1

Pierre Y. Julien

Sedimentation and Erosion Hydraulics: Theory and Practice

Department of Civil EngineeringColorado State University

Fort Collins, Colorado

UNITEN Short CourseKuala Lumpur – July 20 2006

Objectives

Brief overview of the theory and practice of erosion and sedimentation:

1. Hydrology and Hydraulics; 2. Sediment Transport Mechanics;3. Fluvial Geomorphology;4. River Sedimentation Examples;5. Reservoir Sedimentation.

Erosion and River Mechanics Textbooks

1. Hydrology and Hydraulics

Niger River Inner delta Niger river basin

BamakoKoulikoro Niamey

Niger R.

Bani

R.

Tchad LakeMopti

Guinea Gulf0 200 400 km

Lakoja

Sokoto R.

Benue R.

Arid Semiarid Dry subhumid Moist subhumid Humid Perhumid

Arid

Humid

Climate

Tombouctou

Malanville

Kaduna R.

(a)

20 10 0 10 20

40 30 20 10 0 10 20 30 400

5

10

15

20

25

30

35

40

45

50

55

6018

16

14

12

10

8

6

4

2

0

Storm Mountain Big

Thompson River

Distance from Storm Mountain (km)

Alti

tude

abo

ve m

ean

sea

leve

l (th

ousa

nds o

f fee

t)

Distance from Storm Mountain (miles)

Alti

tude

abo

ve m

ean

sea

leve

l (th

ousa

nds o

f met

ers)

-25 °C

0 °C

0°

1525

3545

4535

2515

15

Schematic lines of airflowSchematic area of rainfallRadar reflectivity observed at Grover, Colo. Dashed where approximately located. Interval 10 dBZLine of equal air temperature, in degrees Celsius Dashed within the cloud

Loveland

Basin boundary

Glen Haven

Glen Comfort

Estes Park

Mouth of Big Thompson Canyon

Ft. Collins

Loveland powerplant

Big Thompson River

Little Thompson River

South Platte R

iver

0 5 10 miles0 5 10 15 km

2 4 6 10

64

2

2

8

6

810

4 6

8

108

2

Masonville

02468

1012

Rai

nfal

l pre

cipi

tatio

n (in

ches

)

Drake

2

Surface runoff divide

Groundwater divide

Groundwater flow

Subsurface flow

Channel precipitation

Interception

Transpiration

Evaporation

Infiltration

Deep percolation

Snow

Surface-detention storage

Precipitation

Surface runoff

Evaporation

Exfiltration

Condensation

AGU Hydrology days 2005

Rainfall distribution of Typhoon Maemi in Korea

Total rainfall of Typhoon Maemi in 2003 Water stage and discharge graph at Gupo bridge

5.06m 4.95m

9/4/03 9/9/03 9/13/03 9/17/03 9/21/03-4

0

4

8

12

16

-20000

-10000

0

10000

20000

Water level (m)

Discharge (m3/s)

14,312 cms13,217 cms

Date (mm/dd/yy)

Disch

arge

(m3/s)W

ater

leve

l(m

)

M-1

M-3

M-2

Energy grade line

Hydraulic grade line² E0.2 m

0.25 m hh = 0.788 m

h = 0.467 m

cn

c

AB C D E

F G HI J

τ = γ h SonnNot to scale

τ bed

1

10

102

-1 2 3 4 5101010101010 1

h/ds

Manning-Strickler

= 5.75 log 2 hd s

8 f

ghSf

Vgh

S=

8 ff

C g=

V = 5 hds

( )1 6

n = 0.064 d ds1 6 with in ms

3

AGU Hydrology days 2005 Flood Damages

2. Sediment Transport Mechanics

Sand Gravel Cobblesv.f. fine med. c. v.f. fine med. c.v.c. v.c. small large

100

90

80

70

60

50

40

30

20

10

0

% b

y w

eigh

t fin

er th

an

25612864321684210.50.250.1250.0625

d d d10 50 90Diameter (mm)

Vs

d d d16 50 84

Vv

φ

Los Corales

Θβ

δλ

A

Au

F

F sin

F sinF a

FBed

Top of bank

Sideslope gradient

Streamline

View normal to sideslope

Horizontal

s θ1

s

D

s 1

s 0

F sins 1

F

F cos

F 1 - a cos

O'

