Transcript Mod25 Aquatic Restoration

Aquatic Restoration
Rivers
Unit 6, Module 25
July 2003
Objectives
Students will be able to:
 describe current statistics regarding the physical degradation,
water quantity, and water quality of streams.
 identify goals and considerations of stream restoration.
 evaluate the factors that influence the dynamic equilibrium of
streams.
 provide examples of potential causes of bank erosion.
 describe restoration techniques used to alter accelerated bank
erosion.
 identify potential causes and restoration measures for altered
width/depth ratios in streams.
 identify potential causes and restoration measures for altered
sinuosity in streams.
 identify potential causes and restoration measures for altered flow
in streams.
 identify potential causes and restoration measures for altered
temperatures and dissolved oxygen levels in streams.
Developed by: Peichel, Reed
Updated: 7/14/03
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Overview
 Introduction
 Lake Restoration
 Stream Restoration
 Wetland Restoration
Developed by: Peichel, Reed
Updated: 7/14/03
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Restoration philosophy
“Process of returning
a river or watershed
to a condition that
relaxes human
constraints on the
development of
natural patterns of
diversity.
Developed by: Peichel, Reed
Updated: 7/14/03
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Restoration philosophy
Restoration does not
create a single,
stable state, but
enables the system
to express a range of
conditions dictated
by the biological and
physical
characteristics of the
watershed and its
natural disturbance
regime”
(Frissell and Ralph 1998)
Developed by: Peichel, Reed
Updated: 7/14/03
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State of the Streams
Approximately 3.2 million miles (5.15 km) of
streams in the U.S.
 Only about 2% of streams remain in relatively
undisturbed, natural conditions
 Less than 1/3 of 1% preserved as national and
scenic rivers
(Echeverria 1989)
Developed by: Peichel, Reed
Updated: 7/14/03
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Physical Degradation
40% U.S. perennial streams affected by siltation
Siltation
Bank erosion
Channel modifications
Migratory blockages
Bank encroachment
Miles
265,000
152,000
143,500
9,700
9,000
Percent
39.8
22.8
21.5
6.0
1.4
(Modified from Judy et al. 1984)
Developed by: Peichel, Reed
Updated: 7/14/03
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Water Quantity Issues
40% U.S. perennial streams affected by low flows
Diversions
Agricultural
Municipal
Industrial
Miles
Percent
105,000
10,700
3,290
15.8
1.6
0.5
30,800
26,900
24,800
4.6
4.0
3.7
Dams
Water supply
Flood control
Power
(Modified from Judy et al. 1984)
Developed by: Peichel, Reed
Updated: 7/14/03
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Water quantity issues
 Over 2.5 million
dams in the U.S.
(Johnston Associates
1989)
 Only about 75,000
dams more than 6
feet tall (USACE 2002)
 600,000 stream miles
are under reservoirs
(Echeverria 1989)
Developed by: Peichel, Reed
Updated: 7/14/03
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Water Quality Issues
Over 41% of nation’s streams impacted by turbidity
Turbidity
Elevated temperature
Excess nutrients
Toxic substances
Dissolved oxygen
pH
Salinity
Gas supersaturation
Miles
277,000
215,000
144,000
90,900
75,400
26,000
14,600
5,500
Percent
41.6
32.3
21.6
13.6
11.3
3.9
2.2
0.8
(Modified from Judy et al. 1984)
Developed by: Peichel, Reed
Updated: 7/14/03
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Stream restoration goal
To alter biophysical processes and structures to
promote a dynamic equilibrium with diverse
abundant aquatic species and channel stability
Developed by: Peichel, Reed
Updated: 7/14/03
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Other stream restoration considerations
In addition to in-stream habitat, current
restoration projects should consider:
 Geomorphology at a watershed scale
 Inclusion of physical scientists (interdisciplinary)
 Fluvial geomorphology, sediment transport,
channel hydraulics, hydrology
 Historical information to document the evolution of
the channel
 How processes have been altered by human
activities in the watershed
Developed by: Peichel, Reed
Updated: 7/14/03
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Stream channel stability
 “Morphologically defined as the ability of the
stream to maintain, over time, its dimension,
pattern, and profile in such a manner that it is
neither aggrading nor degrading and is able to
transport without adverse consequences the
flows and detritus of its watershed” (Rosgen
1996)
Developed by: Peichel, Reed
Updated: 7/14/03
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Dimension: (cross section)
 Width/depth ratio at bankfull stage
 Entrenchment ratio
 Width of flood prone area/bankfull width
 Dominant channel materials
 sizes or types
•Image: Stream Corridor Restoration: Principles, Processes,
and Practices, 10/98, by FISRWG.
