Culvert Scour Assessment

A—480

Culvert Scour Assessment

Youngs Creek

YoungS Creek

Site Information

Site Location: Willamette NF, Forest Rd 21

Year Installed: Circa 2002

Lat/Long: 122°26’10.61”W

43°30’40.77”N Watershed Area (mi2): 2.92

Stream Slope (ft/ft)1: 0.0635 Channel Type: Step-pool

Bankfull Width (ft): 13.5 Survey Date: March 21 2007

1Water surface slope extending up to 20 channel widths up and downstream of crossing.

Culvert Information

Culvert Type: Pipe arch Culvert Material: Annular CMP

Culvert Width: 14 ft Outlet Type: Mitered

Culvert Length: 62 ft Inlet Type: Mitered

Pipe Slope (structure slope): 0.067

Culvert Bed Slope: 0.028

(First hydraulic control upstream of inlet to first hydraulic control downstream of outlet.)

Culvert width as a percentage of bankfull width: 1.02

Alignment Conditions: May have been constructed in alignment with previous channel location but channel adjustment upstream has resulted in the culvert being off-alignment. Scour of culvert bed on left side at inlet may be partially due to alignment.

Bed Conditions: Well-graded bed material distribution in culvert. Large cobbles/boulders forming steps.

Pipe Condition: Some structure joints open but not leaking. Little to no rust.

Hydrology

Discharge (cfs) for indicated recurrence interval

25% 2-yr Qbf

2 2-year 5-year 10-year 50-year 100-year

21 60 85 135 170 250 2862Bankfull flow estimated by matching modeled water surface elevations to field-identified bankfull elevations.

A—481

Site evaluations

Youngs Creek

Figure 1—Plan view map.

Points represent survey points

A—482


Youngs Creek

HISTOrYThe Youngs Creek culvert was installed in 2002 and replaced a smaller, closed-bottom pipe. Bed material was placed into the culvert during construction, and is assumed to have been sourced from the channel bed beneath the previous culvert. There was no sorting or grading of material during placement and no bedforms or banks were constructed in the culvert. The culvert was placed on the existing horizontal alignment of the old structure and was placed on a vertical alignment between the lower and upper channel slopes. It is possible that the outlet scour pool was filled during construction.

The culvert lost most of the placed material at some point after construction. Since then, in the last year or two, stream headcutting and channel edge adjustment sediments have been deposited in the culvert. The culvert has not experienced overtopping. There has been no significant maintenance or management of the site since construction.

The above information was furnished byKim Johansen, USFS.

An assessment of nearby stream gauges suggests that nothing more than a 5-year recurrence interval event has occurred in the region since construction.

SITe DeSCrIPTIOnThe Youngs Creek culvert is a large pipe arch mitered to conform to the roadfill. There are a series of cascades and steps just upstream of the inlet to the culvert. This steep channel transitions to a flatter slope through a scour pool exposing the bottom of the pipe through the inlet. Below the inlet, material from upstream has deposited on top of the original fill, altering the grade. Grade through the culvert is controlled by the downstream aggradation of material, evident by the drop in channel elevation at the outlet.

The upstream representative reach was located above a long cascade. The representative segment consisted of a series of log and rock steps interspersed by plunge pools, backwater pools, and riffles. Small boulders and large cobble comprised the majority of the bed, with the deposition of small gravels and even some fines in the backwater pools. With the exception of a narrow active terrace along the right bank, the channel abutted the valley walls. Downed trees were prevalent through this reach, adding structure to the channel and providing cover.

Downstream of the culvert, the channel flows through oversized angular rocks which appear to be sourced from either the culvert or the adjacent banks which were lined with riprap. Riprap lines both banks upstream and downstream of the culvert. Debris from roadside clearing covered the section of channel downstream of the outlet. Below this, the channel consisted of a series of steep riffles interspersed by pools. A tall terrace along the left bank confines flows to the channel. Below the downstream boundary of the downstream reach, the channel opens up to a wide flood plain before joining the Middle Fork Willamette. While some wood was present in the channel, it did not serve a structural role as it did in the upstream reach.

The crossing is located in an area of gradual valley transition from the Youngs Creek stream valley into the broad flood-plain valley of the Middle Fork Willamette. The greatest transition occurs a couple hundred feet downstream of the culvert.

SurveY SuMMArYFourteen cross sections and a longitudinal profile were surveyed along Youngs Creek in March 2007 to characterize the culvert, an upstream reference reach, and a downstream reference reach. Representative cross sections were taken in the culvert through a pool/glide and at a steep riffle/step. One additional cross section

A—483

Site evaluations

Youngs Creek

was surveyed upstream to characterize the inlet as well as the contraction of flow. Another two cross sections were surveyed downstream of the culvert to characterize the outlet and the expansion of flow.

Representative cross sections in the upstream channel were taken through a step and between steps. An additional two sections were taken to characterize the upstream and downstream boundaries of the representative reach. Representative cross sections in the downstream channel were taken through two riffles. An additional two sections were taken to characterize the upstream and downstream boundaries of the reach.

PrOfILe AnALYSIS SegMenT SuMMArYThe profile analysis resulted in a total of nine profile segments. The two segments downstream of the outlet, which had similar gradient, were not combined in order to separate out the outlet transition segment for analysis. The culvert consisted of one profile segment. The culvert segment had gradient comparable to one representative profile segment in the upstream channel. Two upstream transition segments were each comparable to one representative profile segment in the upstream channel. The downstream transition segment was comparable to two representative profile segments, one in the upstream channel and one in the downstream channel. See figure 2 and table 1.

