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Chapter 5: Water
Section 1.1: The Blue Planet
Water Facts
70-75% of the Earth is covered by water.
About 97% of the water on Earth is salt
water found in the oceans.
The remaining 3% is freshwater.
Of the Earth’s freshwater, 70% is frozen
in glaciers or polar caps.
Water is continually recycled
by the water cycle.
Groundwater
Some rain and melting snow seeps into
the ground and becomes groundwater.
About 22% of the Earth’s freshwater is
groundwater, which is accessed through
wells and supplies most of the daily
household, agricultural, and industrial
needs.
Water Wells
Groundwater Contamination
Because groundwater
supplies much of the
Earth’s drinking water,
its quality in many
countries is closely
monitored for
contamination.
Hard Water
Hard water is a natural
contamination.
As groundwater flows
down through the soil and
rocks, it dissolves certain
minerals.
Minerals that are
commonly dissolved are
calcium, iron and
hydrogen sulfide.
Human sources of
groundwater pollution
Septic tank systems that are not properly
installed.
Human sources of
groundwater pollution
Septic tank systems that are not properly
installed.
Pesticides often used on farms and lawns.
Landfills.
Landfills
Human sources of
groundwater pollution
Septic tank systems that are not properly
installed.
Pesticides often used on farms and lawns.
Landfills.
Chemical spills (including oil from cars)
Leaking storage tanks
Salt used for deicing roadways
In Pennsylvania,
our groundwater’s
overall quality is
considered good!
How do rivers Begin?
They begin when runoff flows along tiny
channels known as rills.
How do rivers Begin?
They begin when runoff
flows along tiny
channels known as rills.
Rills merge to form
larger bodies of water
called creeks and
streams.
Creeks and streams
merge to form rivers!
Stream Characteristics
The place where any river or stream
begins is known as the source or
headwaters.
The place where the river empties into
another body of water is called the
mouth.
Rivers of Western Pennsylvania
Two Types of Water Flow
Laminar flow occurs when water moves
in straight paths that are parallel to the
streams channel.
Thus very little mixing of stream
contents occurs.
Turbulent flow occurs when water moves
in tiny circular paths as it flows
downstream.
Other Stream
Characteristics
1. Velocity – is the distance water flows
during a period of time (ie: feet per
second) – typically determines if the
stream is laminar or turbulent.
 Determines the kind and amount of
sediment, or load, that the water can
carry.
Other Stream
Characteristics
2. Sediment Load – streams are capable
of carrying sediment in one of three
ways:
 Dissolved load: the amount of
dissolved sediment carried in the water.
* Enters the water as it flows over
rocks and soil.
* Much of the dissolved load comes
from groundwater that returns to the
Earth’s surface.
Other Stream
Characteristics
 Suspended Load – is sediment such as
silt and clay that is in suspension.
* Most of the streams load is
typically suspended.
 Bed Load – is the sediment that is
carried along the bottom of the channel
(includes sand, gravel, pebbles)
Other Stream
Characteristics
3. River Deposits – Sediment that is
dropped by the river as the river slows
down.
 Deposits called bars are made from
sand and gravel and are found on the
inside of a river bed.
Stream Bars
Other Stream
Characteristics
3. River Deposits – Sediment that is
dropped by the river as the river slows
down.
 Deposits called bars are made from sand
and gravel and are found on the inside of a
river bed.
 Rivers also deposit sediment when they
overflow or flood – these areas that
commonly are covered during a flood are
called flood plains.
Flood plains
Flood plains are very
fertile areas of land
often used for farming.
Pennsylvania has more
miles of streams and
rivers per square mile
than most states.
Major rivers of
Pennsylvania
1.
2.
3.
4.
5.
Ohio
Allegheny
Monongahela
Genesee
Susquehanna
6.
7.
8.
9.
Juniata
Delaware
Lackawaxen
Lackawanna
Major drainage patterns
of Pennsylvania
1. Dendritic
Most rivers have this drainage
pattern – tends to resemble mature
trees.
Dendritic drainage patterns are the
function of the slope of the land
over which the river or stream
flows.
Dendritic river pattern
Major drainage patterns
of Pennsylvania
2. Radial
 Typically form when streams
flow from a high central point
such as a plateau or volcanic
mountain.
Radial River Pattern
Major drainage patterns
of Pennsylvania
3. Rectangular
 Form when bodies of rock are
broken by a series of faults
and other fractures in the earth
surface.
 Bends in this type of river
pattern are right angles.
Rectangular river
patterns
Rectangular river
patterns
Major drainage patterns
of Pennsylvania
4. Trellis
 This pattern is a special
rectangular river pattern in
which the tributary streams are
nearly parallel to each other.
 Form in softer, nonresistant
rocks alternating with harder,
resistant rocks.
Trellis River Pattern
The drainage patterns
in western
Pennsylvania is
typically Dendritic.