the storm. Hammersmith
is likely to be affected as are
Stratford and Bow where the River
Lea joins the Thames.
Depth
and ponding. The depth of water
in the streets and the length of
time it remains will be determined
by the height of the land, or contour
level. Behind the embankment walls
a frighteningly large area of London
falls below the 10 metre contour
line (see map).
Paradoxically,
the walls are part of the problem.
London was once marshland with a
river flowing through. The Romans
started building flood defences
to make berths for their cargo ships.
Now twenty miles of embankment enclose
the Thames as it passes through
the city.
If
marshland is protected from flooding
its characteristic silts and peats
dry out and the level of the land
behind flood defences sinks. This
has happened in London. When flood
water overtops the embankment it
will pool in these low-lying areas
taking days, weeks in some places,
to drain away. The official term
for this is 'ponding' and the ponds
could be up to 3 metres deep.
Districts
most susceptible to ponding are:
parts of Chiswick; Hammersmith;
Barnes; riverside Fulham and Chelsea;
parts of Pimlico; Battersea; Westminster
from the river into St James's Park;
Southwark; Isle of Dogs; Greenwich
Peninsula; Newham; North and South
Woolwich; Beckton and Barking.
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Personal
Survival
Information.
The EA's Floodline number 0845 988
1188 gives information and advice
on all matters concerning flooding.
Severity is indicated by a code
system: All Clear; Flood Watch;
Flood Warning; Severe Flood Warning.
Unfortunately,
telephoning may not be an option.
With a large scale emergency such
as the flooding of London, telecommunications
are likely to be disrupted, either
by water damage or by pressure of
calls overwhelming the system. In
addition the mobile network may
be closed down to give precedence
to emergency services. Television
and radio, particularly local radio,
are an alternative source for announcements.
A battery or wind-up radio is a
useful standby.
Sandbagging.
If there is sufficient warning,
sandbagging will help to keep water
out. Sandbags are available at builders'
merchants but can be homemade from
carrier bags or pillow cases filled
to three-quarter capacity with sand
or earth. Over-filled bags will
not lie together snugly and water
will seep through the chinks. Put
a plastic sheet underneath to act
as a seal and arrange the bags end
to end like brickwork. If the sandbag
wall is to be more than two bags
high, lay a double line at the bottom
to give stability. All other possible
entry points for water, such as
air vents and utility inlets, should
be sealed.
In
a prolonged flood sandbagging will
delay but not prevent water from
entering. Eventually water will
seep through brickwork and percolate
up through the floor.
Before
the flood. In the home, turn
off gas and electricity, fill the
bath with drinking water and have
buckets and mops ready in case of
back-up from drains and lavatories.
Move all people and pets upstairs
with supplies of food, warm clothes
and blankets, any medication needed,
and a torch.
If
in a basement or ground floor apartment,
arrange to lodge with a neighbour
on a higher level. Do not use lifts,
they may cease running suddenly
as power is cut.
During
the flood. Do not go out unless
absolutely necessary. It is easy
to underestimate the power of a
flood. Twenty centimetres of fast-flowing
water can knock an adult off his
feet. Floods suck off manhole covers,
uproot paving stones and distribute
debris. Roadworks, steps and other
hazards are concealed by water.
Driving is equally hazardous. If
caught in water, the technique at
fordable levels is to proceed slowly
but evenly in a low gear to avoid
the build up of a bow wave. Most
4WDs will operate up to their wheel
arches but saloons are in trouble
sooner. Once water enters the air
intake, an engine is likely to be
damaged.
Evacuation.
In severe conditions, the authorities
may decide to evacuate. Information
will be given over the usual channels
and/or by hailer. You may be told
to hang a sheet out of the window
to alert rescuers. If evacuated
you will be taken to a reception
centre where warm clothing and food
will be provided.
Rules
for evacuation are: dress warmly,
take the minimum (remembering any
medication) and be ready to leave
at short notice.