Developed by: Peichel, Reed
Updated: 7/14/03
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Pattern (plan view)
 Sinuosity
 stream
length/valley
length
 Meander width
ratio (secondary
measurement)
 meander belt
width/bankfull
width
•Image: Stream Corridor Restoration: Principles,
Processes, and Practices, 10/98, by FISRWG.
Developed by: Peichel, Reed
Updated: 7/14/03
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Profile (longitudinal)
 Slope
 difference in elevation/stream length
 Bed features (secondary measurement)
 Description of characteristics such as
riffle/pools
•Image: Stream Corridor Restoration: Principles, Processes,
and Practices, 10/98, by FISRWG.
Developed by: Peichel, Reed
Updated: 7/14/03
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Dynamic equilibrium
Qs . D50
in balance with
Qs = sediment load
D50 = sediment size
(Lane 1955)
Qw . S
Qw = stream discharge
S = stream slope
•Image: Stream Corridor Restoration: Principles, Processes, and Practices, 10/98, by FISRWG.
Developed by: Peichel, Reed
Updated: 7/14/03
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Dynamic equilibrium
Qualitatively…variables are in balance at channel
equilibrium. If one factor changes, the other
variables change to reach a new equilibrium.
Sediment load
Sediment size
Stream discharge
Stream slope
•Image: Stream Corridor Restoration: Principles, Processes, and Practices, 10/98, by FISRWG.
Developed by: Peichel, Reed
Updated: 7/14/03
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How would the stream respond. . .
if stream discharge (Qw) increased?
 Width, Depth (Dimension)
 Meander wavelength (Pattern)
 Slope (Profile)
if sediment load (Qs) increased?
 Width, Depth (Dimension)
 Meander wavelength? (Pattern)
 Slope (Profile)
Developed by: Peichel, Reed
Updated: 7/14/03
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How would the stream respond. . .
if stream discharge (Qw) increased and
sediment load (Qs) decreased?
 Width, Depth (Dimension)
 Sinuosity, Meander wavelength (Pattern)
 Slope (Profile)
Developed by: Peichel, Reed
Updated: 7/14/03
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Potential causes of bank erosion
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Vegetative clearing
Channelization
Streambed disturbance
Dams
Levees
Soil exposure or
compaction
Overgrazing
Dredging for mineral
extraction
Woody debris removal
Piped discharge
Water withdrawal
Developed by: Peichel, Reed
Updated: 7/14/03
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Measuring bank erosion potential
Measure the following
variables then rate
from very low to
extreme
 Bank height/bankfull
height
 Root depth/bank
height
 % root density
 Bank angle (degrees)
 % Surface protection
 Soil stratification
 Particle size
Developed by: Peichel, Reed
•Image: Stream Corridor Restoration: Principles,
Processes, and Practices, 10/98, by FISRWG.
Updated: 7/14/03
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Restoration Techniques for Accelerated
Bank Erosion
 Bank shaping
 Fascines
 Live Staking
 Root wads
Developed by: Peichel, Reed
Updated: 7/14/03
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Bank shaping
Purpose
• Alter the bank angle so that bank angle (degrees) that
it is stable
Efficacy
• Usually necessary before vegetation can be added to
the bank
•Image: Stream Corridor Restoration: Principles,
Processes, and Practices, 10/98, by FISRWG.
Developed by: Peichel, Reed
Updated: 7/14/03
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Fascines
 Live shrubs (willow) bundled together with rope
 Purpose: Vegetate eroded banks providing
stabilization and habitat (root density and soil
surface protection)
Image: Ontario's Stream Rehabilitation Manual.
Developed by: Peichel, Reed
Updated: 7/14/03
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Fascines
 Efficacy
• Simple and works
immediately because
shrubs grow rapidly to
hold soil in place
• Higher success if
allowed to grow for one
year before water
rerouted
• Works well by itself for
small streams
Developed by: Peichel, Reed
Updated: 7/14/03
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Live staking
Purpose: Vegetate eroded banks providing
stabilization and habitat (root density and soil
surface protection)
Efficacy
•Effective with small erosion
problems or in combination
with brush mattresses,
fascines, or erosion control
blankets
•Best if allowed to grow for
one year before water rerouted
Developed by: Peichel, Reed
Updated: 7/14/03
Image: Ontario's Stream
Rehabilitation Manual.
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Live staking
•Image: Stream Corridor Restoration: Principles,
Processes, and Practices, 10/98, by FISRWG.
Developed by: Peichel, Reed
Updated: 7/14/03
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Root wads
• Purpose
• Deflects current away from unstable banks
• Provides complex instream cover for fish and substrate
for aquatic macroinvertebrates
• Efficacy
• Effective with larger erosion problems
•Image: Stream Corridor Restoration: Principles,
Processes, and Practices, 10/98, by FISRWG.
