aquatic restoration rivers unit 6, module 25 july 2003

Aquatic RestorationRivers

Unit 6, Module 25 July 2003

Developed by: Peichel, Reed Updated: 7/14/03 U6-m25-s2

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.


Overview

Introduction Lake Restoration Stream Restoration Wetland Restoration


Restoration philosophy

“Process of returning a river or watershed to a condition that relaxes human constraints on the development of natural patterns of diversity.


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)


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)


Physical Degradation

40% U.S. perennial streams affected by siltation

Miles PercentSiltation 265,000 39.8Bank erosion 152,000 22.8Channel modifications 143,500 21.5Migratory blockages 9,700 6.0Bank encroachment 9,000 1.4

(Modified from Judy et al. 1984)


Water Quantity Issues

40% U.S. perennial streams affected by low flows

Miles PercentDiversions

Agricultural 105,000 15.8Municipal 10,700 1.6Industrial 3,290 0.5

DamsWater supply 30,800 4.6Flood control 26,900 4.0Power 24,800 3.7



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)


Water Quality Issues

Over 41% of nation’s streams impacted by turbidity

Miles Percent

Turbidity 277,000 41.6

Elevated temperature 215,000 32.3

Excess nutrients144,000 21.6

Toxic substances 90,900 13.6

Dissolved oxygen 75,400 11.3

pH 26,000 3.9

Salinity 14,600 2.2

Gas supersaturation 5,500 0.8



Stream restoration goal

To alter biophysical processes and structures to promote a dynamic equilibrium with diverse abundant aquatic species and channel stability


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


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)


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.


Pattern (plan view)

Sinuosity stream

length/valley length

Meander width ratio (secondary measurement) meander belt

width/bankfull width



Profile (longitudinal)

Slope difference in elevation/stream length

Bed features (secondary measurement) Description of characteristics such as

riffle/pools



Dynamic equilibrium

Qs . D50 in balance with Qw . SQs = sediment load Qw = stream dischargeD50 = sediment size S = stream slope

(Lane 1955)•Image: Stream Corridor Restoration: Principles, Processes, and Practices, 10/98, by FISRWG.


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 dischargeStream slope



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)


How would the stream respond. . .

if stream discharge (Qw) increased and sediment load (Qs) decreased? Width, Depth (Dimension) Sinuosity, Meander wavelength (Pattern) Slope (Profile)


Potential causes of bank erosion

Vegetative clearing Channelization Streambed disturbance Dams Levees Soil exposure or

compaction Overgrazing Dredging for mineral

extraction Woody debris removal Piped discharge Water withdrawal


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



Restoration Techniques for Accelerated Bank Erosion

Bank shaping Fascines Live Staking Root wads


Bank shaping

Purpose• Alter the bank angle so that bank angle (degrees) that it

is stableEfficacy• Usually necessary before vegetation can be added to the

bank



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.


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


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



Live staking



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



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


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


Vermilion River: Methods

Fascines Rootwads


Vermilion River: Methods

Bank shaping Boulder vanes


Live Staking


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


Altered width/depth ratio

Potential causes: Vegetative clearing Water withdrawal Channelization Streambank

armoring Streambed

disturbance Dams Levees Hard surfacing

Roads and railroads Overgrazing Reduction of

floodplain Dredging for mineral

extraction Bridges Woody debris

removal Piped discharge


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



Wing Deflectors

Efficacy• Effective, but require monitoring and maintenance



Potential causes of altered sinuosity

Channelization Streambank armoring Streambed disturbance Dams Levees Hard surfacing Reduction of floodplain Land grading Woody debris removal Piped discharge


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


Sinuosity: restoration

• Systems approach• Analyze meanders on

a watershed scale• Evaluate

geomorphology• Compare to find

dominant meander wavelength

(Fourier analysis)


Potential causes of altered flow

Vegetative Clearing Channelization Streambank

armoring Water withdrawal Dams Levees Soil exposure or

compaction

Irrigation or drainage

Hard surfacing Overgrazing Roads and

railroads Reduction of

floodplain Land grading Piped discharge


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


Dam removal

•1. Breaching of dam•2. Temporary coffer-dams built to work behind

•3. Sediment removal •4. Disposal of timbers off-site


Increased Water Temperatures and Reduced Instream Oxygen Concentrations

Potential Causes Vegetative Clearing Channelization Streambank

armoring Water withdrawal Dams Levees

Hard surfacing Overgrazing Reduction of

floodplain Dredging for mineral

extraction Woody debris

removal Piped discharge


Altered Temp and DO: Restoration

Revegetation of riparian areasSite preparation:• Possibly re-grade bank• Control existing exotic speciesCheck the soil conditions (lack of nutrients)Tillage and mulching may increase planting success

and decrease weedinessBest management practices such as fencing

livestock


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


Revegetation

• Planting techniques • Final density, multi-stage, dense initial, or

accelerated succession Works well as a community stewardship

project


Revegetation

Other considerations• Landscape

connectivity to existing habitats

• Increase in woody debris could be positive

• How will nutrient cycles be impacted?



Revegetation

Management• Vital to water plants• Continue to control

exotic species• Consider impacts of

herbivores

•Two years after planting



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


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


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


Weminuche River, Colorado

Evaluation Channel stability returned

Width/depth returned to 14Slope from 0.01 to 0.005Sinuosity returned to 2.0Meander wavelength established at 10 bankfull widths

Meander radius of curvature at 2.8 bankfull widthsWillow transplanted along streambanks

Great example of considering stream morphology instead of just addressing bank erosion in small sections



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 non-point pollution


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



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



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



Evaluation Good example of a watershed

scale restoration with cooperation between multi-state 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

aquatic restoration rivers unit 6, module 25 july 2003

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