11.3 water underground

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11.3 Water Underground

p. 378-381


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Objectives

Describe springs and how watermoves through underground layers

of soil and rock.Explain what an aquifer is and how

people obtain water from an

aquifer.


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Engage/Explore

Spring water

What was the

original source ofthis water?

Where does the

water in springsand wells comefrom?


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Discover - Where Does the

Water Go?Clear jar, pebbles,

sand, water

P. 378


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Introduction

P. 378

Digging a hole


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Underground Layers

Where does underground water comefrom?

Answer: Precipitation that soaks in theground and trickles downward.

Water underground trickles down

between particles of sol and throughcracks and spaces in layers of rock.


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Pores - different types of rock andsoil have different-sized spaces.

Permeable - materials that allowwater to easily pass through orpermeate.

Examples of permeable materialsare sand and gravel.


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Impermeable - materials that watercannot pass through easily.

Examples of impermeable materialsare clay and granite.

Saturated zone - the area of

permeable rock or soil tat is totallyfilled or saturated with water.


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Water table - the top of thesaturated zone.

Unsaturated zone - the layer of rocksand soil above the water table.


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Layers Underground

What is differentabout the pores in thetwo pictures?

Which picturerepresents apermeable rocklayer?

In this picture how dothe pores differabove and below thewater table?


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Aquifers

Aquifer - anyunderground layerof rock orsediment thatholds water.

Size - smallundergroundpatch of to anarea the size ofseveral states.


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Aquifers

The huge Ogallala

aquifer lies

beneath the plainsof the west, from S.

Dakota to Texas. It

provides drinking

water and waterfor crops and

livestock.


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Aquifers

The water in aquifer moves only afew centimeters a day which equals

out to be about 10 meters a year.The movement depends largely onhow steeply the aquifer slopes and

how permeable the rocks are.


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Wells

People can obtain

groundwater from

an aquifer bydrilling a well

below the water

table.

Fig. 12 - Comparethe well and dry

well.


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Wells

History of wells

Dug by hand

Lined with brick or

stone to keep thewalls from collapsing.

Lowered and raised abucket to brink up

water. Today, most are dug

with well-drillingequipment.


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Wells

Pumping water out of an aquiferlowers the water level near the well.

If too much water is pumped outtoo fast, the well may run dry.

Then it may be necessary to dig

deeper to reach the lowered watertable or to wait for rainfall to refill theaquifer.


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Wells

Recharge - New water that entersthe aquifer from the surface.

Artesian well - a well in which waterrises because of pressure within theaquifer.


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Bringing Groundwater to

the Surface Springs - where the

water table meets

the groundsurface,

groundwater

bubbles or flows

out of cracks inthe rock in places.

11.3 water underground

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