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River landscapes and processes . Geography CCEA GCSE 2009. The earth’s crust is modified by fluvial processes which result in distinctive landforms . River Structure. Stages in the Development of a River Valley. The river cuts downward to form a ‘V’shaped valley. The river starts

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river landscapes and processes

River landscapes and processes

Geography CCEA GCSE 2009

slide5
The river cuts downward to

form a ‘V’shaped

valley.

The river starts

to meander

slide7
River uses its meanders to cut from side

to side eating into

the valley

Floodplain

starts to

form

1

2

slide9
1

2

slide11
Floodplain

River bluffs

Alluvial

deposits

River cliff

river processes
River Processes

A river process is something that happens in the river. The main processes in the river are

Erosion - where parts of the river bed and bank get eroded / removed from the landscape

Transportation - where the eroded material is carried from one place to another through the river system

Deposition - where the river load becomes too heavy for the river to carry and is dumped down / deposited.

a river can erode material from its bed and banks in 4 main ways
A river can erode material from its bed and banks in 4 main ways
  • Abrasion – Moving water throws particles it is carrying against the bed and banks of the river which dislodges more material
  • Hydraulic Action - The sheer force of the water pounding into the bed and banks can dislodge material
  • Attrition - Particles being carried downstream knock against each other, wearing each other down. This results in smaller, rounder particles as you move downstream

Use your text book to see if you can find the 4th type!

methods of erosion
Methods of Erosion
  • Abrasion –
  • Hydraulic Action -
  • Attrition -
  • Solution-
methods of transportation
Methods of Transportation
  • Rivers transport material in 4 main ways
  • Solution - Some minerals (particularly in limestone areas) dissolve easily in water and are not visible to the naked eye
  • Suspension – As the speed or velocity of a river increases, it is able to pick up and carry larger and larger particles in its flow. Where particles are carried along in the flow and are not in contact with the river bed, they are said to be travelling in suspension.
methods of transportation16
Methods of Transportation
  • Saltation - Heavier particles may not be held in the flow all the time but may be bounced along the bed
  • Traction - The heaviest particles are rolled along the bed. Such particles may only be moved when the river has a large volume of water in it
methods of transportation17
Methods of Transportation
  • Solution -
  • Suspension-
  • Saltation -
  • Traction -
river features
River Features
  • Rivers are eroding, transporting and depositing constantly within the drainage basin system.
  • The river can be divided into 3 sections – Upper Course at the Source, Middle Course and Lower Course at the Mouth of the river. The river displays different characterisitics at each section
slide20
How to take notes on each of the River Features!

Course: Upper / Middle / Lower

Feature: Eg Waterfall

Diagram to illustrate: (make sure that this is labelled!)

Notes to explain how the feature happens:

Example of this feature:

Make sure that you take a new page for each new feature!

slide31
Why does it erode downwards?
  • How does it erode downwards?
slide37
Upper Course

Also known as ‘Torrent’ or ‘Youth’ stages

Interlocking Spurs

In the Upper Course, the river is fast flowing, but there is little water and load. The river is often called a stream and does not have the erosive power to remove the hillsides (spurs), but erodes downwards instead.

EROSION TYPE: Vertical and Headward

draw the stages in the formation of a waterfall explain in as much detail what is happening at 3
Draw the stages in the formation of a waterfall

Explain in as much detail what is happening at 3

3. What is happening here? (see next slide)

slide44
USA

Canada

Case study:

Niagara Falls

slide45
USA

Canada

slide55
Hard Resistant Rock - Limestone

52 meters

Weak Rock - Shale

gorges upper middle course

Gorges (Upper & Middle Course)

Case study: Niagara Falls (USA and Canada)

slide61
Upper Course

Waterfall and Gorge 1

(OBLIQUE AERIAL VIEW)

EROSION TYPE: Vertical and Headward

slide62
Upper Course

Waterfall and Gorge 2

(PROFILE VIEW)

EROSION TYPE: Vertical and Headward

use the niagara falls pictures powerpoint

Use the Niagara Falls Pictures PowerPoint

Notes to be taken from Page 10 from the Green Connections books

slide65
1. Can you mark the fastest flow on this?

2. What type of erosion do you think is happening?

slide71
Middle Course

Also known as the ‘Mature’ stage

Meanders 1

(Aerial View)

Meanders are formed because the current swings to the outside of a bend and concentrates the erosion there. Deposition occurs on the inside of the bed where there is not enough energy to carry load.

EROSION TYPE: Lateral

slide72
Middle Course

Meanders 2

(Profile View / Cross Section X - Y)

EROSION TYPE: Lateral

This cross section clearly shows the eddy current (near ’X’) formed by the velocity of the river being concentrated on the outside of the bend. These UNDERCUT the bank causing the formation of a RIVER CLIFF. On the inside (NEAR ‘Y’), a SLIP-OFF-SLOPE is formed where current is too slow to carry any load.

slide83
Middle Course

Ox-Bow Lake 1

(Aerial View)

Ox-bow lakes are formed when two meander RIVER CLIFFS are being eroded towards each other. These will eventually meet, causing the river to then flow across the bottom of the diagram.

EROSION TYPE: Lateral

slide84
Middle Course

Ox-Bow Lake 2(Aerial View)

slide86
Leeves

River

slide87
Lower Course

Leveés and Raised Beds 1(Front View)

DEPOSITION FEATURE: no erosion in the Lower Course

Leveés are formed when rivers flood. The river water overflows the banks of the river and immediately slows down due to friction with the FLOODPLAIN. This drops the larger particles first, building up a raised river bank called a LEVEÉ.

slide88
Lower Course

Leveés and Raised Beds 2(Front View)

DEPOSITION FEATURE: no erosion in the Lower Course

Raised beds form in the Summer months when the river volume and energy are low and load is dropped onto the river bed. The bed raises up and the capacity of the river reduces, causing flooding in the winter. This in turn builds up the leveés and the whole process raises up the level of the river in the landscape.

slide89
Lower Course

Braided Channels(Oblique Side View)

DEPOSITION FEATURE: no erosion in the Lower Course

In the Summer months, load is dropped by the low volume of low-energy water in the river. These build up to form obstructions in the river and it divides up to flow around them. In the winter, it is likely that the river volume will increase and remove these obstructions.

slide91
Lower Course

Delta(Aerial View)

This deposition feature is one of the largest. When the flowing river hits the non-flowing sea, energy is suddenly lost. This causes all of the load in the river to drop in the river MOUTH. This builds up over time to create a delta – an area of land. The river divides into DISTRIBUTARIES to continue to the sea, which is now some way away from its original meeting point.

slide93
What's the Point of all This?

Can you work out what the river is trying to do by using this diagram?

slide98
What's the Point of all This?

Can you work out what the river is trying to do by using this diagram?

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