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Water scarcity

An international perspective

Prof Alan MacDonald

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Are we running out of fresh water?

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It depends....

• What do you want to use it for...Withdrawals

• 60,000 km3 annual renewable freshwater

• 4,000 km3 annual withdrawalsAgriculture

Industry

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• Ignores rain fed agriculture – so much more used

g

Source FAO 2010

global water stress...(population, access and water availability)

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“people should be even more worried if you start to account for climate change and population growth” BBC September 2010

Nature 467: 555–561

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© NERC All rights reservedSource Tony Allan

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waterfootprint.org

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Water future is in our hands

99 billion

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Back to basics

0 1 3

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1 – 34 – 67 – 11 12

Length of dry season(average 1951 – 1995 is < 25 mm)

Source: Hunter et al. PLOS Medicine 7(11)

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150

0 b

irth

s)

< 11 - 22 5

GDP per capita(1000 US$)

< 11 - 5

5 20

Population(million)

Improved access to water: fundamental

50

100

fan

t m

ort

alit

y (p

er 1

000 2 - 5

> 55 - 20

> 20

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800

0 20 40 60% without clean water

Inf

Source: Hunter et al. PLOS Medicine 7(11)

Irrigation: small-scale and/or intensive

© NERC All rights reserved Source: Calow et al 2010 Ground Water 48, 246-256

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So where does the water come from?

... groundwater

Naturally protected

Can meet dispersed rural demand

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Generally good natural quality

DFID grant 2010-11: to improve understanding of groundwater

Looking deeper: groundwater

understanding of groundwateracross Africa and its resilience to climate change

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Volumes of groundwater storage

1. Overall storage high: 0.5 - 1 million km3

2. Dominated by north yAfrican basins

3. But often 20 times more storage than used annually by a handpump

© NERC All rights reservedSource: MacDonald et al 2012 ERL 7 (2)

Accessing groundwater

© NERC All rights reservedSource: MacDonald et al 2012 ERL 7 (2)

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www.bgs.ac.uk

New project Indo-GangeticBasin: 2012 – 2014

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What about renewability?

Headlines – recharge will decline with climate change

Evidence much more

Recharge vs rainfall for 80 African studies

Evidence much more complicated - recharge could increase

Importance of natural stores and episodic recharge

© NERC All rights reservedSource: MacDonald et al 2011. BGS OR/11/031

Water quality issues – from agriculture

Salinisation (e.g. Mongolia)

Nitrate / pesticidesp

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Source: Ó Dochartaigh et al 2010

Hydrogeology Journal18: 1939-1952

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27o

Arsenic( g L--1)

<10

Water quality issues: natural

arsenic (e.g. Bangladesh)

fluoride (e g Ethiopia)

23o

24o

25o

26o<1010-5050-200>200

INDIA

INDIA

fluoride (e.g Ethiopia)

natural salinity

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88o 89o 90o 91o 92o 93o20o

21o

22o

'Groundwater Studies of Arsenic Contamination in Bangladesh'DPHE/BGS/DFID (2000)

INDIA

200 km

n=3546

01020304050

%

Summary

Water Scarcity – its complicated

Needs a thorough understanding of theNeeds a thorough understanding of the water resources and processes

Don’t ignore groundwater

Water security and water scarcity are different

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Drinking water should always be found –Water for Food is the big user

Need to manage the water resources for others and future generations

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© NERC All rights reservedSource Tony Allan