International Forum on Waterfront and Watershed Restoration

River Restoration in Korea- The past, the present and the future -2006. 11. 09
Chang Wan KIM, Ph.D. and Hyoseop WOO, Ph.D.

Korea Institute of Construction Technology
Korea Institute of Construction Technology
www.kict.re.kr

Natural Background

International Forum on Waterfront and Watershed Restoration

Precipitation• Large variation of seasonal precipitation
9 Almost 65 % of annual precipitation concentrates in Juneto September due to monsoon and typhoons

200100Dec

NovOctSepAugJulJunMayAprFebMar0Jan

Rainfall [mm]300MonthKorea Institute of Construction Technology
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International Forum on Waterfront and Watershed Restoration

River Slope• River bed slopes are very steep
9 Extreme variation of river flow (Q(Qmax/Qmin ): 100 to 700

Elevation [m]

1,500
Tone
1,000

Han

Rhine

Roire
Colorado

500

Seine
Mekong

00500

1,000

1,500

Distance from River Mouth [km]Korea Institute of Construction Technology
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Social Background

International Forum on Waterfront and Watershed Restoration• Urbanization
9 Cityity dwellers increased from 36 % in 1960s to 90 % in2000.

• Industrialization
9 About 12th largest trade and GDP in the world has
accelerated channelization,channelization, damming and gravel mining inthe rivers. (including readjustment of arable land)• Water quality
9 BOD ranges from 1.4 to 6.5 mg/L in five major rivers.

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International Forum on Waterfront and Watershed Restoration

River Management Practice
Natural Stream• Before 1960s, most rivers were in natural condition with afew artificial structures.

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Disaster-Prevention Stream• In 1970s, river management mainly focused on the flood control(channelization).
channelization). So rivers lost environmental functions; ecologicalhabitat, selfself-purification, and riparian scenery.

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International Forum on Waterfront and Watershed Restoration

Occupied Stream• In 1980s, floodplains of streams were occupied by parking
lots,lots, recreation areas, roads and farmland, etc.

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Park Stream• In late 1980s, parks in urban streams were constructed.
Most parks were constructed on the floodplains.

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Ecological Stream• Since mid 1990s, ecological river improvement techniques
have been employed to enhance the environmental functionof the stream.

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Transition of River Management Practice

NaturalNaturalStreamStreamDisasterDisasterPrevention
Prevention
StreamStreamOccupiedOccupied
StreamStream
ParkPark
StreamStreamEcological
EcologicalStream
StreamKorea Institute of Construction Technology
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International Forum on Waterfront and Watershed Restoration

Situation of Stream Restoration
History of River Environment• Before 1980’
1980’s:9 River regulation focused on flood control and water use• Late 1980’
1980’s:9 Social needs for improvement of river environment(water quality and aesthetics)• In 1990’
1990’s:9 Research projects on stream restoration and somedemonstration projects• In 1999:
9 Revision of River Act: Legislation of river environment
and implementation• In 2004:
9 Publication of River Planning Guideline
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River Planning Guideline• Emphasis on reflection of residents
and NGO to river projects• Zoning of a river into three
categories for better management
9 Conservation zone for ecosystemand culture
9 Restoration zone
9 Amenity zone

• Introduction of environmentally
sustainable new flood control
methodKorea Institute of Construction Technology
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International Forum on Waterfront and Watershed Restoration

River Restoration Projects• In early 1990s:

9 Introduction and adaptation of naturenature-friendly river
improvement works from Japan and Germany to Korea(MOCT/KICT)• In mid 1990s:
9 A researchresearch-oriented project of stream restoration(MOE/KICT)• In late 1990s:

9 Implementation of demonstration restoration projects(OsanOsan-cheon,cheon, GyeonganGyeongan-cheon,cheon, AnyangAnyang-cheon,cheon, etc)

• In early 2000s:
9 Implementation of the CheonggyeCheonggye-cheon Project (Seoul)
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Stream Restoration Research Works
Location of Project Site

