Water Footprint Accounting for Water Quality
CEO Water Mandate Stockholm, 16 August 2009 Maite M. Aldaya Arjen Hoekstra Twente Water Centre – University of Twente – the Netherlands Water Footprint Network
www.waterfootprint.org Overview Presentation
1. Introduction to water footprints
2. Accounting for water quality
3. The way forward Introduction to water footprints Water footprint of a product
► 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.
► type of water use: Green water footprint Blue water footprint Grey water footprint Components of a water footprint
Direct water footprint Indirect water footprint consumption Green water footprint Green water footprint Water Water withdrawal
Non-consumptive water use (return flow) Blue water footprint Blue water footprint pollution Water
Grey water footprint Grey water footprint The traditional statistics on water use
[Hoekstra, 2008] The water footprint of a business
Virtual Virtual Virtual water water water flow Food flow flow Farmer processer Retailer Consumer
green blue blue blue grey grey grey water grey and water water water water water water blue use use use water use
Supply chain WF Operational WF End-use WF of a product
The traditional statistics on corporate water use
[Hoekstra, 2008] Accounting for water quality Grey water footprint
• volume of polluted freshwater that associates with the production of a product in its full supply-chain. • calculated as the volume of water that is required to dilute pollutants to such an extent that the quality of the water remains above agreed water quality standards. Grey water footprint
Load L 3 ► Total WFgrey of activity (m ) = = Standard cmax
L / cmax 3 ► WFgrey per unit of product (m /ton) = Prod
L – Load of pollutants entering the water system (kg/yr) 3 cmax– Maximum acceptable concentration for the pollutant considered (kg/m ) Prod – Production (ton/yr)
[Hoekstra & Chapagain, 2008] Grey water footprint
1. Estimation for the different pollutants
2. Select the pollutant with the highest dilution volume as the most critical one (if this pollutant has been sufficiently diluted, all the other pollutants have been sufficiently diluted as well)
[Hoekstra, 2009] Grey water footprint related to nitrogen
Grey WF related to cotton production in India
L Applic. rate = 66 kg/ha L = 6.6 kg/ha ► Total WF of activity = grey c Leaching rate = 10% max = 5,887 106 m3/yr cmax = 10 mg/l * Y = 0.6 ton/ha L / cmax ► WFgrey per unit of product = Prod
= 1,062 m3/ton
* EPA (2005) [Hoekstra & Chapagain, 2008] Grey water footprint related to nitrogen of EU´s cotton consumption
[Hoekstra & Chapagain, 2008] Grey water footprint related to nitrogen used in cotton production
3 WFgrey per unit of product (m /ton)
Turkmenistan Uzbekistan Turkey USA Greece China Syria Egypt Mexico Pakistan Mali India
Brazil
Australia
Argentina
World average - 622 m3/ton
[Hoekstra & Chapagain, 2008] The way forward www.waterfootprint.org
Mission: Promoting sustainable, equitable and efficient water use through development of shared standards on water footprint accounting and guidelines for the reduction and offsetting of impacts of water footprints.
Network: bringing together expertise from academia, businesses, civil society, governments and international organisations.
Thank you