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March 20, 2009March 20, 2009
Lead Specialist of Water Resources EngineeringLead Specialist of Water Resources Engineering
Japan Water AgencyJapan Water Agency ( ( JWA)JWA)
Michio OTA
Roles of Dams for the Future in Japan
Japan Commission on Large Dams
Japan Commission on Large Dams (JCOLD)
Topic 3.2 Session 3.2.3 in the 5th World Water Forum
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Contents
1. Condition of Water Affairs in Japan
2. Roles of Dams up to the present in Japan
3. Roles of Dams for the Future in Japan
4. Roles of Dams for the Future in the World
with regard to Food Security
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Contents
1. Condition of Water Affairs in Japan
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Rivers and Precipitation in Japan
Tokyo
-10
0
10
20
30
Temp.(℃ )
0
100
200
300
400
Precipitation(mm)
1 2 3 4 5 6 7 8 9 10 11 12
Source: Ministry of Land, Infrastructure, Transport and Tourism, MLIT
Annual mean rainfall: 1,700mm
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Distance from river mouse (km)
Elevation
(m)
Comparison of Riverbed Gradients
Rivers in JapanRivers in Continents
Source: MLIT
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Feature of Rivers in Japan is,- huge difference in the condition between flooding time and normal time- the water flow out soon after the flooding time
Tone River Kiso River Yodo River
Thems River Danube River
Mississippi River
Source : MLIT, Annual Report of Flow Rate ( 1984 ~ 1993 )
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7
Tokyo after the war in 1945
Source: Prof. Tuneaki Yoshida, Tokyo Univercity
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Source: http://bluestyle.livedoor.biz/
Tokyo in 2008
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9
0
100
200
300
400
500
600
0
20
40
60
80
100
120
140
1950 1960 1970 1980 1990 2000
-2
0
2
4
6
8
10
12
14Pop. (Million)
GDP (Trillion YEN)
DGP growth rate (%)Population
GDP
Periods according to the Change of Economic Condition
Source: MLIT
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Serious Water Shortage in Metropolitan Area
Supply trough Water Tank Truck
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11
Pollution in Urban River
Smelled badly and no fish
In 1960s to early 1970s
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Digging
of d
eep
wells b
egins
in va
rious
loca
tions
Cumulative ground subsidence (cm)
0
-50
-100
-150
-200
-250
-300
-350
-400
-450
-500
18
90
19
00
19
10
19
20
19
30
19
40
19
50
19
60
19
70
19
80
19
90
20
00
Groun
d su
bside
nce
is co
nfirm
ed
Indu
strial
Wat
er L
aw is
ena
cted
Indu
strial
Wat
er la
w is re
vised
and
Buil
ding
Wat
er L
aw is
ena
cted
Basic
Law fo
r Env
ironm
enta
l Poll
ution
is e
nacte
d
Guideli
nes f
or G
roun
d Sub
siden
ce P
reve
ntion
esta
blish
ed fo
r
C
hikug
o an
d Sag
a Plai
ns a
nd N
obi P
lain
Guideli
nes f
or M
easu
res t
o Pre
vent
Gro
und
Subsid
ence
,
e
tc. e
stabli
shed
for n
orth
ern
Kanto
Plai
n
Minamiuonuma (Yokawa, Muika Town, Niigata Prefecture)
Chikugo / Saga Plains (Yokote, Shiroishi Town, Saga Prefecture)Kanto Plain (Higashiowa, Washinomiya Town, Saitama Prefecture )
Nobi Plain (Hakke, Nagashima Town, Mie Prefecture)
Niigata Plain (Sakai, Niigata City, Niigata Prefecture)
Osaka Plain (Hyakushima, Nishiyodogawa Ward, Osaka)
Kanto Plain (Kameido, Koto Ward, Tokyo)
Changes Over Time in Ground Subsidence
Source: http://www.ara.go.jp/arage/keisei/keisei02.html
1970
4.5m
0 m
GL
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Tokyo area hit by Kathleen Typhoon in 1947
Flood Disaster
Source: MLIT
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Normal condition
Struck by the disaster
Inomori-cho, Tenpaku-ku, Nagoya city in 2000Inomori-cho, Tenpaku-ku, Nagoya city in 2000
“Source: MLIT
12Flood Disaster
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Contents
2. Roles of Dams up to the present
in Japan
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Manno-Ike Pond:Presented by Manno-Ike Land Improvement District
Change of Farm Land Area and PopulationIn Japan
Agricultural Water
Source: National Land Agency
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- 18681868- 19121912- 19261926- 19451945-unknown
24%
9%
3%7%
47%
10%
Percentage of Active Storage Capacity of Irrigation Ponds and Dams in Japan
(a supply area of 2 ha or more)
Total Active Capacity : 2,999,712×103 m3
Total Supply Area : 1,225,882 ha
Number of Ponds and Dams :63,591
Source: Ministry of Agriculture, Forestry and Fisheries, MAFF
Agricultural Water
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1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
1995
1883
1890
Transition of Water Supplied Population and Average Life ExpectancyW
ater
util
izat
ion
capa
city
of d
am (h
undr
ed th
ousa
nds
m3 )
Wat
er s
uppl
ied
popu
latio
n (te
n th
ousa
nds)
Dam water utilization capability of the water supply
Ave
rage
life
exp
ecta
ncy
(yea
rs)
Average life expectancy
Water supplied population
18
Domestic Water
Source: MLIT
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Energy for Water
Source: Electric Power Civil Engineering Association
Changes of Electric Power Production at the Early Stage
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Energy for Water
Comparison of Electric Power Source
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Flood Control: Mitigation of Flood Disasters in Japan
0
1,000
2,000
3,000
4,000
5,000
6,000
0
500
1000
1500
2000
2500
3000
3500
4000
1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
Tota
l Num
ber o
f Dam
s ('0
00)
Floo
d C
ontr
ol C
apac
ity (m
illio
n m
3)
Ann
ual D
eath
Tol
l by
Floo
ds (p
erso
n)
Number of Dams in J apanCapacity of Flood Control DamsDeath Toll by Floods
Data source:国交省水害統計、ダム年鑑(1999); Graphed by Imamura & Yoshida
Old RiverLaw mainly for flood control
RiverLaw for multi-purpose
objectives
New River Law inclusive of
environmment and ecology
21
Flood Control
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Japan has around 2,800 dams which heights are over 15m.
