Boscastle Flood 2004 Case Study Effects Of Raising

Floods devastate village

On 16 August 2004, a devastating flood swept through the small Cornish village of Boscastle.

Very heavy rain fell in storms close to the village, causing two rivers to burst their banks. About two billion litres of water then rushed down the valley straight into Boscastle.

Residents had little time to react. Cars were swept out to sea, buildings were badly damaged and people had to act quickly to survive. Fortunately, nobody died – thanks largely to a huge rescue operation involving helicopters — but there was millions of pounds worth of damage.

Physical Impacts

On the day of the flood, about 75mm of rain fell in two hours — the same amount that normally falls in the whole of August. Huge amounts of water from this sudden downpour flowed into two rivers, the Valency and Jordan (which flows into the Valency just above Boscastle). Both overflowed, and this caused a sudden rush of water to speed down the Valency — which runs through the middle of Boscastle.

Destruction of houses, businesses and gardens
Floodwater gushed into houses, shops and pubs. Cars, walls and even bridges were washed away. The church was filled with six feet of mud and water. Trees were uprooted and swept into peoples’ gardens. The weight of water eroded river banks, damaged gardens and pavements.

Human Impacts
There was a huge financial cost to the floods. This included:

  • the rescue operation – involving helicopters, lifeboats, and the fire service.
  • the loss of 50 cars
  • damage to homes, businesses and land
  • a loss of tourism, a major source of income for the area

The flooding also had several other key impacts on Boscastle and its inhabitants. These included:

  • environmental damage to local wildlife habitats
  • coastal pollution caused as debris and fuel from cars flowed out to sea.
  • long-term disruption to the village, as a major rebuild project had to be carried out.
  • long-term stress and anxiety to people traumatised by the incident.

Responses to the flooding

  • 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.
  • Prince Charles, who is the Duke of Cornwall, made a large 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 carried a major project to increase flood defences in Boscastle, with the aim of preventing a similar flood happening again.
  • We are investing in new ways of predicting heavy rainfall events on a small scale to produce better warnings.

In pictures

Aerial photo of the flood waters gushing through Boscastle (courtesy of Apex News &∓ Pictures)

Slide show of photographs of the Boscastle flood. This link opens in a new window.

Map of the area affected

What happened to cause this event?

Weather map
Fig. 1 shows the weather map for midday on 16 August.

The wind is blowing anticlockwise about the low pressure area, so the air is arriving into Boscastle from a south-westerly direction. It is a warm and moist tropical maritime air mass.

The line labelled (known as a trough line) caused very heavy rain and thunderstorms. A trough is an area of localised rain and thunderstorms. A line of convergence formed near the coast line, where air moving in almost opposite directions collides, this helped to increase the rate of ascent and produced very heavy rain.

There is more about surface pressure charts in the weather section of the Met Office website.

Weather chart

Fig 1. A weather chart from 16/08/2004.

Radar imagery
Fig. 2 shows an animation radar pictures from 12 p.m. (midday) to 7 p.m. on 16 August.

The rainfall rate key shows how the colours in the image relate to the rate the rainfall is falling. For example, the red areas indicate that rain is falling at between eight and 16 mm per hour.

A line of very heavy rain starts at 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.

There is more about rainfall radar in the weather section of the Met Office website.

Radar imagery

Fig 2. Rainfall Radar

Animation of rainfall radar. Flash Player required.

Satellite imagery
Fig. 3 shows an animation of satellite pictures from 12 p.m. (midday) to 7 p.m. on 16 August

Satellite imagery

Fig. 3: Satellite image

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.

Animation of Satellite images(Flash Player required).

Further information on other websites
BBC News website covering the Boscastle flooding
BBC News article – Boscastle one year on

Web page reproduced with the kind permission of the Met Office

Figure 9: Boscastle Flood Defence Scheme (Nicholas Pearson Associates, 2012)

· 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, see Figure 9. 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.
(Environment Agency, 2012).

BBC, 2004a. In Pictures: Dramatic Floods in Boscastle [image online] Available at: <> [Accessed 31 January 2012].

BBC, 2004b. The Boscastle Floods 2004 [image online] Available at: <> [Accessed 27 January 2012]. 

BBC, 2004c. In pictures: Flooding in Cornwall [images online] Available at: < [Accessed 14 March 2012].

BBC, 2005a. In pictures: Boscastle then and now [image online] Available at: <> [Accessed 27 January 2012]. 

BBC, 2005b. ‘Ghost town’ fears over Boscastle. [Online]. Available at: <> [Accessed 27 January 2012].
BBC, 2005c. Accommodation worry for Boscastle [Online]. Available at: <> [Accessed 27 January 2012].

Burt, S., 2005. Cloudburst upon Hendraburnick Down: The Boscastle storm of 16 August 2004. Weather, 60(8), pp.219-227.

Bull, J., 2007. The Boscastle Flood 2004.Staffordshire Learning Net. [Online] Available at: <> [Accessed 27 January 2012].

Cherrington, J., 2006. Boscastle Flood- The Silver Linings, Ranger, 76, [Online]. Available at: <> [Accessed 27 January 2012]. 

Environment Agency, 2012. Boscastle to benefit for years to come from new flood defence scheme and regeneration projects [Online] Available at:<> [Accessed 27 January 2012]. 

Golding, B., Clark, P. and May, B., 2005. The Boscastle flood: Meterorological analysis of the conditions leading to flooding on 16 August 2004. Weather, 60(8), pp.230-235.

Met Office, n.d. Floods devastate village [image online] Available at: <> [Accessed 27 January 2012].

MightyQuinn57, 2007. Boscastle, Flash Flood. [video online] Available at: <> [Accessed 27 January 2012].

Nicholas Pearson Associates, 2012. Boscastle Flood Alleviation Scheme [image online] Available at: <> [Accessed 31 January 2012].

North Cornwall District Council, 2004. Boscastle The Flood. [Online]. Available at: <> [Accessed 27 January 2012].

Roseveare, N. and Trapmore, G., 2008. The sustainable regeneration of Boscastle. BHS 10th National Hydrology Symposium, Exeter, 2008.

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