Sec 1 Chap 4

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

How are flash floods caused? (Pg 77)

• 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.

Most of the rainwater that falls onto the ground becomes ___________ ____________ which quickly floods low-lying areas.

What are river floods caused by?

• sustained heavy rainfall

• low rainfall

• meltwater produced when snow and ice start to melt in spring season

• large amounts of rainwater and meltwater enter streams and tributaries which then flow into rivers.

• water level rises rapid and eventually overflow the banks, flooding the areas

What are droughts?

• long period of little or no rainfall in a specific area

• may last for months or years

• may last only a few days

• may not be enough water to replenish the amount used for human activities

• it is caused by people wasting water

How is water used for agriculture?

• to wash buildings

• used to grow crops

• used for machines

• rear animals for human consumption

How is water used for industry?

• to heat up equipment

• to cool equipment in factories and power plants

• to have faster water supply

• to generate electricity

• used as cleaning agent in wafer fabrication

Water pollution occurs when ____________ substances enter water bodies and cause water quality to fall.

How does water pollution pose a threat to aquatic ecosystems? (page 84)