OF a

1

2 3

4

2

s θ D δ

s βθ

LParticle P

Section A - A

1

3

F sinD δParticle P

OF 1 - a sin2

s βθ

Section normal to section A - A

Θ

ΘΘΘ

ΘDownstream

1Θ0Θ

δ βλ ΘDownstream

Streamline drag component

Particle pathline

Weight component

Q

l

l

l

l l

l

1

10

101 10 10 10

-1

-22 3

50 2m

1/3

*d = d(G - 1) g

υ

c *τ Motion

Sand Gravel

Hydrauli- cally smooth

Hydraulically rough

No motion

Transition

4

Los Corales

1.5

*

*

*

*

τ

*q = 40 τ 3

– 0.391τ

1/τ

q

10 10 1 102 -1

2

-1

-2

-3

-4

10

10

1

10

10

10

10

310

10 10 1 10-1-2

bv*

bv*

*

bvq

=w

d os

q = 15 τ

q = 2.15 e

bv*

bv*

10

10

1

1010 10 1 10 10 10

1

11

R = 0.63

oR = 0.49

o

Run 19 Vanoni, 1946 h = 0.236 ft d = 0.10mm κ = 0.33

Run 55 h = 0.590 ft d = 0.10mm κ = 0.34

Run S-16 Einstein & Chien, 1955 h = 0.390 ft d = 0.274mm κ = 0.18

R = 1.86

o

Hyper-conc.Suspension

2

-1-2 -1 2 3

Concentration C (g/ )

(h -

z)/z

50

5050

l

1.0

0.8

0.6

0.4

0.2

01 10

Bedload Suspended load

d = 190 µm d = 270 µm d = 280 µm d = 450 µm d = 930 µm

5050

50

50

50

Data Guy et al., 1966h = 0.1 - 0.3 m

Ratio shear velocity - fall velocity, u /ω*

st

Rat

io su

spen

ded

- tot

al lo

ad, q

/q

Mixed load

10 -1

Lowest incipient motion (gravel)

100010 000

100 000

100

h/d = 100s100010 000100 000

5

3. Fluvial Geomorphology

Concept of Equilibrium

τ tan λ τ

λoo

τ tan λ o

Thalweg

Sedimentation Erosion

λ = 10°SF

1

Thalweg

Lateral migration

Sedimentation Erosion

(a)

(b)

(c)

(d)

Fine Coarse

Equilibrium

Point bar

Fine sediment in suspension

Coarse sediment bedload

Migration of the Mississippi River

6

250

750

30004000

Right bank Left bankWater surface12

10

8

6

4

2

00 100 200 300 400 500 600 700 800 900

Stationing across section (ft)

Dis

tanc

e ab

ove

stre

am b

ed (f

t)

= 31 600 ft /s = 4.9 ft/s = 838 ppm - sand = 0.20 mm - bed sediment = 1.5 x 10

Q V S

C d

m50 -4

3

3500

500

1000

15002000

2500

5000

Mississip

pi Rive

r

< - 20 ft below LWRP

> - 20 ft below LWRP

> - 30 ft below LWRP

Fine sand concentration

0 100 200 300 400 500 mg/L

Old River Control Complex

Mississippi RiverMississippi River

Outflow ChannelOutflow Channel

w+ h

Before

After

S+

Sz

x

1

Braided

Anabranched

Avulsion

Before

After

River A River BCapture

BeforeAfter

High

Low

Aggrading

Avulsing

H

L

Anastomosing

Island sand-gravel-cobble

H

L

Anabranching

Gravel-cobble- bedrock

HL

PerchingNatural

LeveeFloodplain

H

L

Braiding

Bars

Sand-gravel

HL

ShoalingShoal

Sand-silt

Before

After

Hardinge Bridge

Gorai Off-take

TillyAricha

Baruria

Arial Khan Off-take

Mawa

Bazar

0 20 40 km

(Teota)

