Virtual Water Trade to Japan and in the World

2

“Required water”…the water that is used in the production process of agricultural or industrial goods

Two types of required water:•Really Required Water (Real Water ; RW)

water used in exporting countries for production•Virtually Required Water (Virtual Water ; VW)

water needed in importing countries if the same amount of products were produced domestically

Really RequiredWater

Really RequiredWater

Virtually RequiredWater

Virtually RequiredWater

exporting country importing countryimport !

export !

What is virtual water?

(Oki, et. al, 2002, IHE-UNESCO)

3

Basic Arithmetic of Virtual Water

UWR: Unit Water Requirement (VW) ET: Evapotranspiration BWC: Beneficial Water Consumption L: Loss, nonbeneficial Water Consumption D: Dry weight, W: embodied “true” water ETR: Evapotranspiration Ratio BE: Basin Efficiency

D

ETETR

LBWC

BWCBE

rWD

LETBWCETUWR

)(

)(

4

Evapotranspiration ratio (ET/D) is determined by photosynthesis efficiency of each crop. e.g., 350 kg/kg for maize, 400-800 kg/kg for rice, and 1,000 kg/kg for wheat.

UWR↓ for fresh and juicy food (D<<W) UWR↑ for small fruit/seeds (r << 1) UWR↑ for poor agricultural efficiency

(BWC << L)

rWD

LETBWCETUWR

)(

)(

Basic Arithmetic of Virtual Water

5

3,600

Unit Water Requirement of Major Crops

(m3/t)

2,600 2,5002,000 1,900

(based on crop yield in Japan 、 FAOSTAT mean 1996-2000)

Unit Requirement of Water--Crops--

(Oki, et. al, 2002, IHE-UNESCO)

6

Model life of a cow

Dairy Cow Beef Cattle

7

5,900

4,100

3,200

20,600

4,500

3,000

14,400

0 5,000 10,000 15,000 20,000 25,000

牛（正肉）

牛（枝肉）

豚（正肉）

豚（枝肉）

鶏（正肉）

鶏（枝肉）

鶏卵

(m3/t)

Unit Water Requirement 　ーMeat ー

WholeBeef

WholePork

Pork

Beef

PoultryWhole Poultry

Egg

Unit Water Requirement of Major Meat

(based on crop yield and the way of raising in Japan)

560 m3/t for milk

(Oki, et. al, 2002, IHE-UNESCO)

8

4.9

38.9

8.9

1.4

2.21.3

2.5

Other:3.3 　 　 　 　 　 　 　　 　

Total : 64.0km3/y

Virtual Water Import to Japan 　

Vi rtual 　 Water　 I mport　 to　 J apanthrough　 each　 products

(km3/ y)

14, 5

12, 1

9, 42, 4

2

14

3, 6

2, 5

2, 2

1, 3

Mai ze

Soybean

Wheat

Ri ce

Barl ey

Beef

Pork

Chi cken

Mi l k

I ndustri alProducts

(for JFY in 2000)

0.30.3

Domestic Withdrawals in Japan: 89 km3/yDomestic Blue Water in Japan: 400 km3/yDomestic Green Water in Japan: 30 km3/y

Blue+Green water

Blue water only

(Oki, et. al, 2002, IHE-UNESCO)

9

(Oki, et. al, 2002, IHE-UNESCO)

CaribbeanCaribbean

NorthNorth AmericaAmerica

Central Central AmericaAmerica

South South AmericaAmerica

WestWest

AfricaAfrica

OceaniaOceania

East &East &South East AsiaSouth East Asia

SouthSouth

AsiaAsia

USSRUSSR

North WestNorth WestAfricaAfrica

WesternWesternEuropeEurope

MiddleMiddle

EastEast

1~5 5~10 10~15 15~20 20~30 30~50 50<

Importer based, over 5 km3/y

km3/y

(Based on Statistics from FAO etc., for 2000)

78.5

33.5

46.2

57.538.8

36.4

“Virtual Water” flow in 2000 (cereals only)

10

•7 out of top 10 importing countries are seriously poor in water resources.

