SEDIMENT TRANSPORT IN STREAM RESTORATION

choppedspleenMechanics

Feb 22, 2014 (3 years and 4 months ago)

71 views

Peter
Wilcock


Geography and Environmental Engineering

National Center for Earth
-
surface Dynamics

Johns Hopkins University

SEDIMENT TRANSPORT IN STREAM RESTORATION

19 September 2012

Sediment transport is complicated, predictions are highly uncertain.

But with a few basic concepts, and some tools for incorporating uncertainty …


We will propose coherent strategies for incorporating sediment transport and its
uncertainty in stream restoration

Classic concepts from fluvial geomorphology dominate steam channel design

We will evaluate these concepts and their utility and …

suggest their appropriate role in stream design

Two broad channel types were defined by drainage engineers a century ago:

threshold and alluvial channels. We will update these definitions and …

add another!

Lane/Borland Balance (USBR 1955
-
1960)

Sediment Supply

Transport Capacity

Sediment supply
>

Transport capacity

Sediment supply
<

Transport capacity

Does the sediment balance matter in this stream?

It has super capacity with respect to supply,

but it is also unable to entrain sediment from the bed.


Flow competence


Will a flow move the grains on the bed?



Transport Capacity
.


At what rate can the flow transport sediment?


(hint: think of the sediment supplied, not what is in the bed!)


There are two basic transport problems

These are different problems!!!

Define
Q
c
the water discharge at which grains on the bed begin to move

Q


Q
c

does not mean that the sediment supplied
can be transported!

Q < Q
c

does not mean there will be no transport!

Competence
v.

Capacity

Flow Competence

Can a flow entrain the

grains on the bed?

Applied to the channel
bed

Leads to a threshold channel

Transport Capacity

At what rate can a flow

transport sediment?

Compare to sediment
supply

Leads to a mobile channel

Will a channel accumulate or evacuate


sediment ?

How much sediment do we need to add to


restore streams below dams
?

Can we mine sediment from a stream


w/o causing downstream problems?

How will a sediment slug move through a
channel? How far downstream will changes
occur? How long will it take?

Will channel bed and banks


remain stable (static) at a design flow?

Will a channel will need ‘repair’


in the next 25 yrs?

What flow will mobilize the bed surface,


in order to flush fines from subsurface?

Will the frequency of bed disturbance change
with alterations to the flood regime?

D (
climate, land use, reservoir operation, fire)

(

(

2/3
5/3
1
5/3
1
*
1
5/3
1
*
7/6
/
so
or
( 1) so
( 1)
b
b
b
c c
b
c c
Q BhU
B aQ
h gS
S
U h
n
S
Q aQ
gS n
a S
Q
n gS
s gD
a
Q s D
nS
 




  







 

 
 
 
 
 

 
 
 
 
 
 
 
 
 
Transport model for a
threshold channel is based on a
definition of incipient sediment
motion

Uncertainty Exercise

For a simple, wide, prismatic
channel, find critical discharge
Q
c

for incipient motion

*
Your transport model:
0.045
( 1)
c
c
s gD



 

hydraulic geometry

momentum

Manning’s eqn.

continuity

2/22/2014

8

What if you are not
too sure about some
of the values needed
to determine
Q
c
?

Like
n, D
, and


*
c


what do you do?

(

(

2/3
5/3
1
5/3
1
*
1
5/3
1
*
7/6
/
so
or
( 1) so
( 1)
b
b
b
c c
b
c c
Q BhU
B aQ
h gS
S
U h
n
S
Q aQ
gS n
a S
Q
n gS
s gD
a
Q s D
nS
 




  







 

 
 
 
 
 

 
 
 
 
 
 
 
 
 
2/22/2014

9

Suppose your best estimate of Manning’s
n

is 0.035

and that you are pretty sure that the real value falls
between 0.03 and 0.04.

We could approximate your assessment of the

value of
n

with a normal distribution with

mean = 0.035 & standard deviation = 0.0025.


95% of this distribution falls between 0.03 and 0.04,

as can be seen in the cumulative frequency plot, so

we are saying that the real value of
n

is 95% likely to fall
between 0.03 and 0.04 and that it is more likely to be
around the center of the distribution (0.035) than in the
tails. We use this distribution to pick values of
n

in our
Monte Carlo simulation.


