1. Groundwater a Fresh water source Essential Question: What is the distribution of fresh and salt water on Earth ?

2. What is Groundwater?  Water located within rocks below earth’s surface is called groundwater  Groundwater fills the open spaces in rocks, sediment, and beneath the surface  Groundwater fills the open spaces in rocks, sediment, and soil beneath the surface  Groundwater is an important source for domestic, industrial, and agricultural use, but is also an important role in erosion and as an energy source in some areas

3. Ground Water and the Water Cycle  Groundwater is about 22% of the world’s fresh water comes from precipitation, percolating through soils and sediment comes from precipitation, percolating through soils and sediment streams, lakes, and snowmelt also contribute streams, lakes, and snowmelt also contribute

4. How Does Groundwater Move?  Gravity moves groundwater, just as it does water in channels  Moves from areas of high pressure to areas of low pressure  May move up to 250 m per day, or less than a few cm/day

5. The Water Table  Zone of aeration pore spaces contain mostly air pore spaces contain mostly air  Zone of saturation pore spaces contain mostly water pore spaces contain mostly water  Water table the top of the zone of saturation the top of the zone of saturation Groundwater Zone of aerationSaturated ZoneWater Table

6. What Properties of Earth’s Materials Allow Them to Absorb Water?  Aquifer A rock layer that stores ground water and allows the flow of groundwater A rock layer that stores ground water and allows the flow of groundwater  Porosity The percentage of open space between individual rock particles The percentage of open space between individual rock particles  Permeability A rocks ability to let water pass through A rocks ability to let water pass through

7. What are Springs?  Groundwater movement is determined by the slope of the water table  Groundwater tends to move down slope  If the water table reaches Earth’s surface, water will flow out from the ground and form a spring  Springs are an important source of drinking water and can form lakes

8. What Are Water Wells?  A human-made hole that is deeper than the level of the water table is called a well  If a well is not deep enough it can dry up

9. What Are Artesian Systems?  A sloping layer of permeable rock sandwiched between two layers of impermeable rock is called an artesian formation  An artesian spring is a spring whose water flows from a crack in the cap rock or top impermeable layer  Often found in deserts where they are the only source of water

10. Groundwater Contamination  Most common sources: sewage, landfills, toxic waste disposal sites, and agriculture sewage, landfills, toxic waste disposal sites, and agriculture  practices by industry and citizens

11. Groundwater and Erosion  Groundwater causes erosion by dissolving rock  This erosion can form caves and sinkholes  When the water table is lower than the level of the cave, the cave is no longer supported by the water underneath causing it to collapse