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Health and the Global Water Supply
Dennis P. Lettenmaier
Department of Civil and Environmental Engineering
University of Washington
Seattle, WA
for presentation at
Lecture Series on Global Health Issues confronting the World
Community
University of Washington
Extension Service
November 8, 2004
Outline of this talk
• The global (and regional) water and
energy cycles
• Human needs for potable water
• Water and food
• Water development
• Water and climate
• Water quality and health
• Conclusions – the path forward
1. The global (and regional) water and
energy cycles
Source: NRC 1975
From Bras, 1990
From Taikan Oki, AMS 2005
Annual Water Balance for Major Continental Land Areas
1800
1600
1400
(mm/year)
1200
Precip
1000
ET
800
Runoff
600
400
200
0
Europe &
Iceland
Asia
Africa
North &
Central
America
South
America
Australia
World
Surface Area and Annual Runoff Volume of Major Continents
Million square km (area) or Thousand cubic km (runoff)
140
120
100
80
Surface Area
Runoff Volume
60
40
20
0
Europe &
Iceland
Asia
Africa
North &
South Australia
Central America
America
World
Column water balance (e.g. of a region)
Source: Kooiti Masuda, 2002
Water balance of major global rivers
Source: Kooiti Masuda, 2002
Water balance of major global rivers
Source: Kooiti Masuda, 2002
2. Human needs for potable water
• Domestic consumptive use (U.S.) is ~200-250
liters/day
• Compare with drinking water requirement (about
5 l/day). U.S. domestic consumption has
declined slightly over the last two decades.
Much of difference between potable water
requirement and use is sanitation, laundry, etc.
• Industrial requirement in developed world is of
same order as domestic
• Total water withdrawals are about 6000 km3/yr
• Compare with global (land) precip ~150,000
km3/yr (or global runoff ~0.4 x runoff)
Table courtesy Peter Gleick
Table courtesy Peter Gleick
Table courtesy Peter Gleick
3. Water and food
Blue and Green water (after
Falkenmark)
• Green Water is rainfall that is stored in the soil
and available to plants. Globally, it makes up
some 65 per cent of fresh water resources. It is
the basis of rain-fed farming and all terrestrial
ecosystems.
• Runoff, stream base flow and groundwater
constitute blue water. Green water may be used
only in situ: whereas blue water may be
transported and used elsewhere – for irrigation,
urban and industrial use, and as environmental
flow in streams.
Courtesy Wageningen University
Figure courtesy of world soil
information, Wageningen University
Figure courtesy of world soil
information, Wageningen University
Notes
•
Rain-fed agriculture contributes most of the world’s farm
production: 95 per cent in Sub-Saharan Africa where it makes
use of only 15-30 per cent of rainfall, the rest is lost, mostly
as destructive runoff;
•
The partitioning of rainwater is a dynamic process (governed
by rainfall intensity, terrain, land cover and soil) that may be
controlled by management of land cover, micro topography
and soil conditions;
•
Soils process several times more water than they retain;
while soil erosion by runoff and bank erosion by peak flows
contribute nearly all the sediment load of streams, leading to
the siltation of reservoirs and water courses. This means that
management of green water is also management of blue
water;
•
Finally, agricultural demand for water is in competition or,
even, conflict with the needs of industry, urban populations
and the environment.
Courtesy Wageningen University
Global Runoff & Water use
(http://hydro.iis.u-tokyo.ac.jp/GW/result)
An Adaptation Strategy to Cope with Scarcity?
