Channel Response Prediction for
Abandoned Channel Restoration andApplicability Analysis

ARRN Forum 2013
10th International Forum on Waterfront and Watershed Restoration“Comprehensive treatment of Small & Medium-sized Rivers”
10 Sep. 2013, Chengdu, China

Yonguk RYU, Il HONG, Joon Gu KANG, Hong Koo YEO
Korea Institute of Construction Technology
Suk Hwan JANG
Daejin University

Contents
BackgroundResearch purpose
Studyy process
p& method
Study area
Results
Conclusions

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Natural River Types
Dong River

Schematic drawing of a natural riverHwang River• Many rivers were in natural conditionsbefore 1970's in Korea.

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Artificial Maintenance
Yeongsan River

Ab dAbandonedd channelhl

Mangyeong River

Channel straightening• Artificial maintenance brought about many problems,such as decreasing floodplain and disturbed ecosystem.
• Channel straightening caused geomorphological problems,such as the decreasing of meander rivers and the formation of abandoned channels.

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Abandoned Channel Restoration

Hampyeong stream
Abandoned channel

Abandoned channel restoration
Restoration• Abandoned channel restoration is one of the projects
related to river restoration.
• This study targets past channels disconnected frommain channels.

Research Objective

ARRN Forum 2013

• The abandoned channel restoration is about geomorphological restoration for
natural channels.
• The restoration channel shape and channel evaluation are very importantconsiderations for channel design.

• The purpose of the present study is to provide a way of channel design
for river restoration projects through analysis of channel planformchange and channel stability.
stability• The channel design method targets the assessment of main channel
stability prediction preparing for abandoned river restoration.
restoration

Study Procedure & Method

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Channel Planform changeAnalysis
Image Analysis Technique
Tool : ERDAS IMAGINE, ARC GIS

Stable Channel Analysis
Copeland(1994)’s Method
Tool : SAM(Stable ChannelAnalysis Model)

Ch
Channell EEvaluationl tiComparison between Channel
Planform Change Result and Stable
Channel Result

Channel Shape, Slope, Width,
Depth
Direction for Restoration
Channel Design

Study Procedure & Method
Channel Planform changeAnalysis
Image Analysis Technique

ARRN Forum 2013

Image Analysis Technique• The image analysis technique analyzed geomorphologicalinformation after coordinate correction of the past andTool : ERDAS IMAGINE, ARC GIS

Stable Channel Analysis

present image data in GIS environment.
environment• The analysis used the image data of 1918 year's topographicalmap and aerial photographs
photographs.

Copeland(1994)’s Method
Tool : SAM(Stable ChannelAnalysis Model)

ChChannell EEvaluationl ti

1918’s Topographical map and aerial photographs.
Comparison between Channel
Planform Change Result and Stable
Channel Result

Channel Shape, Slope, Width,
Depth
Direction for Restoration
Channel DesignStudy Procedure & Method

ARRN Forum 2013

Channel Planform changeAnalysis
Image Analysis Technique
Tool : ERDAS IMAGINE, ARC GIS

SAM Hydraulic Design Package
Stable Channel Analysis• The stable channel analysis used SAM model fromCopeland(1994)’s Method
Tool : SAM(Stable ChannelAnalysis Model)

the U.S. Army Corps of Engineers.
• The SAM model (equilibrium method) has been widely used for theplan and design of river restorations.

ChChannell EEvaluationl tiComparison between Channel
Planform Change Result and Stable
Channel Result• The results
res lts of SAM modeling can predict hhydraulicdra lic conditionof stable channel, such as a width, depth and slope.

Channel Shape, Slope, Width,
Depth
Direction for Restoration
Channel Design

Study Procedure & Method

ARRN Forum 2013

Channel Planform change
AnalysisImage Analysis Technique
Tool : ERDAS IMAGINE, ARC GIS

Stable Channel Analysis
Copeland(1994)’s Method
Tool : SAM(Stable Channel
Analysis Model)

Channel Evaluation & Channel Design
Ch
Channell EEvaluationl tiComparison between Channel
Planform Change Result and Stable
Channel Result

Channel Shape, Slope, Width,
Depth
Direction for Restoration
Channel Design• For the channel evaluation, the measured channel planformchange results were compared with the stable channel
analysis using SAM model.
• The restoration channel design will be determined afterconsidering the channel evaluation.

