“boscastle: the village washed on to the map”. write a question about the image in your book
TRANSCRIPT
“Boscastle: The village washed on to the map”
Write a question about the image in your book
Boscastle – “Washed on to the map”What are we learning today ?
Key questions
• Where is Boscastle?• What caused the flooding?• What were the primary effects of the flooding?
Two key terms • Primary effects
• Flash flood
Effects that happen as a DIRECT RESULT of the flooding e.g. “trees ripped from the ground”
A sudden local flood that often happens due to intense rainfall and happens over around 8 hours
Where is Boscastle?
A small town on the north coast of Cornwall. 30 kms north west of Plymouth.
CAUSE 1: VERY HEAVY RAIN
Most of the rain fell in a five hour periodPeak intensities were in excess of 30mm/hr (0.5mm per minute)
A month’s rain fell in just 2 hours
CAUSE 2: THE STEEP SIDED VALLEYS
CAUSE 3 – SLATEY IMPERMEABLE ROCKS with CLAY SOILS
The cause was the combination of
• intense convectional rain,
• local topography and
• the geology
= resulting in a flash flood no one could have predicted.
12.15 Rain gauge at nearby Lesnewth some 4km (2½ miles) up the valley, shows no rainfalland it is dry in Boscastle’s harbour area, yet there are torrential showers at Camelfordand at the top of Boscastle.
What happened?
16.00 a 3 metre wall of water runs through Boscastle car park at 40 mph.
17.00 Rescue Helicopters.
In an operation lasting from mid-afternoon until 2:30 AM, a fleet of seven helicopters rescued about 150 people clinging to trees and the roofs of buildings and cars. Amazingly, no major injuries or loss of life were reported.