Bhairab

Old Brahmaputra

Jamuna

Dhaleswari

Ganges

Padma

Lower Meghna

Upper Meghna

Dhaka

0 2.5 5.0 7.5 10W (km)

0-4-8

-12-16-20

0-4-8

-12-16-20

0-4-8

-12-16-20

0-4-8

-12-16-20

Dep

th (m

)

1977

1979

1981

1985

1977

1978

1984

W

W

W

0 2.5(km)

N

Reference point Cross-section Previous situation Bare sand

7

4. River Sedimentation Examples

Q QQQin s in in s in

Qs out Q s in Q out Q in<

=Q out Q in=Qs out Qs in>

2 W W

2 WW

Convergence implies

degradation

Divergence implies

aggradation

a) b)

Environmental Considerations

DragC - 2000 ppm

Pump

HoppersOverflow C - 20 000 ppm

GantryH frame A frame

HoistPumpDischarge line

Spud Suction lineLadder

C - 10 000 ppmCutterhead basket

Closed-nose basket Open-nose basket

A frame

Anchor lines

DustpanLadder

Short dis- charge pipe

Water injectionDetail of dustpan

(a) Hopper dredge

(b) Dustpan dredge

(c) Cutterhead dredge

Suction line

Cutterhead

Anchor

Port swing cable

Dredge

Starboard swing cable

Anchor

Spud up Spud down

Pontoon

Flexible discharge

To disposal site

Construction Dredging

8

5. Reservoir Sedimentation

Dis

char

ge

Time

Without reservoirs

With reservoirs

Reservoir storage - release

Design flood

2 3 4 5 10 25 50 1006

5

4

3

2

11 510 20 40 60 80 90 95 99

Return period (years)

Probability (%)

Dis

char

ge

All data

With

out re

servo

ir

With reservoir

A

T T

T

T

1 2

3

4

Peak discharge reduction

20 000

10 000

5 000

1 000

500

2000.05

0.10.5 1 2 5 10 30 50 70 90 95 96

9999.8

99.9

Before

AfterDominant discharge

Duration of discharge (% time)

Mea

n da

ily d

isch

arge

(cfs

)

AfterBefore

Q

Q

S

s

250

200

150

100

50

01940 1950 1960 1970 1980

Year

Sand

Silt

Clay

Susp

ende

d se

dim

ent l

oad

(mill

ions

tons

/yea

r)

Clear water release at dam

Original bed

Scour and channel degradation Local scour Final bed

(c)

(b)

(a)

1 m /s = 35.5 ft /s33

1947-1952 7,376 mg/L

1952-1956 31,145 mg/L

1956-1966 7,250 mg/L

1963-1978 8,004 mg/L

1968-1977 10,777 mg/L

1982-1997 2,227mg/L

1978-1995 ,.290 mg/L

3

2

1

0

(x 1

0 m

etric

tons

)8

350

300

250

200

150

100

50

0

Cumulative discharge (10 acre-feet)60 4 8 12 16 20 24 28 32 36

Cum

ulat

ive

sedi

men

t loa

d (1

0 t

ons)

6

San Acacia Bernardo + Rio Puerco

9

10

8

6

4

2

00 5 10 15 20 25 30 35 40

Distance (km)

Uni

t sed

imen

t dis

char

ge (x

10

m

/s)

-52

25 dt

200 dt

Initial

12 dt

50 dt100 dt

(a) Sediment transport

0 5 10 15 20 25 30 35 40Distance (km)

12 dt

50 dt100 dt

Initial

(b) Aggradation-degradation

25 dt

200 dt

Initial

200 dt

Initial

200 dt

16

14

12

10

8

6

4

2

0

Elev

atio

n (m

)

Alluvial bed

Water

Bed Profile - 1988

250

270

290

310

330

350

370

0 10 20 30 40 50 60

Distance from Main Dam (KM)

Elev

atio

n (m

)

OGL,1967SURVEYED,1988SIMULATED,1988

Acknowledgments

• Un Ji and James Halgren, CSU• Dr. Claudia Leon, CSU and RTI• Dr. Phil Combs, USACE-ERDC• Dr. Drew Baird, US Bureau of Reclamation

THANK YOUfor your

attention!

pierre@engr.colostate.edu