Developed by: Peichel, Reed
Updated: 7/14/03
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Stream restoration case study #1
Vermilion River, Minnesota
 Impact - bank erosion
 Over 220 feet in length, 8
feet above water level in
one spot
 Receded over 6 feet in 1
year
Developed by: Peichel, Reed
Updated: 7/14/03
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Vermilion River restoration
 Goals of 1997-2000 Restorations
 Reduce the sediment load to improve
downstream water quality
 Create more productive fish habitat
 Protect the adjacent property
 Provide a demonstration project for other
erosion problems on the Vermillion River
Developed by: Peichel, Reed
Updated: 7/14/03
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Vermilion River: Methods
 Fascines
 Rootwads
Developed by: Peichel, Reed
Updated: 7/14/03
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Vermilion River: Methods
 Bank shaping
 Boulder vanes
Developed by: Peichel, Reed
Updated: 7/14/03
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Live Staking
Developed by: Peichel, Reed
Updated: 7/14/03
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Vermilion River restoration
 Evaluation
 Property is protected
 Valuable as demonstration projects
 Clear objectives
 But, were objectives based on stream morphology
or just chosen because the techniques are new?
 Unknown if fish habitat and sediment loads have
been measured
Developed by: Peichel, Reed
Updated: 7/14/03
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Altered width/depth ratio
Potential causes:




Vegetative clearing
Water withdrawal
Channelization
Streambank
armoring
 Streambed
disturbance
 Dams
 Levees
 Hard surfacing
Developed by: Peichel, Reed
 Roads and railroads
 Overgrazing
 Reduction of
floodplain
 Dredging for mineral
extraction
 Bridges
 Woody debris
removal
 Piped discharge
Updated: 7/14/03
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Altered width/depth ratio: restoration
Wing deflectors:
Purpose
• Reduces the width to
depth ratio
• Forms scour pools and
increases velocity and
depth providing habitat
• Single wing deflectors
can direct current away
from eroding banks
Developed by: Peichel, Reed
Image: Ontario's Stream Rehabilitation Manual.
Updated: 7/14/03
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Wing Deflectors
Efficacy
•
Effective, but require monitoring and maintenance
Image: Ontario's Stream Rehabilitation Manual.
Developed by: Peichel, Reed
Updated: 7/14/03
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Potential causes of altered sinuosity
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Channelization
Streambank armoring
Streambed disturbance
Dams
Levees
Hard surfacing
Reduction of floodplain
Land grading
Woody debris removal
Piped discharge
Developed by: Peichel, Reed
Updated: 7/14/03
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Sinuosity: restoration
• Carbon Copy Technique
• Restore stream to the pattern before
disturbance
• Use historical aerial photographs
• May not be stable with current conditions
• Empirical relationships
• Measure bankfull width and discharge then
calculate meander length and sinuosity
• Use if soil conditions have remained the same
Developed by: Peichel, Reed
Updated: 7/14/03
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Sinuosity: restoration
• Systems approach
• Analyze meanders on
a watershed scale
• Evaluate
geomorphology
• Compare to find
dominant meander
wavelength
(Fourier analysis)
Developed by: Peichel, Reed
Updated: 7/14/03
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Potential causes of altered flow
 Vegetative Clearing
 Channelization
 Streambank
armoring
 Water withdrawal
 Dams
 Levees
 Soil exposure or
compaction
Developed by: Peichel, Reed
 Irrigation or
drainage
 Hard surfacing
 Overgrazing
 Roads and
railroads
 Reduction of
floodplain
 Land grading
 Piped discharge
Updated: 7/14/03
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Altered Flow: Restoration
Dam Removal
• Sediment
• Needs treatment if contaminated
• Concentrations of nutrients in sediment probably
high
• Hard to predict what will happen when dam
removed
• Stream type will evolve after dam removal
Developed by: Peichel, Reed
Updated: 7/14/03
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Dam removal
•1. Breaching of dam
•2. Temporary coffer-dams
built to work behind
•3. Sediment removal
•4. Disposal of timbers off-site
Developed by: Peichel, Reed
Updated: 7/14/03
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Increased Water Temperatures and Reduced
Instream Oxygen Concentrations
Potential Causes
 Vegetative Clearing
 Channelization
 Streambank
armoring
 Water withdrawal
 Dams
 Levees
Developed by: Peichel, Reed
 Hard surfacing
 Overgrazing
 Reduction of
floodplain
 Dredging for mineral
extraction
 Woody debris
removal
 Piped discharge
Updated: 7/14/03
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Altered Temp and DO: Restoration
Revegetation of riparian areas
Site preparation:
• Possibly re-grade bank
• Control existing exotic species
Check the soil conditions (lack of nutrients)
Tillage and mulching may increase planting success
and decrease weediness
Best management practices such as fencing
livestock
Developed by: Peichel, Reed
Updated: 7/14/03
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Revegetation
Method:
• Use a reference site
• Determine species diversity, horizontal and
vertical structure of canopy, sub-canopy,
understory, and ground-layer
• Determine which plants will recolonize site
naturally
• Small existing plant populations, seed bank, nearby
populations of wind and animal dispersed species a
reference site
Developed by: Peichel, Reed
Updated: 7/14/03
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Revegetation
• Planting techniques
• Final density, multi-stage, dense initial, or
accelerated succession
 Works well as a community stewardship
project
Developed by: Peichel, Reed
Updated: 7/14/03
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Revegetation
Other considerations
•
•
•
Landscape
connectivity to
existing habitats
Increase in woody
debris could be
positive
How will nutrient
cycles be impacted?
