Rivers - Boscastle Flashcards
1
Q
phy
confluence
valency and jordan
A
main cause of the flood in 2004 as the two rivers came together to produce a high discharge
2
Q
phy
steep slopes
A
- valency valley
- steep valley sides = high surface run-off = less time for infiltration in soil = increased surface runoff
3
Q
phy
catchment area small
A
relatively impermeable upland area of Bodmin Moor = more surface runoff = increase flood risk
4
Q
phy
heavy rains from remains of a hurricane
A
- heavy rainfall over 8hrs from hurrican Alex
- 200 mm of rain in 4hrs - avg monthly rainfall au is 100-120 mm on high ground
- high water vol exceeded infiltration capacity = high surface runoff & flooding
5
Q
hum
bridges
A
- when water levels increased small bridges became blocked by cars & plants = water had to flow around bridge = properties flooded
- river had been narrowed to construct bridges = not enough space to carry all the water
6
Q
hum
other causes
A
- building creating impermeable surfaces.
- removal of vegetation
- no flood defences
7
Q
economic cons
A
- cars (115 vehicles), walls, bridges were washed away.
- tourism: ~90% of Boscastle’s economy touristy, it was closed to tourists = loss of revenue
- damage to homes, businesses, land
8
Q
environmental cons
A
- environmental damage to local wildlife habitats
- coastal pollution bc debris and fuel from cars flowed out to sea
9
Q
social cons
A
- thousand of tons of mud and debris left throughout the village
- no deaths
10
Q
mang strat
river channel widened + deepened
A
- increased the capacity of the river = less likely to overflow its banks in future heavy rainfall events
- expensive
11
Q
gauging station
A
- near the Riverside Hotel
- ultrasonic detectors to measure the speed of water flowing = computer can calculate the river volume = warn of an impending flood
- expensive
12
Q
debris screen
A
- catch floating objects and prevent them from hitting houses and bridges
- interrupted migrating fish
13
Q
dead trees cut
A
- dont block bridges when floods occur
14
Q
river made straighter
A
- more efficient at transporting water
- expensive
15
Q
bridges improved
A
- widened/replaced with modern bridges
- changes character of town
