Stream Restoration - Walter Scott, Jr. College of Engineeringpierre/ce_old...Lima Peru – September...

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Pierre Y. Julien

Stream Restoration

Department of Civil and Environmental Engineering

Colorado State University

Fort Collins, Colorado

Short Course on

Restauracion Fluvial e Ingenieria de Rios

Lima Peru – September 27, 2016

Objectives

Brief overview of stream restoration and rehabilitation guidelines:

1. Stream Dynamics and Equilibrium;

2. Stream Degradation;

3. Streambank Stabilization;

4. Ten Guidelines for Stream Restoration.

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1. Stream Equilibrium and Dynamics

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Objectives

Stream Equilibrium and Dynamics

a) Concept of equilibrium

b) Dynamic changes

c) Concept of time scales

1a) Concept of Equilibrium

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1b) Dynamic changes

• The system is dynamic

• A stable river is one in which, over a period of years, slope is delicately adjusted to provide just the velocity required to transport the available water & sediment supplied from the drainage basin. (… after Mackin, 1948)

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Middle Rio Grande, 1996

1996

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Rivers with excess

sediment tend to braid

Middle Rio Grande , 2009

2009

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Rivers with less

sediment tend to meander

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Upper Basin: high-elevation snowpack; snowmelt runoff

Diverse Topography: highest mountains in Colorado – Elbert, Massive, Harvard, etc.

Pine beetle and the Colorado Forest

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Upper Basin: high-elevation snowpack; snowmelt runoff

Diverse Topography: highest mountains in Colorado – Elbert, Massive, Harvard, etc.

Waldo Fire

Colorado June 2012

Waldo Fire

Colorado June 2012

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Photo from US Geological Survey

Post- fire erosion

Buffalo Creek, CO

Photo from US Geological Survey

Post-fire erosion

Buffalo Creek, CO

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Impact on water quality

EPA Superfund Site Restoration

California Gulch near Leadville, Colorado

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TREX Model California Gulch near Leadville, Colorado

1c) Concept of Time Scales

• Geological ~ 1,000,000 years

• Glaciation ~ 10,000 years

• Engineering ~ 100 years

• Vegetation ~ 10 years

• Aquatic life ~ 1 year

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“ … four glaciations were

recognized, each lasting

approximately 100,000 years…

the maximum ice thickness was

close to 4,000 metres”

The Canadian Encyclopedia

Peligre Dam in Haiti (deforestation)

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Subsistence Farming

Peligre Dam (sedimentation)

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Peligre Dam (reduced life expectancy)

2. Stream Degradation

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65

70

75

80

85

90

0 5000 10000 15000 20000 25000

Meters Upstream of Highway 8

Ya

lob

us

ha

Riv

er

Th

alw

eg

Ele

va

tio

n (

m)

Headcutting

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Bank Caving

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2. Bank Protection

Vertical Degradation

Headcutting

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Vertical Degradation

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Low Drop Structure

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High Drop Structure

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Riser Pipe

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3. Streambank Stabilization

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Figure 3.3 Typical Meandering River

Meandering

Channel

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Braided Channel

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1935 1972 1992

Hydraulic geometry of the Rio Grande

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Willow posts

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Retards

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Figure 7.10 Longitudinal Stone Fill Toe Protection Placed Adjacent to Bank With

Tiebacks

Figure 7.3 Schematic Diagram of Windrow Revetment

Windrows

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Figure 7.4 Conventional Windrow Placed on Top Bank

Figure 7.5 Placement of Windrow Rock in Excavated Trench on Top Bank

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Figure 7.6 Launched Windrow Rock

Hardpoints

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Figure 8.2 Typical Impermeable Dikes

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Fence Dikes

(b) Board Fence Dikes

Figure 8.1 Typical Permeable Dikes

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MEI

Jetty System (near Bernardo), USACE 1963

Jetty fields and vegetation of the Rio Grande

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Debris Deposition

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#1 There is no cookbook approach to stream

restoration projects.

#2 Solutions normally require equilibrium conditions

between sediment regime and stream ecology.

#3 Solutions need to be effective,

environmentally acceptable and economical.

Stream Restoration Summary

4. Ten Guidelines for Stream Restoration

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Restoration

•returning a resource to some former condition.

Rehabilitation

•maximize the potential beneficial uses of a

resource to some reasonable and practical level.

Restoration vs Rehabilitation

Objectives

Ten Guidelines and Case Study

1. Guidelines for Stream Restoration Projects

2. Case-study on the Rio Grande with special thanks to Dr. Drew Baird

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Stream Restoration Guidelines

1. OBJECTIVES - Clearly define the

engineering and ecological objectives

- restoration vs rehabilitation.

2. PAST, PRESENT and FUTURE

– Consider present conditions in the

perspective of past events and

examine future changes.

