Download Lesson 1.1

Watersheds and Wetlands
CHAPTER 1
Lesson 1.1
 The Blue Planet
 Groundwater
 Surface Water
 Stream Characteristics
 Major Drainage Patterns
 Pennsylvania’s Drainage Patterns
PA Academic Standards for
Environment & Ecology
Standard 4.1.10.B
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Explain the relationship among landforms,
vegetation and the amount and speed of water.
Lesson Objectives. Students will be able to …
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Analyze a stream’s physical characteristics.
Describe how topography influences streams.
Explain the influence of mountains on precipitation.
Explain how vegetation affects storm water runoff.
Delineate the boundaries of a watershed.
Describe factors that affect the quality of groundwater.
Explain how the speed of water and vegetation cover
relates to erosion.
The Blue Planet
• Water is the most common substance on Earth.
 97% of the Earth’s water is saltwater.
Example: oceans
 3% of the Earth’s water is freshwater.
Example: lakes, rivers, streams, and glaciers
• There are three main forms (states) in which
water exists as it circulates through the water
cycle.
 Solid
• Example: ice
 Liquid
• Example: water
 Gas
• Example: water vapor
• The three forms of water move water through the
environment via the water cycle --- an unending
circulation process powered by the sun.
Major Processes
Evaporation – changing from a liquid to a gas (heating)
Condensation – changing from a gas to a liquid (cooling)
Precipitation – when water returns to the Earth
Transpiration – when plants release water vapor from
their leaves (stomata)
Percolation/Infiltration – when surface water seeps into
the ground
Groundwater
• Some precipitation runs off the surface of the ground
into near-by surface water sources. However, some
water seeps into the ground and becomes
groundwater.
• Definition: Groundwater
– water from rain and melting snow that seeps into
the ground and is stored beneath Earth’s surface
Groundwater
Where is the groundwater supply?
• About 22% of the Earth’s freshwater supply is groundwater.
• Groundwater can be accessed by private and public wells.
• How is groundwater used in PA?
• People and industry use more than 1 billion gallons of
groundwater each day.
• Major source of drinking water for residents.
• Major source of water for mining and agricultural operations
throughout the state.
Overdrawing Groundwater
Intro: To increase supplies of high quality
freshwater, groundwater is being used
• Groundwater is not an unlimited resource
• Balance should be:
Groundwater withdrawal = recharge
• The truth:
Withdrawals exceed recharge!
The Biggest Problem with overdrawing
groundwater: Falling Water Tables
The affects of this would be:
1. Irrigation
• Uses up by far the most groundwater
• In the Midwest, Ogallala Aquifer
• Over the past 40 years, the water table has dropped 100
feet
• It continues to fall at a rate of 6 feet per year
2. Diminishing Surface Water:
• Springs and seeps dry up (lakes and ponds are affected)
• Wetlands dry up
3. Land Subsidence:
• Water pressure underground acts as a support
• When that water is lost, the earth may settle or
suddenly sink (sinkhole)
• Very typical in the southeast U.S.
4. Saltwater Intrusion:
• Coastal regions have springs that empty into the ocean
• As long as the water table is high, the pressure of the
groundwater exiting the spring results in freshwater
entering the ocean
• If the water table diminishes, then saltwater flows back
into the freshwater
Groundwater Quality
• Groundwater supplies much of the Earth’s drinking water
supply.
• Therefore, the quality of the groundwater in many
countries is closely monitored for contamination.
• Major causes of contamination
 Natural sources
 Human activities
Video Clip – Water Contamination
Contamination: Natural Sources
• As water flows through
and around soils and
rocks, it dissolves certain
minerals, which
contaminate the water.
• If the water is acidic, it can
leach out metals from the
ground.
 Example: hard water
(Ca & Mg)
 Example: overall
reduced water quality
(Fe,Zn,Cu and S)
Contamination: Human Activities
• Groundwater quality
can also be adversely
affected by human
activities that occur
above ground.
 Examples: septic tanks,
pesticides and fertilizers,
storage tanks, chemical
spills, landfills, and
roadway salts.
