Flash floods occurred in the valleys of the River Valency and the River Jordan on 16th August 2004.
Physical:
The village of Boscastle is situated:
in a narrow valley with interlocking spurs which acted like a funnel
in a steep valley which encouraged rapid run-off
on a flat flood plain
in an area where the soil is impermeable clay which does not allow much infiltration
Climatic:
185 mm if rain fell in five hours
The soil was saturated from recent rainfall so no more rain could infiltrate
The collision of winds on a very warm day caused the excessive rainfall (the air mass from the south met the air mass from the south-west and converged on Bodmin which led to towering cumulonimbus clouds. The air was very unstable and the clouds were up to 10 km high).
Human:
The natural channel of the river had been walled (for the construction of the B3263 and a pedestrian area) which prevented it from adjusting to a variation in the discharge of the water.
The village had been built on a flat flood plain.
There was no flood control system.
Cars, trees and boulders became stuck under the bridge and created a temporary dam which caused the water to build up behind it.
The sewers and drainage systems were old and small in capacity; they broke and the water that was in the, took an overland route.
50 cars were swept into the harbour.
The bridge was washed away and roads were submerged under 2.75 m of water, making communication difficult.
The sewerage system burst.
For health and safety reasons Boscastle was declared inaccessible.
The Museum of Withcraft lost 50 per cent of its artefacts.
Four buildings were demolished and 58 flooded and the High Street was badly damaged.
The visitors' centre, a clothes shop and two gift shops were badly damaged.
The youth hostel was flooded.
People were in shock and there were concern about hypothermia or being swept away.
There was no power in the village for some time (an emergency generator had to be blown in).
90 per cent of the economy in Boscastle is based on tourism and there were still three weeks of the summer holidays left; twenty accommodation providers were shut.
Visitors whose cars had been washed away were not able to leave.
A speedy, well-co-ordinated and well-resourced rescue operation ensured that remarkably there was no loss of life. Even by the standards of developed countries, this was outstanding and a tribute to Britain's rescue services.
Emergency workers rescued residents and holiday-makers from a 32 km stretch of the north Cornwall coast.
Hundreds were evacuated from homes, rooftops (120 from rooftops), trees and vehicles.
Seven helicopters from the Coastguards, Royal Navy and RAF were used.
People took emergency shelter in The Rectory, which was on high ground.
The village was cordoned off by building inspectors for the clean-up operation.
People dug out guttering and removed rubble so that the water could flow away.
Sandbagging was used as a form of defence.
People came to see the catastrophe.
Prince Charles and the Deputy Prime Minister at the time, John Prescott, came to see the damage.
There was a church service to give thanks that no one had died.
The repairs were very costly and time consuming.
There was a huge fund-raising effort to help rebuild the village.
Insurance is now costlier in Boscastle.
The Environment Agency carried out a major investigation.
A £2 million grant was given to Boscastle to help with flood prevention.
No more schools or old people's homes are built in the valley.
The Environment Agency removed debris from upstream, which meant there was more room for the water to flow freely under the new bridge.
A flood defence system (building a flood wall, widening the River Jordan, raising car parks, removing bridges and using relief channels) was planned and is now complete. This also included building a high-arched single-span bridge which would not impeded flood water debris.
Only watch the first 11.07 minutes of the video.