Transcript Chapter 10 S3

Chapter 10 S3
Water Underground
Essentials Questions Ch10 S3
1. How does water move through
underground layers of soil and
rock?
2. How do people obtain water
from an aquifer?
When precipitation falls on the
ground, what happens to it?
• Evaporates and/or is transpired (plants) back to
•
•
the atmosphere
runs over surface
Infiltrates (soaks) the surface
and
percolates downward due to gravity
and
becomes ground water
Ground Water As Part of the Hydrologic Cycle
How Water Moves Underground
Water underground trickles down between
particles of soil and through cracks and
spaces in layers of rock.
Much of the water in soil seeps downward
until it reaches the zone of saturation.
The zone of saturation is the area where
water fills all of the open spaces in
sediment and rock.
Groundwater is the water within this zone
Groundwater moves by twisting and turning
through interconnected small openings.
The groundwater moves more slowly when
the pore spaces are smaller
Effects of Different Materials
•
•
•
Permeable materials
allow water to pass
through
have large connected
pores or cracks
Ex. sand and gravel
allow water to pass
easily
Impermeable materials
• don’t allow water to
pass through
• have few or no pores
or cracks
• Ex. clay and granite
don’t allow water to
pass easily
Water Zones
Once water reaches an impermeable layer, it is trapped. It
can’t soak down any deeper. Instead, it begins to fill up the
spaces above the impermeable material.
Saturated zone
Unsaturated zone
• area of permeable rock
• area of permeable rock or
The top of the saturated
zone is the water table.
The area above the water
table contains moisture too
but contains air as well.
Therefore, the layer of
rocks and soil above the
water table is unsaturated.
or soil that is totally
filled with water
soil that is not saturated
Bringing Up Groundwater
Aquifers are permeable rock layers or
sediments that transmit groundwater
freely (any underground layer of rock or
sediment that holds water)
A well is a hole bored into the zone of
saturation. People can obtain groundwater
from an aquifer by drilling a well below
the water table.
Using Pumps
People use to dig wells by hand and lined
with bricks. To bring up water, they
lowered and raised a bucket.
Today, most wells are dug with wellequipment. Mechanical pumps bring up
the groundwater. Pumping water out of an
aquifer can lower the water table.
Pumping can form a cone of depression in
the water table.
Cone of Depression
Relying on Pressure
An artesian well is any formation in which
groundwater rises on its own under
pressure.
An artesian well forms when groundwater
becomes trapped between two layers of
impermeable rock or sediment. If the top
layer is punctured, the pressure sends
water spurting up through the hole. No
pump need.
Springs & Geysers
Spring
A spring forms whenever the water table
intersects the ground surface. (forms where
groundwater bubbles or flows out of cracks in
the rock) Most springs contain water at normal
temperatures.
 Hot Springs contain water that is warmed by
the hot rocks deep below the surface. The hot
water bubbles to the surface in a hot spring.
Springs & Geysers
Geyser
A geyser is a type of hot spring from which
the water periodically erupts. A geyser
forms when very hot water that has been
circulating deep underground begins to
rise through narrow passages in the rock.
Geyser Eruption Cycle
Essentials Questions Ch10 S3
1. How does water move through underground
layers of soil and rock?
• It trickles down between particles of soil
and through cracks and spaces.
2. How do people obtain water from an
aquifer?
• by drilling a well below the water table