Ground Water

Ground Water...An underground lake Ground Water is water that is located within the rocks below the Earth’s surface. Zone of Aeration Water easily passes through the uppermost zone As water percolates, contaminants and particles are filtered out of the water Zone of Saturation Water collects between the spaces of rock particles and creates an underground “lake”

Locate the Zone of Aeration and Zone of Saturation. Compare these zones.

The water table is the boundary between the zone of aeration and saturation The water table varies in depth from a few centimeters below the soil surface to hundreds of meters below the Earth’s surface Water table rises during wet seasons Water table falls during dry seasons What lies between

The water cycle revisited

Exactly what is an Aquifer? An Aquifer is a rock layer in which ground water can freely flow Characteristics of an Aquifer: Porosity (pores or spaces)- the more space between particles of an aquifer the more water it can hold - Larger particles= more porous - smaller particles= less porous

Additional Characteristics Permeability (permeate)- the ability of a rock layer to let water pass through Larger particles = less surface area and less friction therefore more permeable Smaller particles = more surface area and more friction therefore less permeable

Best of the Best! The best aquifers form in permeable materials such as sandstone, limestone, or layers of sand and gravel. An aquifer depends on the water cycle to continuously recharge itself. Water enters an aquifer through a surface recharge zone The surface recharge zone is permeable for water to percolate through easily.

Springs and Wells Springs Artesian Springs When the water table reaches the Earth’s surface, a spring forms If the table is higher than the Earth’s surface, a lake is created Springs are important sources of drinking water Artesian Springs Unlike a regular spring, an artesian formation occurs when an aquifer is sandwiched between 2 layers of impenetrable rock. An artesian spring occurs in a crack of the cap rock

A human made hole that is deeper than the level of the water table is called a well. Can dry up if the water table drops below the well Additionally, can be depleted if too many wells access the aquifer and water is removed too quickly Wells