Water Systems Unit Test

Earth's Supply of Water

• 97% of Earth's water supply is saltwater, which is undrinkable.
• 3% of Earth's water supply is freshwater, which is the only water suitable for drinking.

Three States of Water

• Water exists in three states: solid (ice), liquid (water), and gas (water vapor).
• When water changes from one state to another, it requires a transfer of energy.

Groundwater

• Most of Canada's freshwater exists underground rather than on the surface.
• Scientists estimate that one-third of the world's freshwater lies underground.
• The groundwater zone is the area where water fills all the air spaces in the soil and rock.
• The upper surface of the groundwater zone is called the water table.
• An aquifer is an underground freshwater reservoir that stores large amounts of water.
• Groundwater is constantly moving and eventually reaches the surface, forming wetlands, rivers, lakes, or oceans.

Ice Sheets and Ice Caps

• An ice sheet is a large glacier that covers the land, with only two existing on Earth (in Greenland and Antarctica).
• Ice sheets are formed on a larger scale, similar to a mountain glacier.
• The term "Polar Icecap" is sometimes used to refer to these large ice masses at the poles.

The Water Cycle

• The water cycle is a continuous process with no beginning or end.
• The sun provides thermal energy that drives the water cycle.
• Water is constantly changing states as it moves from Earth's surface into the atmosphere and back into the Earth again.
• The sun's heat energy drives the water cycle, causing water to change states through evaporation, melting, freezing, sublimation, condensation, and deposition.

Water Cycle Processes

• Evaporation: the process of water changing from a liquid into water vapor.
• Melting: the process of solid ice becoming liquid by adding heat.
• Freezing: the process of becoming ice by losing heat.
• Sublimation: the process of going from solid ice to water vapor without first becoming liquid.
• Condensation: the process of water vapor turning into liquid by cooling.
• Deposition: the process of water vapor changing directly into a solid without becoming a liquid first.

Water Table and Watersheds

• A watershed is an area of land where all the water eventually drains into one main water body, such as a stream, river, wetland, lake, or ocean.
• Activities that affect water in one part of the watershed have an effect downstream in the watershed.
• Small watersheds connect to larger watersheds, forming a network of water systems.