The Boscastle floods on August 16, 2004, were caused by over 60 mm of rainfall falling in two hours on already saturated ground, leading to rapid surface runoff in the steep v-shaped valley. The disaster affected 58 properties and 1000 people, causing significant damage estimated at £2 million, although it eventually led to economic benefits through new construction and tourism revitalization. In response to the floods, a comprehensive £10 million flood defense scheme was implemented, which included improvements to river capacity and infrastructure, completed by 2008.

1. Boscastle Floods
16th August 2004

2. Key words from this case study
Impermeable surfaces – where water cannot soak into
the ground and so runs straight over the top e.g.
concrete, tarmac and rocks such as slate or clay.
Surface run-off – where water that has not soaked into
the ground flows over the surface. This way water enter
rivers much faster than if it soaked into the ground.
Saturated – when the ground is so full of water it cannot
soak up anymore. This is also when surface runoff occurs.

3. Causes
• Over 60 mm of rainfall (typically a month's rainfall) fell in
two hours.
• The ground was already saturated due to the previous two
weeks of above average rainfall.
• Boscastle sits in a V shaped valley and has many steep
slopes, and has areas of impermeable slate causing rapid
surface run-off.
• Boscastle is at the confluence (where tributaries meet) of
three rivers - Valency, Jordan, and Paradise. A large quantity
of water all arrived within a short space of time causing the
rivers to overflow.
• The flooding coincided with a high tide, making the impact
worse.

4. Effects
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The flooding affected 58 properties and 1000 people, with belongings being
destroyed and lost.
4 properties were demolished, including the visitor centre.
In addition, 84 wrecked cars were in the harbour, with another 32 out at sea.
Damage to buildings and services cost North Cornwall District Council up to £2
million.
A dramatic decrease in tourist numbers immediately after the flood led to the
town being described by business leaders as a ‘tourist ghost town’.
However, when businesses reopened the village was ‘bustling’ with
‘sightseers’.
Despite this, hotel businesses suffered from a decrease in overnight visitors.
However, it could be seen that the flood in Boscastle has benefited the village
economically in the long run.
The benefits include new shops built with insurance money, a new, bigger
visitor centre, a reshaped car park away from the river and a new flood
alleviation scheme.

11. Prevention
• In 2005, a new £800,000 flood defence scheme opened in
Boscastle which includes a new, larger culvert on the river
Jordan which will be able to carry double the amount of
floodwater.
• In August 2006, construction started on the river Valency flood
defence scheme.
• In order to increase its capacity the river has been widened
and deepened and the lower bridge replaced.
• A new car park has been built which is raised and set back
from the river and a new tree management scheme has been
introduced to reduce the chances of tree blockage.
• Two new sewing pumps and stations and a new sewer pipe to
assist with flood flows have also been introduced.
• Flood defence works together with the regeneration scheme
cost £10 million and were officially opened in October 2008.

12. The new bridge

13. Cutting out a wider, deeper channel

14. New culvert for the river Paradise which
drains twice as much water as the river
channel used to.