6th International Forum on Waterfront and Watershed Restoration
29 September 2009 (Asian River Restoration Network)

Flow Regime Restorationin Japanp- Past, Present and Future
Naoki SHIRAKAWA(University of Tsukuba, Japan)

Contents
1. River restoration in Japan -Overview2 Flow allocation problems (in past)2.
3. Current rules and regulations on flow
alteration
lt ti
4. Studies for future

1. River restoration in Japan
Local management- Historical context Navigation
gIrrigation(Old) River Law
1896

River management by Central government

Flood control… Industry, Hydropower, Population, …

(New) River Law
1964Flood control+ Water supply
1988 Normal Flow
1990 Nature-Oriented River Works(Amended) River Law
1997
Local involvement
Flood control, Water Supply+ Environment

Going back or Creation ?
Value ofRiver Environment
High

Low
(Natural)Original(Wild nature)High(Artificial)

Managementby human

Restoration
Conservation

Similarto nature ?

Creation
Mitigation
PresenttP(Damaged)
Low

Biodiversity
Happiness…

What we can manage …
Sh
Shape/ Edge

LAND
• Channel direction• Revetment works• Riverside vegetation• Floodplain management•…

ContentsFlowWATER• Flow quantity• Water qqualityy• Sediments• Aquatic lives•…

Management categories
LANDRestoration
Creation¾Re-Meander¾Human-friendlyy(space for rivers) (Urban rivers)¾Alien species¾Habitat creation(mitigation)¾Landscape

WATER ¾Flow Regime
Restoration¾Normal Flow
¾Flushing Flow

Re-meander Projects
jKayanuma((Kushiro river))

LAND - Restoration
Channelization(1967)
Oxbows(Old channel)

Original
Meandering
Wetlands

Straight
C t ffCut-off(1973-84)

Flood drainage
Farmland development
pRe-meander(2006-)

Re-meander(2002-)

Shibetsu river

Countermeasures against Alien Species
LAND - Restoration
Black locust(Robinia pseudoacacia )Number of rivers confirmed
1008060
40200
1990-95

96-2000

2001-05

Lance - leaved coreopsis(Coreopsis lanceolata L. )Star cucumber(Sicyos angulatus )Landscapep Restoration
LAND - Restoration

1947

Tama river

Braided channels
Large open sandbars(best habitat for native species)

Sand mining
Damming
Flood control (less disturbances)1997
Simplified, straight channels
Vegetated floodplain(alien species)

Vegetation management
Sediment supply
Flow regime control

Habitat Creation
LAND - Creation
reservoirwetlands

Haizuka Dam(Gonokawa River)2 Flow allocation problems
2.
• Irrigation <–> Irrigation– since ancient times• Hydropower <-> Fishery, Forestry– since 1920s• Urban use <-> Irrigation– 1950s -• Hydropower <-> Scenery, Local community– 1960s -Conflicts on river flowKurobe
u obe Dama
Highest Dam in Japan (186m)
Constructed in 1963 …novel,novel movies
Hydropower (72 m3/s, 545m)
Located in National Park

Agreement
Hydropower generation (335MW)

10 or 15m3/s(6/26-10/15(6/2610/15,6:00-17:30)

Natural beauty (downstream)
Tourism resource (flow release)

Power loss
78 billion MWh

Conflicts on river flow
SandanSada GoGorgegeAgreement
0.4 or 1.0 m3/s
(5/1 11/15(5/1-11/15,morning to evening)

Tarudoko Dam (42m)
Constructed in 1957
Hydropower(24MW, 7.0m3/s, 403m)

Conflicts on river flow
Oi RiverOeDams“River Desert”

Hydropowerstations“Get back the water”

1975 Request for flow releases (local gov.)
1977 0.5m3/s release from Shiogo dam
1988 33.0m
0 3/s/ releasel
1989 5.0m3/s release (3/20-12/5)

82 km … Tunnel
160 km … RiverConflicts on river flow
Tamaa a Rivere

Hamura weir(1653)

1936
2.0 m3/s(5/20 - 9/20)
requests(1982 86 89)(1982,86,89)

