Fresh Water Chapter 7 Sections 1-4 SOL 6.7

Less than 1% of the water on Earth is usable to humans. Earth is called the “water planet” because nearly ¾ of Earth is made up of water. 97% salt water 3% fresh water Less than 1% of the water on Earth is usable to humans.

Water is found in several forms on Earth, including: Oceans Ice (glaciers) Rivers and lakes Groundwater Far more fresh water is found underground than in all of Earth's rivers and lakes.

In addition to household purposes, people use water for agriculture, industry, transportation and recreation.

Example: Plants need water to carry out photosynthesis. Water is also important for living things to grow, reproduce, and carry out other important processes. Example: Plants need water to carry out photosynthesis.

A river and all its tributaries together make up a river system. Tributaries = the smaller streams and rivers that feed into a main river due to the pull of gravity.

All the water in a river system drains into the main river All the water in a river system drains into the main river. The land area that supplies water to a river system is called a watershed (also called drainage basins).

Virginia has many watersheds. The largest watershed in VA is the James River Watershed which stretches from Chesapeake Bay to the Virginia/West Virginia border. The smallest watershed in VA is the Yadkin Watershed which stretches into North Carolina.

The Continental Divide is the longest divide in North America. One watershed is separated from another by a ridge of land called a divide. Streams on each side of the divide flow in different directions. The Continental Divide is the longest divide in North America.

A flood occurs when the volume of water in a river increases so much that the river overflows its channel. Flood water has a lot of energy and can uproot trees and wash away bridges and houses.

Ponds and lakes form when water collects in hollows and low-lying areas of land. They are made up of still or standing water. Ponds are generally smaller and shallower than lakes.

Ponds have many plant species living in them because of how shallow they are, which allows sunlight to reach all the way to the bottom. The bottom of a pond is usually covered with mud and algae. Not all ponds exist-year round. Some dry up in the summer and reappear when runoff from spring rains and melting snow collects in low areas.

Most lakes are deep enough that sun does not reach all the way to the bottom. A lake bottom may usually consist of sand, pebbles or rock.

People can create a lake by building a dam across a river People can create a lake by building a dam across a river. The lake may be used for supplying drinking water, irrigating fields or for boating and fishing. A reservoir is a lake that stores water for human use.

A lake environment can gradually change over time A lake environment can gradually change over time. (Notice the green algae growth.)

When a glacier reaches the seacoast, icebergs form When a glacier reaches the seacoast, icebergs form. About 90% of an iceberg lies below the surface. The underwater part is a hazard to ships because it is often much wider than the visible part.

People can bring groundwater to the surface through the use of a well. Groundwater comes from precipitation that soaks into the ground instead of evaporating. Water underground trickles down between particles of soil and through cracks and spaces in layers of rock. People can bring groundwater to the surface through the use of a well.

3 types of wetlands: marshes, swamps and bogs A wetland is an area of land that is covered with a shallow layer of water during some or all of the year. They form in places where water is trapped in low areas or where groundwater seeps onto the surface of the land. 3 types of wetlands: marshes, swamps and bogs

Wetlands are protected because they: Because of their sheltered waters and rich supply of nutrients, wetlands provide habitats for many living things. Wetlands are protected because they: act like a filter for polluted water, prevent erosion, and control floods by absorbing extra runoff from heavy rains.

The Florida Everglades and other wetlands are protected by laws to protect many endangered species that live there.