How does that work? We use a random number
generator to pick a number between 0 and 1 and then
use this number to find a value of
n

for the cumulative
frequency distribution. For example,

for 0.88,
n

= 0.0379

for 0.23,
n

= 0.0332

n
n

0.02
0.03
0.04
0.05
Frequency
Manning's
n
2
n


0.035
0.0025
n
n



0
0.2
0.4
0.6
0.8
1
0.02
0.03
0.04
0.05
Cumulative Frequency
2
n


Manning's
n
0
0.2
0.4
0.6
0.8
1
0.02
0.03
0.04
0.05
Cumulative Frequency
Manning's
n
2/22/2014

10

The Monte Carlo simulation

1
. Pick values of
n
, , and
D

from specified frequency distributions.

2
. Calculate critical discharge and transport rate.

3
.
Repeat 1000 times
.

4
. Distribution of calculated values gives

estimate of the effect of input uncertainty

on calculated critical discharge and transport rate.

*
c

(

(

2/3
5/3
1
5/3
1
*
1
5/3
1
*
7/6
/
so
or
( 1) so
( 1)
b
b
b
c c
b
c c
Q BhU
B aQ
h gS
S
U h
n
S
Q aQ
gS n
a S
Q
n gS
s gD
a
Q s D
nS
 




  







 

 
 
 
 
 

 
 
 
 
 
 
 
 
 
0
100
200
300
400
0.020
0.024
0.028
0.032
0.036
0.040
0.044
0.048
Manning's n
(a)
0
50
100
150
200
0.030
0.034
0.038
0.042
0.046
0.050
0.054
0.058
*
c

(b)
0
50
100
150
200
250
14
20
26
32
38
44
50
56
Grain Size D
(mm)
(c)
0
50
100
150
200
250
300
0
3
6
9
12
15
18
21
Critical Discharge
Qc (m^3/s)
(d)
Manning's
n
n
Manning's
n
D
Manning's
n
*
c

1
.

2
.

4
.



Monte Carlo

2/22/2014

11

3/2
3/5
1 0.7
3 *
( 1)
( 1)
b
s o c
nQ S
Q cB s gD
a s D


 
 
 
  
 
 
 

 
 
 
(

1
5/3
1
*
7/6
( 1)
b
c c
a
Q s D
nS


 
 
 
 
Threshold Channel

Find critical discharge
Q
c

at
which grain motion begins

Mobile Channel

Find transport capacity for

different water discharge
Q

Estimating uncertainty in sediment transport

It’s the input, not the formula !!!


These terms have lots of uncertainty !!

0
50
100
150
200
250
300
0.026
0.028
0.030
0.032
0.034
0.036
0.038
0.040
Manning's n
(a)
0
50
100
150
200
250
300
0.023
0.027
0.031
0.035
0.039
0.043
0.047
0.051
*
c

(b)
0
50
100
150
200
250
44
49
55
60
66
71
76
82
Grain Size D (mm)
(c)
0
50
100
150
200
250
13.0
17.0
21.0
25.0
29.0
33.0
37.0
41.0
Critical Discharge (m^3/s)
(d)
5.0
11.0
17.0
23.0
29.0
35.0
0
187
374
561
748
935
1122
Discharge (cms)
Time (hrs)
Discharge (m^3/s)
(e)
0
50
100
150
200
250
300
0
100
200
300
400
500
600
700
Cumulative Transport
(metric tons)
(f)
2x

2x


10x

http://stream.fs.fed.us

2/22/2014

15

0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0
5
10
15
20
25
Slope
Depth (m)
Bottom Width (m)
Depth
Slope
*
Given discharge , grain size , Limerinos
roughness & trapezoidal channel shape,
find slope producing incipient motion.
Specify 12.5 m and 0.047,
solution is 0.0064 with depth 0.54 m
c
Q D
S
B
S h

 
 
S
v

*
0.047
c


(

6( 1)
1
10/7
7
*
( 1)
b
b
c
c
aQ
S s D
n



 
 
 
 
 
2/22/2014

16

0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0
5
10
15
20
25
Slope
Depth (m)
Bottom Width (m)
Depth
D = 32 mm, t* = 0.03
Slope
D = 32 mm, t* = 0.03
*
*
Other values of ,, and could have been
chosen
Changing 0.047 0.030 and 45 mm 32
mm
c
c
n D
D


 
(

6( 1)
1
10/7
7
*
( 1)
b
b
c
c
aQ
S s D
n



 
 
 
 
 
S
v

Calculated slope 3x
bigger!


