Efforts to Solve Problems of Global Water Resources and ... · Water covers two-thirds of the surface of our "watery planet". But most of this global water (1.39 billion km3) is seawater

Part One ●

Efforts to Solve Problems ofGlobal Water Resources andAgricultural Water

Part One ●

6

Water covers two-thirds of the surface of our "watery planet". But most of this global water (1.39billion km3) is seawater. Freshwater accounts for only about 2.5% of the total. Of this freshwater,two-thirds is made up of ice on the north and south poles, plus glaciers. The remaining third isgroundwater. Freshwater existing on the land surface in easily usable forms such as lakes, pondsand rivers accounts for only 0.008% (104,620 km3) of all the water on the planet.

The planet earth which we inhabit is one of the few in the universe that haswater. In fact, the earth has abundant resources of this commodity. But the realityis that only a tiny proportion of the water on the planet is available to us in theform of freshwater resources.We use water resources for various production activities. In fact, global waterusage is increasing at a continuously faster pace, particularly the use ofdomestic water. Nevertheless, the world's biggest user of water remains - asbefore - agriculture. If we are to make appropriate use of the water resources on our planet - in theform of agricultural water - we will need to rethink our concept of a water cyclethat is not only healthy but also environmentally sustainable.

The Reality of Water Cycles

Freshwater available for use by man: Only 0.008% of all water on the planet

1

State of Earth's Water

Source: I, A. Shiklomanov, Assessment of Water Resources and Water Availability in the World, 1996 (WMO)

Types of water Volume(1,000km3)

Ratio tototal water (%)

Ratio to total freshwater (%)

●Saltwater

●Freshwater

Total

96.5 0.94 0.006 97.5

― ― ― ―

1,338,000 12,870 85.4 1,350,955

2.12 91.0 11.5 104.62 10,530 24,064 16.5 300 1.12 12.9 35,029

0.0002 0.007 0.0008 0.0075 0.76 1.74 0.001 0.022 0.0001 0.001 2.5

0.006 0.26 0.03 0.3 30.1 68.7 0.05 0.86 0.003 0.04 100

1,385,984 100 ―

SeawaterSalty groundwaterSaltwater in lakes Total saltwater

River waterFreshwater in lakesFreshwater in swamps SubtotalFresh groundwaterGlaciers and permanent snow coverSoil moistureUnderground ice in permafrost zonesWater in living organismsAtmospheric water Total freshwater

1

7

The history of global water usage can be traced to the four great ancient civilizations, whichdeveloped agriculture using water from their rivers. These four civilizations each developed theirown irrigation methods and crop cultivation practices to suit the climatic and topographicalconditions in their respective regions, thereby establishing urban states and dynasties.Global water usage has continued to increase since these ancient times. It took thousands ofyears for global water usage to reach 1,000 km3 per year. But then it took only about 30 years todouble to 2,000 km3 per year, and not even another 20 years to reach 3,000 km3 per year.

The quickening pace of increase in global water usage2

Nature and agriculture of the four great ancient civilizations


Semi-continental250 - 300mm

Tigris-Euphrates5m

End March - early JuneBarley, 2 crops/yr

Year-round (channels)

ClimateAnnual precipitationMother riverRise of river surfaceSeason of outflowMajor cropsIrrigation method

Mesopotamia

Semi-tropical150 - 250mm

Nile6 - 9ｍ

August - early OctoberWinter barley

Storage (basin)

Egypt

Semi-tropical250 - 300ｍｍ

Indus4 - 5m

April - AugustBarley, 2 crops/yr

Year-round (channels)

Indus River

Continental500 - 600ｍｍ

Huang He4 - 7m

July - AugustMillet

Basin or year-round

Huang He River Basin

Domestic use

3,500

3,000

2,500

2,000

1,500

1,000

500

0

Wat

er u

se (k

m3 /y

ear)

