Objectives
After participating in this activity, students will:
- Experience the relative scarcity of freshwater on the planet
- Explain why some of the earth’s water is not easily accessible
- Compare and contrast surface water systems and groundwater in regard to their relative sizes as Earth’s freshwater reservoirs
- Manipulate simple tools that aid observation and data collection, make accurate measurements with appropriate units
- Use tools and equipment appropriate to scientific investigations
- Conduct scientific investigations using appropriate tools and techniques
Summary
Even though the earth contains an abundance of water, only a small percentage is fresh water. An even smaller amount of this freshwater is accessible and usable by the people and animals that need it. As the human population grows, the amount of freshwater available per person shrinks. The relatively small amount of available freshwater demonstrates how critical it is for everyone to help maintain clean, healthy lakes and streams.
Background
Oceans and seas contain more than 97 percent of the water on the planet. Because it is salt water, it is not healthy for humans and animals to drink. The remaining supply of water on Earth is fresh water.
The amount of freshwater available for use by living beings is very small (See chart). The Great Lakes contain 20 percent of the world’s supply of surface freshwater. Other reservoirs of freshwater are not available for use by humans. For instance, more than 2 percent of the Earth’s freshwater is “locked” in ice caps and glaciers.
The Earth’s supply of water remains the same: the planet has as much water as it will ever have. Yet world population continues to grow. The relatively small amount of available freshwater supports more than 6 billion people. As this number increases, the amount of fresh water available per person decreases. Thus maintaining the quality of the Earth’s available fresh water is vitally important.
Amount of water in each major reservoir on earth:
Saltwater in oceans: |
97.2% |
Ice caps and glaciers: |
2.14% |
Groundwater: |
0.61% |
Surface water: |
0.009% |
Soil moisture: |
0.005% |
Total: |
100% |
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