“Virtual Water” flow in 2000 (cereals only)
78.5
USSR
North
America
33.5Middle
Western
Europe
38.8North West
Africa
Central Caribbean
America
36.4
East
West
Africa
South
America
East &
South East Asia
57.5
South
Asia
46.2
Oceania
Importer based, over 5 km3/y
km3/y
1~5
5~10
10~15
(Oki, et. al, 2002, IHE-UNESCO)
15~20
20~30
30~50
50<
(Based on Statistics from FAO etc., for 2000)
4. Water development
Global Reservoir Database
Location (lat./lon.), Storage capacity, Area of water surface,
Purpose of dam, Year of construction, …
13,382dams,
(4)
Δ V (km 3 )
7
1
20
18
16
14
12
10
8
6
4
2
0
20
00
/0
7
20
00
/0
1
19
99
/0
7
19
99
/0
1
98
/0
7
19
98
/0
1
19
97
/0
7
19
97
/0
1
19
96
/0
7
19
96
/0
1
19
95
/0
7
19
95
/0
1
19
94
/0
7
19
94
/0
1
/0
19
93
/0
92
363
20
7
1
/0
7
20
20
00
00
/0
1
19
99
/0
/0
99
19
19
98
/0
7
1
7
/0
98
19
19
97
/0
1
97
19
96
19
Turkana
AVE_mm/mon
ΔV(km3)
日付
965 839 773 923 963 995 693 829
954
40
35
25
20
15
10
5
7
/0
1
20
00
/0
7
20
00
/0
1
19
99
/0
7
19
99
/0
1
19
98
/0
7
98
19
19
97
/0
1
7
19
97
/0
1
19
96
/0
7
19
96
/0
1
19
95
/0
7
19
95
/0
1
19
94
/0
7
19
94
/0
1
19
93
/0
7
/0
93
19
/0
92
/0
1
0
Δ V (km3 )
30
19
92
/0
7
/0
1
96
19
19
95
/0
/0
7
7
1
19
95
/0
1
19
94
/0
7
19
19
94
/0
1
/0
93
/0
93
92
/0
7
0
0
50
100
150
200
250
300
350
400
450
500
19
Δ V (k m 3 )
40
19
92
平 均 降 水 量 (mm/ mo n )
Δ V (km 3 )
30
25
20
15
10
5
0
-5
-10
-15
-20
-25
120
60
(3) Turkana
7
1
20
00
/0
7
20
00
/0
1
19
99
/0
7
19
99
/0
1
19
98
/0
7
19
98
/0
1
19
97
/0
7
19
97
/0
1
19
96
/0
7
19
96
/0
1
19
95
/0
7
19
95
/0
1
19
94
/0
7
19
94
/0
1
19
93
/0
7
19
93
/0
1
/0
/0
19
Volta
(4) Volta
92
/0
Precipitation (mm)
AVE_mm/mon
Δ V(km3)
日付
887 898 1040 960 1037 902 1052 1162 948
19
417
80
1
Cabora-Bassa
Kariba
平 均 降 水 量 (m m / m o n )
409
100
19
Mweru
92
412
AVE_mm/mon
Δ V(km3)
日付
713 711 801 705 728 750 767 805 665
0
50
100
150
200
250
300
350
400
450
500
平 均 降 水 量 (mm / mon )
Malawi
Tanganyka
19
394
(2) Nasser
Volta
0
50
100
150
200
250
300
350
400
450
500
374
Nasser
Victoria
dV(km3)
19
Turkana
19
(3)
19
Kainji
92
/0
7
Tana
1
(1)
/0
(2)
325
93
平 均 降 水 量 (m m / m o n )
Nasser
382
0
50
100
150
200
250
300
350
400
450
500
AVE_mm/mon
Δ V(km3)
日付
419
19
(1) Chad
Variation of Reservoir Storage
(estimated by RS, 1992-2000)
Chad
Chad
Global Water System Project
IGBP – IHDP – WCRP - Diversitas
Global Water System Project
IGBP – IHDP – WCRP - Diversitas
Human modification
of hydrological systems
Historic Naturalized Flow
Estimated Range of
Naturalized Flow
With 2040’s Warming
Regulated Flow
Figure 1: mean seasonal hydrographs of the Columbia River prior to (blue) and after the completion of reservoirs
that now have storage capacity equal to about one-third of the river’s mean annual flow (red), and the projected
range of impacts on naturalized flows predicted to result from a range of global warming scenarios over the next
century. Climate change scenarios IPCC Data and Distribution Center, hydrologic simulations courtesy of A.
Hamlet, University of Washington.
Reservoir construction has slowed.
800
.
