1. WHAT CAN YOU REMEMBER? ocean land 2) _________ 3) _________
4) _________
1) ________
5) __________
6) ________
ocean
land

2. WHAT CAN YOU REMEMBER? ocean land condensation precipitation
transpiration
evaporation
surface runoff
ground water
ocean
land

3. PHYSICAL LANDSCAPES
INTRODUCING RIVERS

4. WHAT ARE WE GOING TO LEARN?
What is a drainage basin?
Why is a drainage basin like a kitchen sink?
What are the four processes of erosion in rivers?
What are the four processes of transportation in rivers?

5. THE DRAINAGE BASIN Dyfi
A drainage basin is an area of land that is drained by a river and its tributaries.
DRAINAGE BASIN

6. THE DRAINAGE BASIN WATERSHED Nature’s ‘kitchen sink’
The higher land that forms the edge, or boundary, of a drainage basin is called the watershed.
Nature’s ‘kitchen sink’
WATERSHED

7. Drainage basins act like nature’s kitchen sinks.
THE DRAINAGE BASIN
All the rain that falls within a drainage basin flows into a single river channel that flows to the sea (or lake).
Drainage basins act like nature’s kitchen sinks.

9. River Basin Features
Watershed the area of high land forming the edge of a river basin.
Source where a river begins.
Mouth where a river meets the sea.
Confluence the point at which two rivers meet.
Tributary a small river or stream that joins a larger river.
Channel this is where the river flows.
Drainage Basin this is the area of land drained by a river and its tributaries.

10. DRAINAGE BASIN TERMS
SOURCE
TRIBUTARY
CONFLUENCE
CHANNEL
MOUTH

11. PHYSICAL LANDSCAPES
THE RIVER COURSE

12. THE RIVER COURSE
UPPER COURSE
MIDDLE COURSE
LOWER COURSE

13. RIVER PROCESSES Rivers play a big role in shaping our landscape.
They are able to do this because they have energy.
This means that they can do work.
The work they do is erosion and transportation.
When they run out of energy they have to stop doing work, so they drop what they are carrying. This is called deposition.

14. EROSION PROCESSES Erosion is the wearing away of the river bed, river
There are four processes of river erosion:
attrition
corrasion
corrosion
hydraulic action

15. TRANSPORTATION PROCESSES
There are four processes of transportation:
traction
saltation
suspension
solution

16. TRANSPORTATION PROCESSES
Solution
Suspension
Saltation
Traction

17. RIVER EROSION

18. THE SOURCE The source is the start or beginning of a river.
The source of a river is usually found in the hills or mountains.

19. Water can sink through gaps in the rocks
SPRINGS
rain
Water can sink through gaps in the rocks
Underground water emerges where the rock type changes
Permeable rock ie Limestone
Rocks are saturated
Impermeable rock ie Clay
Spring

20. THE RIVER COURSE
UPPER COURSE
MIDDLE COURSE
LOWER COURSE

21. UPPER COURSE CHARACTERISTICS
steep valley sides
steep channel gradient
narrow valley floor
narrow, shallow channel

22. Upper Course Characteristics large, angular stones and boulders

23. UPPER COURSE CHARACTERISTICS
turbulent river flow at a section of rapids

24. Upper Course Landforms
a typical V-shaped valley

25. Key Features:
V-shaped valley
A steep sided and narrow valley that is formed due to vertical erosion. The load of the river cuts downwards and deepens the bed of the river.

26. Upper Course Landforms
a typical V-shaped valley

27. Upper Course Landforms
interlocking spurs
interlocking spurs

28. Upper Course Landforms
interlocking spurs
interlocking spurs

29. Angel Falls, Venezuela

30. Hopetoun Falls, Australia

31. Victoria Falls, Zambia/Zimbabwe

32. Jog Falls, India

33. Niagara Falls, Canada/USA

38. WATERFALL
RETREATS . .
UPSTREAM . .
OVERHANG
PLUNGE
POOL
UNDERCUTTING
OF SOFT ROCK

39. Upper Course Landforms
interlocking spurs
interlocking spurs

40. Rapids
A series of gentle breaks in the slope of a river bed due to different types of rock.

41. Hydro-electric power

42. River Model
Upper
Course
Middle
Course
Lower
Course

43. S3 Rivers:
The Middle Course

44. At the middle stage of the river the valley sides become less steep
The river is now wider and deeper
It does not flow at the same speed throughout its middle course, some parts are slower, some are faster

45. Meander ( = bend in a river’s channel)

46. What do you notice about the bank of the river channel on the outside of the bend?

47. Which is the fastest side of a river?

49. Why do rivers meander (bend)?
Copy the diagram above and put the following labels in the correct place:
Deposition Fast flow of river Shallow water
River Cliff Lateral Erosion Slow flow of river Deeper water River beach (Slip-off slope)
2. Describe why one side of the river bend is different from the other.

51. S3 Rivers:
The Lower Course

52. The river is closest to its mouth
At its lower stage, the river is in a wide flat valley with gentle valley sides
The river is closest to its mouth

53. E A F B C D

54. Ox-bow Lakes

55. The river erodes the outside of the bend and deposits on the inside so its course is changing. This erosion narrows the neck of the meander.
Often during a flood the river will cut through the neck.
The river continues in the new bed and the meander is abandoned. New deposition seals off the ends and the cut-off becomes an ox-bow lake.

56. Ox-bow lake on Mississippi

57. Levee formation

58. Built-up levees

59. 1. When a river with a very low gradient floods a lot of silt is deposited on the river banks and much less on the flood plain.
2. Frequent flooding continues this build up of silt. When the river is flowing normally it deposits in the river bed.
3. This raises the river above the flood plain but, usually the built up levées protect the plain from flooding.