SCOur COnDITIOnSObserved conditionsStructure scour – This closed-bottom culvert has been scoured to the base at the upstream end (on right bank for 2 feet and on left bank for 20 feet). The main flow is along the side/base of the culvert on the left side at the upstream end and along the right side at the downstream end.

Culvert-bed adjustment – According to the structure designer, originally placed material scoured out of the pipe and it subsequently refilled. Slope measurements indicate there has been a flattening of the culvert bed profile (assuming the original culvert bed was constructed at the same gradient as the structure). The pipe slope is 6.7 percent compared to a bed slope of 2.8 percent.

Profile characteristics – The profile has a concave shape through the crossing, with the maximum concavity occurring at the inlet and just upstream. The profile shape may be partly due to the natural valley transition occurring in this area as the Youngs Creek valley meets the broad valley of the Middle Fork Willamette. However, site observations suggest that much of the shape is also due to crossing-related channel incision at the inlet and upstream. The culvert may have been placed lower in the profile than the original stream. This could relate to channel adjustments from the previous culvert or may also be a result of restrictions in height imposed by the height of the road prism.

Residual depths – Culvert residual depths have a similar and slightly greater range than those in the representative profile segment (F) (figure 21). The upstream transition segments (D and E) have greater residual depths than the corresponding profile segment (I), but there was only one residual depth in segment I. The downstream transition segment had lower residual depths than corresponding profile segments.

Substrate – Culvert bed material distributions are similar to the natural channel, with generally more boulder-sized material in the natural channel. Pebble counts are provided at the end of this summary. Bed-material sorting in the culvert was lower than the range found in the natural channel but values did not diverge from the range significantly. Culvert-skewness values were within the range of the natural channel.

A—484


Youngs Creek

Predicted conditionsCross-section characteristics – Cross-section characteristics vary between the culvert and the corresponding profile segment (F) for most of the cross-section metrics beginning at or above the Q

10 (figures 5 through 9 and 12 through 17).

These results reflect the flow contraction created by the pipe. The upstream- and downstream-transition segments have values that are mostly within the range of their corresponding profile segments, except the upstream transitions have lower widths and greater depths than the natural channel at high flows.

Shear stress – The range of shear stress in the culvert becomes less than that of the natural channel segment (F) as flows increase above the 25-percent Q

2, but maximum shear stress values

remain similar (figures 10 and 19). Shear stress in the upstream transition segment E becomes greater than the corresponding profile segment (I) above the Q

bf, but the other transition segment

(D downstream) is within the range of segment I. Shear stress in the downstream transition remains within the range of the corresponding profile segments for all modeled flows.

Excess shear – The excess shear analysis suggests that the culvert excess shear may be at the lower end of the range of that found in the natural channel (figure 20).

Velocity – Velocity in the culvert has a broader range of that found in the natural channel but the median values remain similar for all flows (figures 11 and 18).

Scour summaryOriginal material has scoured out of the pipe but has been replaced by material from upstream. This is an acceptable scenario for a stream-simulation type design; except that the new culvert bed has adjusted to a flatter slope than the originally constructed bed (assuming the original culvert bed was constructed at the same gradient as the structure). There is now scour to

the culvert base at the upstream end of the pipe and aggraded material at the downstream end. The reduced slope of the bed reduces shear stress and may prevent the efficient transport of material through the pipe. Slope adjustments may be related to the culvert being placed at a low elevation in the profile, possibly due to height limitations imposed by the height of the road prism.

Site observations suggest that the low elevation of the inlet may have initiated scour at the inlet area, which triggered upstream incision. Material sourced from the bed and banks as a result of this incision then collected upstream of the inlet (visible as cobbles and small boulders just upstream of the inlet), possibly during a large event when the culvert was backwatered (debris plugging?). The aggraded material upstream of the inlet resulted in lateral boundary adjustment, resulting in the sinuous planform upstream of the inlet.

The historical occurrence of material scouring out of the culvert indicates a risk of loss of bed material; however, the excess shear analysis and the fact that the culvert re-filled suggest that any scour will likely be replaced by material moving in from upstream.

AOP COnDITIOnSCross-section complexity – The sum of squared height difference in the downstream culvert cross section is within the range of those in the channel (table 3). The sum of squared height difference in the upstream culvert cross section is lower than the range in the natural channel, but the habitat units differ (pool in culvert versus riffle/step in channel), making comparisons difficult.

Profile complexity – Vertical sinuosity in the culvert is lower than that found in the natural channel (table 4). The abundance of wood in the natural channel may account for greater profile complexity.

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Site evaluations

Youngs Creek

Depth distribution – Depth distribution (at the 25-percent Q

2) in the culvert is at the upper

range or above that which is found in the natural channel (table 5). The high values in the culvert are related to the aggraded bar material that is just inundated at the 25-percent Q

2 (see figure 4).

Habitat units – The culvert has a greater abundance of pool habitat compared to the natural channel (table 6), which is related to the flatter profile that allows for a long pool in the upstream portion of the culvert that is in contrast to the short step-pools typically found in the natural channel.

Residual depths – Culvert residual depths have a similar and slightly greater range than those in the representative profile segment (F) (figure 21). The upstream transition segments (D and E) have greater residual depths than the corresponding profile segment (I), but there was only one residual depth in segment I. The downstream transition segment had lower residual depths than corresponding profile segments.

Bed material – Culvert bed material distributions are similar to the natural channel, with generally more boulder-sized material in the natural channel. Pebble counts are provided at the end of this summary.

Large woody debris – There was no LWD present in the culvert (Table 8). The representative channel had moderate to high LWD abundance. LWD formed steps and scour pools in the channel outside the crossing and played a primary role in habitat unit creation and complexity. Features in the culvert did not mimic the role of wood in the natural channel.