剉卋

2/22/2014

17

Strategy
What is probability of failure? What pro
bability are you willing to accept?
( ) ( ) ( )
Choose width, slope, sediment combinatio
n to match acceptable risk.
For example, for a 25yr
D D c
D
P failure P Q P Q Q
Q
 
and a channel design with 10% failure p
robability,
( ) ( ) ( ) (0.04)(0.1) 0.004
giving a 0.4% chance of failure in any y
ear.
D D c
P failure P Q P Q Q
   
0
50
100
150
200
250
300
6.0
10.0
14.0
18.0
22.0
26.0
30.0
34.0
Critical Discharge (m^3/s)
Frequency
From Monte Carlo Uncertainty Analysis
Q
D

Failure in a threshold channel = grain entrainment

The core questions:


What is the supply of water and sediment?

What do you want to do with it?

1.
What is the water discharge
Q
(
t
) and

sediment supply rate
Qs
(
t
) and grain size
D
(
t
)

delivered to the upstream end of the design reach?

2.
How will the available flow move

the supplied sediment through the design reach?

More precisely,

Sediment Transport in Channel Design

How do we incorporate transport in channel design? When do we need to?

2/22/2014

19

The imaginary:
What is the dominant discharge?


Why only one flow?

The wishful
:
Q
bf
(field)



Q
bf

(DA)



Q
eff



Q
1.5
?

Basis for connecting to core questions?

The core questions may be difficult to answer


But we cannot wish them away


& ignoring them is the basis for project failure

The core questions are often

replaced by other questions

2/22/2014

20

“Stream stability is
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 or degrading

and is
able to effectively
transport the
flows and sediment delivered to
it by its watershed
.

Sediment
Transport
Capacity

Sediment
Supply

Why do we hope for this convergence?

Why do we expect this similarity to produce a “stable” channel

Nicely stated, but why is it that one would think that a channel sized to the
1.5 yr flow, or some field indicator of such a flow, would neither aggrade or
degrade and be able to
transport the flows and sediment delivered to it by
its watershed?

2/22/2014

21

When does a disturbance here



show up here?

Is that before, during, or
after the impact from a
disturbance here?

Where is steady state found in a real watershed?

In many cases, there is no steady state, & there is no template

2/22/2014

22

Morphology: Choose
bankfull geometry

from a template:


a reference reach, regional hydraulic geometry

Process: specify flood frequency
AND

sediment supply

resistance eqn.


bankfull flow


flood frequency curve


flood frequency


incipient motion, transport criteria


flow competence, capacity

flood frequency curve


bankfull flow


+


hydraulic & transport relations


channel
slope & width

+

channel shape relations


bankfull geometry

Design channel from a template, then check for transport? OR


use drivers to develop the design?

In either case: is hard to get an accurate estimate of sediment supply.

Template vs. Prediction

2/22/2014

23

But there are more fundamental problems!

At the core of the template approach is a
correlation

between


channel geometry, flow, and sediment supply

The correlation
requires
that the channels have
adjusted

to their


water and sediment supply.

But what if channel is currently adjusting, or perpetually adjusting?

How would you know?

A template approach provides no basis for
linking cause and
effect

in a logically complete and
testable

framework.



I

II

If a template
-
designed project “fails”,

how is the method to be improved?

!

This correlation
is

remarkable:

The flow that moves the most sediment, over time, tends to
just fill the channel and occurs ever year or few.

The width of channels increases very consistently with the
square root of discharge.

1
10
100
1000
1
10
100
1000
10000
Alberta
Britain I
Idaho
Colorado R
Britain II
Maryland
Tuscany
Bankfull Discharge (cms)
Bankfull with (m)


2/22/2014

24

Connecting sediment supply to the design problem

1.
Reconnaissance phase
: What is the trajectory of the stream? How has it
responded to changes in water and

sediment supply over the years?
{
Henderson relation


mixed
-
size seds
}

2.
Develop flood series, specify flood frequency


Q
bf
.


{
Select Q
bf

for flood frequency specified to maintain riparian

ecosystem & prevent vegetation encroachment
}

3.
Estimate sediment supply

4.
Planning phase
: What slope
S

is needed to carry

the sediment supply with the available flow?

