S1_4.1 Floods and Droughts

How do variations in precipitation affect water availability?

• They have no effect

• They can lead to floods and droughts

• They always increase water availability

• They only affect coastal areas

What are floods?

• An overflow of a large amount of water into what is normally dry land

• An underflow of a large amount of water into what is normally dry land

• A flow of water over the ground

What is a primary cause of flash floods?

• Light rainfall over a long period

• Heavy rainfall over a short period

• Moderate rainfall over a short period

• Light rainfall over a short period

Flash floods often occur on land that is cleared of __________.

Which of the following best describes a flash flood?

• It takes place suddenly

• It lasts for a short period of time

• It only occurs in an area with low permeability

• There is a quick rise in water level

Identify the type of flood shown in the photograph.

• River

• Coastal

• Flash Flood

Flash floods are caused by __________________.

• exceptionally heavy rainfall over short period of time

• exceptionally heavy rainfall over long period of time

• heavy rainfall over short period of time

• normal rainfall over short period of time

Flash floods occur in dry areas where there is not enough soil or vegetation to allow rainwater to ____________ the ground.

When land is cleared of vegetation, surface runoff ________.

• increased

• decreased

• remains the same

What happens when groundwater flow and surface runoff enter a river?

• The river dries up

• The river's water level decreases

• The river's water level rises

• The river changes direction