AOP summaryScour to the base in the upstream portion of the culvert may create lack of bed roughness elements for fish passage. The thalweg also runs along the edge or base of the culvert for much of the length, again indicating a lack of roughness and velocity refuge for migrating fish. And there are fewer boulders in the culvert that are important for providing velocity refuge. Profile complexity is less in the culvert; however, depth distribution is good in the culvert at the 25 percent Q

2, suggesting the availability of channel

margin habitat for passage at this flow. At the low flow level during the survey, there was aggraded material along the banks in the culvert that could provide for passage of terrestrial organisms; however, the banks were not continuous through the culvert on either side.

DeSIgn COnSIDerATIOnSInlet scour, upstream incision, and upstream lateral boundary adjustment could likely have been reduced by raising the invert elevation of the culvert bed; however, this may have required raising the elevation of the road prism at considerable expense. Adding stable, embedded boulders into the culvert bed would reduce risk of scour to the culvert base, which is currently occurring. Use of an open-bottom arch at this location would allow for the construction of stable bed elements while not significantly reducing culvert capacity. Creation of continuous banks along the culvert walls would reduce the smooth wall-based flow currently occurring along much of the length and would also benefit terrestrial organism passage.

A—486


Youngs Creek

Fig

ure

2—Y

oung

s C

reek

long

pro

filet

.

Tabl

e 1—

Seg

men

t Com

paris

ons

90

95

10

0

10

5

11

0

11

5

12

0

12

5

13

0

05

01

00

15

02

00

25

03

00

35

04

00

45

05

00

Dis

tan

ce

alo

ng

be

d (f

ee

t)

Rela

tive

elev

atio

n (f

eet)

A

C

D

E

F

G

H

I

XS 1

3:

Peb

ble

coun

t

(riffl

e/st

ep)

XS 2

:

Peb

ble

coun

t(ri

ffle)

XS 5

:

Peb

ble

coun

t

(riffl

e/st

ep)

XS 6

:

Peb

ble

coun

t

(poo

l)

XS 1

2:

Peb

ble

coun

t

(riffl

e/st

ep)

Cul

vert

Rep

rese

ntat

ive C

hann

el

Rep

rese

ntat

ive C

hann

el

BXS

1:

Peb

ble

coun

t

(riffl

e)

XS 1

4

XS 3

XS 1

1

XS 1

0

XS 9

XS 8

XS 7

XS 4

A

580.

058

B52

0.05

9C

900.

028

D24

0.13

1E

750.

101

F58

0.03

9G

340.

081

H22

0.03

4I

440.

088

Seg

men

t S

eg

me

nt

Len

gth

(ft

)S

eg

me

nt

Gra

die

nt

Relative elevation (ft)

CF

27

.4%

Up

str

ea

m T

ran

sit

ion

DI

32

.7%

EI

12

.3%

Do

wn

str

ea

m T

ran

sit

ion

BA

1.6

%B

G2

6.5

%

Cu

lve

rt S

eg

me

nt

Re

pre

se

nta

tiv

e

Ch

an

ne

l Se

gm

en

t

% D

iffe

ren

ce

in

Gra

die

nt

A—487

Site evaluations

Youngs Creek

Tabl

e 2—

Sum

mar

y of

seg

men

ts u

sed

for

com

paris

ons

S

egm

ent

ran

ge

of

Man

nin

g's

n v

alu

es1

# o

f m

easu

red

XS

s #

of

inte

rpo

late

d X

Ss

A

0.

1417

– 0

.143

2 1

7

B

0.

1415

– 0

.151

7 2

7

C

0.

0929

– 0

.151

7 4

10

D

0.

1206

– 0

.136

2

4

E

0.

1358

– 0

.136

2

9

F

0.

1335

– 0

.136

9 1

9

G

0.

1245

– 0

.136

9 1

6

I

0.13

95 –

0.1

445

1 6

1 Obt

aine

d us

ing

equa

tion

from

Jar

rett

(198

4): n

= 0

.39S

0.38

R-0

.16,

whe

re S

=st

ream

slo

pe; R

=hy

drau

lic r

adiu

s.

Jarr

ett’s

equ

atio

n on

ly a

pplie

d w

ithin

the

follo

win

g ra

nges

: S =

0.0

02 to

0.0

8, R

= 0

.5 ft

to 7

ft. F

or c

ross

sec

tions

ou

tsid

e th

ese

rang

es, n

was

com

pute

d ei

ther

from

adj

acen

t sec

tions

that

fell

with

in th

e ra

nges

, usi

ng th

e gu

idan

ce

of A

rcem

ent a

nd S

chne

ider

(19

87),

or

from

the

HE

C-R

AS

rec

omm

enda

tions

for

culv

ert m

odel

ing.

Fig

ure

3—H

EC

-RA

S p

rofil

e.

01

00

20

03

00

40

05

00

90

10

0

11

0

12

0

13

0

Ma

in C

ha

nne

l Dis

tan

ce (

ft)

Elevation (ft)

Le

ge

nd

WS

Q

10

0

WS

Q

50

WS

Q

10

WS

Q

bf

WS

2

1 c

fs

Gro

un

d

1.8

1.9

33.2*

3.35*

3.5

4.5

4.75

4.9

5.3*

66.25

6.5

7.6

8.4

9.1*

9.2

9.4

9.6

9.73333*

9.86666*

1010.5

1111.3333*

11.6166*

11.9

12.05*

12.1

12.2

12.4

12.5

13.25*

13.55*

13.6

13.8

13.85*

13.9

1414.1

Elevation (ft)

Sta

tions

with

dec

imal

val

ues

are

inte

rpol

ated

cro

ss-s

ectio

ns p

lace

d al

ong

the

surv

eyed

pro

file.