{
How does S vary with Q
s

and width b?
}

5.
Develop flow duration curve

6.
Design phase
: Evaluate trial designs. Will the sediment

supply be routed through the reach over the flow duration curve?

{
Build 1
-
d hydraulic model for trial design. Calculate cumulative transport over flow duration
curve at each section; evaluate sediment continuity.
}

2/22/2014

25

Borland’s stable channel stability relationship illustrated by James Vitaliano, BOR, in 1960.

From Pemberton, E.L. and R.I. Strand, 2005, “Whitney M. Borland and the Bureau of Reclamation, 1930

1972”, J.
Hydraulic Engineering, May 2005, pp. 339
-
346.

The Lane/Borland Stable Channel Balance

R
e
c
o
n
n
a
i
s
s
a
n
c
e

2/22/2014

26

3
3
3/2
3/2
3 2
3
3/2
2 2
3/2
3/4
3/4
2
2 2 1
1 1 1 2
Einstein-Brown depth-slope continuity
Chezy
* ( *)
( )
or
or for two cases
b
b
b
b
b
b
q RS q UR U RS
q q R S
D
RS q
q R
S
D
q S
q
D
q D
S
q
q
S D q
S q D q
 

   
 
 


   

   
   
The Lane Balance, quantified 45 yrs ago

by Henderson (1966, Open Channel Flow)

What if q
b

increases
and D decreases?
Lane’s balance is
indeterminate.

R
e
c
o
n
n
a
i
s
s
a
n
c
e

2/22/2014

27

Steady state: sediment supply balanced
by transport capacity. Slope is stable.

Increase sediment supply

Sediment supply > transport capacity


S
2

> S
1

sediment accumulates


3/4
2
2 2 1
1 1 1 2
b
b
q
S D q
S q D q
   

   
   
Increase water supply

Sediment supply < transport capacity


S
2

< S
1

sediment evacuates


Interpretation, for evaluating stream history

R
e
c
o
n
n
a
i
s
s
a
n
c
e

We will add a
version for
mixed
-
size
sediment
shortly

2/22/2014

28

Given


Water discharge and
sediment supply

Find


channel

slope, depth & width

(& velocity & shear)

We have enough general relations to solve for

all but one of these unknown variables

If we
specify

channel width, we can solve for the rest of the variables

What slope is needed to transport the supplied sediment with the available water?

How big the channel?

P
l
a
n
n
i
n
g

2/22/2014

29


Hydraulic Design of Stream Restoration Projects
September 2001


RR Copeland, DN McComas, CR Thorne, PJ Soar, MM Jonas, JB Fripp

For a specified supply of
water

and
sediment
,

what
slope

is needed to transport the

supplied sediment with the available flow?

Mobile channel design = match transport capacity to sediment supply

1
10
100
1000
1
10
100
1000
10000
Alberta
Britain I
Idaho
Colorado R
Britain II
Maryland
Tuscany
Bankfull Discharge (cms)
Bankfull with (m)


Sometimes, yes

Does sediment supply matter?

Sometimes, no

2/22/2014

31

So, there must be a boundary between cases where
sediment supply matters or not

Threshold

Alluvial

Bed & banks immobile

Active transport

Easier to model & design

Bed & banks must only be
strong enough

Harder to design

Requires a balance
between transport capacity
& sediment supply

Extend Threshold definition
to include small sediment
supply rates requiring a
slope negligibly larger than
the zero supply case

Focus on cases in which
slope is sensitive to supply

Nothing new under the sun … see SCS in the ’30s

2/22/2014

32

Why we can ‘neglect’ small sediment supply rates

1.
Small sediment supply rates


many storms (and many decades) req’d to
produce significant aggradation and degradation.

2.
Small sediment supply rates



channel morphology and slope required to transport the supplied sediment can
be negligibly larger than that of a threshold channel.

2/22/2014

33

Stress (Pa)

Transport Rate (kg/hr)

0.00001
0.0001
0.001
0.01
0.1
1
10
0.1
1
10
100
0.00001
0.0001
0.001
0.01
0.1
1
10
0.1
1
10
100
Sediment Supply (kg/hr)

Slope

0.001

0.0001

0.01

0.1

So, what is a SMALL sediment supply rate?

