Water Underground 11-3

1. Water Underground11-3 By 6C

2. 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 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.

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.