After
the flood. Contact your insurance
company immediately. As well as
dealing with claims, insurers can
usually recommend professional cleaners
and other help.
The utilities (gas, electricity
and water) will advise about reconnection.
Household appliances and electrical
wiring should be tested before use.
In
the event of sewage contamination
vaccinations may be necessary, particularly
for children, and drinking water
should be boiled. The local authority
will be able to give guidance.
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Emergency
Response
The
principal function of all three
emergency services is the saving
of life.
The
Metropolitan Police are in overall
command at a major incident in the
capital, controlling access and
liaising between the other services,
local authorities, the military
and voluntary agencies. Additional
duties include collection of casualty
information and indentification
of the dead. The Thames Division,
based in Wapping, has half a dozen
boats and a team of specialist divers.
London
Fire Brigade (LFB) is responsible
for fire-fighting, the pumping of
flooded premises and for the search
and rescue of survivors. LFB is
also charged with the containment
of chemical spills and management
of hazardous materials.
London
Ambulance Service (LAS) provides
treatment, stabilisation and care
of injured at the scene as well
as transport to hospital. LAS will
establish effective triage points
where the injured can be prioritized.
Each
service has a command and control
structure using the titles, Gold,
Silver and Bronze to cover strategic,
tactical and operational functions.
Gold is the senior position and
when gold commanders from the three
services meet, the police take the
chair.
Triple-C.
If a severe tidal flood is threatened,
the Home Secretary will convene
the Civil Contingency Committee
(Triple-C) at the Cabinet Office
in Whitehall. Gold commanders will
attend, along with the military,
senior civil servants and civilian
experts, to manage the disaster.
Triple-C
meetings are usually held in COBRA
(Cabinet Office Briefing Room A)
in the basement of the Cabinet Office.
With Whitehall in the flood zone,
Triple-C will have to evacuate to
a temporary location. The Guards'
Barracks in Hyde Park, Knightsbridge
is a likely choice.
Evacuation
and withdrawal. A massive flood
will take out the entire heart of
government. Every ministry and major
department will be forced to evacuate
at short notice. Communications
will be disrupted, data lost and
key personnel unavailable. From
interviews with senior officers
and the study of procedural manuals,
it is clear that while the Emergency
Services are prepared for a major
but contained incident, a terrorist
bomb, an industrial accident, an
airplane crashing on the city, they
will be impossibly stretched in
the event of serious and widespread
tidal flooding.
The
Met has its headquarters at New
Scotland Yard. This falls within
the flood zone so the Central Command
Complex, including the Special Operations
Room from which disasters are monitored,
will have to move out to back-up
facilities at the Police College,
Hendon. All police vehicles within
the zone will also be withdrawn.
Initially,
the main problem for the Met will
be traffic management. The rush
to leave will cause gridlock on
exit routes and cars will be jammed
in vulnerable areas such as the
embankment and Blackwall tunnel.
The
police will be responsible for the
safety of those in custody in police
cells in the flood zone. They are
also likely to be called upon to
assist in the evacuation of HMP
Belmarsh. This maximum security
prison holds 850 category A prisoners
including terrorists. It is located
on low-lying land at Thamesmead
near the Barrier.
Large
scale evacuation of the population
is a government, not a police, decision
although the police would be involved
in implementation. In practice,
government would be reluctant to
give an evacuation order because
of the inevitable chaos and loss
of life that would ensue.
LFB
headquarters are in Lambeth, also
in the flood zone. Control will
be transferred to a station in Clapham.
Fire engines cannot operate in water
above exhaust level and will be
moved out to high ground. The LFB
has two launch-type fire boats but
these are designed for fire-fighting
on the river and are not suitable
for rescue work in flooded streets.
LAS
Central Control is run from Waterloo
with a back-up in Bow, east London.
Both of these locations are in the
flood zone. Like other emergency
service vehicles, ambulances cannot
operate in water of any depth.