That sounds dangerously like a real question, so first, lets deal
with real sediments, which contain a mixture of sizes

But for mixed
-
size sediment, there are complications …


Grain size of bed


grain size of transport


Bed is sorted spatially and vertically


Transport is a function of the changing population of grains on
the bed surface

2/22/2014

34

0.00001
0.0001
0.001
0.01
0.1
1
10
0.1
1
10
100
*
i
W
ri


/
0.1
1
10
0.01
0.1
1
10
100
J06
J14
J21
J27
BOMC
A 'hiding' function


r
i

r
s
m

D
i
D
s
m
48 flume runs w/ 5 sediments

Incorporates sand

And effect of sand on transport
of other sizes

Tested against field data

Transport Function

Hiding Function

Sand Interaction Function

2/22/2014

35

Surface
-
based transport model can be used in both
forward & inverse forms


Forward
: predict transport rate & grain size

as function of


慮搠扥b獵sf慣攠杲慩a獩e


Inverse
: predict


慮搠扥搠獵sf慣攠杲慩渠獩se

慳⁦畮捴楯渠潦⁴o慮獰潲琠a攠☠杲慩渠獩e

Don’t try this with a subsurface

based model!

We can use an inverse transport model to forecast, or
design, a steady state channel that will transport a
specified sediment supply rate
and

grain size with the
available flow (!)

2/22/2014

36

1. State Diagram I




transport v. discharge
, lines of constant slope

2. State Diagram II




transport v. slope
, lines of constant discharge

3. Channel Stability Diagram

Presenting ….

iSURF


Inverse Model
: predict


慮搠扥搠獵牦慣攠杲慩渠
獩s攠e猠普⡴s慮獰潲琠a攠☠杲慩渠獩s攩


Specify discharge and basic channel geometry
and solve for slope (
& depth
)

2/22/2014

37

h
z
1
b
iSURF


Channel Stability Diagram

what slope is needed to
transport a specified transport
rate of specified size
distribution with a specified
discharge through channels of
different widths?

Given ,(,),,,,
Find ,(,),,,,
Using transport, continuity,
momentum, resistance,
& Strickler
s i i s
b i i D
Q p D Q n z b
F D n U h S

D (mm)
Case 1 Transport Grain Size
(% Finer)
Case 2 Transport Grain Size (%
Finer)
128.00
100.00
100.00
90.00
99.70
99.50
64.00
98.50
98.07
45.30
93.71
91.92
32.00
83.21
78.42
22.40
71.32
63.14
16.00
61.45
50.46
11.20
50.11
35.88
8.00
39.91
22.77
5.60
30.07
10.13
4.00
22.19
0.00
2.80
15.06
2.00
9.87
1.40
6.04
1.00
3.41
0.70
1.56
0.50
0.00
Parameter
Value
Description
Units
Q
1
17
Case 1 water discharge
m
3
/s
Q
T1
0.0001
Case 1 sediment supply rate
m
3
/s
Q
2
17
Case 2 water discharge
m
3
/s
Q
T2
0.00001
Case 2 sediment supply rate
m
3
/s
b
min
4.00
Minimum bottom width
m
b
max
24.00
Maximum bottom width
m
0
20
40
60
80
100
0.1
1
10
100
GSD1
GSD2
% Finer
Input transport size distributions
P
l
a
n
n
i
n
g

2/22/2014

38

Channel Stability Diagram

As a bonus, you find out how
armored the bed becomes !

0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
5
10
15
20
25
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Slope Case 1
Slope Case 2
Depth Case 1
Depth Case 2
Channel Width (m)
Slope
Depth (m)
Discharge 1 = 17.0
Discharge 2 = 17.0
Sed Supply 1 = 954 kg/hr
Sed Supply 2 = 95 kg/hr
0
0.005
0.01
0.015
0.02
0.025
0.03
1
10
100
1,000
10,000
100,000
1,000,000
Case 1
Case 2
Your sediment supply
Sediment Supply Rate (kg/hr)
Slope
Discharge 1 = 17.0 cms
Discharge 2 = 17.0 cms
b = 14.0 m



0
20
40
60
80
100
0.1
1
10
100
1000
Grain Size (mm)
Case 1 Transport
Case 2 Transport
Case 1 Bed Surface
Case 2 Bed Surface
% Finer

b = 14.0 m
P
l
a
n
n
i
n
g

And get a measure of where
you are relative to the
threshold/alluvial channel
boundary !

