Boscastle, Cornwall In August , the village of Boscastle saw a month’s worth of rain fall in two hours. Floods devastate village On 16 August , a devastating flood swept through the small Cornish village of Boscastle. Steep valley sides – water flowed into the river channel very quickly. It flooded in August , washing cars and buildings into the sea and putting peoples’ lives in danger. It remains over the area for about six hours. Raising the car park and using a permeable surface – this allowed cars to be much higher and so they were less likely to be swept away.
Removing low bridges and replacing them with wider bridges – this meant large amounts of water could flow freely underneath the bridge and the bridge wouldn’t act like a dam in the flood, vegetation and debris became blocked, creating the effect of a dam. It is a warm and moist tropical maritime air mass. A few old arch bridges got blocked up with the flood debris. The flooding also had several other key impacts on Boscastle and its inhabitants. It flooded in August , washing cars and buildings into the sea and putting peoples’ lives in danger. For example, the red areas indicate that rain is falling at between eight and 16 mm per hour. Cars were swept out to sea, buildings were badly damaged and people had to act quickly to survive.
Tree management – dead trees were removed to prevent them being swept away, causing blockages under bridges. The bridge acted like a dam and eventually smashed through causing a surge of water up to 5m high.
The pictures show cloud forming over Boscastle at about 1 p. Destruction of houses, businesses and gardens Floodwater gushed into houses, shops and pubs.
Human Impacts There was a huge financial cost to the floods. The drainage basin of Boscastle is steep and impermeable rock.
Fortunately, nobody died — thanks largely to a huge rescue casd involving helicopters — but there was millions of pounds worth of damage.
Weather chart Fig 1.
British Isles case study: It flooded in Augustboscasyle cars and buildings into the sea and putting peoples’ lives in danger. These became saturated so water became surface run-off very quickly. Physical Impacts Flooding 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.
There were very few trees to absorb water and slow flokd amount of water going into the river. The thickest cloud is shown by the brightest white areas on the picture. Rainfall rates of at least 32 mm per hour are being measured. Map of the area affected What happened to cause this event? Increase in buildings within the drainage basin meant that there more impermeable surfaces which directed water back to the river faster.
These factors led to a flash flood which caused over one thousand homes, cars and businesses to be swept away and damaged. Huge amounts of water from this sudden downpour flowed into two rivers, the Valency and Jordan which flows into the Valency just above Boscastle. Satellite image The thickest cloud is shown by the brightest white areas on the picture.
About two billion litres of water then rushed down the valley sudy into Boscastle. Rain for 12 out of 14 days in August. Floods devastate village On 16 Augusta devastating flood swept through the small Cornish village of Boscastle. Raising the car park and using a permeable surface – this allowed cars to be much higher and so they were less likely to be swept away. The line labelled known as a trough line caused very heavy rain and thunderstorms.
Radar imagery Fig 2.
A trough is an area of localised rain and thunderstorms. Boscastle is at the confluence of three rivers – Valency, Jordan, and Paradise. A line of very heavy rain starts at about 1 p.
The weight of water eroded river banks, damaged gardens and pavements. A large quantity of water arrived within a short space of time causing the rivers to overflow.
The flooding also had several other key impacts on Boscastle and its inhabitants. This limited interception and water went straight into the river channel. Widening and deepening the river channel – this allowed the river to carry more water.
It remains over the area for about six hours. There is more about rainfall radar in the weather section of the Met Office website.