Db boscastle flood overview and essay planning

1. Boscastle floods August
16th 2004
LO: 1. Identify the causes of the Boscastle floods.
2. Explain the causes of flooding in Boscastle.
NOTE: You will write an essay in class on this,
Thursday April 6th

2. Boscastle is on the north coast of Cornwall
(SW England), has a picturesque harbour and
a 16th Century quay, cliff top walks, and is a
tourist destination.

3. Before the flood it looked like this…

4. The rock type might be significant…

5. Can you picture the contour lines?

6. Don’t be fooled by the greenness;
there’s a lot of farmland in the hills…

7. TASK1: As they’re unclear on the map, highlight the course of the rivers Jordan,
Paradise + Valency AND mark the confluence points (I’ll show you first)
1: Paradise feeds Valency 2: Source of Jordan 3: Source of Paradise 4: Jordan feeds Valency
5: Route of River Valency 6: Another tributary
1
2
6
4
5
5
5
5
5
3

8. TASK2: Study the map; identify features/characteristics of the area which could lead
to flooding. You have 4:45mins to come up with an initial list of possible flooding
factors indicated through this map at each table, then we’ll make a class list.
TASK3: Circle or label each feature + write an annotation to explain its relevance to
flooding – we’ll look at an example linked to the contour lines on the next slide…
1
5
6
4
3
2
1: Main urban area
(town)
2: Close contour
lines; slope from
257m to sea level
within just a few
100m!
3: Lack of vegetation
on bare hillsides.
4: Farm, grazing
animals: in winter
there will be even
less + grazing
animals compact
land, reducing
infiltration.
5: Mostly
impermeable rock
6: Wooded area – crucially, small and at the bottom of the slope…

9. Example
The contour lines being close together show the land
is steep. This means when it rains there would not
be much infiltration but rapid surface run off, leading
to flooding.
This is a short explanation of the point (though it
does use some terminology), lacking specific
evidence – you should aim for clearer, more
developed analysis in your essay!
Any suggestions on how we could develop this
point?

10. 1. Infiltration
2. Saturation
3. Meander
4. Tributary
5. Confluence
6. Drainage basin
7. Abrasion
8. Traction
9. Deposition
10. Transpiration
A quick spelling test
• Write down the following terms, then we will mark
your spelling /10 and check our understanding of
these [freeze screen!]
BBC
BBC
1. Infiltration
2. Saturation
3. Meander
4. Tributary
5. Confluence
6. Drainage basin
7. Abrasion
8. Traction
9. Deposition
10. Transpiration

11. Infiltration
Saturation
Meander
Tributary
Confluence
Drainage basin
Abrasion
Traction
Deposition
Transpiration

12. Here’s how the flood advanced
15:43 Bank Full

13. 16:06 +23 min

14. 16:13 +30 min

15. 16:44 +1hr 01 min

16. 16:51 +1hr 08 min

17. 16:53 +1hr 10 min

18. 16:58 +1hr 15 min

23. 18:13 +2hr 30 min

29. AUGUST 17TH 2004
When the flood water receded, the
devastation was clear…

39. We will look at 2 videos;
you can re-view these at
home through my blog.
stgeog.blogspot.lu
These focus on the impact
of the flood; your focus
must be on the CAUSES of
the flood (the essay title!).
You need to keep updating
your list of factors, but also
need to take clear, specific
notes on facts, figures, data
which might help you in
your essay!
Video (BBC News explains
the floods 2:20mins)
Video clip2: slips of the
flood from multi cameras
(4:29mins)

40. You will have a copy of this
essay planning framework

41. ROOM CHANGES
• On the following days, to be noted in your planners,
we will be in B348, to help you to carry out
research + preparation for your Boscastle essay.
Please note:
• Bring headphones if you want to view videos
• You cannot access my blog in school; save/email links to
yourself if you want to find these resources
• You do not have to use PCs in the lesson – feel free to
practice writing the essay!
• 7CW: Thursday 30th P3 + Tuesday 4th P4
• 7PAC: Thursday 30th P4 + Wednesday 5th P6

42. ESSAY TITLE:
Explain the causes of the Boscastle flood.
• What physical factors could you use as a focus for a
paragraph? You will need to pick two of these
including the basic element…
• What human factors could you use as a focus for a
paragraph? You will need to pick at least one of
these (total 3 or 4 main points plus introduction +
conclusion)
 Amount of rainfall (precipitation)
 Steep slopes (tight contour lines) … impacts SPEED (think about
drainage basin too)
 3 rivers meeting (confluence point; tributaries)
 Rock type (impermeable)
 Farming: lack of vegetation, deforestation, grazing
compacting land
 Urbanisation Concreting, tarmacking, buildings

43. Essay WAGOLL – main body
paragraph
One of the main reasons why Boscastle flooded was due to
the high levels of rainfall. On the day of the flood over
130mm of rain fell in 6 hours. This is especially significant
when the average monthly rainfall is only 70-90mm. It
meant that the drainage basin couldn't cope with so much
additional water. The soil and rock rapidly became saturated
meaning that no further infiltration could take place. This
meant the water could not get into the soil so had no where
else to go other than flow rapidly over the land, as surface
run-off, into the bottom of the valley where it led to a rapid
rise in the river level leading to a flood.
 Your task: PEE colour code this paragraph: Point,
Evidence, Explanation

44. Essay WAGOLL – main body
paragraph (PEE)
One of the main reasons why Boscastle flooded was due to
the high levels of rainfall. On the day of the flood over
130mm of rain fell in 6 hours. This is especially significant
when the average monthly rainfall is only 70-90mm. It
meant that the drainage basin couldn't cope with so much
additional water. The soil and rock rapidly became saturated
meaning that no further infiltration could take place. This
meant the water could not get into the soil so had no where
else to go other than flow rapidly over the land, as surface
run-off, into the bottom of the valley where it led to a rapid
rise in the river level leading to a flood.