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990（year）

Industrial use

Agricultural use

Transitions in world water use

Source: Toru Mase

The Reality of Water Cycles1

8

4,000

3,000

2,000

1,000

0

Wat

er u

se (k

m3 )

1950 (year)1995

1,359km3

3,572km3

Population 5.57 billion

Population 2.49 billion

10

8

6

4

2

0

Popu

latio

n (b

illion

)

populationWater use

Water use

Water use

Total volume①(km3/yr)1,124 182 53

1,359 2.49 billion

Agricultural useIndustrial useDomestic useTotalPopulation

1950

Per-capita②(L/day) 1,235 200 58

1,493 ―

1995

Total volume③(km3/yr)2,504 714 354 3,572

5.57 billion

Per-capita④(L/day)1,231 351 174 1,756 ―

③／①(%)223 392 668 263 224

④／②(%)100 176 300 118 ―

Rate of increase

3

In the 45 years from 1950 to 1995, the world's population grew by about 2.2 times. The world'sannual usage of water increased by about 2.6 times in the same period. In terms of water use percapita of population during that time, domestic water increased by about 3 times and industrialwater by about 1.8 times. In contrast, however, the use of agricultural water remained more or lesslevel during this period.,

Growth in per capita water usage: "Domestic water ＞industrial water ＞ agricultural water"

Transitions in world water use and world population

World water use and per-capita water use in 1950 and 1995



9

19953,572km3/year

Australia & Oceania16km3 0.7％

South America152km3 4.3％

Europe497km3 13.9％

North America652km3 18.2％

Africa161km3 4.5％

Asia2,085km3 58.4％

2,000

1,500

1,000

500

0

Europe

North A

merica

Africa

Asia

South A

merica

Australia

& Oceania

World

Japan

Domestic use Industrial use Agricultural use

Per-c

apita

wat

er u

se (L

iters

/day

)

280

911795

428

1,602

1,897

63 37

494

132 151

1,432

277160

840

274

639

1,461

174

352

1,231

356305

1,276

4

Every year, the world uses about 3,572 km3 of water (figure for 1995). About 60% of this is used inAsia. Globally, agriculture is the biggest user of freshwater. Of the world's annual water usage,about 70% or 2,504 km3 is used as agricultural water, and about 70% of that is used in Asia.Meanwhile, in terms of water use per capita of population, the respective uses of domestic water,industrial water and agricultural water differ greatly from region to region. But in all three cases,North America uses the greatest volume of all.

Regional diversity of water use: Large per capita usage inNorth America, high proportion of agricultural water in Asia

Ratio of water use by region (1995)


Per-capita water use by region and purpose (1995)

Source: 1) I, A. Shiklomanov, Assessment of Water Resources and Water Availability in the World, 1996 (WMO)2) Ministry of Land, Infrastructure and Transport, 2002

The Reality of Water Cycles1

10

Wor

ld p

opul

atio

n (1

00 m

il.)

20

30

40

50

60

70

80

90

100

110

120

1950 2000 2050（year）

U.N. Population Division (Medium variant) 93.22

60.57

25.19

109.34

91.04

78.66

U.N. Population Division (High variant)

U.N. Population Division (Low variant)

U.S. Bureau of the Census

1961

2,000500

1,000

1,500

2,000

2,500

3,000

3,000 4,000 5,000 6,000 7,000 8,000 9,000

1970

1980

19901999

2015

7,207 million

2,379million tons

2,831million tons

8,270 million

2030

ｙ＝1894Ln(x)-14344

Ｒ2＝0.99

World population (million)

Cere

al re

quire

men

ts (m

il. to

ns)

1

2

According to UN estimates, the world'spopulation, 6.06 billion in 2000, is forecastedto grow by about 1.5 times to 9.32 billion bythe year 2050. As the world population was2.52 billion in 1950, it will have grown byabout 3.7 times in just one century.

