Transcript Water Underground powerpoint

11.3 Water Underground
p. 378-381
Objectives
 Describe springs and how water
moves through underground layers
of soil and rock.
 Explain what an aquifer is and how
people obtain water from an
aquifer.
Engage/Explore
 Spring water
 What was the
original source of
this water?
 Where does the
water in springs
and wells come
from?
Underground Layers
 Where does underground water come
from?
 Answer: Precipitation that soaks in the
ground and trickles downward.
 Water underground trickles down
between particles of soil and through
cracks and spaces in layers of rock.
 Pores - different types of rock and
soil have different-sized spaces.
 Permeable - materials that allow
water to easily pass through or
permeate.
 Examples of permeable materials
are sand and gravel.
 Impermeable - materials that water
cannot pass through easily.
 Examples of impermeable materials
are clay and granite.
 Saturated zone - the area of
permeable rock or soil that is totally
filled or saturated with water.
 Water table - the top of the
saturated zone.
 Unsaturated zone - the layer of rocks
and soil above the water table.
Layers Underground
 What is different
about the pores in the
two pictures?
 Which picture
represents a
permeable rock
layer?
 In this picture how do
the pores differ
above and below the
water table?
Aquifers
 Aquifer - any
underground layer of
rock or sediment that
holds water.
 Size - small
underground patch
of permeable
material to an area
the size of several
states.
Aquifers
 The huge Ogallala
aquifer lies
beneath the plains
of the west, from S.
Dakota to Texas. It
provides drinking
water and water
for crops and
livestock.
Aquifers
 The water in an aquifer moves only
a few centimeters a day which
equals out to be about 10 meters a
year. The movement depends
largely on how steeply the aquifer
slopes and how permeable the
rocks are.
Wells
 People can obtain
groundwater from
an aquifer by
drilling a well
below the water
table.
 Fig. 12 - Compare
the well and dry
well.
Wells
 History of wells
 Dug by hand
 Lined with brick or
stone to keep the
walls from collapsing.
 Lowered and raised a
bucket to bring up
water.
 Today, most are dug
with well-drilling
equipment.
Wells
 Pumping water out of an aquifer
lowers the water level near the well.
If too much water is pumped out
too fast, the well may run dry.
 Then it may be necessary to dig
deeper to reach the lowered water
table or to wait for rainfall to refill the
aquifer.
Wells
 Recharge - New water that enters
the aquifer from the surface.
 Artesian well - a well in which water
rises because of pressure within the
aquifer.
Bringing Groundwater to
the Surface
 Springs - where the
water table meets
the ground
surface,
groundwater
bubbles or flows
out of cracks in
the rock in places.