“Water, water everywhere nor any drop to drink…”
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“Water, water everywhere nor any drop to drink…” Talk by Ron Oxburgh Hong Kong 11January 2002 Material derived from many sources but particularly from Postel et al., Science ,1996
description
“Water, water everywhere nor any drop to drink…”. Talk by Ron Oxburgh Hong Kong 11January 2002 Material derived from many sources but particularly from Postel et al., Science ,1996. Water Cycle annual fluxes. RAIN 110. RAIN 390. Evaporation. 70. 430. Runoff. 40. Ocean. Land. Water. - PowerPoint PPT Presentation
Transcript of “Water, water everywhere nor any drop to drink…”
“Water, water everywhere nor any drop to drink…”
Talk by Ron OxburghHong Kong 11January 2002
Material derived from many sources but particularly from Postel et al., Science,1996
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Water Cycle annual fluxes
RAIN 110 RAIN 390
Land Ocean
Evaporation
Runoff
70 430
40
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Water
• only 2.5% of the Earth’s water is fresh• 2/3 of fresh water (1.73%) exists as ice• remainder 0.77% = 10,665 km3 (rivers, lakes,
swamps & atmosphere)• all human extraction is from runoff• much is inaccessible• uncertainty in estimates
The Present
Inaccessible Water% Global Runoff % global popln.
Amazon 15 0.4Zaire/Congo 3.5 1.3Tundra rivers 5 0.2
21% of Global Runoff is not useable
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1990 Global water use and consumption
Use Consumption km3 pa km3 pa %
Agriculture 2880 1870 65Industry 975 90 9Municipaities 300 50 17Reservoir losses 275 275 100TOTALS 4430 2285
Stream flow needs 2350 2350 100
Total as % of Runoff 62% 43%
Different Water Withdrawals
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 2 4 6 8 10 12
distance km
rela
tive
prop
ortio
n of
flow
Series1
Series2
Min. flow
The past
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Global water withdrawals over time, per cap. & total
01234
1940 1950 1960 1970 1980year
per cap, thou. m3/yr
Total thou. km3/yrUS
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Population, water withdrawals & irrigation
0
1000
2000
3000
4000
5000
600019
00
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
YEAR
mill
ion
& k
m3/
yr
0
50
100
150
200
250
300
mill
ion
ha
populnWat. withdrawsIrrigated areas
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Irrigation
• driven by food needs• much of Earth’s surface too steep, too cold
or too dry for cultivation• irrigation allows cultivation in some dry
areas & enhances yield in others• BUT irrigation water is CONSUMED• at present is 80% of consumption• significant energy for pumping
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Growth in Irrigated land
0.00
50.00
100.00
150.00
200.00
250.00
300.00
1950 1960 1970 1980Year
mil.
ha
OceaniaS.AmericaN.AmericaEuropeAsiaAfrica
Increase in irrigated land area
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World land use 1700 - 2000
Forest
Pasture
Crops
010002000300040005000600070008000
1600 1700 1800 1900 2000year
mill
ion
ha
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Rice yields in Japan 600 - 2000
Japanese rice production over time Mather & Chapman p82
t/ha600 0.6800 1
1000 1.61200 1.71400 1.81600 21800 2.51900 2.72000 6
0
1
2
3
4
5
6
7
600 800 1000 1200 1400 1600 1800 2000 2200time
tonn
es /h
a
Irrigated Area Vs World Population 1950 – 2000
0.00
50.00
100.00
150.00
200.00
250.00
300.00
0.0 1000.0 2000.0 3000.0 4000.0 5000.0 6000.0 7000.0
World Population, millions
Irrig
ated
are
as, m
illion
ha
The Future
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World Population(middle estimate)
EuropeN. America
Latin Amer./Carib.CHINA
INDIA
Rest of Asia
Africa
Oceania
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
1950 1975 2000 2025 2050
peop
le -
mill
ions
Population Growth and Water Needs
0
2000
4000
6000
8000
10000
12000
14000
km3
fres
h w
ater
6000 6500 7000 7500 8000 8500 9000World Population, millions
DeficitAvailableBorrowUSEFlow needsInaccessible
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What next?
• Water not where needed - population growth in ‘wrong’ places
• Climate change• Novel resources ?
– desalination - expensive in energy– Ice– Pipe-lines -water expensive to transport
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Santa Barbara story
• 1970s drought• Water only $0.47/m3 - severe W shortage!• Desalination plant and pipe line built• 1996: Water now expensive - $1.55/m3 • demand drops to 61% of pre-drought level• desal. plant unnecessary (now only as back-
up)
Conclusions
• not enough water overall – there will be problems
• so solutions have to be more or less local• New technology• Litigation• War?