• YangjaeYangjae-cheon (stream)
9 Secondary tributary of theHan river
9 Drainage area: 59 km2
9 Slope: 1/3001/300-1/500
9 Discharge
 Normal period: 1 m3/s
 Flood period: 300 m3 /s

9 Severely impaired habitat
due to channelization
9 D50 of bed material: 11-10 mm

9 BOD: 3.0 - 10.0 ppm

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International Forum on Waterfront and Watershed Restoration

Upstream Test Reach of Yangjae-cheon

Before(1996)
After (1997)
After (1998)

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Recent View
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Recent View
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Downstream Test Reach of Yangjae-cheon

A sand bar wasformedBefore (1998)
After (1999)

After Flood (1999)
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Recent View
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Recent View
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GreenBlocks

Layout of Applied Techniques

p+Gabionynt nit Br idPla mmuge
Brush CoMattresskenyio•`atetag
DBoulder Riprapeg
WatereB
Ripap+v
ertionWi r
uldd
Purificaoell
B
V-shape Ripple
Fi
neSto
Alternate Boulders
rapipRr
Riprap+Gabion
eBouldgs
Green Ba
Ri
pra

Open Biotope

ing
pp rs
Steoulde
B

Closed Biotope

0 1050

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Demonstration Projects

Osan-cheon Stream Restoration ProjectBefore (1999)

After (2001)
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International Forum on Waterfront and Watershed Restoration

Gyeongan-cheon Stream Restoration Project

Before (2001)

After (2003)
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Anyang-cheon Stream Restoration Project

Before (2001)

After (2003)
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Hakyi-cheon Stream Restoration Project

Before (2001)

After (2001)
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Urban Stream Restoration Projects

Cheonggye-cheon Stream Restoration Project

Before (1959)•Video Clips:

Before (2002)

9About Restoration Project
9Before Restoration
9After Restoration

After (2006)
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International Forum on Waterfront and Watershed Restoration

Limitations of Urban Stream Restoration• Water quality:

9 Poor water quality is a very serious constraint on theimplementation of stream restoration projects in theurban streams.

• Water quantity:

9 Pavements with nonnon-permeable material such as asphalt
and concrete in urban areas cause lack of groundwater
recharge and thus lack of stream flow.

• Variation of stream flow:

9 Large floods in summer render ecoeco-engineering approachin the stream restoration works sometimes dangerous.

• Price of land:

9 High land price renders project managers discouraged.
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Future Prospect

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Interaction among five abiotic/biotic factors

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International Forum on Waterfront and Watershed Restoration

Problems in Ecological River Engineerng• Interaction between hydraulic and ecological factors in rivers
is not fully understood.

• Stability of river restoration works is not still verified.

• Quantative evaluation of ecological enhancement is difficult.

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Real-scale River Experiment Station
L=400 m
B=10B=10-20 m
S=1/100S=1/100-1/1,000
Qmax=16 m3/s
Vmax=4 m/s
A3 A2 A1

A1. MultiMulti-function Experiment Channel• Hydraulic stability of structures• Bed deformaion by structures• Influence of vegetation on river• Influence of bank on ecosystem

A2. Stability Experiment Channel
Lake and MarshExperiment Pond

• Stability of levee and bank protection• Stability of multimulti-functioned bank
• Roughness coefficient of vegetation

A3. Ecology Experiment Channel• Changes of channel course• Formation of natural bank
• Floods and phycology• Channel forms and habitat
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International Forum on Waterfront and Watershed Restoration

Andong Dam
HaahHaah-ri
Nakdong River

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Numerical Simulation

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Conclusions

International Forum on Waterfront and Watershed Restoration• A paradigm shift of flood control and stream restoration isneeded.
• Incorporating ecological engineering approach into every
sector of flood control works is needed. Stream restoration
can be implemented only when flood safety is ensured.
• It is needed to consider restoring stream ecosystem to be
an ultimate goal of stream restoration and enhanced
biodiversity to be a major output expected from the stream
restoration works.
• We have to progress further the interdisciplinary approaches,among engineers, ecologists, landscape architect,geomorphologists,geomorphologists, economists and sociologist.

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Thank you!

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