2/22/2014

39

0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
1
10
100
1,000
10,000
100,000
1,000,000
Slope
Your sediment supply
Sediment Supply Rate (kg/hr)
Slope
Discharge = 25.0 cms
b = 11.0 m



If your sediment supply is safely below the boundary
between “low” slope and “high” slope, channel slope is
relatively insensitive to sediment supply


you are less likely
to accumulate sediment given an error in estimating
sediment supply

Is an accurate sediment supply estimate needed?

2/22/2014

40

Strategy for a mobile channel

(i)
Determine if the sediment supply is a big number or a little number

(a) if big,

invest in more accurate estimate of sediment supply



be prepared for a dynamic channel



reserve riparian corridor and let the stream go




or plan to trap and remove sediment

(b) if little,

design a threshold channel

(ii)
Estimate uncertainty and account for the consequences

esp. potential for
aggradation
, degradation

0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
1
10
100
1,000
10,000
100,000
1,000,000
Q = 70.8 cms
Your sediment supply
Sediment Supply Rate (kg/hr)
Slope
b = 19.0 m
OR
, Design a flume

Make your channel


(i) steep enough: transport capacity exceeds supply



and


(ii) strong enough: bed material immobile


… a washload threshold channel

Design Basis:

Flow
Competence

Competence
& Capacity

Transport
Capacity

Channel Type

Threshold
Channel

Threshold
Channel w/
washload

Alluvial
Channel

Topography &
Bed Material

Static

Static

Dynamic

Flumes: an increasingly common & safe design option,


may provide acceptable aesthetics.

Note: does not provide anything like natural structure & function

“small”

“large”

Threshold
channel design

Use risk assessment
and
P
(failure) to
guide design

Alluvial
channel design

Allow for
dynamic
stream

Invest in
improved
sediment
estimate

Build a flume

Is the sediment supply small or large?

1.
Reconnaissance phase
:
What is the trajectory of the stream? How has it
responded to changes in water and sediment supply

over the years?


2.
Develop flood series, specify flood frequency


䑥獩杮D
Q
.


{
Select Q
bf

for flood frequency specified to maintain riparian

ecosystem & prevent vegetation encroachment
}

3.
Estimate sediment supply

4.
Planning phase
: What slope
S

will transport

the sediment supply with the available
Q
bf
?

Calculate (b, S) combination {S and valley

slope determine sinuosity}


Check if alluvial
v.

threshold channel

5.
Develop flow duration curve

6.
Design phase
: Evaluate trial designs. Will the sediment

supply be routed through the reach over the flow duration curve?

{
Build 1
-
d hydraulic model for trial design. Calculate cumulative transport over flow duration
curve at each section; evaluate sediment continuity.
}

7.
Bottlenecks or blowouts? Adjust for sediment continuity

3/4
2
2 2 1
1 1 1 2
b
b
q
S D q
S q D q
   

   
   
0
0.002
0.004
0.006
0.008
0.01
0.012
0
5
10
15
20
0
0.5
1
1.5
2
2.5
3
3.5
Slope Case 1
Slope Case 2
Depth Case 1
Depth Case 2
Channel Width (m)
Slope
Depth (m)
Discharge 1 = 15.0
Discharge 2 = 25.0
Sed Supply 1 = 954 kg/hr
Sed Supply 2 = 2862 kg/hr
0
0.005
0.01
0.015
0.02
0.025
1
10
100
1,000
10,000
100,000
1,000,000
Case 1
Case 2
Your sediment supply
Sediment Supply Rate (kg/hr)
Slope
Discharge 1 = 15.0 cms
Discharge 2 = 25.0 cms
b = 11.0 m



Design steps incorporating sediment supply

iSURF

State Diagrams

2/22/2014

44

Objective

sediment & nutrients

property & infrastructure

biological recovery

aesthetic

penance

What

needs

fixing?

Stormwater control

Nothing

Channel change

Introduced species

Disturbance

Internal or

external?

Internal

External

Fence out the cows!

Remove the concrete!

Template approach

can work

Small

Channel
Design

Sediment
supply large
or small?

Large

Estimate flood
frequency

Design threshold
channel

Estimate sediment
supply & flow
duration

Design mobile
channel

Mobile or

Threshold Channel
?



Sediment Transport in Stream Restoration

Environmental

Drivers

You don’t always have to consider sediment transport in stream restoration


e.g. if the problem does not involve channel change

There are two types of transport problem



competence

and
capacity







(
threshold

and
mobile bed
) (and flume)

Most error in transport calculations is in the input, not the formula.


