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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!