An
additional concern is the strain
on the NHS. At least twenty of the
capital's NHS and private hospitals
are at risk of flooding and likely
to lose power and sanitation. These
hospitals will be unable to receive
flood casualties and will experience
problems with resident patients,
particularly those in high dependency
units.
Hospitals in Flood Zone
Military
Assistance. In the event of
a major incident, the armed services
are authorised to provide all possible
assistance to the emergency services
where a threat to life exists.
During
the 1953 floods the military played
a key role in rescue and repair
operations. In the 1950's there
were at least a million men in the
armed services; today the figure
is 220,000, of which a significant
proportion will be unavailable because
of overseas commitments.
Against
this, airpower has increased. With
up to 75 square miles of London
potentially under water and emergency
vehicles incapacitated, helicopters
will be essential for transport
of sandbags and machinery, rescue
and evacuation.
There
are approximately thirty-five Search
and Rescue (SAR) Sea Kings, capable
of carrying thirty passengers, dotted
round the country but they are already
committed to covering the coast.
The RN also possesses Sea Kings
but the majority are deployed abroad,
or are in service with ships, and
others will be undergoing maintenance.
Around twenty could probably be
found in a relatively short time.
The RAF has thirty-six twin-engined
Chinook medium-lift helicopters
with capacity for one hundred passengers.
Some of these may be abroad but
the majority will be stationed in
Hampshire and readily available.
In addition the RAF has a few Pumas
and twenty-two Merlins three or
four hours' away in Northern Ireland.
Further help may be expected from
US air bases in the UK and from
European neighbours, but this will
take time to arrive.
Helicopter
operations over the capital will
be coordinated by the RAF.
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Fire
Storm- the added threat
Petrochemicals
in the Estuary. The Thames is
London's fuel pipeline. From Purfleet
down to the mouth of the Estuary,
the north bank of the river is dotted
with oil storage depots. The greatest
concentration is around Canvey.
On the island itself there are liquid
petroleum gas installations and
an oil storage facility and around
half a mile away across the Creek
at Coryton, BP operates one of the
U.K.'s nine major oil refineries.
The river is deep and wide enough
at this point for giant supertankers
to berth and deliver their crude
before heading back out to sea.
The
BP Coryton plant covers 370 acres
and employs around 500 people. It
processes 10 million tonnes of crude
a year and since, by law, oil companies
are required to hold stocks sufficient
for three months, there is considerable
storage on site and at neighbouring
Thames Haven.
All
along the Estuary flood protection
meets Barrier standards, but in
the case of petrochemicals flooding
is not seen as a major risk. Even
at the oil refinery a two to three
hour warning would be enough to
run close-down procedures and the
worst outcome would be a costly
cleaning programme to rid pipes
of solidified bitumen.
Fire, on the other hand, is potentially
devastating. The scenario in FLOOD
involves a supertanker out of control
on the swollen river and the piercing
of a liquid petroleum gas tank.
LPG is heavier than air, so disperses
slowly, and is flammable. Add a
stray spark and conflagration results.
Fire
on Flood. Oil storage depots
are planned with fire in mind, the
tanks surrounded by earth berms
to contain and isolate chemical
spills. This system is effective
for fire alone but in the face of
fire and flood it is all but useless.
Floodwater would fill the ditches
allowing oil to spread freely across
the surface.
Once
out into the Thames the burning
oil slick would be carried with
the storm surge towards London,
the flames fanned by wind and the
fire fed from sources close to the
banks (oil storage and Ford engineering
works at Dagenham, paper and chemicals
at Tilbury, oil storage at Dartford,
the Tate & Lyle sugar factory
in North Woolwich, fuel reserves
at London City Airport, filling
stations etc.). In the streets of
the capital the fires would be near
impossible to put out. Conventional
fire fighting equipment cannot operate
in flooded conditions; appliances
are useless above exhaust level.
Other than fire boats and tugs,
of which there are only six on the
Thames, the only effective mode
of attack would be from the air.
The U.K. has two helicopters equipped
for fire-fighting, one is located
in Plymouth, the other in the Highlands
of Scotland.
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