IB Geography Topic A.1.3 River Processes Revision Notes (SL/HL)

IB Geography Topic A.1.3 River Processes Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Mechanisms of Change in River Systems

Rivers are dynamic systems that shape landscapes through three interconnected processes: erosion, transportation, and deposition.
Each process plays a critical role in altering river channels and creating landforms.

Note

These processes are interconnected and influence each other. For example, erosion provides the sediment that is transported and eventually deposited.

There Are 4 Main Mechanisms to Erosion

Definition

Erosion

Erosion is the process by which rivers wear away their beds, banks, and the surrounding landscape.

1. Hydraulic Action: The Power of Water

Hydraulic action involves the sheer force of water dislodging material from the riverbed and banks.
When water flows rapidly, it compresses air into cracks and crevices.
As the pressure builds, the trapped air expands, causing the rock to break apart.

Example

Imagine a fast-flowing river crashing against a rocky bank.
The force of the water pushes air into tiny cracks.
Over time, this repeated pressure weakens the rock, causing pieces to break off.

2. Abrasion: The River’s Sandpaper

Abrasion occurs when sediment carried by the river scrapes against the bed and banks, wearing them down.
This process is most effective when the river is carrying a large load of coarse material, such as gravel or sand.

Example

Think of a river as a giant piece of sandpaper.
As it flows, the sediment it carries grinds against the riverbed, gradually smoothing and eroding it.

3. Attrition: Breaking Down the Load

Attrition refers to the process by which particles in the river collide with each other, breaking into smaller, rounder pieces.
This reduces the size of the sediment as it moves downstream.

Example

Imagine pebbles tumbling in a river.
As they collide, sharp edges break off, and the pebbles become smaller and smoother.

Solution: Chemical Erosion

Solution (or corrosion) involves the dissolving of soluble minerals, such as calcium carbonate, in the water.

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Note

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Mechanisms of Change in River Systems

Rivers are dynamic systems that shape landscapes through three interconnected processes: erosion, transportation, and deposition.
Each process plays a critical role in altering river channels and creating landforms.

Note

These processes are interconnected and influence each other. For example, erosion provides the sediment that is transported and eventually deposited.

There Are 4 Main Mechanisms to Erosion

Definition

Erosion

Erosion is the process by which rivers wear away their beds, banks, and the surrounding landscape.

1. Hydraulic Action: The Power of Water

Hydraulic action involves the sheer force of water dislodging material from the riverbed and banks.
When water flows rapidly, it compresses air into cracks and crevices.
As the pressure builds, the trapped air expands, causing the rock to break apart.

Example

Imagine a fast-flowing river crashing against a rocky bank.
The force of the water pushes air into tiny cracks.
Over time, this repeated pressure weakens the rock, causing pieces to break off.

2. Abrasion: The River’s Sandpaper

Abrasion occurs when sediment carried by the river scrapes against the bed and banks, wearing them down.
This process is most effective when the river is carrying a large load of coarse material, such as gravel or sand.

Example

Think of a river as a giant piece of sandpaper.
As it flows, the sediment it carries grinds against the riverbed, gradually smoothing and eroding it.

3. Attrition: Breaking Down the Load

Attrition refers to the process by which particles in the river collide with each other, breaking into smaller, rounder pieces.
This reduces the size of the sediment as it moves downstream.

Example

Imagine pebbles tumbling in a river.
As they collide, sharp edges break off, and the pebbles become smaller and smoother.

Solution: Chemical Erosion

Solution (or corrosion) involves the dissolving of soluble minerals, such as calcium carbonate, in the water.

Definition

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Duis aute irure dolor in reprehenderit

Note

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Excepteur sint occaecat cupidatat non proident

Tip

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Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
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1 Changing Population3 subtopics

2 Global Climate - Vulnerability and Resilience3 subtopics

3 Global Resource Consumption and Security3 subtopics

4 Power, Places and Networks (HL only)3 subtopics

5 Human Development and Diversity (HL only)3 subtopics

6 Global Risks and Resilience (HL only)3 subtopics

Option A Freshwater - Drainage Basins4 subtopics

Option B Oceans and Coastal Margins4 subtopics

Option C Extreme Environments4 subtopics

Option D Geophysical Hazards4 subtopics

Option E Leisure, Tourism and Sport4 subtopics

Option F The Geography of Food and Health4 subtopics

Option G Urban Environments5 subtopics

IB Geography A.1.3 River Processes Notes

1 Changing Population3 subtopics

2 Global Climate - Vulnerability and Resilience3 subtopics

3 Global Resource Consumption and Security3 subtopics

4 Power, Places and Networks (HL only)3 subtopics

5 Human Development and Diversity (HL only)3 subtopics

6 Global Risks and Resilience (HL only)3 subtopics

Option A Freshwater - Drainage Basins4 subtopics

Option B Oceans and Coastal Margins4 subtopics

Option C Extreme Environments4 subtopics

Option D Geophysical Hazards4 subtopics

Option E Leisure, Tourism and Sport4 subtopics

Option F The Geography of Food and Health4 subtopics

Option G Urban Environments5 subtopics

Mechanisms of Change in River Systems

There Are 4 Main Mechanisms to Erosion

1. Hydraulic Action: The Power of Water

2. Abrasion: The River’s Sandpaper

3. Attrition: Breaking Down the Load

Solution: Chemical Erosion

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Mechanisms of Change in River Systems

There Are 4 Main Mechanisms to Erosion

1. Hydraulic Action: The Power of Water

2. Abrasion: The River’s Sandpaper

3. Attrition: Breaking Down the Load

Solution: Chemical Erosion

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account