Global Agriculture and
Water Use
Marty Matlock, Ph.D., P.E., C.S.E.
Professor and Area Director,
Center for Agricultural and Rural Sustainability
Ecological Engineering Group
Biological and Agricultural Engineering Department
University of Arkansas
mmatlock@uark.edu
Global Agricultural Water Use
• Agricultural use accounts for over 70
percent of all human use of water.
• Agricultural water use is predominantly
from rainfall.
• Water scarcity is experienced by humans as
famine.
• Demand for food, feed, fiber and fuel from
agriculture will double by 2050.
• We have to meet that need without one drop
more of water, one hectare more of land.
• We must freeze the footprint of agriculture
Sources of Information
World Wildlife Fund
http://www.wwf.org/
Encyclopedia of Earth
http://www.eoearth.org/
World Resources Institute
http://www.wri.org/
The Millennium Ecosystem Assessment
Report
http://www.millenniumassessment.org/
Everything is Connected
Source: Ricklefs
Economy of Nature
Everything is changing
We’re all in this together
http://media.photobucket.com/image/poverty/chenpn/thegivinghands/poverty1.jpg
Global Freshwater
Resources, in KM3
Water Use by Sector
Water Resource Use by Sector
Water Resource Use by Sector
Availability of Fresh Water
Water Resource Scarcity
Water Resources and Prosperity
–5 to possibly 25% of global freshwater use exceeds
long-term accessible supplies (low to medium
certainty)
–15 - 35% of irrigation withdrawals exceed supply
rates and are therefore unsustainable (low to medium
certainty)
Water Resources Per Capita
Sustainability 2050: The Challenge
UN Population Projections
Population (Billions)
12
10
8
6
4
2
0
1950
1960
1970
1980
1990
2000
Year
2010
2020
2030
2040
2050
Sustainability 2050: The Challenge
UN Population Projections
12
Population (Billions)
Projected with current fertility rates
10
8
6
4
2
0
1950
1960
1970
1980
1990
2000
Year
2010
2020
2030
2040
2050
Sustainability 2050: The Challenge
UN Population Projections
Population (Billions)
12
10
8
Median Estimate
6
4
2
0
1950
1960
1970
1980
1990
2000
Year
2010
2020
2030
2040
2050
Sustainability 2050: The Challenge
UN Population Projections
Population (Billions)
12
What we do in
the next 10
years will shape
Earth and
Humanity for the
next 100 years
10
8
6
4
2
0
1950
1960
1970
1980
1990
2000
Year
2010
2020
2030
2040
2050
Projected Population Change
by Country
Percent Population Change, 2005-2050
Source: Population Reference Bureau, 2005 World Population Data Sheet.
Growth in More versus Less
Developed Countries
Billions
10
9
8
7
6
5
4
3
Less Developed Regions
2
1
0
1950
More Developed Regions
1970
1990
2010
2030
Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.
2050
Association Between Fertility and
Education
Percent of Girls Enrolled
in Secondary School
Uruguay
100
Palestinian Territory
80
60
Morocco
40
20
0
0
1
2
3
4
5
6
7
8
Total Fertility Rate
Source: Population Reference Bureau, Population & Economic Development Linkages 2007 Data Sheet.
Association Between Fertility and
Poverty
Percent of Population
Living on <$2 per Day
100
Niger
Mongolia
80
60
40
20
Jordan
0
0
1
2
3
4
5
6
7
8
Total Fertility Rate
Source: Population Reference Bureau, Population & Economic Development Linkages 2007 Data Sheet.
Sustainability 2050: The Challenge
Malnourished Population (Percent of Total)
Percent of Total Population
30
25
20
15
10
5
0
1965
1970
1975
1980
1985
Year
1990
1995
2000
2005
Ecological Services
Largest Cities, Worldwide
Millions
1950
2000
2015
36
34
21
17
11
23
18
12
8
London Tokyo
New
York
Sao Mexico Tokyo
Paulo City
Delhi Mumbai Tokyo
(Bombay)
Source: United Nations, World Urbanization Prospects: The 2003 Revision (medium scenario), 2004.
Largest Cities Worldwide
• The largest cities in the world are
growing rapidly, and they are shifting
from the more developed regions to the
less developed regions.
• In 1950, New York was the largest city in
the world, with a population of about 12
million.
• By 2015, the largest city worldwide is
projected to be Tokyo, with triple this
population size: 36 million.
Worldwide extent
of human land-use
and land-cover
change
J. A. Foley et al.,
Science 309, 570
-574 (2005)
Published by AAAS
Human Activities Dominate Earth
Croplands and pastures are the largest terrestrial biome, occupying over
40% of Earth’s land surface
Meeting Food Needs by 2050
Jason Clay
The role of
research
Water Footprint Concepts
Water footprint is
the amount of
water required to
produce a unit of
product.
1 Kg Corn requires
900 L water.
30
Water Footprint Concepts
Blue water is water
that is collected
for use (river,
reservoir,
groundwater)
Green water is soil
moisture from
precipitation
Grey water is water
to dilute pollution
concentration
31
2000 Corn Yield Data (SAGE)
Blue vs Green Water from Water
Balance Model
Water Stress Index
•The WSI the ratio of water use to availability with a weighted factor
dependent on watershed variations in annual water availability.
•A WSI of 0.5 is the threshold between moderate and severe water
stress.
•The above represents climate data from 1961-1990
35
Pfister, S; Koehler, A; Hellweg, S. Assessing the Environmental Impacts of Freshwater Consumption in LCA.
Environ. Sci. Technol. 2009, 43, 4098-4104
Water Use Impacts on
Ecosystem Quality
•In places where plant growth is water-limited, withdrawals of blue water may eventually
reduce the availability of green water and thus diminish vegetation and plant diversity.
•Ecosystem Quality (EQ) is represented as the area-time ecosystem damage as a
function of water use availability and potentially disappeared fraction of species.
Pfister, S; Koehler, A; Hellweg, S. Assessing the Environmental Impacts of Freshwater Consumption in LCA. Environ. Sci.
Technol. 2009, 43, 4098-4104
36
Water Use Impacts on Human
Health
•The damage induced by water consumption in a watershed or country is measured in
disability adjusted life years (DALY) as outlined in the Eco-Indicator 99 method.
•The impact on human health is a function of expected specific damage per unit of water
consumed
37
Pfister, S; Koehler, A; Hellweg, S. Assessing the Environmental Impacts of Freshwater Consumption in LCA.
Environ. Sci. Technol. 2009, 43, 4098-4104
Global Agricultural Water Use
• Agricultural use accounts for over 70
percent of all human use of water.
• Agricultural water use is predominantly
from rainfall.
• Water scarcity is experienced by humans as
famine.
• Demand for food, feed, fiber and fuel from
agriculture will double by 2050.
• We have to meet that need without one drop
more of water, one hectare more of land.
• We must freeze the footprint of agriculture