A—488


Youngs Creek

Fig

ure

4—C

ross

-sec

tion

plot

s. O

nly

mea

sure

d cr

oss

sect

ions

are

incl

uded

. Man

ning

’s n

val

ues

are

incl

uded

at t

he to

p of

the

cros

s se

ctio

n.

The

sta

tioni

ng (

RS

) co

rres

pond

s to

the

stat

ioni

ng o

n th

e H

EC

-RA

S p

rofil

e. G

reen

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ows

defin

e th

e in

effe

ctiv

e flo

w a

reas

. Bla

ck a

rrow

s re

pres

ent p

oint

s id

entifi

ed in

the

field

as

the

bank

full

chan

nel b

ound

ary.

Onl

y th

ose

poin

ts id

entifi

ed in

the

field

and

sup

port

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y hy

drau

lic a

nd

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grap

hic

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yses

are

sho

wn

belo

w.

010

2030

4050

6012

012

112

212

312

412

512

612

712

812

913

0

R

S =

14

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.144

5.1

445

.144

5

010

2030

4050

6011

511

611

711

811

912

012

112

212

312

412

5

R

S =

13

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.124

5.1

245

.124

5

010

2030

4050

6011

311

411

511

611

711

811

912

012

112

212

3

R

S =

12

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q1

00

WS

Q5

0

WS

Q1

0

WS

Qb

f

WS

21

cfs

Gro

un

d

Le

vee

Ba

nk

Sta

.136

9.1

369

.136

9

010

2030

4050

6011

111

211

311

411

511

611

711

811

912

012

1

R

S =

11

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.136

.136

.136

Elevation (ft)Elevation (ft)


A—489

Site evaluations

Youngs Creek

Fig

ure

4—C

ross

-sec

tion

plot

s. O

nly

mea

sure

d cr

oss

sect

ions

are

incl

uded

. Man

ning

’s n

val

ues

are

incl

uded

at t

he to

p of

the

cros

s se

ctio

n.

The

sta

tioni

ng (

RS

) co

rres

pond

s to

the

stat

ioni

ng o

n th

e H

EC

-RA

S p

rofil

e. G

reen

arr

ows

defin

e th

e in

effe

ctiv

e flo

w a

reas

. Bla

ck a

rrow

s re

pres

ent p

oint

s id

entifi

ed in

the

field

as

the

bank

full

chan

nel b

ound

ary.

Onl

y th

ose

poin

ts id

entifi

ed in

the

field

and

sup

port

ed b

y hy

drau

lic a

nd

topo

grap

hic

anal

yses

are

sho

wn

belo

w. (

cont

inue

d)

010

2030

4050

6010

810

911

011

111

211

311

411

511

611

711

8

R

S =

10

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.136

.136

.136

010

2030

4050

6010

310

410

510

610

710

810

911

011

111

211

3

R

S =

9

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.136

.136

.136

010

2030

4050

6010

010

110

210

310

410

510

610

710

810

911

0

R

S =

8

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.136

.136

.136

010

2030

4050

6010

010

110

210

310

410

510

610

710

810

911

0

R

S =

7

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q1

00

WS

Q5

0

WS

Q1

0

WS

Qb

f

WS

21

cfs

Gro

un

d

Ine

ff

Ba

nk

Sta

.096

8.0

968

.096

8



A—490


Youngs Creek

Fig

ure

4—C

ross

-sec

tion

plot

s. O

nly

mea

sure

d cr

oss

sect

ions

are

incl

uded

. Man

ning

’s n

val

ues

are

incl

uded

at t

he to

p of

the

cros

s se

ctio

n.

The

sta

tioni

ng (

RS

) co

rres

pond

s to

the

stat

ioni

ng o

n th

e H

EC

-RA

S p

rofil

e. G

reen

arr

ows

defin

e th

e in

effe

ctiv

e flo

w a

reas

. Bla

ck a

rrow

s re

pres

ent p

oint

s id

entifi

ed in

the

field

as

the

bank

full

chan

nel b

ound

ary.

Onl

y th

ose

poin

ts id

entifi

ed in

the

field

and

sup

port

ed b

y hy

drau

lic a

nd

topo

grap

hic

anal

yses

are

sho

wn

belo

w. (

cont

inue

d)

-20

-10

01

02

03

04

01

00

10

11

02

10

31

04

10

51

06

10

71

08

10

91

10

R

S =

6 N

ote

: n

valu

es

for

first

pro

file.

Sta

tion

(ft

)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.103

4

-20

-10

01

02

03

04

09

91

00

10

11

02

10

31

04

10

51

06

10

71

08

10

9

R

S =

5 N

ote

: n

valu

es

for

first

pro

file.

Sta

tion

(ft

)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.100

6

010

2030

4050

60989910

010

110

210

310

410

510

610

710

8

R

S =

4

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q1

00

WS

Q5

0

WS

Q1

0

WS

Qb

f

WS

21

cfs

Gro

un

d

Ine

ff

Ba

nk

Sta

.136

2.1

362

.136

2

010

2030

4050

609697989910

010

110

210

310

410

510

6

R

S =

3

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.144

9.1

449

.144

9



A—491

Site evaluations

Youngs Creek

Fig

ure

4—C

ross

-sec

tion

plot

s. O

nly

mea

sure

d cr

oss

sect

ions

are

incl

uded

. Man

ning

’s n

val

ues

are

incl

uded

at t

he to

p of

the

cros

s se

ctio

n.

The

sta

tioni

ng (

RS

) co

rres

pond

s to

the

stat

ioni

ng o

n th

e H

EC

-RA

S p

rofil

e. G

reen

arr

ows

defin

e th

e in

effe

ctiv

e flo

w a

reas

. Bla

ck a

rrow

s re

pres

ent p

oint

s id

entifi

ed in

the

field

as

the

bank

full

chan

nel b

ound

ary.

