Figure 3.
Concept map
describing the
relationships
among plate
boundaries,
magma, and
volcanoes.
1
The Good Earth/Chapter 6: Volcanoes and Other Mountains
ESC1000 • Earth Science • Summer 2016
2
Streams and Floods
(Chapter 11)
Groundwater and Wetlands
(Chapter 12)
What are unique features of some bodies of water in Florida?
- Kissimmee River, Lake Okeechobee, the Everglades
Which areas of Florida are prone to flooding, and why?
What are the major types of groundwater systems and
aquifers here? Which factors influence them?
How have the Everglades changed over time?
What is unique about this ecosystem?
Why are there so many invasive species in South Florida?
(questions to be continued, for Florida’s ocean, atmosphere,
weather, and climate)
Unit 3 of ESC1000 (also known as the next two weeks)Learning Goals: Florida Ecosystems
3
Florida’s Rivers and Wetlands:Focus on the Everglades
The Good Earth/Chapter 11: Streams and Floods
Wildlife:
https://www.youtube.com/watch?v=xfYAj1k9uZM
4
Chapter 11: Streams and Floods
Copyright © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
1.
2.
3.
4.
5.
6.
7.
Humans and Rivers
The Hydrologic Cycle
Drainage Networks and Patterns
Factors Affecting Stream Flow
The Work of Streams
Floods
Flood Control
5
We will cover the basics of all these topics.
Focus on how these concepts apply to
Florida bodies of water.
The Hydrologic Cycle
The Good Earth/Chapter 11: Streams and Floods
6
The Hydrologic Cycle
The Good Earth/Chapter 11: Streams and Floods
The vast majority of Earth’s water is in the oceans (97%) with only about
3% on land.7
The Hydrologic Cycle
The Good Earth/Chapter 11: Streams and Floods
Most of the water on land is stored in ice or groundwater.8
The Hydrologic Cycle
The Good Earth/Chapter 11: Streams and Floods
9
The Hydrologic Cycle
The Good Earth/Chapter 11: Streams and Floods
Land receives more moisture by precipitation than it supplies by evaporation.
The balance comes from evaporation from the oceans. This excess water is
returned to oceans via surface streams. 10
Drainage Networks and Patterns
The Good Earth/Chapter 11: Streams and Floods
What controls the amount
of water in a stream
channel?
The size of the area it
drains
The average precipitation
over the area
The Nile and the Mississippi have
the largest drainage basins, each
covering over 1 million sq mi.
Drainage basin = the area drained by a stream and its
smaller streams (tributaries). Above, the Mississippi
drainage basin is composed of several smaller drainage
basins (colored areas). It takes up half the land area of the
U.S.11
Drainage Networks and Patterns
The Good Earth/Chapter 11: Streams and Floods
Why do stream patterns
look like the branches
of a tree?
Streams will follow the
path of least resistance,
forming valleys where
rock is most readily
eroded or following the
steepest slope.
Dendritic drainage
patterns are
characteristic of areas
where the geology is
relatively uniform.
The tips of the v’s
where streams come
together point down
stream.
12
Drainage Networks and Patterns
The Good Earth/Chapter 11: Streams and Floods
Trellis patterns – streams
intersect at right angle
forming rectangular
drainage patterns.
Found in areas of
alternating layers of weak
and resistant rocks.
Main streams flow parallel
to ridges, cutting across at
water gaps.
Smaller streams flow
down slope perpendicular
to the course of the main
stream.13
Drainage Networks and Patterns
The Good Earth/Chapter 11: Streams and Floods
Rectangular patterns – occur in
regions where the streams are
controlled by joints, fractures in
the underlying bedrock. Streams
exploit these fractures and flow in
them.
Radial patterns – typically found
on the flanks of volcanoes, where
streams flow downhill from the
summit.
14
Factors Affecting Stream Flow
The Good Earth/Chapter 11: Streams and Floods
Gradient = the slope of a stream. It is the change in elevation
of the stream over a horizontal distance.
15
The Work of Streams
The Good Earth/Chapter 11: Streams and Floods
Erosion produces stream load,
which is the combination of
bed load, suspended load, and
dissolved load.
How is stream color affected by load?
Suspended load increases when discharge increases
(higher velocity = more energy to move particles).
http://highered.mheducation.com/sites/007
3524107/student_view0/chapter11/modes_
of_sediment_transport.html
Animated
Version:
16
The Work of Streams
The Good Earth/Chapter 11: Streams and Floods
As a stream
slows down it
drops some of
its load. Heavier
particles drop
out first.
When a stream
has a heavy
load, sediment is
often deposited
in the stream
channel itself to
form bars or
islands.
These deposits
split the channel
into smaller
channels
forming a
braided channel.
A braided
channel,
Alaska
The Yellow River,
China, carries the
highest sediment
load relative to its
discharge of any
river in the world!
17
The Work of Streams
The Good Earth/Chapter 11: Streams and Floods
Meanders = broad curves in a stream. Velocity of the stream varies as it
moves through these large bends.
As a meander
becomes larger
the channel
migrates across
the flood plain in
the direction of
erosion.