If you need an accurate of sediment transport, you must make field observations.


They need not be fancy, but it takes care


Often, you can avoid this effort …


Uncertainty can be estimated AND


you can incorporate that uncertainty into your design strategy

If the sediment supply is not “large”, you can go to the simpler threshold design problem

If the sediment supply is “large”, you can


let the channel go


design a flume channel



(if you have enough slope)


do the work to properly design



a mobile
-
bed channel

(1) Chapters 1 and 2 in Wilcock, Peter; Pitlick, John; Cui, Yantao. 2006.
Sediment Transport Primer
: Estimating Bed
-
Material Transport in Gravel
-
bed
Rivers, Gen. Tech. Rep. RMRS
-
GTR
-
xxx. Fort Collins, CO: U.S. Department of
Agriculture, Forest Service, Rocky Mountain Research Station.

(2) Chapters 2, 7, 8, 9 in NRCS, 2007.
Stream Restoration Design Handbook
(NEH 654), USDA.


You can either download individual chapters of NEH 654 or request a free cd.



There are no paper copies.


(I) Download the book chapter by chapter from


http://policy.nrcs.usda.gov/index.aspx




navigate to Handbooks, Title 210
-

Engineering, National Engineering Handbook, Part
654
-

Stream Restoration Design


(II) To request a CD, go to
http://landcare.nrcs.usda.gov/
and search for NEH
-
654.


The CD version is free and includes navigation bookmarks, is fully searchable with
keywords, and has high quality files for selective printing.




The CD also contains a copy of Federal Interagency Stream Restoration Working Group
(FISRWG). 1998. Stream Corridor Restoration: Principles, Processes and Practices

Readings

(3) RiverRat
www.restorationreview.com

Skidmore, P. B., C. R. Thorne, B. Cluer, G. R. Pess, J. Castro, T. J. Beechie, and C.C. Shea.
In review 2009. Science base and tools for evaluating stream engineering, management, and
restoration proposals. U.S. Dept. Commerce, NOAA Tech. Memo. NMFS
-
NWFSC.

2/22/2014

47

Bibliography

Allmendinger, N.E., Pizzuto, J.E., Potter, N., Johnson, T.E., Hession, W.C., 2005, The influence of riparian
vegetation on stream width, E. Pennsylvania, U.S.A.
Geological Society of America Bulletin
, 117:229
-
243.

Brierly, G.J., and Fryirs, K.A., 2005, Geomorphology and river management: Applications of the River Styles
Framework. Blackwell, Malden, MA USA, 398 p.

Clark, J.J. and P.R. Wilcock, 2000. Effects of land use change on channel morphology in northeastern Puerto
Rico, Bulletin, Geol. Society of America, 112(12):1763
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1777.

Copeland, R., D.N. McComas, C.R. Thorne, P.J. Soar, M.M. Jonas, and J.B. Fripp, 2001. Hydraulic Design of
Stream Restoration Projects. U.S. Army Engineer Coastal and Hydraulics Laboratory, HL TR
-
01
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28.

Doyle, M.W. and F.D. Shields Jr., 2000. Incorporation of bed texture into a channel evolution model,
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309.

Henderson, F.M., 1966. Open Channel Flow, Ch. 10, p. 448, McMillan.

Jacobson, R.B., and Coleman, D.J. (1986). Stratigraphy and recent evolution of

Maryland Piedmont
floodplains.
Am. J. of Science
, 286: 617
-
637.

Lane, E.W., 1955. Design of stable channels, Transactions, ASCE, Paper no. 2776, 20, 1234
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Phillips, J.D., 1992, The end of equilibrium.
Geomorphology
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Schmidt, J.C. and P.R. Wilcock, 2008. Metrics for assessing the downstream effects of dams,
Water Resour.
Res
., 44, W04404, doi:10.1029/2006WR005092

Shields, F D, R R Copeland, P C Klingeman, M W Doyle, and A Simon; 2003 (August); Design for Stream
Restoration, Journal of Hydraulic Engineering; 129, 8: 575
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584

Soar, P. and C.R. Thorne, 2001. Channel Restoration Design for Meandering Rivers, U.S. Army Engineer
Coastal and Hydraulics Laboratory, ERDC/CHL CR
-
01
-
1.

Wolman, M.G., 1967. A cycle of sedimentation and erosion in urban river channels.
Geografiska Annaler

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48