In August 2004, the village of Boscastle saw a month's worth of rain fall in two hours. The drainage basin of Boscastle is steep and impermeable rock. Boscastle is also located on a confluence of three rivers. These factors led to a flash flood which caused over one thousand homes, cars and businesses to be swept away and damaged.
The flood defence scheme
To prevent this type of flood happening again, the environmental agency invested £10 million into several flood defences, such as:
Widening and deepening the river channel - this allowed the river to carry more water.
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 2004 flood, vegetation and debris became blocked, creating the effect of a dam).
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.
Tree management - dead trees were removed to prevent them being swept away, causing blockages under bridges. Land owners were encouraged to maintain vegetation and plant new trees.