1. The Changes downstream in a river valley
RIVER STUDIES
The Changes downstream
in a river valley

2. The Hydrologic Cycle Infiltration = Groundwater System
Runoff = Surface Water System

3. Satellite view of river drainage, Middle East
What is this features?

4. Upper valley characteristics

5. Upper valley characteristics

6. Upper valley characteristics
“V”shape valley, vertical erosion dominant

7. Upper valley characteristics
“V”shape valley, vertical erosion dominant
Interlocking spurs

8. Upper valley characteristics
“V”shape valley, vertical erosion dominant
Interlocking spurs
Slumping and landslides - very active hill slopes

9. Upper valley characteristics
“V”shape valley, vertical erosion dominant
Narrow, shallow channel, low velocity and discharge
Interlocking spurs
Slumping and landslides - very active hill slopes

10. Upper valley characteristics
“V”shape valley, vertical erosion dominant
Narrow, shallow channel, low velocity and discharge
Interlocking spurs
Slumping and landslides - very active hill slopes
Large bed load derived from upstream and from valley sides

11. Interlocking spurs, Robinson, Lake District
A typical upper course valley with interlocking spurs, steep valley sides and active slope processes

12. River load in upper course
Why are they rounded?
Boulders are large and semi-rounded, due to attrition within the load and abrasion with the stream bed and banks

13. Rapids in the Upper Tees Valley
WHAT IS A RAPID?

14. High Force waterfall, R. Tees
WHAT IS A WATERFALL?

15. High Force waterfall, R. Tees
Waterfall creates gorge as it recedes upstream by eroding the base and neck
What is this feature called?
HOW IS A GORGE FORMED?
Plunge pool

16. Waterfall formation
Look at the diagram, How is a waterfall formed?

17. High Force Waterfall R. Tees

18. Close-up of potholes
How are these formed?

19. Potholes, human scale!!

21. Erosion Processes
Corrosion -
Attrition -
Abrasion (Corrasion) -
Hydraulic Action -
is when the river is loaded with material in suspension and scours away at the river banks. (Sandpaper effect)
is the shear force of the river impacting on the sides of the river banks.
is substances carried in solution such as acids. They dissolve rocks away over long periods of time.
is when bed load collides into each other with the current flow and breaks down into smaller particles.

22. Middle course, R. Tees
HOW DOES THIS DIFFER FROM THE UPPER SECTION?

23. Middle course, R. Tees WHAT DO YOU THINK THE ARROWS POINT TO?
Valley opens out, more gentle slopes, wider valley bottom
First signs of meanders
River channel wider, deeper, greater velocity and discharge

24. Meandering Rivers
WHAT IS A MEANDER?

25. Formation of Meanders

26. Point bar deposits

27. Point Bar Deposits
Point bar deposits grows laterally through time

28. Meander, R. Lavant, Chichester

29. Meander, R. Lavant, Chichester
WHAT DO THE ARROWS POINT TO?
WHICH WAY IS THIS MEANDER MOVING?
Floodplain
Slip-Off Slope
River Cliff
Point bar deposits on the inner meander bend where there is low energy

30. } Cut bank erosion (River Cliff) Point bar deposits Meander loop
WHERE IS EROSION TAKING PLACE?
Cut bank erosion (River Cliff) F A E B
Point bar deposits }
Meander loop C D
WHERE IS DEPOSTION TAKING PLACE?

31. Meander on the R. Colorado
WHY IS DEPOSITION OCCURING HERE?

32. How did these meanders form?

34. REVISION: What River features do you get here?

35. Migrating meanders, R. Gongola, Nigeria
WHY ARE THEY MIGRATING?

36. What happens to the river when it moves to the middles course
Gradient becomes less steep
River continues to erode vertically but LATERAL erosion now occurs in MEANDERS
What is MEANDER MIGRATION ?
Name three effects it have on the valley?
What factors effect how much load is being carried?

37. Transportation What are the four methods of transportation?
Traction - is when large particles roll along the river bed
Saltation - is when smaller particles bounce and collide in a leapfrog manner across the river bed.
Suspension - is when the river holds even smaller particles and carries them in its current. This is when the river appears to be murky.
Solution - is when dissolved material is carried.

39. Lower Course: Severn Valley

40. Lower Severn Valley
Very wide floodplain
Well developed meanders with bars in the channel indicating high sediment load
Very gentle valley side gradients
HOW DOES IT DIFFER FROM THE MIDDLE COURSE?