•Image: Stream Corridor Restoration: Principles,
Processes, and Practices, 10/98, by FISRWG.
Developed by: Peichel, Reed
Updated: 7/14/03
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Revegetation
Management
•
•
•
Vital to water plants
Continue to control
exotic species
Consider impacts of
herbivores
•Two years after planting
Developed by: Peichel, Reed
Updated: 7/14/03
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Stream restoration case study #2
Weminuche River, CO
 Drains 30 mi2 in
southwestern
Colorado
 Shows how
observation and
understanding of
stream classification
and historical
information helped set
specific goals to create
channel stability based
on the stream type
Developed by: Peichel, Reed
Updated: 7/14/03
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Weminuche River, Colarado
Impacts of 1978 riparian vegetation removal (government
cost-share program increasing grazing areas) caused
channel instability
 Width/depth ratio increased form 14 to 35
 Meander width ratio decreased from 10 to 2
 Down valley meander migration rate increased




approximately 8 feet/year
Increased sediment supply (erosion) and decreased
transport capacity led to excessive bar deposition
(aggradation)
Meander length and radius of curvature increased (sinuosity
decreased)
Fish habitat and aesthetic values decreased
Poised to cut through banks to create new main channel
Developed by: Peichel, Reed
Updated: 7/14/03
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Weminuche River, Colorado
 Funded as a mitigation
 Goal of 1987 restoration
 Return stream function and channel stability to
benefit brook trout
 Techniques
 Recreated dimension, pattern, profile of a stable
stream type
 Studied pre-disturbance features, developed
empirical relationships
Developed by: Peichel, Reed
Updated: 7/14/03
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Weminuche River, Colorado
 Evaluation
 Channel stability returned
 Width/depth returned to 14
 Slope from 0.01 to 0.005
 Sinuosity returned to 2.0
 Meander wavelength established at 10 bankfull
widths
 Meander radius of curvature at 2.8 bankfull widths
 Willow transplanted along streambanks
 Great example of considering stream
morphology instead of just addressing bank
erosion in small sections
Developed by: Peichel, Reed
Updated: 7/14/03
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Stream restoration case study #3
 Merrimack River,
New Hampshire &
Massachusetts
 Drains 5010 mi2 in
NH and MA flowing
to the Atlantic Ocean
 Demonstrates a
watershed approach
to stream restoration
of point and nonpoint pollution
Developed by: Peichel, Reed
Updated: 7/14/03
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Merrimack River, MA and NH
 Impact from human use
 1930s contamination from pollutants such as
raw sewage, paper mill waste, tannery sludge
 Too polluted for domestic water supply uses
 One of the 10 most polluted streams in nation
Developed by: Peichel, Reed
Updated: 7/14/03
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Merrimack River, MA and NH
 Passing of the Clean Water Act of 1977 (water
quality standards) and formation of the
Merrimack Watershed Council brought about
restoration actions:
 84 wastewater treatment plants constructed
 Majority (~85%) of industries complying with
federal standards
 Suspended solids decreased (by 1/3 in one
reach), coliform bacteria and organic loading
concentrations reduced, dissolved oxygen levels
increased
Developed by: Peichel, Reed
Updated: 7/14/03
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Merrimack River, MA and NH
 Future goals of the Merrimack Watershed
Council
 Improve the protection of present and future
water supply
 Improve water quality through…interagency
cooperation on water quality issues
 Continue work on flow issues
 Promote growth management within the
Watershed
 Continue to improve access to the River and the
acquisition of open space
Developed by: Peichel, Reed
Updated: 7/14/03
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Merrimack River, MA and NH
 Evaluation
 Good example of a watershed
scale restoration with
cooperation between multistate agencies and
organizations
 Reminder that some industries
still not in compliance with
water quality standards set in
1977
 Shift from a point pollution
focus to non-point and water
quantity issues
Developed by: Peichel, Reed
Updated: 7/14/03
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Developed by: Peichel, Reed
Updated: 7/14/03
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