700
Number of Reservoirs
600
500
Australia/New Zealand
Africa
Asia
Europe
Central and South America
North America
400
300
200
100
0
Up to 1901- 1911- 1921- 1931- 1941- 1951- 1961- 1971- 1981- 19901900 1910 1920 1930 1940 1950 1960 1970 1980 1990 1998
All reservoirs larger than 0.1 km3
Visual from Palmieri, NAS Sackler symposium, 2004
5. Water and climate
Global Climate Change
Selected Basins
90
-150 -120 -90
-60 -30
0
30
1
60
60
0
120 150
5
4
2
30
90
7
9
6
8
90
60
30
0
3
-30
-30
-60
-60
-90
-150 -120 -90
1
2
3
4
5
-60 -30
MacKenzie
Mississippi
Amazon
Severnaya Dvina
Yenisei
0
30
60
90
6
7
8
9
120 150
Amur
Yellow
Xi
Mekong
-90
Selected Basins
Basin Characteristics
River Basin
Predominant Climatic
Zones
Area (km2)
upstream of gauge
Amazon
Tropical
4.62 106
Amur
Arctic
Mid-Latitude rainy
1.73 106
Mackenzie
Arctic
1.57 106
Mekong
Tropical
0.55 106
Mississippi
Mid-Latitude rainy
2.96 106
Severnaya Dvina
Arctic
0.35 106
Xi
Mid-Latitude rainy
0.33 106
Yellow
Arid-cold
Mid-Latitude rainy
0.73 106
Yenisei
Arctic
2.44 106
GCM Predicted Climate Change
Change in precipitation (%)
Change in precipitation and temperature for selected basins
40
30
20
10
0
-10
-20
-30
-40
40
30
20
10
0
-10
-20
-30
-40
40
30
20
10
0
-10
-20
-30
-40
0
Amazon
Amur
Mackenzie
Mekong
Mississippi
Severnaya Dvina
Xi
Yellow
Yenisei
1
2
3 4
5
GFDL_CGCM
CCCMA-CGCM1
2025
6
7
8
0
1 2
HCCPR-CM2
CCSR-CGCM
2045
3
4
5
6
7 8
Change in temperature (C)
2095
0
1
HCCPR-CM3
CSIRO-CGCM
2
3
4 5
6 7
8
9
MPI-ECHAM4
DOE-PCM3
Predicted Precipitation Changes
2045
Amur
MacKenzie
100
0
mm
300
200
Mekong
Mississippi
50
25
0
-25
-50
Severnaya Dvina
100
0
mm
300
200
Xi
Yellow
50
25
0
-25
-50
Yenisei
100
0
J F M AM J J AS O N D J F M AM J J A S O N D J F M AM J J A SO N D
HCCPR-CM2
HCCPR-CM3
MPI-ECHAM4
50
25
0
-25
-50
% change
Amazon
% change
200
% change
mm
300
DOE-PCM3
Predicted Temperature Changes
Amazon
Amur
MacKenzie
°C
4
0
40
20
0
-20
-40
Mekong
Mississippi
-4
Severnaya Dvina
8
4
°C
0
40
20
0
-20
-40
Xi
Yellow
°C
8
°C
40
20
0
-20
-40
-4
Yenisei
8
4
0
J F M AM J J AS O N D J F M AM J J A S O N D J F M AM J J A SO N D
HCCPR-CM2
HCCPR-CM3
MPI-ECHAM4
°C
°C
2045
-4
DOE-PCM3
Simulated Streamflow
m3/s
2025
300000
25000
20000
15000
10000
5000
0
50000
40000
30000
20000
10000
0
4000
Amazon
200000
100000
m3/s
0
40000
Mekong
30000
20000
10000
m3/s
0
15000
Xi
10000
5000
0
J F M AM J J A S O N D
Baseline
Amur
30000
20000
10000
Mississippi
0
20000
Severnaya Dvina
15000
10000
5000
Yellow
0
100000
3000
75000
2000
50000
1000
25000
0
MacKenzie
J F M AM J J A S O N D
0
Yenisei
J F M AM J J A S O N D
HCCPR-CM2
MPI-ECHAM4
HCCPR-CM3
DOE-PCM3
Simulated Streamflow
2045
m3/s
300000
25000
20000
15000
10000
5000
0
50000
40000
30000
20000
10000
0
4000
Amazon
200000
100000
m3/s
0
40000
Mekong
30000
20000
10000
m3/s
0
15000
Xi
10000
5000
0
J F M AM J J A S O N D
Baseline
30000
Amur
20000
10000
0
20000
Mississippi
Severnaya Dvina
15000
10000
5000
0
100000
Yellow
3000
75000
2000
50000
1000
25000
0
MacKenzie
J F M AM J J A S O N D
0
Yenisei
J F M AM J J A S O N D
HCCPR-CM2
MPI-ECHAM4
HCCPR-CM3
DOE-PCM3
Western U.S.
regional study
GCM grid mesh
over western U.S.
