Introduction
On 16 August 2004, flooding took place in the village of Boscastle
in south west England. Fortunately, nobody died in the floods but
many people had to be rescued by helicopters. Much damage was caused
to houses and local businesses during the flooding which cost millions
of pounds. Two rivers burst their banks, allowing flood water to
sweep through the village. Around fifty vehicles were destroyed.
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| Fig 1: The rescue operation. |
Fig 2: Flooding at Boscastle |
Areas affected
Fig 3: United Kingdom. |
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Fig 4: Location of Boscastle |
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Fig 5: Map of Boscastle, South-west England. |
Physical impacts
Flooding
The village of Boscastle was severely damaged by flooding. About
75 mm of rainfall (the average for the month of August) fell in
two hours. The sudden rainfall caused two rivers, including the
River Valency, to burst their banks and a wall of water flowed
through the main street, washing cars, walls, and river banks
away. About two billion litres of water are estimated to have
flowed through Boscastle that day.
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| Figures 6 and 7: Cars washed
away in floodwaters. |
Destruction of houses, businesses and gardens
| About 25 business properties were destroyed in the flooding.
Minster church was filled with six feet of mud and water.
Trees were uprooted and were dumped in peoples’ gardens.
The weight of water eroded river banks, damaged gardens and
pavements.
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| Fig 8: Chris Rodda in the remains of his neighbour’s garden
after the floodwater transported about 20 tonnes of rock
and earth. |
Human impacts
- Financial costs. Costs of operating the rescue bid
by helicopter, lifeboats and fire services.
- Long-term stress and anxiety to people traumatised
by the incident.
- Long-term financial loss in tourism income.
- Fifty cars damaged beyond repair, fuel from which was
spilt into the water and sea
- Increased amount people have to pay for their car and
home insurance in Boscastle. It is estimated that insurance
companies have paid out about £15 million.
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| Fig 9:
Businesses damaged by the floodwaters |
Theory
Weather map
Figure 10 shows the weather map for midday on 16 August
2004. The wind is blowing anticlockwise about the low
pressure area. Therefore the air is arriving into Boscastle
from a south-westerly direction. It is a warm and moist
tropical maritime airmass.
The trough line labelled caused very heavy rain and
thunderstorms. A trough is an area of very localised
rain and thunderstorms. A line of convergence formed
near the coast line (where air moving in almost opposite
directions collides) and helps to increase the rate of ascent and therefore
produce heavy rain.
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| Fig 10: Weather chart for 16
August 2004 |
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| Radar imagery
Figures 12 to 19 show a sequence of radar pictures
from midday (12 p.m.) to 7 p.m. on 16 August. Alternatively,
Figure
11 shows an animation of the same images.
The
'Rainfall Rate' key shows how the colours in the image
relate to the rate at which rainfall is falling. For
example, the red areas indicate that rain is falling
there at between 8 and 16 mm per hour.
A line of very heavy rain starts about 1 p.m. on the
moors close to Boscastle. It remains over the area for
about six hours. Rainfall rates of at least 32 mm per
hour are being measured.
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Fig 11: Sequence of radar pictures
from midday (12 p.m.) to 7 p.m. on 16 August 2004 (click
on the image for an animated version) |
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Fig 12: Radar picture for 12 p.m. on 16 August 2004
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Fig 13: Radar picture for 1 p.m. on
16 August 2004
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Fig 14: Radar picture for 2 p.m. on
16 August 2004
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Fig 15: Radar picture for 3 p.m. on
16 August 2004
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Fig 16: Radar picture for 4 p.m. on
16 August 2004
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Fig 17: Radar picture for 5 p.m. on
16 August 2004
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Fig 18: Radar picture for 6 p.m. on
16 August 2004
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Fig 19: Radar picture for 7 p.m. on
16 August 2004
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| Satellite imagery
Figures
21 to 28 show satellite pictures from 12 p.m. (midday)
to 7 p.m. on 16 August 2004. Alternatively, Figure
20 shows
an animation of the same images.
The thickest cloud is shown by the brightest white areas
on the picture. The pictures show cloud forming over Boscastle
at about 1 p.m. and staying there for much of the afternoon. |
Fig 20: Animation of satellite images
for the period 12 p.m. (midday) to 7 p.m. on 16 August
2004 (click on the image for an animated version) |
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Fig 21: Satellite image for 12 p.m.
on 16 August 2004
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Fig 22: Satellite image for 1 p.m.
on 16 August 2004
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Fig 23: Satellite image for 2 p.m.
on 16 August 2004
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Fig 24: Satellite image for 3 p.m.
on 16 August 2004
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Fig 25: Satellite image for 4 p.m.
on 16 August 2004
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Fig 26: Satellite image for 5 p.m.
on 16 August 2004
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Fig 27: Satellite image for 6 p.m.
on 16 August 2004
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Fig 28: Satellite image for 7 p.m.
on 16 August 2004
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Rainfall totals
The map in Figure 29 shows the amount of rainfall (in millimetres)
that fell in 24 hours on 16 August 2004. About 200 mm
(that’s 20 cm) of rain fell close to Boscastle in that
24-hour period, with much of this falling in around five
hours |
 Fig
29: Rainfall totals for 16 August 2004 |
Responses - discussion
A total of 150 people were airlifted to safety from stranded
cars, rooftops and trees where they had climbed to safety.
John Prescott, the Deputy Prime Minister and Prince Charles
visited members of the emergency services and the local GP
surgery, which acted as the emergency centre, in the days following
the disaster.
The Office of Deputy Prime Minister provided around £450,000
to pay for 'uninsurable' insurance costs in the village.
| Prince Charles, who is the
Duke of Cornwall, made a sizeable donation to a fund
to help rebuild parts of Boscastle.
The Environment Agency is responsible for
warning people about floods and reducing the likelihood
of future floods. The Environment Agency has laid a larger
flooding relief channel for the river and is looking at
altering the narrow bridge which tends to block floodwater.
The Met Office is investing in new ways of predicting
heavy rainfall events on a small scale to produce better
warnings. |
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| Fig 34: 26 August 2004, when villagers
were allowed back into their homes to begin clearing
up. © APEX |
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Rebuilding Boscastle
Tourist numbers were up to near normal for day trips to Boscastle,
a year later in August 2005, but overnight stays were down
a little.
Some rebuilding work has been done since, with business and
homes reopened. However some businesses remain closed and unrepaired,
due to problems in reclaiming money from insurance claims.
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Fig
35: When the flood was
flowing through Boscastle on 16 August 2004 and after
the event.
Image courtesy of BBC News |
Fig
36: When the flood was
flowing through Boscastle on August 16 2004 and after
the event. Image courtesy of BBC News |
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