Fun Facts about Freshwater


The world's freshwater is an important resource for all of the planet's living creatures. Without freshwater, the world would be a much different place, and it would be difficult for humans, plants, and animals to survive. While the water cycle constantly recycles the water in our planet, lifting it from one place and raining it down in another, the amount of water in the world is limited. People all over the world must work together to ensure that the world's freshwater does not become too polluted for use. Additionally, people must be sure to conserve water so that there will be enough for all of the world's needs.

Quantity of Freshwater

Freshwater is necessary for humans to survive. Unfortunately, water is scarce in many places, which affects the quality of life for people living in these regions. While the earth holds a lot of water, only a small fraction of this water is fresh.

  • Water covers about 71 percent of the Earth's surface. The oceans hold the vast majority of the water, totaling about 96 percent of all the water on the planet.
  • At any given time, about 20 percent of the Earth's fresh water is in the Amazon Basin.
  • Only about 4 percent of the water on the planet is fresh water; the vast majority of Earth's water is salt water.
  • If all of the water in the atmosphere rained down at one time, the entire globe would receive about one inch of rainfall.
  • There is much more fresh water below the surface of the soil than exists in the rivers, lakes and streams.

How Much Water Is on the Earth?

Important Freshwater Rivers

Rivers carry freshwater from a source to another river, a lake, or the ocean. Some of the world's largest rivers are so wide that you cannot see all the way across them. Rivers are not only important for people, but they serve as habitat for countless plants and animals as well.

  • The sum of all the water in the world's rivers is about 509 cubic miles, or about 560 trillion gallons.
  • The Amazon River is the world's largest in terms of volume. At some points, the river is over 120 miles wide. No bridge spans any part of the Amazon River.
  • Scientists consider the Nile River to be the longest in the world, as it stretches nearly 4,135 miles from its source to its mouth.
  • The Mississippi River is the longest river in the United States, and it travels nearly 4,000 miles from Minnesota to the Gulf of Mexico.
  • The Yellow River flows from west to east in China. One of the biggest rivers in the world, the Yellow River is prone to frequent floods. In 1931, the river flooded badly, killing an estimated 1 million people.

The World's Most Polluted Rivers

Important Freshwater Lakes

Lakes hold a great deal of the world's freshwater. While lakes are landlocked bodies of water, they often connect to oceans via long rivers. The world's lakes are very important to their local ecosystems, and they even affect the local climate.

  • The world's lakes hold about 20 percent of the planet's fresh water that sits on the surface.
  • Lake Superior has the largest surface area of any freshwater lake in the world. It covers an area that is approximately the same size as the state of Maine.
  • The Caspian Sea is landlocked, leading many geographers to classify it as a lake. In fact, if considered a lake, it is the larger than Lake Superior. However, the lake's water is salty so many geographers consider it a sea instead of a lake.
  • While Lake Superior is only the third largest freshwater lake in terms of volume, it has enough water to cover both North and South America in over 12 inches of water.
  • Lake Baikal holds the most water of any freshwater lake in the world. This single lake holds more water than all five of the Great Lakes combined.

Great Lakes Information

World's Largest Lakes Information

Frozen Freshwater

When water gets too cold, it freezes into ice. However, water has some unique properties that distinguish it from other liquids. One of the most interesting properties of water is that it becomes less dense when it freezes. This is what allows icebergs to float instead of sinking to the bottom.

  • Glaciers contain about 75 percent of the world's fresh water. If all of the frozen glaciers and ice caps melted, the worldwide sea level would rise by about 230 feet.
  • Glaciers cover about 10 percent of the world's surface, including the polar ice caps, the ice sheets of Antarctica and Greenland, and the glaciers covering northern North America and Asia.
  • The quantity of ice and glaciers varies over time. During the last ice age, glaciers covered approximately 32 percent of the world's surface.
  • Glaciers are so heavy that they may push some of the land under them lower than sea level.
  • Icebergs may be very large, but about 90 percent of their mass is below the surface of the water.

All about Glaciers

NASA Explores the Ice Caps

Pollution of Freshwater

When water has toxic chemicals or other harmful substances in it, environmentalists consider it polluted. People must treat polluted water before consuming it to avoid illness. Unfortunately, animals and plants cannot treat their water and many perish from polluted rivers and streams.

  • In 1972, the Clean Water Act became U.S. law. This was the first major legislation that sought to protect the country's water supply.
  • Many of the world's rivers and lakes become polluted when it rains. As the rain washes over parking lots, agricultural areas and rooftops, it picks up toxic chemicals, which end up in lakes and rivers.
  • Environmentalists classify water pollution depending on where it comes from. Some pollution enters the water at a single place, such as the discharge from a factory. Environmentalists call this type of pollution "point source pollution." By contrast, some pollution enters the freshwater supply via a number of different places. For example, the fertilizers that find their way into a creek often originate in small quantities from a wide area. Environmentalists call these types of pollution "non-point source pollution."
  • Fracking is a relatively new technique for mining natural gas from the bedrock. Fracking works by injecting very toxic chemicals into the bedrock before attempting to siphon out the natural gas. Unfortunately, fracking is harming and polluting a significant amount of the nation's freshwater supplies.
  • Each year, the United States alone produces over 29 billion disposable water bottles, which must take up space in landfills if they are not recycled.

Twelve Simple Steps for Reducing Water Pollution

The Dangers of Fracking

Water for People

Water is essential for people's drinking and hygiene needs. Unfortunately, some people live without ample access to clean, fresh water. Many countries that lack enough fresh water also suffer politically and economically.

  • Only about 1 percent of the world's fresh water is readily accessible to people. This water fills the world's lakes, rivers, and underground sources.
  • Humans first began moving water around in significant quantities about 7,000 years ago. As water shortages threatened agriculture and food production, humans invented primitive irrigation techniques to keep their crops alive.
  • Some historians and archeologists believe that a significant drought led to the collapse of the Mayan civilization. This drought occurred about 1,100 years ago during the Middle Ages.
  • Many countries have difficulty supplying enough fresh water for their citizens. Currently, approximately 430 million people live in countries that scientists classify as "water stressed."
  • People are about 60 percent water by weight. This means that humans have to drink enough water each day to stay healthy. According to the Mayo Clinic, humans need between 2 and 3 liters of water each day.

Pathogens in the Water Supply

Water Scarcity in the Developing World

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