Boscastle floods

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Case Study for GCSE students needing to learn the causes, effects and prevention for the Boscastle floods in 2004.


<ul><li> 1. Boscastle Floods 16th August 2004</li></ul> <p> 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 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. 5. 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. 6. The new bridge 7. Cutting out a wider, deeper channel 8. New culvert for the river Paradise which drains twice as much water as the river channel used to.</p>