1. 2.3 How does a river shape the land along its different courses?

2. Can you find these kinds of landform at the same place?
How do the characteristics of a river change along its course?
Can you find these kinds of landform at the same place?

3. They are different in _________ and _____ _______.
What are the different sections along a river course?
They are different in _________ and _____ _______.
Upper course
Middle course
Lower course
gradient
river
energy
Relatively straight, with bends around obstacles
Winding
Big bends occur

4. What are the different sections along a river course?
Gradient of the upper course: ______
steep
Gradient of the lower course: _______
Gradient of the middle course: __________
moderate
gentle

5. What are the different sections along a river course?
The energy and work vary along the three courses, different landforms are formed!
Therefore, different landforms are found at different sections along a river course.
Upper course
Middle course
Lower course

6. Is this the impression you have for the upper course?
What landforms are formed at the upper course?
How much energy is there?
What do you think about the energy of river at the upper course when compared with the middle and lower course? (Greater / Less)
The energy is less because:
Is this the impression you have for the upper course?
The catchment areas of the tributaries at the upper course is (large / small). The amount of the channel water is (large / small).
Large boulders in the channel (increase / decrease) the channel roughness.
(Much / Less) of the energy are used for overcoming friction.

7. What is the direction of the erosion at the upper course?
What landforms are formed at the upper course?
What is the direction of the erosion at the upper course?
What is the work involved?
________ erosion is the dominant work at the upper course.
Vertical
Headward erosion also occurs when water starts to gather.
Because of the small river energy, the rate of erosion is (slow / fast).
The cross-section of a valley at the upper course
(Small / Large) load can be transported.
Deposition is (common / rare).

8. Landforms at the upper course
What landforms are formed at the upper course?
What are the landforms produced?
Landforms at the upper course
Interlocking spurs
Rapids
Potholes
Gorges
Waterfalls

9. How is the land shaped at the middle course?
How much energy is there?
Do you know why?
How much energy is there at the middle course when compared with the upper course? (Greater / Less).
More tributaries are joining the river.
The amount of river water (increases / decreases).
The river energy (increases/ decreases).
The channel becomes _________. The water flows ______.
smoother
faster

10. How is the land shaped at the middle course?
What is the work involved?
The river flow is faster and with more energy.
Why?
(Erosion / Transportation / Deposition)
What is the main work at the middle course?
Erosion occurs, but there is extra energy for _____________.
transportation

11. Landforms at the middle course
How is the land shaped at the middle course?
What are the landforms produced?
Landforms at the middle course
Slip-off slopes
River cliffs
Meanders
Bluffs

12. Is the energy large or small at the lower course?
What landforms are formed at the lower course?
How much energy is there?
Is the energy large or small at the lower course?

13. The cross-section of s valley at the lower course
What landforms are formed at the lower course?
How much energy is there?
It has the (smallest / largest) discharge among the three courses.
The river bed is (smooth / rugged), so the friction here is greatly (reduced / risen).
Therefore, the flows are at a (low / high) speed.
The lower course has the (highest / lowest) energy.
The channel here accommodates (less / more) water than that of the upper course.
The cross-section of s valley at the lower course

14. What landforms are formed at the lower course?
How much energy is there?
Does it mean the river energy is high all the time at the lower course? (Yes / No)
The river energy drops when:
the channel flow is blocked by sea water at the _______ of the river.
mouth
the amount of river water is reduced during the (wet / dry) seasons.
flooding occurs and the flood water has not yet retreated from the valley floor.

15. What landforms are formed at the lower course?
What is the work involved?
Ha! Ha! All three work occur at the lower course!
What is the work at the lower course?
Erosion- at the (inner / outer) banks of the river.
(Erosion / Transportation / Deposition)
Transportation- bringing the load towards the mouth of the river.
Deposition- whenever and wherever speed of flow is lowered.

16. Landforms at the lower course
What landforms are formed at the lower course?
What are the landforms produced?
Landforms at the lower course
Flood plains
Deferred tributaries
Oxbow lakes
Deltas
Levees
Braided streams

17. Case study: How does the Chang Jiang change along different courses?
Tuotuo He
Yichang
Hukou
Upper course
Middle course
Lower course

18. Do you know any characteristics of the Chang Jiang?
Case study: How does the Chang Jiang change along different courses?
The longest river in China and ______ longest in the world.
third
Do you know any characteristics of the Chang Jiang?
Average annual discharge: 30,000 m3/sec.
The load is not heavy as compared with the __________.
Huang He
humid
subtropical
It flows past the ___________ _______ humid area of China.
About % of the river water comes from _______.
rainfall

19. Case study: How does the Chang Jiang change along different courses?
Middle course
Lower course
Upper course

20. What are the characteristics of the upper course of the Chang Jiang?
The river source: The Tuotuo He
The discharge is small.
Vertical erosion
The Hutiaoxia at the Jinsha Jiang
The gradient is gentle.
The river flows slowly.
At the Jinsha Jiang
South-flowing.
The channel winds through interlocking spurs.
The gradient is steep.

21. What are the characteristics of the upper course of the Chang Jiang?
At the Sichuan Pendi
More rainfall
Many large tributaries join the main channel
Discharge increases rapidly
Great erosive power
Forms Sanxia

22. What are the characteristics of the middle course of the Chang Jiang?
A big drop in _______ and the _________.
altitude
gradient
Meanders are formed.
286 km
Numerous lakes are found, e.g. Dongting Hu.
Length of the river between them: 712 km

23. What are the characteristics of the lower course of the Chang Jiang?
The land is flat and low, e.g. the Chang Jiang Delta plain.
The tributaries are shorter than those in the middle and upper courses.
Many meanders and braided streams.
Levees and deferred tributaries are found.
Delta and lagoon are formed, e.g. Tai Hu.

