IB Geography Topic A.2.2 Human Impacts on Flood Risk Revision Notes (SL/HL)

IB Geography Topic A.2.2 Human Impacts on Flood Risk Revision Notes (SL/HL) | RevisionDojo

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Changes to Flood Behavior

Floods are dynamic events shaped by natural processes and human activities.
Understanding how these factors interact is crucial for managing flood risks and protecting communities.

Urbanization: Impermeable Surfaces and Increased Runoff

Imagine a city during a heavy rainstorm. Water cascades off rooftops, rushes down streets, and pools in low-lying areas.
Why does this happen more in urban areas than in natural landscapes?
The answer lies in impermeable surfaces.
Surfaces that do not allow water to infiltrate into the ground, such as roads, pavements, and buildings.
1. Increased Runoff: Water that would naturally soak into the ground is forced to flow over the surface, increasing the volume of runoff.
2. Higher Peak Discharge: More water reaches rivers and streams quickly, raising the peak discharge and increasing flood risk.
3. Shorter Lag Time: The time between peak rainfall and peak discharge is reduced, giving less warning before floods occur.

Example

In a forested area, rainwater is absorbed by soil and vegetation, reducing runoff. In contrast, a city with extensive concrete surfaces channels rainwater directly into storm drains and rivers, overwhelming the system.

Note

Tip

Urban hydrographs typically show a steeper rising limb, higher peak flow, and shorter lag time compared to rural hydrographs.

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Tip

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Changes to Flood Behavior

Floods are dynamic events shaped by natural processes and human activities.
Understanding how these factors interact is crucial for managing flood risks and protecting communities.

Urbanization: Impermeable Surfaces and Increased Runoff

Imagine a city during a heavy rainstorm. Water cascades off rooftops, rushes down streets, and pools in low-lying areas.
Why does this happen more in urban areas than in natural landscapes?
The answer lies in impermeable surfaces.
Surfaces that do not allow water to infiltrate into the ground, such as roads, pavements, and buildings.
1. Increased Runoff: Water that would naturally soak into the ground is forced to flow over the surface, increasing the volume of runoff.
2. Higher Peak Discharge: More water reaches rivers and streams quickly, raising the peak discharge and increasing flood risk.
3. Shorter Lag Time: The time between peak rainfall and peak discharge is reduced, giving less warning before floods occur.

Example

Note

Tip

Urban hydrographs typically show a steeper rising limb, higher peak flow, and shorter lag time compared to rural hydrographs.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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.2.2 Human Impacts on Flood Risk 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

Changes to Flood Behavior

Urbanization: Impermeable Surfaces and Increased Runoff

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

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Changes to Flood Behavior

Urbanization: Impermeable Surfaces and Increased Runoff

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