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Water Underground.  Most of the fresh water on the Earth that is not frozen is underground.  Dig almost anywhere on the Earth and you will eventually.

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Presentation on theme: "Water Underground.  Most of the fresh water on the Earth that is not frozen is underground.  Dig almost anywhere on the Earth and you will eventually."— Presentation transcript:

1 Water Underground

2  Most of the fresh water on the Earth that is not frozen is underground.  Dig almost anywhere on the Earth and you will eventually hit water, and the hole will start to fill!

3 Precipitation Infiltration  Water from precipitation trickles into the soil through cracks and spaces.  Spaces between rocks and soil are called pores.  Porosity is the percentage of open spaces in the rock or soil.  The pore size determines how easily the water will sink into the ground.

4 Underground Layers

5 Permeable  Allows water to easily pass through.  Your clothes are permeable, so you get wet when it rains.  Sand and gravel will have large pores between the grains, so they are very permeable.

6 Impermeable  Does not allow water to easily pass through.  Has few pores or cracks.  Will cause water to pool on top of it.  Clay and granite are impermeable as are umbrellas!

7 Saturated Zone  When water reaches an impermeable layer, it cannot soak in any deeper.  The water will start to fill the spaces above the impermeable layer.  This layer that is totally filled with water is called the saturated zone.  If you dig a hole this deep you will see your hole start to fill with water.  Saturated means to soak or fill completely.

8 Water Table  The top of the saturated zone is called the water table.  The more it rains, the higher the water table will get.  The more water you take out through a well, the lower the water table will get.  Knowing the depth of the water table will tell you how far down you must dig to find water.  Where the water table is above ground you will find streams, ponds, and lakes.

9 Unsaturated Zone  The area above the water table is the unsaturated zone.  This permeable layer allows the water to infiltrate down to the water table.  Also called the Zone of Aeration

10 Aquifers  Underground layer of rock that holds water.  Range in size to small underground patches to an area covering several states.  Great places to dig wells.

11 Aquifer Diagram

12 Bringing Groundwater to the Surface

13 Springs  If the water table is at ground level, water may flow out of the ground.  This is called a spring.  Usually occur on sides of hills or in low areas.

14 Water Table Wells  A human made hole that extends down past the water table.  Well head is above the water table.  Water must be pulled or pumped up to be used.

15 Artesian Springs  Water that gets trapped between two impermeable layers will be under pressure. It will be forced out through cracks in the soil.  Water will flow out of springs below the water table.

16  An artesian aquifer is a confined aquifer containing groundwater that will flow upward through a well, called an artesian well, without the need for pumping.  Water may reach the surface if the well head is below the confined water table, this is called a flowing artesian well.

17 Artesian Wells  Work just like an artesian spring.  Since the well head is below the water table, water pressure forces the water up out of the well.  So you don’t need to pump the water out, it comes to you.

18 Recharge  Aquifers need a constant supply of water to maintain the water table.  The water added is the aquifer’s recharge.  The surface where the water enters the aquifer is the recharge zone.  It may be many miles from the aquifer.

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20 How Homes Get Water  Works by gravity.  Water from water tower is above your home, so the water flows downhill through pipes to give you water.  The higher the source, the more pressure you have.


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