Onl

y th

ose

poin

ts id

entifi

ed in

the

field

and

sup

port

ed b

y hy

drau

lic a

nd

topo

grap

hic

anal

yses

are

sho

wn

belo

w. (

cont

inue

d)

1020

3040

5060

709697989910

010

110

210

310

410

510

6

R

S =

2

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

. 1 4 1 5

.141

5.1

415

2030

4050

6070

80929394959697989910

010

110

2

R

S =

1

Sta

tion

(ft)

Elevation (ft)

Le

ge

nd

WS

Q10

0

WS

Q50

WS

Q10

WS

Qbf

WS

21

cfs

Gro

und

Ban

k S

ta

.142

6.1

426

.142

6

Elevation (ft)

Elevation (ft)

A—492


Youngs Creek

Fig

ure

5—F

low

are

a (t

otal

) pr

ofile

plo

t.

Fig

ure

6—W

ette

d pe

rimet

er.

01

00

20

03

00

40

05

00

0

20

40

60

80

10

0

12

0

Ma

in C

ha

nne

l Dis

tanc

e (

ft)

Flow Area (sq ft)

Le

ge

nd

Flo

w A

rea

Q1

00

Flo

w A

rea

Q5

0

Flo

w A

rea

Q1

0

Flo

w A

rea

Qb

f

Flo

w A

rea

21

cfs

01

00

20

03

00

40

05

00

0

10

20

30

40

50

Ma

in C

ha

nne

l Dis

tanc

e (

ft)

W.P. Total (ft)

Le

ge

nd

W.P

. T

ota

l Q

10

0

W.P

. T

ota

l Q

50

W.P

. T

ota

l Q

10

W.P

. T

ota

l Q

bf

W.P

. T

ota

l 21

cfs

Cul

vert

A

B

C

D

E

F

G

H

I

Flow

Cul

vert

A

B

C

D

E

F

G

H

I

Flow

Flow area (sq ft) W.P. total (ft)

A—493

Site evaluations

Youngs Creek

01

00

20

03

00

40

05

00

5

10

15

20

25

30

35

40

45

Ma

in C

ha

nne

l Dis

tanc

e (

ft)

Top Width (ft)

Le

ge

nd

To

p W

idth

Q10

0

To

p W

idth

Q50

To

p W

idth

Q10

To

p W

idth

Qbf

To

p W

idth

21

cfs

01

00

20

03

00

40

05

00

012345

Ma

in C

ha

nne

l Dis

tanc

e (

ft)

Hydr Radius (ft)

Le

ge

nd

Hyd

r Ra

diu

s Q

10

0

Hyd

r Ra

diu

s Q

50

Hyd

r Ra

diu

s Q

10

Hyd

r Ra

diu

s Q

bf

Hyd

r Ra

diu

s 2

1 c

fs

Fig

ure

7—H

ydra

ulic

rad

ius.

Fig

ure

8—To

p w

idth

.

Hydraulic radius (ft) Top width (ft)

Cul

vert

A

B

C

D

E

F

G

H

I

Flow

Cul

vert

A

B

C

D

E

F

G

H

I

Flow

A—494


Youngs Creek

Fig

ure

9—M

axim

um d

epth

.

Fig

ure

10—

She

ar s

tres

s (c

hann

el)

profi

le.

01

00

20

03

00

40

05

00

0123456

Ma

in C

ha

nne

l Dis

tanc

e (

ft)

Max Chl Dpth (ft)

Le

ge

nd

Ma

x C

hl D

pth

Q1

00

Ma

x C

hl D

pth

Q5

0

Ma

x C

hl D

pth

Q1

0

Ma

x C

hl D

pth

Qb

f

Ma

x C

hl D

pth

21

cfs

01

00

20

03

00

40

05

00

05

10

15

20

25

Ma

in C

ha

nne

l Dis

tanc

e (

ft)

Shear Chan (lb/sq ft)

Le

ge

nd

Sh

ear

Ch

an Q

100

Sh

ear

Ch

an Q

50

Sh

ear

Ch

an Q

10

Sh

ear

Ch

an Q

bf

Sh

ear

Ch

an 2

1 c

fs

Cul

vert

A

B

C

D

E

F

G

H

I

Flow

Cul

vert

A

B

C

D

E

F

G

H

I

Flow

Maximum channel depth (ft) Shear channel (lb/sq ft)

A—495

Site evaluations

Youngs Creek

Fig

ure

11—

Vel

ocity

(ch

anne

l) pr

ofile

plo

t.

01

00

20

03

00

40

05

00

012345678

Ma

in C

ha

nne

l Dis

tanc

e (

ft)

Vel Chnl (ft/s)

Le

ge

nd

Ve

l Ch

nl Q

10

0

Ve

l Ch

nl Q

50

Ve

l Ch

nl Q

10

Ve

l Ch

nl Q

bf

Ve

l Ch

nl 2

1 c

fs

Cul

vert

A

B

C

D

E

F

G

H

I

Flow

Velocity channel (ft/s)

A—496


Youngs Creek

0

20406080100

120

A

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

I

25%

Q2

Qbf

1050

100

Flow

Are

a (f

t2)

Bo

x P

lot

exp

lan

atio

n

Max

imum

val

ue

75th

per

cent

ile

Med

ian

(aka

50t

h pe

rcen

tile)

25th

per

cent

ile

Min

imum

val

ue

100%

of th

eva

lues

50%

of th

eva

lues

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

Flow area (ft2)

Fig

ure

12—

Flo

w a

rea

(tot

al).