•7 out of top 10 exporting countries are rich in water resources.

•Denmark (10) and India (18) are water stressed but exporting RW in net.

Virtual Water Balance in Countries (m3/c/y) in 2000

Blue: Exporting

Red: Importing

Exporting Importing

11

How Virtual Water Trade Saves the Water Resources GloballyHow Virtual Water Trade Saves the Water Resources Globally

Japan2,500m3

Comparing the required water to produce 1 ton of soy bean

in USA and Japan

USA1,700m3

1t of Soy Bean

JapanUSA TradeTrade

Really required water in USA

Virtually required waterin Japan

Export 1,700m3 Import 2,500m31t of Soybean1t of Soybean

Exporting 1t of Soy bean from USA to Japan

Real WaterReal Water Virtual WaterVirtual Water

2,5002,500-1,700 = 800m-1,700 = 800m33

Water Resources is saved by the Water Resources is saved by the VWVW trade! trade!

Comparative advantage of water efficiencyComparative advantage of water efficiency

億ト

ン/

年

Water Productivity varies in time and space!

12

世界の投入水移動（農畜産物）

0

2000

4000

6000

8000

10000

120001961

1963

1965

1967

1969

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

Year

/　　　_

億ト

ン年

現実水 仮想水 効率化分

Virtually Saved Water Resources in the WorldVirtually Saved Water Resources in the World

Virtually Requied Water = Sum of Importing Virtually Requied Water = Sum of Importing VWVW in each country (1), in each country (1),Really Requied Water Really Requied Water = = Sum of Exporting Sum of Exporting RWRW in each country (2), in each country (2),

Saved = (1)-(2)Saved = (1)-(2)

In　2000Really　Required　Water:　

680km3

Virtually　Required　Water:　1,130km3

Saved 　： 450km3

Real Virtual Saved

x0.1

km

3 /y

Cf. Total Agricultural Water Usage in 2000: 3,270 km3

RW and VW (crop & meat) 1961-2000

13

4 34 11

0%

20%

40%

60%

80%

100%

~1, 000　 USD 1, 000~5, 000USD

5, 000~20, 000USD

20, 000USD~

GDP　 per　 capi ta　 (US$/ y/ c)

Sl i ghtl y

Stressed

Seri ous

2

12

0

2

3

6

2

0 0

31

0%

20%

40%

60%

80%

100%

~1, 000　 USD 1, 000- 5, 000USD

5, 000- 20, 000USD

20, 000　 USD~

GDP　 per　 capi ta　 (US$/ y/ c)

Sl i ght l y

Stressed

Seri ous

Water Resources Assesment Considering VW tradeWater Resources Assesment Considering VW trade

22 Countries were classified into “seriously stressed” in 2000 by conventional water resources assessment.

+Virtual Water Import

Rich Countries aresaved by VW importPoor Countries

remainWater Poor

Seriously StressedSeriously Stressed

StressedStressed

Slightly StressedSlightly Stressed

Burundi: 31m3/c/yRwanda:53m3/c/y

VW Balance

Egypt:141m3/c/y

Oman: 512m3/c/yBahrain:313m3/c/y

UAE:4,490m3/c/y

14

Virtual Water for What? More appropriate water stress index for

world water resources assessment considering both real and virtual water resources.

Future projection of water demand for food supply considering diet.

Examination how water is wasted. Increasing the awareness on water of public.Different definitions & the ways of estimation

of VW may be appropriate according to the purpose and the application.

More philosophical discussions are needed.

15

Disadvantage/Limitationof the Index “Virtual Water” Trade

Considers only water quantity no considerations on:

Environmental impacts

Impacts on regional producing communities

Limiting factors other than water resources

Quantification of VWT solely cannot be used for any decision making processes.

16

Concluding Remarks “Natural” hydrological cycle is not “Real”

anymore even on global scale. Process based numerical models are useful for

quantification of natural and real water cycles. Accuracy depends on input data.

Global dataset is there. Accuracy depends on how the global data is estimated.

Surface monitoring network is crucial. Modeling human activities are challenging. From “sustainable development” to

“sustainability development” on water!