The Distribution of Water on Earth
- 0:06 The Blue Planet
- 1:06 How Water Is Distributed
- 3:23 Lesson Summary
Water covers most of Earth but in a variety of forms. In this video lesson you will learn about how water is distributed on Earth, though you may be surprised to find out just how little of it we can access!
The Blue Planet
Earth is known as the 'blue planet' because it is covered with water and from space it is seen as bright blue. Water occurs in many forms on Earth, and it is naturally present in all three phases of matter: liquid water (oceans, lakes and streams), solid (ice caps and glaciers) and gas (water vapor in the atmosphere).
Water on Earth is very important because it is what allows life to exist. Without water, Earth would be dry and desolate, and you wouldn't be here! How water moves through the water cycle, which is the natural cycling of water through places and phases on Earth, affects weather, land features, global temperatures and drinking water supplies.
Water is an important resource to us because we use it for a variety of everyday things - drinking water, cooking food, washing clothes and power production, just to name a few. However, the amount of water available for our use is surprisingly small compared with all the water that is present on Earth.
How Water Is Distributed
When you look at an image of Earth, it's easy to understand that 70% of its surface is covered with water. This is because all that blue you see is water in the oceans - about 97% of all the water on Earth! Ocean water is very salty, much too salty for us to drink, so in the oceans it stays.
That leaves only about 3% for all other water on Earth, which is all freshwater. But even most of that is not available to us! Of that 3%, 2/3 of it (so about 68% of all the freshwater, which is about 2% of all the total water on Earth) is frozen in ice caps and glaciers. While this may sound like an untapped resource, it's actually beneficial to us that this water is frozen where it is because it helps regulate sea levels and global temperatures on Earth.
So we still have 1% of all the water on Earth left to distribute. About 30% of Earth's freshwater (approximately 0.6% of all water on Earth) is found as groundwater. This is one resource we do take advantage of - it's where we get much of our water for drinking and irrigating agricultural crops.
Surface water, which is all the lakes, rivers and streams on Earth, makes up about 0.3% of all the freshwater (about 0.009% of all water on Earth). Think about all the large rivers we have on our planet, like the Nile, the Amazon, the Colorado and the Mississippi. All of these rivers and all of their streams don't even add up to 1% of Earth's total water! And what's even more amazing is that of all the surface water, rivers make up a measly 2%. Most surface water is found in lakes, which constitute more than 85% of all surface water.
There is even more water to be accounted for, such as soil moisture, which is water that is in the ground but above groundwater, and water vapor in the atmosphere. All of this other water, including all those big clouds you see in the sky, makes up less than 1% of all the freshwater on Earth.
Earth is covered with water, and we should be very glad that it is! By moving through the water cycle, which is the natural cycle of water changing phase and location, the water on Earth makes the temperature and climate hospitable for us and provides us with water for drinking and doing daily activities.
What's surprising is how little of the water on Earth we can actually use because 97% of all the water on the planet is salty and in the oceans. Only 3% of Earth's water is freshwater, and most of that is frozen in glaciers and polar ice caps - about 68% of all freshwater, or 2% of all water on Earth. The remaining 1% of Earth's freshwater is found underground (0.6% of all water, 30% of all freshwater), on the surface (0.009% of all water, 0.3% of the freshwater) and in other forms, like soil moisture and water vapor in the atmosphere.
Surprisingly, of Earth's surface water, most of it (about 85%) is found in lakes. All those giant rivers like the Nile, the Amazon and the Mississippi only make up about 2% of Earth's surface water. It's important to remember that even though less than 1% of all Earth's water is available to us as liquid freshwater, the total amount of water on Earth is more than 320 million trillion gallons. So while 1% doesn't sound like a lot, 1% of such a large number is still a pretty large number!
Chapters in Earth Science 101: Earth Science
- 1. Earth Science Basics (7 lessons)
- 2. Geologic Time (8 lessons)
- 3. The Properties of Matter (10 lessons)
- 4. Earth's Spheres and Internal Structure (5 lessons)
- 5. Plate Tectonics (10 lessons)
- 6. Minerals and Rocks (9 lessons)
- 7. Igneous Rocks (5 lessons)
- 8. Volcanoes (7 lessons)
- 9. Weathering and Erosion (9 lessons)
- 10. Sedimentary Rocks: A Deeper Look (4 lessons)
- 11. Metamorphic Rocks: A Deeper Look (3 lessons)
- 12. Rock Deformation and Mountain Building (4 lessons)
- 13. Water Balance (5 lessons)
- 14. Running Water (8 lessons)
- 15. Ground Water (6 lessons)
- 16. Glaciers (7 lessons)
- 17. Oceans (10 lessons)
- 18. Coastal Hazards (7 lessons)
- 19. The Atmosphere (15 lessons)
- 20. Weather and Storms (12 lessons)
- 21. Earthquakes (6 lessons)
- 22. Earth History (8 lessons)
- 23. Energy Resources (13 lessons)
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