Boscastle is a small fishing tourist village on the north Cornwall coastline.
Valency is the main river invlolved in the Boscastle flood.
The were 3 main causes of the flood were:
1) Prolonged rainfall - this is one of the reasons Boscastle flooding, as the whole of August was wet, and it rained for 12 of 14.
2) Heavy rainfall - thunderstorms were produced by a low pressure area on 16th August. At Otterham and Lesnewth, 200mm of rain was recorded within 24 hours (most rainfall fell within 5 hours meaning it was coming down in a great, heavy amount).
3) Small drainage basin - the drainage basin that flows through Boscastle is very small. It is only 7.7 miles squared.