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A—497

Site evaluations

Youngs Creek

Fig

ure

13—

Wet

ted

perim

eter

.

Fig

ure

14—

Hyd

raul

ic r

adiu

s.

01020304050

A

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

I

25%

Q2

Qbf

1050

100

Wet

ted

Perim

eter

(ft)

012345

A

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

I

25%

Q2

Qbf

1050

100

Hyd

raul

ic R

adiu

s (f

t)

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

Hydraulic radius (ft)Wetted perimeter (ft)

A—498


Youngs Creek

Fig

ure

15—

Top

wid

th.

Fig

ure

16—

Max

imum

dep

th.

01020304050

A

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

I

25%

Q2

Qbf

1050

100

Top

Wid

th (f

t)

0123456

A

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

I

25%

Q2

Qbf

1050

100

Max

Dep

th (f

t)A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

Top width (ft) Maximum depth (ft)

A—499

Site evaluations

Youngs Creek

Fig

ure

17—

Wid

th-t

o-de

pth

ratio

.

Fig

ure

18—

Vel

ocity

(ch

anne

l).

0102030405060

A

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

I

25%

Q2

Qbf

1050

100

W-D

Rat

io

02468

A

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

I

25%

Q2

Qbf

1050

100

Velo

city

(ft/

sec)

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

Width-to-depth ratio Velocity (ft/sec)

A—500


Youngs Creek

0

0.51

1.52

2.53

3.54

4.55

050

100

150

200

250

300

350

Dis

char

ge

(cfs

)

Exce

ss S

hear

(Ap

plie

d / t

crit

)

US

Ch

an

ne

l (U

S p

eb

ble

co

un

t) -

riff

le/s

tep

US

Ch

an

ne

l (D

S p

eb

ble

co

un

t) -

riff

le/s

tep

Cu

lve

rt (

DS

pe

bb

le c

ou

nt)

- r

iffle

/ste

p

DS

Ch

an

ne

l (D

S p

eb

ble

co

un

t)

Fig

ure

19—

She

ar s

tres

s (c

hann

el).

Exc

ess

shea

r st

ress

is th

e ch

anne

l she

ar d

ivid

ed b

y th

e cr

itica

l she

ar fo

r be

d en

trai

nmen

t of t

he D

84 p

artic

le s

ize.

Val

ues

of e

xces

s sh

ear

grea

ter

than

1 in

dica

te b

ed m

ovem

ent f

or th

e D

84 p

artic

le s

ize.

Fig

ure

20—

Exc

ess

shea

r st

ress

.

051015202530

A

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

IA

B (

ds tr

ans)

C (

culv

)

D (

us tr

ans)

E (

us tr

ans)

FG

I

25%

Q2

Qbf

1050

100

Shea

r Str

ess

(lbs/

ft2)

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

A

B (DS Trans)

C (Culvert)

D (US Trans)

E (US Trans)

F

G

I

Shear stress (lbs/ft2) Excess shear (Applied/tcrit)

A—501

Site evaluations

Youngs Creek

Table 3—Sum of squared height difference

reach XS unit Sum of squared Within range of Location type height difference channel conditions?

Culvert US Pool 0.03 No

DS Riffle/step 0.10 Yes

Upstream US Riffle/step 0.08

DS Riffle/step 0.12

Downstream Riffle 0.06

Table 4—Vertical Sinuosity

Segment Location vertical Sinuosity (ft/ft)

A DS channel 1.007

B DS transition 1.005

C Culvert 1.005

D US transition 1.033

E US transition 1.018

F US channel 1.008

G US channel 1.016

H US channel 1.028

I US channel 1.006

Table 5—Depth distribution

reach XS 25% Q2 Within range of

Location channel conditions?

Culvert US 6 Yes

DS 10 No

Upstream US 2

DS 6

Downstream 7

A—502


Youngs Creek

Table 6—Habitat unit composition

Percent of surface area

Reach Pool Glide Riffle Step

Culvert 72% 0% 28% 0%

Upstream Channel 29% 0% 39% 2%

Downstream Channel 17% 0% 83% 0%

Figure 21—Residual depths.

Table 7—Bed material sorting and skewness

reach XS unit Sorting Within range Skewness Within range Location Type of channel of channel conditions? conditions?

Culvert US Pool 1.73 No 0.32 Yes

DS Riffle/step 1.67 No 0.42 Yes

Upstream US Riffle/step 2.10 0.36

DS Riffle/step 1.89 0.44

Downstream US Riffle 1.84 0.24

DS Riffle 2.23 0.51

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Segment ASegment B:

DS TransitionSegment C:

Culvert

Segment D:US Transition

Segment E:US Transition

Segment F Segment G Segment HSegment I

Residual depth (ft)

Seg

men

t A

Seg

men

t B

DS

Tra

nsiti

on

Seg

men

t C

Cul

vert

Seg

men

t D

US

Tra

nsiti

on

Seg

men

t E

US

Tra

nsiti

on

Seg

men

t F

Seg

men

t G

Seg

men

t H

Seg

men

t I

Res

idua

l Dep

th (

ft)

A—503

Site evaluations

Youngs Creek

Table 8—Large woody debris

reach Pieces/Channel Width

Culvert 0

Upstream 1.22

Downstream 2.06

Terminology:

US = Upstream

DS = Downstream

RR = Reference reach

XS = Cross-section

View upstream towards culvert outlet. View downstream towards culvert inlet.

View upstream from roadway. View downstream from roadway.

A—504


Youngs Creek

Upstream reference reach. Upstream reference reach – upstream pebble count, between steps.

Upstream reference reach – downstream pebble Downstream reference reach – downstream pebblecount, step. count (step).

A—505

Site evaluations

Youngs Creek

Downstream reference reach – upstream pebble Downstream reference reach.count (riffle).