41. Flood Plains
HOW DO YOU THINK THE TERRACES WERE FORMED?
The entire floodplain can become covered with water during floods.

42. Ox Bow Lake Formation
LOOK AT THE DIAGRAM & EXPLAIN THERE FORMATION

43. Formation of an Oxbow

44. Ox Bow lake on Mississippi

45. Levee formation

46. Levees
WHAT DO YOU THING HUMANS MIGHT HAVE DONE TO THIS LEVEE?

47. Delta Formation WHAT IS A DELTA? DEPOSITON OF MATERIAL BY THE RIVER
WHEN IT ENTERS THE SEA
WHY DOES IT DROP ITS SEDIMENT

48. Mississippi Delta from Space

49. The Nile Delta from space
River Nile

50. Estuary Formation
HOW DOES THIS DIFFER FROM A DELTA?
The Lower Course of a river valley has been DROWNED by a rise in sea level or a fall in the land level.
RAISED VALLEY SIDES
USING YOUR ATLAS
FIND AN ESTUARY
(LOOK AT THE RIVER THAMES)

51. The Rhone Delta
USING YOU ATLAS
LOCATE THE RHONE
DELTA

52. The Rhone Delta S. France
Look at p39 and identify the
KEY FEATURES CAN YOU
SEE IN THE SATELLITE PHOTO?

53. The Rhone Delta
WHY HAS A DELTA
FORMED HERE? LOOK AT P 39

55. Summary of valley characteristics

56. The River Tees TRY AND FIND THE RIVER TEES IN YOUR ATLAS
HINT LOOK AT THE MAP

57. Land Use in Drainage Basin of River Tees
WHAT IS THE AREA IN EACH BOX?

58. Upper Tees COW GREEN RESERVOIR
WHAT HUMAN INFLUENCES EXIST IN THE MAPS?

59. The Upper Tees Cronkley Scar
WHAT ARE THE KEY GEOGRAPHCIAL FEATURES
YOU CAN SEE IN THE PHOTOGRAPH
MOORLAND
STEEP VALLEY
TURBULENT RIVER
CHANNEL
SLOPE DEBRIS
WHAT LAND USES CAN YOU SEE IN THE PHOTO?

60. Upper Tees
WHAT IS THE NAME OF THE WATERFALL?

61. The Lower Course Tees FLAT VALLEY FLOOR URBAN SETTLEMENT WIDE MEANDERS
HOW HAS THE RIVER AND
LAND USE CHANGED?

62. The Lower Tees TEESMOUTH ESTUARY
WHAT LAND USE CAN YOU SEE IN THE PHOTOGRAPH?

63. The River meets the Sea

64. River Management WHAT IS THE FUNCTIONOF THE BARRAGE? LOOK AT P42
WHAT DO YOU THINK
THE PHOTOS SHOW?

65. Formation of the Mississippi River Delta
More recent delta sediments
Modern delta
Early delta

66. Causes of Floods
A Flood can occur when a river exceeds its bank full stage and water will subsequently inundate the adjacent surrounding area.
Heavy rainfall - long periods of heavy rainfall will lead to an increase in surface runoff and increase in river level.
Snow melt and heavy rainfall - water in storage may be freed by Spring melts increasing surface runoff.
Deforestation - cutting down of trees leads to a reduction in interception rates and an increase in surface runoff. This may also lead to rapid erosion rates due to a lack of stability in the soil subsurface.
Urbanisation - tarmac and concrete surfaces are impermeable and lead to an increase in surface runoff.

67. Flood Control and Management
There are a number of ways managing floods:
1. Afforestation - planting trees increases interception rates and reduces surface runoff.
2. Dams and Reservoirs - these hold back and regulate the flow of river water. Can be used as fresh water supply and generation of HEP.
3. Diversion Channels - overflow channels which take surplus water out of a river in times of flood.
4. Channel Straitening and Dredging - smoothens the channel to increase the speed (velocity) of the river and get water out of the drainage basin as quickly as possible.
5. Artificial Levees - makes river banks higher therefore holding more water.
6. Culverts - semi circular, smooth channels increase velocity and gets water away from urban areas as quickly as possible.
7. Revetments and Channel Walls - strengthen river banks from erosion.