Where in the World is the Water?

The World’s Water Water is (almost) everywhere! Yet, some say the world’s largest problem of today is a shortage of water! 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.

The Blue Planet Hydrosphere – the part of the Earth that contains water Hydrologic Cycle - describes the continuous movement of water on, above, and below the surface of the Earth.

Distribution of Earth’s Water 2 categories of water in the Hydrosphere Salt Water Fresh Water Both are based on the percentage of salinity Salinity is the % of salt content

Distribution of Earth’s Water 71% of the Earth’s surface is covered with water. Earth’s oceans contain 97% of the planet’s water (salt water). 3% is fresh water (low concentrations of salts). Where 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)?

Distribution of Earth’s Water Salt water Oceans Freshwater Frozen = 2/3 Liquid = 1/3 (accessible)

Frozen Water Most freshwater is frozen at the polar ice caps!! Glaciers are masses of ice and snow that move slowly over the Earth’s surface.

Surface Water Sources include: Lakes Rivers Streams Reservoirs The main uses of surface water include: Drinking-water and other public uses Irrigation uses Industry and Hydroelectric Power

Lakes The Great Lakes are the largest freshwater system on earth. They contain 84% of North America’s surface freshwater and 21% of the world’s surface fresh water supply. Only the polar ice caps contain more fresh water.

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?

Colorado River and Water Wars There is a longstanding treaty between US and Mexico over this river. Serves over 30 million people. About 45 dams along the river.

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.

Groundwater 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. With the property of both cohesion and adhesion, through capillary action, water is able to move from wet soil to dry areas.

The amount of water that is available to enter groundwater 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 time water spends 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.