GROUND WATER Ground Water An underground lake Ground

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 • Zone of Saturation – Water easily passes through the uppermost zone – Water collects between the spaces of rock particles and creates an underground “lake” – As water percolates, contaminants and particles are filtered out of the water

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

What lies between • 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

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 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 – 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

Wells • 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