(NCAR/DOE
Parallel Climate
Model at ~ 2.8
degrees lat-long)
BAU 3-run average
historical (1950-99)
control (2000-2048)
PCM
Business-as-Usual
scenarios
Columbia River Basin
(Basin Averages)
PCM
Business-AsUsual
Mean Monthly
Hydrographs
Columbia
River Basin
@ The Dalles,
OR
1
month
12
1
month
12
Percent of Control Run Climate
2040-2069
140
120
PCM Control Climate and
Current Operations
100
PCM Projected Climate
and Current Operations
PCM Projected Climate
with Adaptive Management
80
60
Firm
Hydropower
Annual Flow
Deficit at
McNary
Percent of Control Run Climate
2070-2098
140
PCM Control Climate and
Current Operations
120
PCM Projected Climate
and Current Operations
100
PCM Projected Climate
with Adaptive
Management
80
60
Firm
Hydropower
Annual Flow
Deficit at
McNary
Central Valley Water Year Type Occurrence
Percent Given WY Type
0.6
hist (1906-2000)
0.5
2020s
2050s
2090s
0.4
0.3
0.2
0.1
0.0
Critically Dry
Dry
Below Normal
Water Year Type
Above Normal
Wet
Total Basin Storage
Figure 8
70
Minimum
60
Average
Maximum
Storage, BCM
50
40
30
20
10
0
Historical
Control
Period 1
Period 2
Period 3
Annual Releases to the Lower
Basin
Figure 9
14
1.2
Average Annual Release to Lower Basin (BCM/YR)
Probability release to Lower Basin meets or exceeds target (probability)
12
1
target
release
10
8
0.6
6
0.4
4
0.2
2
0
0
Historical
Control
Period 1
Period 2
Period 3
Probability
BCM / YR.
0.8
Annual Releases to Mexico
Figure 10
1.2
Average Annual Release to Mexico
(BCM/YR)
3
Probability release to Mexico meets or
exceeds target (probability)
BCM / YR.
2.5
2
target
release
1.5
1
0.8
0.6
0.4
1
0.2
0.5
0
0
Historical
Control
Period 1
Period 2
Period 3
Probability
3.5
Global Water System Project
IGBP – IHDP – WCRP - Diversitas
Global assessment
of water scarcity
Crisis of Global Water Resources in 2025:
Climate or Population Growth
Vörösmarty, 2000
6. Water quality and health
Material in this section courtesy of Pat Brezonik,
University of Minnesota (presented at NAS Sackler
Symposium, October 2004
The Global Picture
● Water resource issues will have large effects on many
of the world’s major decisions in the next 50 years.
● 1 billion people live on less than $1/day.
● More than 1.2 billion have inadequate drinking water
(poor quality, insufficient quantity, but still priced
beyond the means of the poorest), and twice that
many (2.5 billion) lack sanitation facilities.
● Poorly handled: could result in wars and will result
in premature deaths, poor quality of life for many,
and widespread degradation of aquatic ecosystems.
● Well handled: opportunities for scientific and political
creativity, international collaboration, promoting
cooperation rather than discord.
Global Water Quality: Problems and Issues
A. Definitions:
Water quality has many dimensions. In general, it must be
defined in relation to the use or intended use of the water
Important uses of water include:
● direct human use for drinking, cooking, bathing
● recreational uses: both contact and non-contact
● agricultural: irrigation from crop production, livestock watering
● industrial uses: for manufacturing, cooling
● maintenance of healthy aquatic ecosystems
● fish production
Relative to these uses, water quality is defined in terms of desirable
ranges for numerous physical, chemical, and biological attributes (or
allowable ranges for attributes that are inherently undesirable for some
use); in contrast, water-quality problems occur when values for these
attributes lie outside those ranges.
Global Water Quality Problems/Issues cont.
B. Effects of Poor Water Quality and Sanitation on Sickness and Disease
This presentation will not focus on enumerating the effects of poor water
quality on human health, but a few statistics are relevant to indicate the
seriousness of the problem.
Disease
Millions affected
____________________________________________
Diarrhea
900a
Roundworm
900
Guinea worm
4
Schistosomiasis
200
____________________________________________
a
Number of episodes per year
Source: World Bank, 1992
II. Global Water Quality Problems/Issues cont.
C. Six major categories of water quality attributes for which
there are global issues and problems
1. Nutrients (primarily nitrogen and phosphorus)
lake and coastal eutrophication
hypoxia, harmful algal blooms, loss of desirable fish
nitrate contamination of ground water
2. Microbial pathogens and other disease vectors
bacteria, viruses, protozoa
higher animal vectors (e.g., insects, snails)
3. Persistent organic pollutants
legacy chemicals: PCBs, chlorinated pesticides and solvents
disinfection by-products: halomethanes and haloacetic acids
emerging contaminants: (mostly associated with consumer products)
polybrominated phenylethers (flame retardants), perfluorinated
compounds (PFOS) (“Scotchgard”), MTBE
II. Global Water Quality Concerns, cont.
4. Unregulated, non- (or less) persistent bioactive
compounds of consumer origin:
pharmaceuticals, products for personal care, endocrine
disrupters, antibiotics
5. Heavy metals and metalloids:
arsenic, lead, chromium, mercury
6. Habitat degradation/destruction
e.g., ecosystem fragmentation, siltation, loss of riparian or littoral
vegetation, disruption of water levels and natural hydoperiod
ARSENIC: a major water quality problem in parts of Bangladesh, West
Bengal, Vietnam, and elsewhere—largely of natural geochemical origin,
but exacerbated by human decisions regarding water management
Arsenic in sedimentary aquifers in Bangladesh.
