LEQ:LEQ:How does water move How does water move through underground through underground

layers of soil and layers of soil and rock?rock?

Key Terms: Key Terms: pores, permeable, impermeable, pores, permeable, impermeable, saturated zone, unsaturated zone, water table, saturated zone, unsaturated zone, water table, aquifer, artesian wellaquifer, artesian well

Where does groundwater come Where does groundwater come from?from?

Begins as precipitation.Begins as precipitation. Water from precipitation that doesn’t evaporate, or runoff Water from precipitation that doesn’t evaporate, or runoff

soaks into the ground.soaks into the ground. Affected by the permeability of the land cover.Affected by the permeability of the land cover.

Permeability is determined size of the pores in the land Permeability is determined size of the pores in the land cover.cover.

The smaller the pores the more impermeable the land The smaller the pores the more impermeable the land cover.cover.

The larger the pores the more permeable the land cover.The larger the pores the more permeable the land cover. Water is pulled into the ground by gravity. Water is pulled into the ground by gravity. Some of the water is absorbed by roots and used by plants.Some of the water is absorbed by roots and used by plants. The remainder trickles down between particles of soil and The remainder trickles down between particles of soil and

through cracks and spaces in rock layers.through cracks and spaces in rock layers.

Underground Water LayersUnderground Water Layers

Water will continue to travel downward between the Water will continue to travel downward between the pores or cracks in the soil or rock.pores or cracks in the soil or rock.

When the water reaches an impermeable layer it When the water reaches an impermeable layer it becomes trapped.becomes trapped.

Water then begins to fill the pores and cracks in the soil Water then begins to fill the pores and cracks in the soil or rock above the impermeable layer.or rock above the impermeable layer.

The soil or rock above the impermeable layer becomes The soil or rock above the impermeable layer becomes saturated and is known as the saturated and is known as the saturated zonesaturated zone..

The top of the saturated zone is called the The top of the saturated zone is called the water tablewater table.. Soil and rock layers above the water table still have Soil and rock layers above the water table still have

water flowing through and are not saturated. This layer water flowing through and are not saturated. This layer above the water table is called the above the water table is called the unsaturated zoneunsaturated zone..

To help you visualize this concept, see the image on the To help you visualize this concept, see the image on the next slide.next slide.

The Water TableThe Water Table

Generally follows the shape or contour of the Generally follows the shape or contour of the underground impermeable rock layer. underground impermeable rock layer.

Depth can vary greatly even over a small area of Depth can vary greatly even over a small area of land.land.

Heavy rain or lots of melting snow raises the Heavy rain or lots of melting snow raises the level of the water table.level of the water table.

Level drops during extended periods of dry Level drops during extended periods of dry weather.weather.

Can meet the ground surface and seep onto the Can meet the ground surface and seep onto the surface as a spring or into:surface as a spring or into: Rivers or streamsRivers or streams PondsPonds WetlandsWetlands

AquifersAquifers An aquifer is any underground layer of An aquifer is any underground layer of

rock or soil that holds water.rock or soil that holds water. The saturated zone between the The saturated zone between the

impermeable layer and the water table.impermeable layer and the water table. Range in size.Range in size. Water flows or moves through the aquifer. Water flows or moves through the aquifer.

The movement and speed of the water in The movement and speed of the water in the aquifer depends on:the aquifer depends on: How steep the aquifer slopes.How steep the aquifer slopes. How permeable the rocks and soil are.How permeable the rocks and soil are.

Water can travel hundreds of kilometers Water can travel hundreds of kilometers and stay in an aquifer for thousands of and stay in an aquifer for thousands of years before coming to the surface again.years before coming to the surface again.

Bringing Groundwater to Bringing Groundwater to the Surfacethe Surface People can remove groundwater from an aquifer by People can remove groundwater from an aquifer by

drilling a well.drilling a well. For the well to be filled with water, it must be drilled For the well to be filled with water, it must be drilled

below the water table and into the aquifer. Can become below the water table and into the aquifer. Can become dry if to much water is removed to fast.dry if to much water is removed to fast.

New water from precipitation that soaks in from the New water from precipitation that soaks in from the surface can recharge the aquifer.surface can recharge the aquifer.

Artesian wells.Artesian wells. A well in which water rises because of pressure within the A well in which water rises because of pressure within the

aquiferaquifer Aquifer is trapped between two layers of impermeable rock or Aquifer is trapped between two layers of impermeable rock or

sediment.sediment. Water is under great pressure due to the weight of the water Water is under great pressure due to the weight of the water

above.above. Water will flow out of an artesian well drilled into this aquifer Water will flow out of an artesian well drilled into this aquifer

without pumping. without pumping. To help you visualize this concept, see the image on the To help you visualize this concept, see the image on the

next slide.next slide.

Investigating Investigating GroundwaterGroundwater

Enter the subterranean world of Groundwater

One More Time !One More Time !

The Groundwater Story