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Water Cycle

Water Cycle. The scarcity of fresh water is already posing major problems for more than a billion people around the world, mostly in arid developing countries.

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Water Cycle

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  1. Water Cycle The scarcity of fresh water is already posing major problems for more than a billion people around the world, mostly in arid developing countries. The World Health Organization predicts that by mid-century, four billion of people —nearly 2/3 of the world’s present population—will face severe fresh water shortages. Water is (almost) everywhere!

  2. Distribution of Earth’s Water • Earth’s oceans contain 97% of the planet’s water. • 3% is fresh water (low concentrations of salts). • Most fresh water is trapped as ice in the vast glaciers and ice sheets/tundra of Greenland. Where else is freshwater stored on Earth? Do you think we can drink water from the ocean? What is the main reason why ocean water is not potable (drinkable)?

  3. Surface Water Sources Include: • Rivers • Streams • Creeks • Lakes • Reservoirs The main uses of surface water include: • drinking-water and other public uses • irrigation uses • Industry and Hydroelectric Power

  4. Watersheds Watershed – a land area in which surface runoff drains into a river or a system of rivers and streams What is your local watershed that supplies you with drinking water?

  5. Where else does our Water come from?

  6. According to the USGS, about 77 percent of the freshwater used in the United States in 2005 came from surface-water sources. The other 23 percent came from groundwater. 

  7. Groundwater Largest reservoir of liquid fresh water on Earth Sources include: • Aquifers– a zone of material capable of supplying ground water at a useful rate from a well • porous rock • sediment with water in between(soil) Water is attracted to the soil particles through the property of adhesion and with the property of cohesion, resulting in capillary action, water is able to move from wet soil to dry areas. Aquifers are found at different depths. • Just below the surface (water table) • Some deep underground

  8. The amount of water that is available to enter groundwater in a region is influenced by: • local climate • slope of the land • type of rock found at the surface • vegetation cover • land use in the area • water retention, which is the amount of water that remains in the ground. More water goes into the ground where there is a lot of rain, flat land, porous rock, exposed soil, and where water is not already filling the soil and rock. The residence time of water in a groundwater aquifer can be from minutes to thousands of years. Groundwater is often called “fossil water” because it has remained in the ground for so long, often since the end of the ice ages.

  9. What do we use water for?

  10. “We shall not finally defeat AIDS, tuberculosis, malaria, or any of the other infectious diseases that plague the developing world until we have also won the battle for safe drinking-water, sanitation and basic health care.” Kofi Annan, Former United Nations Secretary-General.

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