18
The Restored, MeanderingKissimmee River
http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites
/dl/free/0073524107/30425/10_22_10_23.swf::River Meander Development
River Meander Development:
19
The Good Earth/Chapter 11: Streams and Floods
Floods
Influenced by:
- Magnitude, timing, and type
of precipitation
- Human modifications of the
physical landscape
- Capability of the ground to
absorb water
- Evaporation rates
- Physical characteristics of
the stream system
Floods usually occur when the amount of
water on the land surface exceeds the
volume of water that can be transported in
stream channels and absorbed into the
surrounding soil.
20
The Good Earth/Chapter 11: Streams and Floods
Floods
This was spatially the largest flood in U.S. history!
It covered 44,000 square km or 17,000 square miles.21
The Good Earth/Chapter 11: Streams and Floods
Floods
How do humans influence flooding?
- Paving covers or alters natural surfaces that otherwise
might absorb water.
- Storm sewers that divert water from surfaces dump it into
natural streams causing them to flood.
- Housing developments or agricultural fields replace
natural wetlands, which act as water storage reservoirs.
- Constructed dams collapse.
22
The Good Earth/Chapter 11: Streams and Floods
Flood Control
• Cities located on flood plains suffer the most economic losses
• Floodwaters can carry contaminated water (sewage, agricultural chemicals)
• Roads get submerged and have to be closed and repaired after the flood
• Farmland submerged – production falls
• Floods can deposit thick layers of sediment where it should not be
• Can halt barge traffic for months
• People die and are uprooted and evacuated
23
Types of Flood Control
The Good Earth/Chapter 11: Streams and Floods
• Levees and Floodwalls
• Dams
• Floodway
24
Florida’s Rivers and Wetlands:Focus on the Everglades
The Good Earth/Chapter 11: Streams and Floods
Wildlife:
https://www.youtube.com/watch?v=xfYAj1k9uZM
Kissimmee River Restoration:
https://www.youtube.com/watch?v=nN95KTVeUDA
25
- How has the shape of the Kissimmee River changed over time?
- How does its shape impact other wetlands and water bodies in
South Florida?
- What is the history of flooding around the Kissimmee River?
- What type of flood control (if any) has been used around the
Kissimmee River and other water bodies or wetlands in South
Florida?
Chapter 12: Groundwater and Wetlands
Copyright © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
1.
2.
3.
4.
Meet Your Drinking Water
Holes in Earth Materials
Groundwater Systems
A Case Study: The High Plains
Aquifer
Groundwater Quality
Introduction to Wetlands
5.
6.
26
Again, we’ll cover the basics of these topics.
Focus on applying the concepts to Florida
bodies of water – especially the Everglades.
The Good Earth/Chapter 12: Groundwater and Wetlands
Meet Your Drinking Water
Which is
better to
drink?
Whether it is
from a bottle
or the tap,
our drinking
water
comes from
the same
place and
undergoes
similar
processing
and
monitoring
to make it
safe. 27
Meet Your Drinking Water
The Good Earth/Chapter 12: Groundwater and Wetlands
• The consumption of bottled water in the U.S. is
growing fast, faster than any other beverage.
• Tap water is just as good, and costs 1,000 times less
than bottled water.
• About ¼ of all bottled water is simply bottled tap water.
• Purified water = tap water that has undergone
additional treatment prior to bottling
Where does our drinking water come from?
Streams and lakes (on the Earth’s surface)
Groundwater (water in rocks or unconsolidated materials
below the Earth’s surface)
28
The Hydrologic Cycle
The Good Earth/Chapter 11: Streams and Floods
Most of the water on land is stored in ice or groundwater.29
The Hydrologic Cycle
The Good Earth/Chapter 11: Streams and Floods
• On average, the length of time that a given volume of water remains in
streams is about 14 days.
• Only a small amount of precipitation on land sinks into the ground, as
infiltration rates are slow compared to runoff rates.
• Many rivers have their sources in springs that bring groundwater to the
surface (e.g. the Nile).
• Many rivers have sources in glacial melt water (e.g. Ganges).
30
Meet Your Drinking Water
The Good Earth/Chapter 12: Groundwater and Wetlands
• Water supplies are most likely to be contaminated by human actions
• e.g. chemical leaks from storage tanks
• 53,000 community water systems in the U.S.
• Few become polluted, but this pollution can cause health risks
• Cleanups can be tricky, especially for underground sources
31
Holes in Earth MaterialsThere’s more water underground than in lakes and streams on
Earth’s surface (about 70% more!)
The Good Earth/Chapter 12: Groundwater and Wetlands
Most groundwater is in billions of tiny spaces between mineral
grains or in narrow cracks.
The amount of groundwater at any location depends on the
porosity and permeability of materials beneath the surface.
Porosity = the proportion
of a material that is made
up of spaces.
(e.g. if ½ the total volume
of a rock is pore space,
the porosity is 50%)
Depends on size and
arrangement of the grains
(better sorted – higher
porosity). 32
Holes in Earth Materials
The Good Earth/Chapter 12: Groundwater and Wetlands
As material grains compacted or cemented, porosity decreases.