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Study Area: Cheongmi Stream• The Cheongmi Stream is 60 km long and is located in
the middle of South Han River.
• The abandoned channels of Cheongmi stream areAC-1 to AC-20 sites.
• AC-17
AC 17 site
it hhas beenbdecided
d id d forf theth currentt projectj tsite after considering its feasibility.

Location of Cheongmi StreamOverlap of 1918's Topographical map and 2006's aerial photographStudy Area: Cheongmi Stream

ARRN Forum 2013
120062006

2

Study reach on Cheongmi Stream

Shape of bars in Cheongmi Stream

Study Area & Shape of Bars
• Alternate bars are located along the study reach of Cheongmi Stream.
• The study area was straightened and levees were constructed.
• The presence of vegetation on some alternate bars suggests that they are old.

3

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Channel Planform Changes Using Aerial Photograph• It is observed that bars and flows in channel has been changed.
quantitativelyy identified the channel pplanform change.
g• We have q

The location of abandoned channel

Aerial photographs from 1918 to 2006

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Change of Micro-landform in Channel• We can see that the vegetation on bars has grown as the flow
width has decreased and sand bar has fixed.

FarmlandWater Area

Sand Bar

Vegetated Bar

Parking Zone

100%

3.8
11.4
19.9
28.2

80%

47.2
37.4
28.5
60%

58.4

53.2

17.7

19.5

40%

15.8
48.7

49.0

40.9

23.1

20%

31.2

23 1
23.1

18.4
0%

2.9

5.0

19691974

10.4
1981

0.0

2.0

4.0199220002006

Ratio of micro-landform area from 1969 to 2006

Comparison of channel planform change from 1918 to 2006

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SAM Modeling for the Study Site
Cross Section Map for Study Site
• The study site is located within station 16+800 to 15+800.
• The standard cross section is station 16+400.

SAM (Stable Channel Analysis Method) Input Data
• Bankfull Discharge : Qb = 488 m3/s
• Specific Gravity : G = 2.65
2 65
• Valley slop : Sv = 0.00088
23• Bank Side Slope : 2.3• Bank Roughness : 0.03
2 18 mmmm, d50 = 1.1
1 1 mmmm, d16 = 0.63
0 63 mm• Bed Material Gradation : d84 = 2.18

Cross section map

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SAM Modeling for the Study Site
Conditions for Stable Channel• The width of stable channel : 40 m ~ 160 m• The depth of stable channel : 2.1 m ~ 7.6 m• The slope of stable channel : 0.0007 ~ 0.0009• These points are suitable for stable channel condition.
0 001
0.001

0 00080.0008Depth at minimum slope
and stream power

0.0009Width at minimum slope
and stream power

Slope

Slope

0.00070.00080.00070.00060.00060.00050.0005050100150

Top Width(m)p and width from SAM
Stable channel slope

02468Depth(m)Stable channel slope and depth from SAM

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SAM Modeling vs. Channel Planform Change
Comparison between SAM Results and Actual Values• Top Width (SAM Results) << Top Width (Actual Values)• Depth (SAM Results) >> Depth (Actual Values)• Slope (SAM Results) < Slope (Actual Values)
Comparison between SAM results and actual values
SAM Modeling ResultsRiverStation

Discharge(m3/s)

SlopeDepth(m/m)
(m)

Width

0.00058

65.918(m)Measurements
Slope
Depth(m/m)( )(m)
0.000747

Width(m)158.6016+400488
Comparison
between
4.83Stable Channel Evaluation
2.08 and Channel Planform
Changes• The SAM modeling simulated that, in the stable channel, the width narrows andthe depth gets deep.
• From the results of the aerial photograph, it is also observed that the width narrows
and vegetated bar increases.
• The results of channel planform change and stable channel results show good agreements.

Conclusions

ARRN Forum 2013

Channel Evaluation• We know that, in the present channel, the width narrows and the depth gets deeper.
• We can see that the vegetated area is increases.
Use of the Method for Abandoned Channel Restoration Design• The prediction by the equilibrium method and channel evaluation helps to design

abandoned channel restoration with keeping the stable conditions of the mainchannel.
channel• The application of the method is expected to give a good answer for future shapeof channels in case channel changes should be carried out.
outThank you

Photos by Korea River Association