Municipal water
1992
Water quality
Landscape2.0 m3/s(throughout a year)3. Current rules and regulations onflow alteration• “NormalNormal Flow”
Flow concept• Government notice 1988
• Estimation guideline• Flushing flow experiments

“Normal Flow” conceptp• River Law (1964, amended in 1997) says in its “Article 1”:– The ppurpose
pof this Law is to contribute to land conservation and thedevelopment of the country, and thereby maintain public security andpromote public welfare, by administering rivers comprehensively toprevent occurrence of damage due to floods, high tides, etc., utilizerivers properly, maintain the normal functions of

the river water by maintaining and conserving the fluvialenvironment.

(Article 1: Purposes)• “Normal flow” should be secured before water allocation among
other users, in all water resources projects. … in principle.
• But actually, it was neglected or underestimated because no one
knew why it is neededneeded… what is the “normalnormal functions of the riverwater”?

Flow maintenance rule inhydropower stations• Government notice in 1988
– Environmental flow release from hydropower stations– Request in water right permission• 0.1-0.3m3/s/100km2 (reference standard)• Single value all over the country,country throughout a year(“minimum flow”)– Must be improvedp((regionalgdifference,, flow fluctuation))“Normal Flow” estimation guideline(1992)
1. Water quality– BOD estimation

2 Scenery2.
S– Water width, River width

3 Ecosystem
3.
– Select key species (usually fish, typical species + local fish)– Water depth & Velocity suitable for each life stage, each season
4. Navigation, Fishery, Saltwater intrusion, Estuary closing,
Groundwater table, Protection of river management works made ofwoods

5. Existing water rights

Flushing flow experiments• Ministry of Land, Infrastructure, Transport()
and Tourism (1997-)• “Flexible“Fl ibl ddam operation”
ti ” ffor ddownstreamtenvironmental restoration

Environmental Flow around the World
U.K.

Minimum flow forwater usage
Groundwater

Spain, Italy

United States

Western part
Salmon and Trout

Reservoir construction
Simple reference indicesfor consensus buildinggSouth Africa

National wildlife parks
Water supply for poor people
Decision making under limited
information

France, Germany

Natural landscapeRiver health•Water qqualityy•Estuary closing•International treatments

Australia

Large scale water transfer
Land use change(S i) Arid(Semi)
A id regionsi
Lowland large rivers(S i l conditions)diti)
Regional situations (Social4. Studies for future
Water use byhuman activities

RiRiverFl
FlowQuantity

Hydropowerstations

TimingChange inflow regime

Unfavorable impacts
on river environment

Reservoir
operation

mitigate

Environmental
Flowo ((EF))

Farmland/ Cities

Studies for future
Water use byhuman activities

1) What is the impact?
Physical / Ecological
Identify / Index

RiRiverFl
Flow
Quantity

Timing2) Flow variation
What does it mean?
Identify / Index

Unfavorable impacts
on river environment
mitigate

Environmental
Flowo ((EF))3) How can we evaluate it?
Conceptual
Cost efficiency

What is the impact?

Dry section

Natural section

Natural section

Dryy section

rifflepool(Sato, 2007)

Flow Variation
Disturbance Regime Curve AnalysisFrequencyF(times / year)
352520151035I
Impairedi d Flow
Fl530
0051015202530
比流量（m3/s/100km2）

3540

Magnitude of Disturbance(m3/s/100km2)

452550回
回数（／年）

回数数（／年）

Less occurrence for
Medium size disturbance(10m3/s/100km2 : 7-11 /year -> 4-9 /year)

N
Naturall Flow
Fl30

2015

105((Shirakawa,, 2007))
00

51015202530
比流量（m3/s/100km2）

3540

4550

Evaluation• Use Values(…resources, spaces)– Environmental Economics– Limited but sophisticated• Existence
E i tVValuesl(feeling,(f libeb happy)h)– Questionnaire ?
– Can we realize all the values correctly?

• Supporting Values (Ecosystem)– Not predictable (especially in Monsoon Asia)– Consensus building, discussion

Thank you !