Flooding in Boscastle
In this report I will assess the causes, both natural and artificial, of the flooding in Boscastle on 17 Aug 2004 and the impact of the floods on the local environment, as well as the measures that could, and are being undertaken to deal with the effects of flooding.
Boscastle, is located in the south-west of England, on the coast, near Cornwall. The settlements position in relation to the mouth of a very narrow river valley leaves it vulnerable to flooding. Flood risk is heightened whenever storm waters are denied a wide flood plain to spread into: in a narrow valley, whatever land exists either side of the channel will become rapidly submerged, once the river has burst its banks. These were the heaviest rains in living memory for the people of the village - 185mm fell in just five hours. Given that the total annual rainfall for much of southern England is around 1,000mm, this is a lot of water to have arrived in such a very short time.
Fortunately, no one died on this occasion, despite the great hydraulic force of the water flowing through the town's streets. In contrast, property damage was high. At least thirty cars were washed straight into the harbour and many more were left upturned and badly damaged. A three-metre high wave of water was reported to have crashed through one street at 40 miles per hour. Fridge-freezers were picked up and swept out of kitchens as water entered properties. Six properties collapsed entirely, as a result of traction and abrasional damage.
What were the physical factors?
* Three rivers - the Valency, Jordan and Paradise - converge on the village of Boscastle. The majority of the damage was attributable to the Valency.
* Heavy rain was caused by extreme frontal activity. In total, an input of 3 million tonnes of water was added to a tiny drainage basin, whose size is just 40 square kilometres.
* 185mm arrived in just five hours, the majority falling in the first two hours. Under such conditions, infiltration-excess overland flow is inevitable, with the rate of input of rainwater ...
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What were the physical factors?
* Three rivers - the Valency, Jordan and Paradise - converge on the village of Boscastle. The majority of the damage was attributable to the Valency.
* Heavy rain was caused by extreme frontal activity. In total, an input of 3 million tonnes of water was added to a tiny drainage basin, whose size is just 40 square kilometres.
* 185mm arrived in just five hours, the majority falling in the first two hours. Under such conditions, infiltration-excess overland flow is inevitable, with the rate of input of rainwater greatly exceeding the infiltration capacity of soil in the area. The soils were already saturated from previous rainfall earlier in the week, encouraging overland flow to begin even sooner.
* The rain coincided with high tide in the bay. This restricted the rate of exit of floodwater into the harbour.
What were the Human factors?
The settlement of Boscastle has been allowed to develop on a narrow flood plain on the west coast of England, where rainfall is often high. Early settlers would have been attracted by site factors such as the presence of a fresh water supply and access to a natural harbour. There are now around 1,000 permanent residents, most of who rely upon the situation of the settlement to provide tourist revenues (it is close to the South West Coast Path).
The rainfall hit at the worst time of year when the settlement population doubles to 2,000 as tourists arrive, many of who are following the South West Coast Path. Much higher levels of motor vehicle damage were also experienced, as a result of this influx. In addition, shops were carrying greater levels of stock than at other times of the year. Although new flood defences were set to be built in October, work had not yet started. Overall, excellent emergency services and Environment Agency response meant no lives were lost.
The long and short term impacts
Economic losses - Much of rural Cornwall is classified as a deprived region. It is one of the UK's poorest rural counties, with EU Objective One status, meaning that incomes are below 75% of the EU average (Financial Times, 18 August 2004). A victim of early deindustrialisation, the region's mining industries are now long-gone leaving it over-dependent on tourism. Luckily, a strong association with Arthurian legends and with the writer Thomas Hardy has helped foster high visitor-numbers for Boscastle (Hardy met his wife there and helped build St Juliot's church). However, most shops will now stay shut for the rest of the season and the bad publicity is likely to reduce tourist numbers during future years, resulting in a negative multiplier effect for the entire local community.
Wider regional impact - In addition, the effect may spread beyond Boscastle if other river-line settlements are perceived to be at risk by tourists. Boscastle businesses can claim compensation from their insurance companies (claims for 'disruption to trading' in Boscastle could amount to £15m). However, others businesses elsewhere in Cornwall cannot, even though they too may suffer reduced trade next year. This is a cause for concern, with tourism accounting for 30% of Cornwall's GDP. The population doubles during July and August each year, with tourists spending up to £1 billion throughout the county.
House price falls -People will find the value of their homes permanently reduced, now that Boscastle is associated with a serious flood risk. It has been suggested that values have halved
Immediate Losses
Heavy property damage - Six properties were destroyed completely. Most others will require between £15,000 and £30,000 for repairs. Shared amenities such as the village green are now covered with silt and up-ended cars. These are serious costs for a small community with a seasonal employment problem, due to its over-reliance on summer tourism. Insurance companies will reimburse most people.
Infrastructure disruption - Both bridges in the village have been destroyed and sections of road have been swept away. Telephone, water, electricity and gas supplies were all immediately interrupted.
Irreplaceable loss of historical artefacts - The 'Witch Museum' - which is fifty years old and receives 50,000 visitors a year - has seen some of its unique contents damaged.
There are a number of methods to prevent flooding in the area that could be used in the future. However, cost is an important factor for such a small community, and some of the more effective strategies may be simply too expensive to put in place. One suggested strategy, is the planting of trees and other vegetation to increase interception, and prevent water from reaching the nearby rivers so quickly. Dredging of the three rivers in the area may also help prevent rivers bursting their banks, and will be relatively low cost in comparison to other methods.
The most popular suggestion with the Environment Agency so far, is to discourage new developments in the area, to prevent any significant losses should flooding occur again. This may have a negative effect on the community however. The area is heavily reliant on tourism and new developments are necessary to attract visitors. The area may sink into decline if the number of tourists visiting the area decreases.
A closer look at the position of Boscastle
Daniel Larrosa 10D 12/12/04
