water footprint a tool for water policy analysislibrary.tee.gr/digital/m2583/m2583_hoekstra.pdf ·...

Water footprint – a tool for water

policy analysis

Prof. Arjen Hoekstra

Universiteit Twente / Water Footprint Network

www.waterfootprint.org

The total water footprint of a consumer in Greece

► about 3% of the water footprint is at home.

200 litre/day

► about 47% of the Greek

water footprint lies abroad.

[Mekonnen & Hoekstra, 2011]

► about 97% of the water footprint is ‘invisible’, it is

related to the products consumers buy in the

supermarket.

5800 litre/day for agricultural products

400 litre/day for industrial products

Total WF: 6400 litre/day

The total water footprint of a consumer in Greece

[Mekonnen & Hoekstra, 2011]

- ► Globalization of water

- ► The water footprint concept

- ► Water footprint of nations

- ► What can we do?

Production

Globalization of water

Water consumption and

pollution related to production

for export; water is not factored into

the price of traded commodities

Consumption

Water saving, but also

water dependency

TRADE Trade

Cotton for export

1989 2008

Former Aral Sea, Central Asia

Flowers from Kenya Decline of lake level in Lake Naivasha

[Mekonnen & Hoekstra, 2010]

Calculated lake level

without accounting for

water abstraction

Copper mining

Sacramento Basin, California, USA

Water pollution

The water footprint

concept

► the volume of fresh water used to produce the product,

summed over the various steps of the production chain.

► when and where the water was used:

a water footprint includes a temporal and spatial dimension.

The water footprint of a product

Green water footprint

► volume of rainwater evaporated

or incorporated into product

Blue water footprint

► volume of surface or groundwater

evaporated or incorporated into product

Grey water footprint

► volume of polluted water.

The water footprint of a product

Direct water footprint Indirect water footprint

Green water footprint Green water footprint

Blue water footprint Blue water footprint

Grey water footprint Grey water footprint

Wate

r

consum

ptio

n

Wate

r

pollu

tion

[Hoekstra et al., 2011]

Return flow

Water withdrawal

The traditional

statistics

on water use

Components of a water footprint

Grey water footprint

Process

Freshwater body

Load = Effl ×ceffl Abstr × cact

Substance intake

= Abstr × cact

Substance output

= Effl ×ceffl

Critical load = R (cmax - cnat)

The water footprint

of a product

sugar crops 200 litre/kg

vegetables 300 litre/kg

starchy roots 400 litre/kg

fruits 1000 litre/kg

cereals 1600 litre/kg

pulses 4000 litre/kg

poultry 4000 litre/kg

pork 6000 litre/kg

beef 15000 litre/kg

global averages

[Mekonnen & Hoekstra, 2010]

The water footprint of products

[Hoekstra & Chapagain, 2008]

Food

► 1300 kg of grains

(wheat, oats, barley, corn, dry peas, soybean, etc)

► 7200 kg of roughages

(pasture, dry hay, silage, etc)

Water

► 24000 litres for drinking

► 7000 litres for servicing.

99%

1%

[Hoekstra & Chapagain, 2008]

[Hoekstra & Chapagain, 2008]

Meat versus vegetarian diet

Meat diet kcal/day litre/kcal litre/day

Vegetarian

diet kcal/day litre/kcal litre/day

Animal

origin 950 2.5 2375

Animal

origin 300 2.5 750

Vegetable

origin 2450 0.5 1225

Vegetable

origin 3100 0.5 1550

Total 3400 3600 Total 3400 2300

Animal

origin 350 2.5 875

Animal

origin 200 2.5 500

Vegetable

origin 2350 0.5 1175

Vegetable

origin 2500 0.5 1250

Total 2700 2050 Total 2700 1750

Meat versus vegetarian diet

Meat diet kcal/day litre/kcal litre/day

Vegetarian

diet kcal/day litre/kcal litre/day

Animal

origin 950 2.5 2375

Animal

origin 300 2.5 750

Vegetable

origin 2450 0.5 1225

Vegetable

origin 3100 0.5 1550

Total 3400 3600 Total 3400 2300

Animal

origin 350 2.5 875

Animal

origin 200 2.5 500

Vegetable

origin 2350 0.5 1175

Vegetable

origin 2500 0.5 1250

Total 2700 2050 Total 2700 1750

Water footprint of biofuels from different crops [litre/litre]

[Gerbens-Leenes, Hoekstra & Van der Meer, 2009]

► coherent energy-

water strategies?

Car driving on

bio-ethanol from

sugar beet:

40-210 litre/km

Water footprint of nations

Consumption

Export

Pro

ductio

n

Imp

ort

Internal

water

footprint

External

water

footprint

WF of

national

consumpt.

Water use

for export

Virtual water

import for re-

export

Virtual

water

export

+

+

=

=

WF

within

nation

Virtual

water

import

+ +

= =

Virtual

water

budget

+

+ =

=

National water use accounting framework

The traditional

statistics on

water use, but

then limited to

withdrawals

Water footprint of national consumption

[Mekonnen & Hoekstra, 2011]

Water footprint of national consumption

[Mekonnen & Hoekstra, 2011]

Global average water footprint

► global water footprint

reduction targets?

► a Kyoto

protocol for

water?

National virtual water balances

[Mekonnen & Hoekstra, 2011]

► WTO trade rules?

Annual average monthly blue water scarcity

Number of months with blue water scarcity > 100%

[Hoekstra & Mekonnen, 2011]

► an international

water pricing protocol? ► minimum

water rights?

Virtual water transfers in China

Northwest Northeast

Huang-huai-hai North-central

North China

Yangtze Southeast

Southwest South-central

South China

26

13

13

14

26

13

1310

Import =2

Import =1

Export =2

Import =3

Export =1 Import =8

Import =8

Export =7

Export =9

Import =6

Unit: Gm3/yr

52 Gm3/yr

[Ma et al., 2006; Hoekstra & Chapagain, 2008]

9

4

2

9

22

10

+4

-8 +34

-46

1

13

5

North India

South India

East India

West India

Virtual water flows India

[Kampman et al., 2008]

What can we do?

Consumers or consumer or environmental organizations

push businesses and governments to address water use and

impacts along supply chains.

Some businesses act voluntarily in an early stage, driven by

consumers or investors.

Governments promote businesses in an early phase and

implement regulations in a later phase.

Governments, companies, consultants and accountants use

same standard definitions and calculation methods.

International cooperation, through UN and other institutions.

Water footprint reduction: a shared responsibility

► product labeling?

► certification of industries?

► water disclosure?

► global water footprint reduction targets?

► a Kyoto protocol on water?

► WTO trade rules?

► an international water pricing protocol?

► minimum water rights?

► coherent energy-water strategies?

International water governance