View downstream within culvert – pebble counts View upstream within culvert – pebble counts at flagged locations. at flagged locations.

A—506


Youngs Creek

Cross-Section: Upstream Reference Reach – Upstream Pebble Count

Sorting Coefficient: 2.10

Skewness Coefficient: 0.36

Material S ize C las s (mm) C ount Item % C umulative %

sand <2 3 3% 3%

very fine gravel 2 - 4 7 7% 10%

fine gravel 4 - 5.7 1 1% 11%

fine gravel 5.7 - 8 5 5% 16%

medium gravel 8 - 11.3 3 3% 19%

medium gravel 11.3 - 16 6 6% 26%

coarse gravel 16 - 22.6 1 1% 27%

coarse gravel 22.6 - 32 2 2% 29%

very coarse gravel 32 - 45 5 5% 34%


small cobble 64 - 90 17 17% 57%

medium cobble 90 - 128 9 9% 66%

large cobble 128 - 180 11 11% 78%

very large cobble 180 - 256 12 12% 90%

small boulder 256 - 362 7 7% 97%

small boulder 362 - 512 3 3% 100%

medium boulder 512 - 1024 0 0% 100%

large boulder 1024 - 2048 0 0% 100%

very large boulder 2048 - 4096 0 0% 100%

bedrock Bedrock 0 0% 100%

0

2

4

6

8

10

12

14

16

18

<22 - 4

4 - 5.75.7 - 88 - 11.3

11.3 - 1616 - 22.622.6 - 3232 - 4545 - 6464 - 90

90 - 128128 - 180180 - 256256 - 362362 - 512

512 - 10241024 - 20482048 - 4096

Bedrock

Partic le Size Category (mm)

Frequency

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Cumulative Frequency

<2

2-4

4-5

.7

5.7

-8

8-1

1.3

11.3

-16

16-2

2.6

22.6

-32

32-4

5

45-6

4

64-9

0

90-1

28

128-1

80

180-2

56

256-3

62

362-5

12

512-1

024

1024-2

048

2048-4

096

Bed

rock

Fre

quen

cy

Cum

ulat

ive

Fre

quen

cy

Particle Size Category (mm)

S ize C las sS ize perc ent finer

than (mm)

D5 4

D16 9

D50 78

D84 205

D95 330

D100 420

Material P erc ent C ompos ition

Sand 3%

Gravel 37%

Cobble 50%

Boulder 10%

Bedrock 0%

A—507

Site evaluations

Youngs Creek

Cross-Section: Upstream Reference Reach – Downstream Pebble Count




sand <2 2 2% 2%


fine gravel 4 - 5.7 1 1% 6%

fine gravel 5.7 - 8 2 2% 8%

medium gravel 8 - 11.3 0 0% 8%

medium gravel 11.3 - 16 0 0% 8%

coarse gravel 16 - 22.6 1 1% 9%

coarse gravel 22.6 - 32 2 2% 12%



small cobble 64 - 90 3 4% 21%

medium cobble 90 - 128 5 6% 27%

large cobble 128 - 180 9 11% 38%


small boulder 256 - 362 8 9% 61%

small boulder 362 - 512 18 21% 82%

medium boulder 512 - 1024 15 18% 100%

large boulder 1024 - 2048 0 0% 100%



0

2

4

6

8

10

12

14

16

18

20

<22 - 4

4 - 5.75.7 - 88 - 11.3

11.3 - 1616 - 22.622.6 - 3232 - 4545 - 6464 - 90

90 - 128128 - 180180 - 256256 - 362362 - 512

512 - 10241024 - 20482048 - 4096

Bedrock


Frequency

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%


<2

2-4

4-5

.7

5.7

-8

8-1

1.3

11.3

-16

16-2

2.6

22.6

-32

32

-45

45

-64

64

-90

90-1

28

128-1

80

180-2

56

256-3

62

362-5

12

512-1

024

1024-2

048

2048-4

096

Bedro

ck

Fre

quen

cy

Cum

ulat

ive

Fre

quen

cy



than (mm)

D5 5

D16 54

D50 240

D84 520

D95 700

D100 700


Sand 2%

Gravel 15%

Cobble 34%

Boulder 48%

Bedrock 0%

A—508


Youngs Creek

Cross-Section: Culvert – Upstream Pebble Count



Material S ize R ange (mm) C ount Item % C umulative %

sand <2 2 2% 2%


fine gravel 4 - 5.7 0 0% 5%

fine gravel 5.7 - 8 5 5% 10%

medium gravel 8 - 11.3 5 5% 15%

medium gravel 11.3 - 16 7 7% 21%

coarse gravel 16 - 22.6 7 7% 28%

coarse gravel 22.6 - 32 3 3% 31%



small cobble 64 - 90 9 9% 56%

medium cobble 90 - 128 8 8% 64%

large cobble 128 - 180 22 21% 85%


small boulder 256 - 362 1 1% 97%

small boulder 362 - 512 3 3% 100%

medium boulder 512 - 1024 0 0% 100%

large boulder 1024 - 2048 0 0% 100%


bedrock > 4096 0 0% 100%

0

5

10

15

20

25

<22 - 4

4 - 5.75.7 - 88 - 11.3

11.3 - 1616 - 22.622.6 - 3232 - 4545 - 6464 - 90

90 - 128128 - 180180 - 256256 - 362362 - 512

512 - 10241024 - 20482048 - 4096

> 4096


Frequency

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%


<2

2-4

4-5

.7

5.7

-8

8-1

1.3

11.3

-16

16-2

2.6

22.6

-32

32-4

5

45-6

4

64-9

0

90-1

28

128-1

80

180-2

56

256-3

62

362-5

12

512-1

024

1024-2

048

2048-4

096

Bedro

ck

Fre

quen

cy

Cum

ulat

ive

Fre

quen

cy



than (mm)