Map based on > 18,000 samples. McArthur et al.
Water Resources Research, in press.
Arsenic Crisis Information Centre: http://www.bicn.com/acic/
http://phys4.harvard.edu/%7Ewilson/arsenic/arsenic_project_introduction.html
Global and continent access to safe
drinking water (DW) and sanitation, 2000*
Urban
DW Sanit
Rural
DW Sanit
Population % Served
Population % Served_
________________________________________________________
Global
2,845
94
86
3,210
71
38
Africa
297
85
85
487
47
45
Asia
1,352
93
78
2,331
74
31
Europe
545
99
99
184
88
74
Latin America
391
93
87
128
62
48
North America
239
100
100
71
100 100
Oceania
21
100
100
9
67
78
________________________________________________________
*Gleick, P.H. et al., The World’s Water 2002-3, Island Press, 2002.
One consequence of poor sanitation is a decline in
dissolved oxygen (DO) levels in low-income countries
during the 1980s; in contrast, DO increased in highincome countries during same period.
Source: World Bank (1992).
Data for rivers at the continental level mostly
show little change in nitrate between the periods
1976-90 and 1991-2000; median values were not
statistically different. European rivers had highest
nitrate loads to the oceans. North American and
European rivers remained fairly stable; major rivers
in south-central and southeast Asia increased
considerably.
Comparison of major watersheds between
1976-90 and 1991-2000 shows that northern
Europe and North America had lower phosphate,
but the Ganges and Brahmaputra watersheds in
south-central Asia had higher values. Nutrient
control programs in municipal and agricultural
activities may explain the observed reductions.
The only information on biological characteristics of global water quality in the UNEP report shows
a marked decline in an index of aquatic species populations for all continents except North America,
but even on that continent there has been a declining trend since 1985.
7. Conclusions and the path
forward
Material in this section courtesy of Dr. Peter Gleick,
Pacific Institute
The Nature of the Resource
• 97.5 percent of all water on the planet is
salt water.
• The vast majority of fresh water is
inaccessible to humans.
• Water is unevenly distributed in both
space and time.
• Massive infrastructure has been built in
many part of the world, at huge cost.
The Nature of Water Issues
• The failure to meet basic human and
environmental needs for water is
arguably the greatest development
failure of the 20th century.
• Huge numbers of water-related
diseases occur every year, with millions
of preventable illnesses and deaths.
• Aquatic ecosystems are under threat of
destruction; deteriorating quality and
quantity.
The Nature of Water Issues (cont.)
• Global climate change will affect water
resources in new ways.
• New solutions are available, but not
widely implemented.
Unmet Basic Human Needs for Water
• 1.1 billion people lack access to adequate
drinking water (mostly in Africa and Asia).
• 2.4 billion people lack access to adequate
sanitation services.
• 2.2 to 5 million die annually from
preventable water-related diseases.
The “New Economy of Water”
• There is growing pressure to let private
companies and markets address water
needs.
• There are many forms of water
privatization, with both potential benefits
and risks to the public good.
• There is growing opposition to private
involvement in water. Do we understand
the risks and benefits?
Understanding the Risks of
Climate Change
• Climate change is a real problem.
• Some climate change – perhaps a lot of
climate change – is unavoidable.
• Convincing evidence suggests that the
climate is already changing.
• Some of the most significant impacts will
be on water resources.
1000
7000
900
800
6000
700
5000
600
4000
500
3000
400
300
2000
200
1000
100
0
0
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Gleick 2001
3
8000
Water Withdrawals (km /yr)
$1996 U.S. GNP
The link between water use and
economic growth can be broken
Widespread efficiency improvements
are possible, in all sectors
•1930s: 200 tons of water per ton of steel
•1980s: 20-30 tons of water per ton of steel
•2002: 2-3 tons of water per ton of steel
(and we are changing the structure of our
economy…)
•Agricultural water use can drop and yields
can increase with better irrigation
technology.
Things are already changing…
• Our understanding of the true costs of
traditional supply – the “hard path.”
• Our understanding of the potential to
improve efficiency of use.
• The nature of our economies.
• Our whole way of thinking about water –
“soft” vs “hard” path.