How does my septic system & well work?
PA’s Groundwater Quality
• Overall quality of groundwater in Pennsylvania is
generally good.
 The decrease in the amount of nitrates in some
Pennsylvania groundwater supplies could be a result
of a combination of changes in agricultural practices
and better installation and maintenance of septic
systems.
 The increases in the amount of other contaminants
in some parts of the state have been attributed to a rise
in the amount of road salt applied to roadways as well
as urban development.
The #1 source of pollution
along the Susquehanna is
agriculture.
What can farmers do?
Terracing
Stream Bank Fencing
Riparian Zone
Proper Manure Management
Reduce Fertilizers & Pesticides
No-till farming
Surface Water
• Common freshwater sources
– Lakes
– Ponds
– Rivers
– Soils
– Air
Stream Characteristics
• Velocity
• Sediment Load
• River Deposits
Stream Characteristics
(1) Velocity
 Definition: The distance water flows during some
period of time, such as meters per second
or feet per second
 As a stream flows from its source to its mouth, the
water flows in one of two ways.
• Laminar flow
– Water moves parallel to the stream channel
• Turbulent flow
– Water moves in tiny circular paths as it flows downstream
• The velocity of a stream or river determines the type of
flow observed in a system.
 Slow moving waters tend to have a laminar flow.
 Fast moving waters tend to have a turbulent flow.
• The velocity of the stream or river determines the kind
and amount of sediment that the water can carry.
(2) Sediment Load
 As streams and rivers flow they carry sediment in three major ways.
• Dissolved load
– Sediment carried in solution
• Suspended load
– Silts and clays
• Bed load
– Sand, gravel, pebbles, and boulders (carried along the bottom)
(3) River Deposits
 Rivers deposit sediment as the velocity of the water
decreases.
• Example: bars, or river deposits, form when a river slows down as it
travels around a bend in the channel.
• A flood plain is the part of a river valley that is covered during a flood.
River deposits and agriculture
• Why are river deposits important to
agriculture?
 Rivers deposit sediment when they overflow their
banks into floodplains, or low lying portions of
land next to rivers that fill with water as river
levels rise.
 These areas are fertile areas for farming, as the
soils are rich with sediments carried from
upstream.
Major Drainage Patterns
• Pennsylvania has more square miles of streams and
rivers per square mile than most states.
• The drainage patterns of these rivers and their
tributaries, or feeder steams, depends largely on
topography, or the physical characteristics of the land.
• All drainage patterns are controlled by the types of rocks
over which rivers and streams flow, as well as the
presence or lack of folds and faults in the rocks.
Topographic Maps
Major Drainage Patterns
• Four major types of drainage patterns
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Dendritic Drainage Patterns
Radial Drainage Patterns
Rectangular Drainage Patterns
Trellis Drainage Patterns
Major Drainage Patterns
Dendritic Drainage Patterns
• Most common type of
drainage pattern.
• Form where bedrock is
uniform and massive, such as
in a plains region.
• Mainly a function of the slope
of the land over which the
stream or river flows.
• Resembles the shape of a
mature tree.
• Common in western
Pennsylvania because of a
massive formation of
sedimentary rock.
Radial Drainage Patterns
• Form where streams flow
from a high, central area
such as a plateau or
other uplifted feature.
• Resemble the spokes of
a bicycle.
Rectangular Drainage Patterns
• Form when bodies of rock are
broken by a series of faults of
other fractures.
• Resembles a series of lines,
all of which turn at right
angles.
• Common in South-central
Pennsylvania because of
fractures and faults in the
Earth’s surface.
Trellis Drainage Patterns
• Form when sections of
softer, nonresistant rocks
alternate with sections of
harder, resistant rocks.
• Resembles rectangular
drainage patterns but
tributaries run parallel to
one another.
• Common in southeastern
Pennsylvania which has
river systems which run
parallel to each other yet
perpendicular to the main
stream or river.
Theme Vocabulary
Lesson 1.1
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bed load
condensation
evaporation
groundwater
mouth
precipitation
runoff
source
topography
transpiration
tributaries
velocity