24. How does a river basin work as a system?
What is a system?
It is a group of things that interact within a boundary to perform some functions.
It includes _______, __________ and ________.
inputs
processes
outputs
Open system
Closed system
Input
Processes
Output
Energy
Energy
Energy
Energy
Matter
Matter
Boundary of the system

25. How does a river basin work as a system?
Inputs
Processes
Outputs
 Weathering  Mass movement  Erosion  Interception  Drip flow/ Stem flow  Surface run-off  Infiltration  Subsurface run-off  Transportation  Deposition
Radiation
Absorption
Conduction
Solar radiation
Heat
Evaporation
Channel
outflow
Water
Precipitation
Water
Evapo-
transpiration
Vapour
Exogenetic
processes
Rocks
Transportation
Sediment

26. The end

27. What are the landforms produced at the upper course?
1 Interlocking spurs
They are the spurs interlocking with each other.
The river has too little energy to remove obstacles, so the river water flows around them.
Interlocking spurs
Valley is deepened
________ erosion deepens the channel and makes the obstacles more marked.
Vertical

28. What are the landforms produced at the upper course?
2 Gorges
Downcutting is (slower / faster) than lateral erosion.
This creates a (deep / shallow) and (narrow / wide) V-shaped valley, i.e. gorges.

29. What are the landforms produced at the upper course?
3 Rapids
The river water is unable to erode the layer of _________ rock.
resistant
Rapids
The river bed becomes (even / uneven).
The turbulent currents are called rapids.

30. What are the landforms produced at the upper course?
4 Waterfalls
Less resistant rock is eroded by river water at a (slower / faster) rate.
Water flow
Waterfall forms
The river falls vertically down.
Plunge pool forms
The falling water produces strong _________ action, forming a circular hollow filled with water.
Large angular boulders
hydraulic

31. Which type of fluvial erosion is involved within the potholes?
What are the landforms produced at the upper course?
Which type of fluvial erosion is involved within the potholes?
Abrasion.
5 Potholes
How does it form?
What is this?
Pothole
When a river flows over an uneven surface, it causes ___________ in the water.
turbulence
A pothole is formed when the water drills with the load it carries.

32. What are the landforms produced at the middle course?
1 Slip-off slopes and river cliffs
What are the two landforms produced?
What are the work involved at the inner and outer bank?
Which part of the river has the fastest flow?
River cliff
Inner bank: __________
deposition
Outer bank: ______________
Slip-off slope
lateral erosion
Fastest part of the river flow
River cliff
Slip-off slope

33. What are the landforms produced at the middle course?
2 Meanders
The outer bank gets worn away through _______.
Inner bank
Outer bank
erosion
Meander appears
More convex
More concave
The inner bank builds up through __________.
Lateral erosion creates river cliffs
deposition
Slip-off slopes form
The river (bends/ straightens).
Each bend is called a meander.
Faster stream of water thrown towards outer banks
Sediment
Low river cliff

34. What are the landforms produced at the middle course?
3 Bluffs
The meanders migrate downstream.
Erosion at outer bank creates river cliffs
They remove the interlocking spurs on their way through ________.
erosion
__________ at outer bank are pushed back and join into lines, forming bluffs.
River cliffs
Bluffs

35. What are the landforms produced at the lower course?
1 Flood plains
The load is carried to the valley floors by the flood water.
Repeated flooding and __________ build up a flat area.
During floods, water overflows from the channel to the lands, bringing sediment with it
_________ builds up on the river bed, silting occurs
Sediment
deposition
The deposits on the flood plain are called ________. They are fertile and good for farming.
Flood plain
alluvium

36. What are the landforms produced at the lower course?
2 Levees
The flood water overflows from the channel.
The (small / large) load is dropped at the river banks.
Levee
The banks are (raised / collapsed).
The levees are the ridge-like features at the river banks.

37. What are the landforms produced at the lower course?
3 Deferred tributaries
Defferred tributary
Tributaries flow _______ to the main channel.
parallel
They finally break through the ______ and join the main channel.
levees

38. What are the landforms produced at the lower course?
4 Oxbow lakes
This is an oxbow lake It is developed from a meander! Do you know how?

39. What are the landforms produced at the lower course?
4 Oxbow lakes
Oxbow lakes are the product of active ______ erosion and ___________ in the river.
Water flow
Little water enters the old channel
Sediment
lateral
Deposition
deposition
The meanders bend more.The (outer / inner) banks are pushed backward
When two outer banks of two bends meet, a new channel is formed.
Oxbow lake
_________ silts the original channel.
Sediment
An oxbow lake is formed.

40. What are the landforms produced at the lower course?
5 Braided streams
Water levels (rise / drop) during dry seasons.
(Erosion / Deposition) forms low ridges and blocks the river flow.
Braided streams
In wet seasons, the river is forced to split into several separated channels.
The braided streams rejoin

41. What are the landforms produced at the lower course?
6 Deltas
A delta is a gently sloping platform of _________ gradually builds up and extends into the ____.
sediment
Onshore current
Onshore current
Onshore current
Onshore current
sea
Mud-flat or marshes
Distributary
It is a fan-shaped mud-flat.
Deposits
New deposits during low-flow season
Lagoon
It is formed at the mouth of the river.
Delta forms
The velocity of flow (rises / drops)
Onshore current