What future now awaits humankind, having created societies that use water insuch large volumes? In fact, the demand for water resources is forecasted togrow still further, due to ongoing growth in population and the development ofsocio-economy.In particular, to keep pace with the increased consumption of cerealsaccompanying population growth, there is an increasing need to expand theirrigation land area and raise the land productivity of agriculture. The role ofagricultural water, therefore, is now more important than ever before.

The Future for Population, Food and Water

Use, including Agricultural Water

World population set toincrease by 50% over thenext half century

The UN Food and Agriculture Organization(FAO) forecasts that the trend for increasingper capita consumption of calories willcontinue in the future, exemplified byincreased consumption of meat and dairyproducts. It predicts that, hand in hand withpopulation growth, the world's overall annualgrain consumption will increase by about 1billion tons by 2030 as compared to now,reaching some 2.8 billion tons.

World's annual grainconsumption to increaseby nearly 1 billion tonsover the next 30 years

Major estimates of world population

Source: 1) World Population Prospects The 2000 Revision, 2001(United Nations Population Division of the Department of Economic and Social Affairs)

2) International Data Base, 2000 (U.S. Bureau of the Census)

Transitions and future prospects for worldpopulation and cereal requirements

Notes: ・See Source 1) below for cereal consumption volumes in 2015 and 2030.・Figures from 1961 to 1999 are cereal production data from

Source 2) below.The approximated curve is based on this.・In the diagram, rice is quoted on an unhulled basis.

Source: 1) World Agriculture:towards 2015/2030, 2002 (FAO)2) Statistical Databases (FAO)3) World Population Prospects: The 2000 Revision, 2001

(Population Division of the Department of Economic and Social Affairs of the United Nations)

2

11

Per-capita arable land area

1,550

1,500

1,450

1,400

1,350

1,300

1,2501961 1971 1981 1991

year

Arable land area

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.00Pe

r-ca

pita

ara

ble

land

are

a (h

a)

Arab

le la

nd a

rea

(mil.

ha)

AsiaAfricaEuropeNorth and Central AmericaSouth AmericaOceaniaFormer Soviet Union countriesWorld

507,071 191,209 138,563 274,582 108,789 53,314 228,920 1,502,448

1990 ①(1,000ha)

511,727 201,784 133,187 268,131 116,131 52,978 217,514 1,501,452

1999 ②(1,000ha)

4,656 10,575 △5,376 △6,451 7,342 △336

△11,406 △996

②－①(1,000ha)

100.9 105.5 96.1 97.7 106.7 99.4 95.0 99.9

②／①(%)

3

The world's total arable land area, which supports the production of cereal and other crops,continued to increase until around 1990. In the 10 years since 1990, however, increases in Asia,Africa, and South America have been matched by similar decreases in other regions, resulting inzero growth overall.Moreover, since the increase in arable land area cannot keep pace with population growth, the percapita arable land area in the world as a whole has continued to decrease gradually from about0.45 ha in 1961, shrinking to about 55% or 0.25 ha in 1999.

World's per capita arable land area continuing to shrink

Transitions in world arable land area and per-capita arable land area

Source: 1) Statistical Databases (FAO)2) World Population Prospects: The 2000 Revision, 2001 (United Nations Population Division of the

Department of Economic and Social Affairs)

Comparison of arable land area in 1990 and 1999

Source: Statistical Databases (FAO)

The Future forPopulation, Food andWater Use, includingAgricultural Water

2

12

4

Rain-dependent arable land82％ 18％

Irrigated arable land

Asia 12.0％（65.8％）

Africa 　0.8％（4.6％）

Europe 　1.1％（6.0％）

North and Central America 　2.1％（11.5％）

South America 　0.7％（3.8％）

　0.2％（1.1％） Oceania

　1.3％（7.1％） Former Soviet Union countries

138,989World irrigated arable land area

1961 ①(1,000ha)

274,166

1999 ②(1,000ha)

135,177

③＝②－①(1,000ha)

3,557

③／38 years(1,000ha/yr)