D5 6

D16 14

D50 74

D84 180

D95 249

D100 420


Sand 2%

Gravel 46%

Cobble 49%

Boulder 4%

Bedrock 0%

A—509

Site evaluations

Youngs Creek

Cross-Section: Culvert – Downstream Pebble Count



<2

2-4

4-5

.7

5.7

-8

8-1

1.3

11.3

-16

16-2

2.6

22.6

-32

32-4

5

45-6

4

64-9

0

90-1

28

128-1

80

180-2

56

256-3

62

362-5

12

512-1

024

1024-2

048

2048-4

096

Bedro

ck

Fre

quen

cy

Cum

ulat

ive

Fre

quen

cy



sand <2 0 0% 0%


fine gravel 4 - 5.7 1 1% 2%

fine gravel 5.7 - 8 2 2% 4%

medium gravel 8 - 11.3 1 1% 5%

medium gravel 11.3 - 16 8 7% 12%

coarse gravel 16 - 22.6 3 3% 15%

coarse gravel 22.6 - 32 7 6% 21%



small cobble 64 - 90 7 6% 39%

medium cobble 90 - 128 6 6% 44%

large cobble 128 - 180 15 14% 58%


small boulder 256 - 362 22 20% 93%

small boulder 362 - 512 6 6% 98%

medium boulder 512 - 1024 2 2% 100%

large boulder 1024 - 2048 0 0% 100%



0

5

10

15

20

25

<22 - 4

4 - 5.75.7 - 88 - 11.3

11.3 - 1616 - 22.622.6 - 3232 - 4545 - 6464 - 90

90 - 128128 - 180180 - 256256 - 362362 - 512

512 - 10241024 - 20482048 - 4096

Bedrock


Frequency

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%



than (mm)

D5 12

D16 25

D50 150

D84 309

D95 423

D100 550


Sand 0%

Gravel 32%

Cobble 40%

Boulder 28%

Bedrock 0%

A—510


Youngs Creek

Cross-Section: Downstream Reference Reach – Upstream Pebble Count




sand <2 3 3% 3%


fine gravel 4 - 5.7 1 1% 5%

fine gravel 5.7 - 8 3 3% 8%

medium gravel 8 - 11.3 2 2% 10%

medium gravel 11.3 - 16 1 1% 11%

coarse gravel 16 - 22.6 4 4% 15%

coarse gravel 22.6 - 32 4 4% 19%



small cobble 64 - 90 12 12% 43%

medium cobble 90 - 128 12 12% 55%

large cobble 128 - 180 17 17% 72%


small boulder 256 - 362 8 8% 91%

small boulder 362 - 512 3 3% 94%

medium boulder 512 - 1024 6 6% 100%

large boulder 1024 - 2048 0 0% 100%



0

2

4

6

8

10

12

14

16

18

<22 - 4

4 - 5.75.7 - 88 - 11.3

11.3 - 1616 - 22.622.6 - 3232 - 4545 - 6464 - 90

90 - 128128 - 180180 - 256256 - 362362 - 512

512 - 10241024 - 20482048 - 4096

Bedrock


Frequency

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%



than (mm)

D5 6

D16 25

D50 105

D84 267

D95 535

D100 580


Sand 3%

Gravel 28%

Cobble 52%

Boulder 17%

Bedrock 0%

<2

2-4

4-5

.7

5.7

-8

8-1

1.3

11.3

-16

16-2

2.6

22.6

-32

32

-45

45

-64

64

-90

90-1

28

128-1

80

180-2

56

256-3

62

362-5

12

512-1

024

1024-2

048

2048-4

096

Bedro

ck

Fre

quen

cy

Cum

ulat

ive

Fre

quen

cy


A—511

Site evaluations

Youngs Creek

Cross-Section: Downstream Reference Reach – Downstream Pebble Count




sand <2 7 7% 7%


fine gravel 4 - 5.7 2 2% 9%

fine gravel 5.7 - 8 1 1% 10%

medium gravel 8 - 11.3 1 1% 11%

medium gravel 11.3 - 16 7 7% 18%

coarse gravel 16 - 22.6 5 5% 23%

coarse gravel 22.6 - 32 8 8% 30%



small cobble 64 - 90 7 7% 46%

medium cobble 90 - 128 14 13% 59%

large cobble 128 - 180 18 17% 76%


small boulder 256 - 362 11 10% 96%

small boulder 362 - 512 4 4% 100%

medium boulder 512 - 1024 0 0% 100%

large boulder 1024 - 2048 0 0% 100%



0

2

4

6

8

10

12

14

16

18

20

<22 - 4

4 - 5.75.7 - 88 - 11.3

11.3 - 1616 - 22.622.6 - 3232 - 4545 - 6464 - 90

90 - 128128 - 180180 - 256256 - 362362 - 512

512 - 10241024 - 20482048 - 4096

Bedrock


Frequency

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%


<2

2-4

4-5

.7

5.7

-8

8-1

1.3

11.3

-16

16-2

2.6

22.6

-32

32-4

5

45-6

4

64-9

0

90-1

28

128-1

80

180-2

56

256-3

62

362-5

12

512-1

024

1024-2

048

2048-4

096

Bed

rock

Fre

quen

cy

Cum

ulat

ive

Fre

quen

cy



than (mm)

D5 1

D16 15

D50 100

D84 220

D95 318

D100 500


Sand 7%

Gravel 33%

Cobble 46%

Boulder 14%

Bedrock 0%

Culvert Scour Assessment

Documents

Transcript of Culvert Scour Assessment