• Protect Levee

• Create a Functioning Floodplain

• Improve Wildlife Habitat

Rio Grande Restoration– Santa Ana

Project Goals

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Bed material size

-1.6

-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

CO-line Number

Ch

an

ge in

Mean

Bed

Ele

vati

on

(m

)

Reach 1 Reach 2 Reach 3 Reach 4

Change in Mean Bed Elevation

Active channel width Sinuosity

1.00

1.05

1.10

1.15

1.20

1.25

Reach 1 Reach 2 Reach 3 Reach 4

Sin

uosi

ty

1918

1935

1949

1962

1972

1985

1992

0

50

100

150

200

250

300

350

Reach 1 Reach 2 Reach 3 Reach 4

Reach

Avera

ged A

ctiv

e C

hannel W

idth

(m

)

1918

1935

1949

1962

1972

1985

1992

0.1

1

10

100

Reach 1 Reach 2 Reach 3 Reach 4

Media

n b

ed m

ate

rial si

ze, d

50 (

mm

) 1918

1935

1949

1962

1972

1985

1992Gravel

Sand

Hydraulic geometry of the Rio Grande

Stream Restoration Guidelines

3. UPPER WATERSHED – Look at the geology,

deforestation, land use changes,

urbanization, climate and extreme events.

Examine water and sediment supply, flood

frequency curves, sediment mass curves

sediment concentrations, water quality, etc.

4. DOWNSTREAM REACH – Look at possible

changes in the downstream reach that may

affect current conditions – like reservoirs,

base level changes, headcutting, etc.

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Hydraulic geometry of the Rio Grande

Stream Restoration Guidelines

5. CHANNEL GEOMETRY – Determine

equilibrium downstream hydraulic geometry

in terms of width, depth, velocity, slope,

discharge and morphology.

6. AQUATIC HABITAT– determine

appropriate aquatic habitat conditions

including low and high flow periods, pools,

riffles, spawning grounds, shade, aeration,

migration, etc.

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Santa Ana Reach - Mid 80’s

Santa Ana Reach – Mid 90’s

Rio Grande Restoration– Floodplain restoration

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• Sandy/silty substrate • Shallow water h < 0.4 m • Water velocities 0.1 m/s < V < 0.5 m/s

• Bimodal sand/gravel bed • Deep water h ~ 1.20 m • Water velocities 1.4 m/s

Restoration

• Create wider channels

Rio Grande Restoration– Endangered Species

Stream Restoration Guidelines

7. EXAMINE ALTERNATIVES – Identify

several different stream rehabilitation

schemes that would suit the engineering

and environmental needs.

8. DESIGN SELECTION – examine the

various alternatives and select the best

possible alternative and proceed with the

design. Solution must be effective,

environmentally sound and economical.

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Gradient Restoration Facility

• Raise Riverbed with GRF

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River Realignment

• Construct Bio-engineering bankline with

Fabric Encapsulated Soils

Floodplain Maintenance

• Lower Terraces with Heavy Equipment

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Floodplain Restoration

• Excavated Sediment Placed near Pilot Channel

Habitat Improvement

• Sediment Storage Upstream from GRF

• Low Velocity Overbank Flows

• Planting and Natural Reseeding of Native Vegetation

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Pilot Channel – Pre-Watering

Stream Restoration Guidelines

9. CONSTRUCTION – Carefully plan the

construction and consider the possible

impact of possible extreme events during

the construction period.

10. MONITORING – Things may not work as

planned. A post-construction analysis and

monitoring should be carried out until the

objectives have been met.

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Opening Pilot Channel

River Realignment

• Divert River into Pilot Channel

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Pilot Channel Widening

Spring Runoff - 2001

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Post-Runoff Assessment

• More Gravel than Anticipated

• Mean Bed Elevation 2 ft Higher than Anticipated

• Pilot Channel 50-100 ft Narrower than Desired

Effects on Bio-engineering

• Most Willows in Fabric Encapsulated Soil (FES)

Completely Submerged

• Sections of Bio-engineering Covered in Sediment

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Rio Grande Conclusions

• Thoroughly study river mechanics and

apply finding to the design process.

• Understand the evolution of the project

and consider intermediate conditions.

• Be flexible…apply adaptive management

techniques.

Stream Restoration Guidelines

1. Clearly define the OBJECTIVES

2. PAST, Present and FUTURE

3. Look at the UPPER WATERSHED

4. Look DOWNSTREAM for degradation

5. EQUILIBRIUM Hydraulic Geometry

6. Appropriate AQUATIC HABITAT

7. Examine various design ALTERNATIVES

8. DESIGN must be Effective, Environmentally sound

and Economical

9. Plan CONSTRUCTION for the unexpected

10. Post-construction MONITORING

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ACKNOWLEDGMENTS Dr. Drew Baird, USBR Jonathan Aubuchon, USBR Robert Padilla, USBR Dr. Craig Fischenich, ERDC Patrick O’Brien, CRREL and ERDC Dr. Tom Pokrefke, ERDC Dr. Otto Stein, MSU Dr. Noel Bormann, GU Dr. Billy Johnson, ERDC, Mississippi Dr. Daryl B. Simons, CSU and SLA Dr. E.V. Richardson, CSU Dr. Stan Schumm, CSU Dr. Marcel Frenette, Canada Dr. Ellen Wohl, CSU … so many others …

CASC2D-SED Modeling 2004

Muchas

Gracias!

pierre@engr.colostate.edu