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Water Underground
How Water Moves Underground• Water underground trickles down between
particles of soil and through cracks and spaces in layers of rock
Effects of Different Materials
• Permeable materials have large and connected pores; materials such as sand and gravel allow water to pass through or permeate.
• Impermeable materials have few or no pores or cracks; therefore the water cannot pass through easily
• Examples: clay and granite
Water Zones
• **The area of permeable rock or soil that is totally filled or saturated, with water is called the saturated zone**
• **The top of the saturated zone is called the water table**
• The area above the water table is called the unsaturated zone
Bringing up Groundwater• In some areas, the water table meets the
surface
• Aquifers:– Any underground layer of rock or sediment that
holds water is known as an aquifer**– Size: small underground patch to the size of
several states
Aquifers continued• Functions: drinking water, water for
crops, and water for livestock
• Rate of Movement: depends on the slope of the aquifer and permeability of rocks
Wells
• **People can obtain groundwater from an aquifer by drilling a well below the water table**
• If the level of the aquifer drops, a well can run dry
• The water table can rise after heavy rain or snow melts
Using Pumps• Mechanical pumps bring up groundwater
• If water is pumped out too fast, a well will run dry
• New water that enters the aquifer from the surface is called recharge
Relying on Pressure• **In an artesian well, water rises because
of pressure in an aquifer**
• If groundwater becomes trapped between two layers of impermeable rock or sediment, the pressure sends water spurting up through the punctured hole
• No pump is necessary
Springs and Geysers• Sometimes, groundwater comes to the
surface through natural processes
• When groundwater bubbles or flows out of cracks in the rock it is called a spring
• A fountain of boiling water is known as a geyser
Springs and Geysers
• The word geyser means gusher
• A geyser forms when very hot water that has been circulating deep underground begins to rise through narrow passages in the rock
• Provide one example of a geyser: Old Faithful
Interesting Sites• http://unmuseum.mus.pa.us/flash/geyflash.htm
• http://www.nps.gov/archive/yell/oldfaithfulcam.htm
• http://www.floridasprings.org • www.unitedstreaming.com (Gushing Geysers; Natural Phenomena)
• Which wells end in a saturated zone?• Which well(s) will not provide water? • How does water enter Aquifer A?