1. Stream Restoration
An introduction…

2. Evolution of “Restoration”
Long history of working on and manipulating
streams and rivers
“Restoration”, “Rehabilitation”, “Stabilization” have
all been used as justification to undertake restoration
We continue to learn about, and evolve the science

3. So, what is “restoration”?
To return to a healthy
state
To recover function
As a stream environment
changes, so do the
expectations
Each project is unique

4. The Order of Restoration
In any stream restoration there is an order that
should be followed.
• Protect
• Maintain
• Restore
• Enhance
Consider passive vs. active restoration, such as
valley wide protection, floodplain restoration before
more intensive efforts such as channel restoration
and habitat enhancement structures.

5. A Restoration Philosophy
• Rivers, like most other natural systems, are highly
dynamic and complex. The numerous processes and
interactions that continually occur at varying scales are
testaments to this natural complexity.
• This complexity provides and sustains the various niches
and habitats for biological organisms.
• Recent advances in both physical and biological
sciences, in addition to our growing understanding of
these systems, has contributed to our ability to restore
the natural dynamics and functions of rivers.

6. Restoration Objectives
•Must meet socio-economic,
ecological, physical,
engineering, and regulatory
goals of the project.
• Result should be stable,
not static.
• Be appropriate for the
physical setting (climate,
land use, development
restrictions, geology)

7. Restoration Tools & Approaches
Approach – form based
versus process based
Awareness of viability
What approach should you
use?
Need for
understanding
processes operating
within your system

8. Design Approaches
- Rational / Cognitive
- Reference Reach
- PFC (Proper Functioning Condition)
- Deterministic / Analytical
- Hydraulic Models
- Permissible Tractive Force
- Other (Specific Approaches)
- Rosgen
- Newbury
- EPA (Natural Channel Design)

9. Channel Evolution
As a channel deepens, it
reaches a limit, a hard
layer that is harder to
erode.
If it cant move downward, it
will move to the side
When if moves to the side,
banks will erode and the
channel becomes wider
The channel will then re-
establish itself

10. Channel Stability
• Essentially a balance
between flow regime
and sediment loads
• While stable, the
channel may adjust its
form, profile and position
on its floodplain
•When stable, the channel can accommodate
changes in flow or sediment, as long as a threshold
is not exceeded without altering its form.

11. When a channel becomes unstable
• Depending upon
nature and magnitude
of the disturbance, a
threshold in the stream
may be exceeded,
which will lead to
substantial change and
adjustment.
• A channel will strive to
achieve equilibrium but
this can take decades
to occur.

12. “Natural Channel Design”
- Emphasizes
geometry, plan,
profile that will be
stable under given
flow/sediment
regime with
minimal
armor/maintenanc
e
- Assumes most
functions follow
from geomorphic
condition

13. Restoration –Considerations
Scale of the site (bank
treatment versus channel
realignment)
Design Process
Data collection
Analyses
Design iterations
Integration of
disciplines/design
components
Implementation

14. Bank Erosion
• Bank material more variable than bed material
• Many factors involved in analysis
– Flow properties
– Bank composition
– Climate
– Subsurface conditions
– Channel geometry
– Mode of failure
– Biology
– Vegetation

15. Data Collection
• Reach and cross-
section scale
• Used to determine &
quantify channel
processes
• Necessary for all
design approaches

16. Design Analyses
• Hydrology
• Sediment transport
• Geomorphic
relations
• System dynamics

17. Hydrology
Flow Duration Curves
The flow duration curve is a
plot that shows the
percentage of time that flow
in a stream is likely to equal
or exceed some specified
value of interest.
Flow Frequency
The probability a given
streamflow will be exceeded
in any given year.
Related to Return-Interval
(e.g. 100-Year Flood)

18. Why do we care about Hydrology?
Properly developed statistical hydrology
Allows for quantification of risk and success/failure
Allows for the development of specific design criteria
Provides tool for estimating bankfull discharges
Critical link to understanding how physical conditions
such as bank and bed shear stress and other
sediment transport functions vary temporally.

19. Hydraulic Analysis
Used to determine the impacts of flow on the
channel, (how much and how fast), and other
relations essential to restoration designs.
Flow modeling
• a simulation that represents the channel through geometry
Sediment transport modeling
•To understand the amount of sediment moving through the
system
•Can help to determine long term stability of the channel
•Can be used to estimate sediment yield, and for comparative
analysis between reaches

20. Design Discharge
How do we select which flow to design for?
• Low flow ~ habitat design
• Bankfull Discharge ~ stable channel design
• Flood Flows ~ regulatory compliance and
flood hazard protection

21. Geomorphic Relations
• Hydraulic Geometry
• Regime Equations
• Regional Curve Information
• Meander Geometry
• Gradient relationships

22. Examples of Natural Design
Typical dynamic meander pattern

23. Options to move or enhance the stream
Existing Section
Restoration Section

24. Construction Implementation
Erosion & Sediment Control
•How we keep the process
from impacting the valley
Constructability
•How can it be constructed?
Details on how to build it
•Where to access the work
•What are the soils like
•How are the flows in the
channel dealt with

25. Access Considerations
•Protect the channel
•Minimize disturbance
•Optimize materials delivery

26. Restoration Transitioning

27. Construction
Techniques using hard materials

28. Construction
Techniques using bioengineering

29. Channel Enhancements
Fish habitat
Habitat Creation using Habitat Creation using
rock bioengineering

30. Thank-you