School of Geography
FACULTY OF ENVIRONMENT

Past and present approaches toriver rehabilitation in Japan
Ulrika Åberg, Paul Waley, Joseph Holden
geoeua@leeds.ac.uk

Overview• Post-war Japan• Nature Oriented River Works• Example: Izumi River, Yokohama• Review and new technical standards• New initiatives for river rehabilitation- Nature restoration projects• Challenges for the future

Post-war Japan• After the Second World War Japan
experienced a period of rapid
industrialisation and urbanisation, thiscaused serious pollution of many rivers.

Tama River,Tokyo, 1970s
Source: River
Front Centre,Tokyo.

• Some devastating typhoons led
to the initiation of a massive flood
control project with a boom oflarge dam constructions and river
channelisation works.
Cadmium poisoning Mercury poisoning
Itai-itai disease

Minamata disease
Many agricultural earth canals were built into concrete torationalize the water usage. Source: W.W. Kelly, Japan Focus.

Post-war Japan• At least three endemic fish species have totallydisappeared, and about 60 fish species arelisted as endangered (Yoshimura 2005).
• The chemical water quality started to return toacceptable levels, but the physical condition
remained poor, especially in lowland rivers.

Vast number of young Yellowtail killed by
red tide (1975)• Huge demand for urban
recreation space in the 1980s.
Furukawa River,eastern Tokyo,
before and after
construction ofrecreation
space. Source:
CTI Engineering.

Nature Oriented River Works• The River Bureau of the Ministry of Land, Infrastructure, Transport andTourism (MLIT) owns and manages all major (class A) rivers in Japan.
Smaller rivers (class B and lower) are managed by the local prefecturesand municipal governments.
• In 1990 the MLIT introduced
its new policy of Nature
Oriented River Works onsome representative rivers.
• In 1997 the NORW policy
became a requirement for
all MLIT financed riverworks.
Number of NORW carried out in Japanbetween 1991 and 2002. Source: MLIT (2007).
www.mlit.go.jp/hyouka/pdf/review /19/kasenkankyou.pdf

School OrientedNatureof something
River Works
FACULTY OF OTHER• All NORW are flood protection projects carried out according to a‘greener’ policy, but they did not have any specific ecological goals.
• Most of these river works were small and reach based, carried out by local
river managers with their own interpretation of the NORW concept. This
led to huge differences in the quality of NORW.

Early attempts to green the banks of flood protection works. Source: Manual for Technical Standards, 2007.

SchoolRiver,Izumiof something
Yokohama
FACULTY OF OTHER• One of these first pioneering rehabilitation
projects was carried out on the Izumi Riverin Yokohama.
• Much effort was put into public
participation, and the main aim of theproject was to enhance the amenity andre-connect the river with its surroundings.

Photo: Yoshimura, Shinichi• A local river management group wasformed to maintain the area and cut thegrass around the river.
Photo:
Higashiyama
VolunteerManagementGroup

Photo: Ulrika ÅbergSchoolRiver,Izumiof something
Yokohama
FACULTY OF OTHER

Higashiyama

Ogamikami

Preferen ce b etwe en Hig ash iyama
an d Ogamikami
5% 2%

Higashiyama
Ogamikami
Do n't know
93%

Frequency of visit

Attractiveness

3%
22%

More
frequently

5%

5% 3%

Change in wildlife

More
attractive

Same asbeforeRemainedthe same

Don't knowLessattractive

12%

12%
LossNo change
IncreaseDon't know
75%

87%

8%

Don'tknow
68%

SchoolRiver,Izumi
of something
Yokohama
FACULTY OF OTHERFish species

Teranowaki

Sekigahara

Freshwater minnow

115224125290Japanese fat minnow

128714683

1Common carp

40

1300

Asian pond loach

129222

Field gudgeon

12230

Freshwater goby

21

100

Eight-barbel loach

100

10

Topmouth minnow

1

7200

Teranowaki

Higashiyama

Higashiyama Futatsubashi

Futatsubashi

ConcreteConcrete

School ofReview
andsomething
new technical standards
FACULTY OF OTHER• In 2005 the MLIT set up a committee to review the past years of NORW.
• The report showed that 42% of all projects lack any kind of pre-projectmonitoring and 87% lack any kind of post-project monitoring.

Pre-project study

On-site survey
conducted

2%

Post-project study
13%

National Census on
River Environme nts

45%

42%

Post-project study
conducted

Literature re search
only

Post-project study notconducted

No study conducted

87%
4%

7%

No answe r

Source: MLIT (2008)

School ofReviewandsomething
new technical standards
FACULTY OF OTHER• The review resulted in the publication of new technical standards.
• One important part of the new guidelines is how to make space forwater.
• If the banks are steepened, some space is created for in-stream
constructions, such as vegetated banks.

Source: Manual for Technical Standards, 2007.

School restoration
Natureof something
projects
FACULTY OF OTHER• From 2002 the MLIT has initiated 35 river restoration projects, these
are all large catchment scale projects. Compared to the NORW theseprojects are not undertaken as part of flood control or waterabstraction projects.
• In 2003 the Ministry of Environment implemented a new naturerestoration promotion law.
• The most famous of the nature restoration projects under the promotion
law is probably the restoration of the Kushiro mire in Hokkaido.

Restorations plans ofKushiro mire, Hokkaido.
Source: River Front
Centre, Tokyo.

School of something
Challenges
for the future
FACULTY OF OTHER• On average, about 100 people are still killed by floods in Japan every
year, and annual costs of flood damage are the highest worldwide. It is a
big challenge to compromise between flood protection and nature
conservation or restoration.
• The new guidelines for NORW published in August 2008 are going to be
mandatory to follow for all NORW financed by the MLIT.
• The 35 ongoing nature regeneration projects of this scale are notinsignificant considering that Japan only has 109 major river systems.

School of Geography
FACULTY OF ENVIRONMENTTHANK YOU