Paper 1 section C - Rivers

Question 1

What is a river

Answer 1

A large natural stream of water flowing in a channel to the sea, a lake, or another stream.

Question 2

What is a long profile

Answer 2

A long profile shows the gradient of a river as it journeys from source to mouth.

Question 3

Parts of a river

Answer 3

Source
Mouth
Tributary
Confluence
Main river channel
Drainage basin
Watershed

Question 4

What is the source of a ricer

Answer 4

The place where a river starts in its upper course

Question 5

What is the mouth of a river

Answer 5

The place where a river meets the sea

Question 6

What is the cross profile

Answer 6

The cross profile shows you what a cross-section of the river looks like

Question 7

Draw the cross profiles of upper, middle and lower course

Answer 7

https://igcsegeography.files.wordpress.com/2015/12/cross-profile-of-a-river.png

Question 8

What does the shape of the valley and channel of a river depend on

Answer 8

The shape of the valley and channel changes along the river depending on whether erosion or deposition is the dominant process

Question 9

Describe how a river changes from source to mouth

Answer 9

Rivers begin in upland areas and flow downhill.

Near the source, the long profile of a river shows a steep gradient.

It gradually gets lower and less steep until the river reaches sea level.

The river has a V-shaped cross profile in the upper course.

By the time the river reaches its lower course, the valley is wide and flat

Question 10

Characteristics and processes happening in Upper Course

Answer 10

Vertical erosion with Hydraulic action,( abrasion and attritio)n - This deepens the river valley and channel making it V-shaped. These are the dominant processes in the upper course

Transport: Traction and saltation at high flow. Load size is large and angular

Deposition: Large boulders deposited

High turbulence causes the rough, angular particles to be scaped along the river bed, causing intense downwards erosion

V shaped valleys

Change: High relief, steep gradient, waterfalls and rapids

Question 11

Characteristics and processes happening in Middle Course

Answer 11

Channel is deeper and wider

Vertical erosion decreasing in importance, more lateral erosion (attrition, abrasion and solution). The lateral erosion widens the river valley and channel during the formation of meanders and deposition

Suspension is the main transportation type occurring here
Load becomes smaller and less angular

Deposition: More deposition on inside bend of meanders

CHANGE:
Discharge has increased
Tributaries have joined
Gradient of long profile is concave

Question 12

Characteristics and processes happening in Lower Course

Answer 12

Channel is at its widest and deepest, and may be tidal
The lateral erosion widens the river valley and channel during the formation of meanders

Deposition more important than erosion (very little erosion, only lateral erosion)

Deposition is now the main fluvial process. Fine material deposited

Transport:
Suspension and solution. Large amount of load but the size is very small and very rounded

Change: Area closest to river mouth, with low-lying land. Erosion is now lateral erosion at meanders. Gradient almost flat.

Question 13

Where is vertical erosion dominant

Answer 13

Vertical erosion is dominant in the upper course of the river

Question 14

Where is lateral erosion dominant

Answer 14

Lateral erosion is dominant in the middle and lower courses of the river

Question 15

Erosion can be _____ or ______ - both types happen __________ but one is usually _______ at different points along the river

Answer 15

Erosion can be vertical or lateral - both types happen at the same time, but one is usually dominant at different points along the river

Question 16

Define dicharge

Answer 16

Discharge is the volume of water passing through a given point on the river. It is measured in cubic meters per second (cumecs).

Question 17

Formula for discharge

Answer 17

Discharge = velocity x cross-sectional area

Question 18

Explain why dicharge increases downstream

Answer 18

Discharge increases downstream since tributary streams join the main river and add their volume of water to it.

In the upper course, the small channel means lots of friction, which slows the water down.

In the lower course, the channel is broad and deep so water has little contact with the banks and velocity is much higher. Speed is boosted by additional discharge from tributaries.

Question 19

State the types fluvial processes

Answer 19

Erosion
Transportation
Deposition

Question 20

Types of erosion

Answer 20

Hydraulic action
Abrasion
Attrition
Solution
Vertical erosion
Lateral erosion

Question 21

What is vertical erosion

Answer 21

Vertical erosion is a type of erosion that deepens the river valley and channel, making it V-shaped

Question 22

What is lateral erosion

Answer 22

Lateral erosion is a type of erosion which widens the river valley and channel

Question 23

What is fluvial

Answer 23

Fluvial means to do with a river

Question 24

What is a fluvial process

Answer 24

A fluvial process is the motion of sediment and erosion or deposition on the river bed.

Question 25

Explain the process of hydraulic action

Answer 25

This is when the sheer force of fast-flowing water hits the river banks and river bed and forces water into cracks.

This compresses air in the cracks.

Repeated changes in air pressure weaken the channel, causing rock particles to break way from the river channel

Question 26

What is hydraulic action responsible for in the upper course of the river and lower course of the river

Answer 26

Hydraulic action is responsible for vertical erosion in the upper course of a river.

In the lower course, it contributes to lateral erosion of the banks, especially when fast-flowing water hits the outside bend of the meander.

Lateral erosion is partly responsible for the migration of meanders across the floodplain.

Question 27

Explain the process of abrasion

Answer 27

Small boulders and stones may scratch and scrape their way down a river during transport, thereby wearing down the river banks and bed.

Stones which have fallen into the channel quite recently will be angular and have sharp, jagged edges.

These are particularly effective tools of abrasion.

Question 28

What is hydraulic action responsible for in the upper course of the river and lower course of the river

Answer 28

Ongoing abrasion is responsible for both vertical erosion and lateral erosion of the channel.

Question 29

The faster a river’s flowing, the more _____ happens

Answer 29

The faster a river’s flowing, the more EROSION happens

Question 30

Explain the process of solution

Answer 30

Solution refers to the dissolving of rocks such as chalk and limestone.

Rivers travelling over these rocks will erode them in this way.

Question 31

Where does solution occur

Answer 31

Solution occurs in streams running through rocks such as chalk and limestone.

Question 32

Describe the process of attrition

Answer 32

Eroded rocks picked up by the river crash into each other and break into smaller fragments.

Their edges also get smoother and more rounded as they rub into each other

The further material travels, the more it is eroded - attrition cause particle size to decrease from a river’s source to its mouth