Dams have played a critical role for Japanese socioeconomic development based on increase of food production, supply of electric power, development of water for domestic and industrial use and improvement of safety level of flood control especially in large cities.
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Contents
3. Roles of Dams for the Future
in Japan
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1,1001,2001,3001,4001,5001,6001,7001,8001,9002,0002,100
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
( mm )
Annual Precipitation
Average rainfall trend
In Japan
Variability
Variability of extreme events is increasing due to climate change
Climate Change
Source: MLIT
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Estimation of the snow depth at 100 years from now• Because of the global warming, at 100 years from now, it is predicted that there will be almost no
snow in West Japan• At the Sea of Japan side, it is predicted that the area which has the greatest snow depth of 100cm
or more will be narrowed drastically
Distribution map of greatest snow depth in cooling season
legend
less than 1cm
from 1cm to less than 5cm
from 5cm to less than 10cm
from 10cm to less than 20cm
from 20cm to less than 50cm
from 50cm to less than 100cm
from 100cm to less than 150cm
150cm and more
Source: “Estimation of change of snow under global environmental change” Inoue Satoshi, Yokohama Kotaro, National Institute for Agro-Environmental Sciences
4
legend
less than 1cm
from 1cm to less than 5cm
from 5cm to less than 10cm
from 10cm to less than 20cm
from 20cm to less than 50cm
from 50cm to less than 100cm
from 100cm to less than 150cm
150cm and more
Present 100 years later
Climate Change
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Changes in water supply capacity of the Kiso River System.
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Source: National Institute of Population and Social Security Research in Japan
Population Projections for Japan: 2006-2055
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• Japan indirectly uses other countries’ water resources through the import of foods etc• The trend in trade will also have impact on the future water demand and supply in Japan
Japan’s total import amount of virtual water
Source: Calculation of the research group of Oki assistance professor at Institute of Industrial Science, University of Tokyo, based on the demand and supply of foods etc.
Total import amount: 64 billion m3/year > Japan’s domestic consumption of irrigation water: 59 billion m3/yearTotal import amount: 64 billion m3/year > Japan’s domestic consumption of irrigation water: 59 billion m3/year
7
Virtual water poured in Japan by import item (billion m3/year )
Corn
Soybean
Wheat
Rice
Barley
Beef
Pork
Chicken
Milk and dairy products
Industrial products
Others
Virtual Water
Self-sufficiency rate in food is 40%
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Contents
4. Roles of Dams for the Future
in the World with regard to Food
Security
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Predictions of the future world population and grain production
Source: Water Resources Dept. MLIT
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1. Secure Food Production in Japan
Japan should increase more food production domestically
and ensure stable supplies of food in the future.
A stable supply of irrigation water must be ensured by
storing unstable river flow with irrigation ponds and dams.
2. Water for Energy in Japan
Japan should have a policy to restrict emission of CO2.
Hydropower is a clean and 100% domestically produced
recyclable energy in Japan.
Dams for hydropower generation will contribute to the above.
Conclusion
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3. Climate Change Adaptation in the view of Dams in Japan
Abnormal phenomena of heavy rain and serious drought et al. will be caused by global warming and make a greater impact on water supply in the future.
Using Dams is one of the effective climate change adaptations.
However, new dams will not being smoothly constructed in Japan, thus the burden on existing dams will continue to rise. The priority issues are redeveloping existing dams and reorganizing of existing dams to optimize their operations.
Conclusion
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Conclusion
4. Roles of Dams for the Future in the World with regard to Food Security
Need of world grain production in the near future will increase demand for agricultural water.
Further expansion of cultivated land and improvement of deteriorated farmland including overgrazing of grassland, land of salt accumulation caused by excessive pumping of grand water and so must be done especially in developing countries. These factors will increase the need for development of new water resources to supply irrigation water.
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Tama River around 1970 Photo: Environment Bureau, Tokyo Metropolitan Government
Thank you for your kind attention