The area of irrigated arable land in the world accounts for about 18% of the total arable land area.About 66% of this is found in Asia. The world's irrigated arable land area nearly doubled from 139million ha to 274 million ha in the 38 years between 1961 and 1999. It is referred to as about 40%of the world's food is produced on this irrigated arable land. Agricultural water (accounting forabout 70% of the world's annual water usage) is thus considered to support increases in foodproduction.For reference, trends in the relationship between the per capita arable land area and the irrigationratio (i.e. the ratio of irrigated arable land to all arable land) between 1961 and 1999 for differentregions of the world, indicate that the irrigation ratio has increased in Asia and Europe, where theper capita arable land area is smaller.

Expansion of irrigated arable land area supportsincreased production of the world's food

Ratio of irrigated arable land by region

Figures in ( ) represent the ratio of irrigated arable land by region to total irrigated arable landSource: Statistical Databases (FAO)

Average annual increase in irrigated arable land area (1961-99)

Source: Statistical Databases (FAO)

13

300

250

200

150

100

50

0

2,500

2,000

1,500

1,000

500

01961 1971 1981 1991 （year）

0

5

10

Per-c

apita

irr

igat

ed a

rabl

e la

nd a

rea

(a)

Wor

ld c

erea

l pro

duct

ion

(mil.

tons

)

Per-capita irrigated arable land area Irrigated arable land area Cereal production

Wor

ld ir

rigat

ed a

rabl

e la

nd a

rea

(mil.

ha)

3.0

2.5

2.0

1.5

1.0

0.5

0.00 5 10 15 20 25 30 35 40

Irrigation ratio (%)

Per-

capi

ta a

rabl

e la

nd a

rea

(ha)

OceaniaOceania

Former Soviet Union countriesFormer Soviet Union countries

North and Central AmericaNorth and Central America

AfricaAfrica

EuropeEurope

South AmericaSouth

America

WorldWorldAsiaAsia

Transitions in world cereal production and irrigated arable land area



Transitions in irrigation ratio by region and per-capital arable land area

The points on the graph are, from the left, values for 1961, 1970, 1980, 1990, and 1999 (Oceaniahas no value for 1961)




2

14

5

1995 ①(km3/yr)

497 652 161 2,085 152 26

3,572 2,504 714 354

EuropeNorth AmericaAfricaAsiaSouth AmericaOceania　 Total

Agricultural useIndustrial useDomestic use

Water use

2025 ②(km3/yr)

602 794 254 2,997 233 33

4,912 3,162 1,106 645

Increase②－①

(km3/yr)

105 142 93 912 81 7

1,340 658 392 291

Rate of increase②／①

(%)

121 122 158 144 153 127 138 126 155 182

To ensure that production keeps pace with increases in global grain consumption in future, it willbe necessary to expand irrigated arable land and increase the supply of agricultural water.According to the World Meteorological Organization (WMO), the world's irrigated arable land areaand the annual usage of agricultural water in 2025 will be 329 million ha and 3,162 km3,respectively. In other words, it is forecast that 658 km3 of agricultural water will be required inaddition to the figure of about 2,504 km3 in 1995 (an increase of 26%). This would be about thesame as global industrial water usage in 1995, and about 1.9 times the domestic water usage inthat year.The WMO also forecasts that global usage of industrial water and domestic water in 2025 will be1,106 km3 and 645 km3, respectively. Adding these to the forecast usage of agricultural water, theworld's annual water usage in 2025 is set to increase by around 1,340 km3 from that in 1995,growing about 1.4 times to 4,912 km3. The use of new water resources depends on investment in areas such as dam development. Witha decline in efficient and economic dam sites and strong demands that environmental protectionbe taken into account, it will require a great deal of wisdom to develop water resources whilemaintaining harmony with the environment.

How can we cope with increases in global water usage?

Future prospects for world water use



2

Documents

Efforts to Solve Problems of Global Water Resources and ... · Water covers two-thirds of the surface of our "watery planet". But most of this global water (1.39 billion km3) is seawater