How does water underground reach the surface? Freshwater flows underground.

Water moves underground. All groundwater comes from precipitation. Water underground trickles down between particles of soil and through cracks and spaces in layers of rock.

Groundwater Formation Differences in the materials that form layers underground determine where groundwater forms.

Different Materials The size of the pores determines how easily water moves through rock and soil. Permeable: allow water to pass through. Large connected pores Ex) sand, gravel Impermeable: water cannot pass through easily. Few or no pores or cracks. Ex) clay, granite

Water Zones Saturated Zone: area of permeable rock that is totally filled with water. Water Table: top of the saturated zone. Unsaturated Zone: layer of rocks and soil above the water table.

Bringing Up Groundwater Aquifer: underground layer of rock that holds water. People can obtain groundwater from an aquifer by drilling a well below the water table. The level of a water table follows the shape of underground rock layers. Water level can rise during heavy rains and then fall in times of drought.

Drilling for Water

Drilling For Water Pumping water out of an aquifer lowers the water table near the well. If too much water is pumped out too fast, the well could run dry. New water that enters an aquifer from the surface is called recharge. Artesian Well: water rises to the surface b/c of the pressure w/in the aquifer. Occurs when water is trapped between layers of impermeable rock. Released when the top layer is punctured and natural pressure sends the water spurting upward.