33
Holes in Earth Materials
The Good Earth/Chapter 12: Groundwater and Wetlands
Permeability = the capacity of
water to flow through earth
materials.
Water can flow readily through
materials with well connected
pore space or many fractures.
Connections between pore
spaces are wider in coarse-
grained material (gravels) than
fine-grained material (sand).
High permeability does not always
go hand in hand with high
porosity.Q: Why do you think
groundwater flows more
slowly than water on the
Earth’s surface?A: More opportunities for friction to slow it
down as it pushes through spaces between
millions of tiny grains. 34
Groundwater Systems
The Good Earth/Chapter 12: Groundwater and Wetlands
Groundwater is stored
in bodies of rock
and/or sediment called
aquifers, which are
composed of sufficient
saturated permeable
material to yield
significant quantities of
water.
35
Aquifers can form in a variety of geologic settings
Aquifers can be
composed of
sands, gravels,
sandstone with
good porosity
and permeability,
and fractured
rocks.
The Good Earth/Chapter 12: Groundwater and Wetlands
Florida:
Sand and gravel aquifers
Carbonate aquifers36
Groundwater Systems
The Good Earth/Chapter 12: Groundwater Wetlands
Aquifer Quality
-High porosity and permeability
-Most productive aquifers are found in unconsolidated earth materials (80% of all
groundwater withdrawn in U.S. comes from sand and gravel aquifers)
-Aquitards – low-permeability materials such as clay, shale, or unfractured igneous
or metamorphic rock, that act as a barrier to water flow
Open water Aquifer. 37
Groundwater Systems
In general, the water table follows the shape of the
land surface
The Good Earth/Chapter 12: Groundwater and Wetlands
The top of the saturated zone is the water table, and it is highest under
hills and lowest in valleys. Water flows down the slope of the water table.
When the water table intersects the land surface a stream, lake, or spring
will occur. 38
Groundwater Systems
The Good Earth/Chapter 12: Groundwater and Wetlands
Confined (Artesian) Aquifer – enclosed above
and below by impermeable materials. Water
can only enter the well through the exposed
rock layer (recharge zone).39
Groundwater Systems
The Good Earth/Chapter 12: Groundwater and Wetlands
How does groundwater interact with oceans?
In coastal regions, fresh water is found floating above a denser layer of
saltwater. Saltwater infiltrates the ground just like fresh water. Where the
freshwater layer meets the coast it flows into the ocean.
In coastal cities, freshwater can be extracted from the freshwater layer, but
if it is extracted faster than it is replenished, saltwater can flow into wells.
40
Groundwater Quality
The Good Earth/Chapter 12: Groundwater and Wetlands
Potential sources of groundwater pollution in the U.S.
41
Introduction to Wetlands
The Good Earth/Chapter 12: Groundwater and Wetlands
To be a wetland an area must be:
• saturated with water and
• have poorly drained soils and
• specific types of plants.
Two types: coastal and freshwater
42
Introduction to Wetlands
The Good Earth/Chapter 12: Groundwater and Wetlands
Wetlands must meet the following criteria:
Hydrologic conditions – water present on land surface, or soils in
root zone must be saturated during growing season or longer.
Hydrophytic vegetation – specific plants that are water-tolerant
and grow under wet conditions (e.g. cattails, wild rice, willows,
sawgrass) must be present
Hydric soils – poorly drained soils that exhibit anaerobic conditions
during growing season
43
Introduction to Wetlands
The Good Earth/Chapter 12: Groundwater and Wetlands
In lower 48, largest wetland areas are in Texas, Florida, Minnesota.
~10% or less of original wetlands remain in California, Ohio, and Iowa.
Losses are due to draining to support agriculture, or draining and infilling
for urbanization and development.
Why should we care?
Wetlands perform many positive functions in the
environment such as improving water quality in rivers by
filtering out sediments and contaminants, providing breeding
grounds for fish and shellfish which supports commercial
fishing, providing ecological habitats for migrating birds,
modifying the effects of flooding by slowing runoff, and
providing recreation for humans.
44
Introduction to Wetlands
The Good Earth/Chapter 12: Groundwater and Wetlands
The Florida Everglades (the “river of grass”) experienced a loss of wetlands due to
population growth and urbanization.
Development in the early 1900’s had four goals – “dike it, dam it, divert it, drain it.”
Lost 50% of original wetlands destroying fish and wildlife habitats.
Wetlands were replaced by agricultural sugarcane, and expansion of coastal cities
further stressed the ecosystem.
Attempts to partially restore the wetlands are ongoing.
45
Earth Science in the News
46
Florida’s Rivers and Wetlands:Focus on the Everglades
The Good Earth/Chapter 11: Streams and Floods
Wildlife:
https://www.youtube.com/watch?v=xfYAj1k9uZM
Kissimmee River Restoration:
https://www.youtube.com/watch?v=nN95KTVeUDA
TEDxUF Everglades Conservation
https://www.ted.com/talks/mac_stone_stunning_photo
s_of_the_endangered_everglades?language=en
47