Grey Water Footprint Guidelines released

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The grey water footprint guidelines have been released:
Franke, N.A., Boyacioglu, H. and Hoekstra, A.Y. (2013) Grey water footprint accounting: Tier 1 supporting guidelines, Value of Water Research Report Series No. 65, UNESCO-IHE, Delft, the Netherlands.

From the introduction:
The Water Footprint Assessment Manual recommends a three-tier approach for estimating diffuse pollution loads entering a water body. […] From tier 1 to 3, the accuracy of estimating the load reaching a water body increases, but the feasibility of carrying out the analysis decreases because of the increasing data demand. […] Tier 1 simply uses a leaching-runoff fraction to translate data on the amount of a chemical substance applied to the soil to an estimate of the amount of the substance entering the groundwater or surface water system. [… Tier 2 and 3 use models to estimate leaching and runoff …]

Up to date, Grey Water Footprint (GWF) studies have been based on the tier-1 level and also in the near future this is expected to remain so, at least in practical applications by business and governments. […] This has been the reason for WFN to develop the tier 1 supporting guidelines as presented in this report. In order to obtain the necessary expert inputs and feedback, a panel of experts was formed. The GWF Expert Panel contributed to this guidance document by advising on key issues that must be addressed when estimating a GWF at the tier 1 level.

The report addresses three subjects: (i) how to estimate leaching-runoff fractions depending on the chemical substance, environmental conditions and application practice; (ii) what water quality standards (maximum allowable concentrations) to use in the calculations; and (iii) what to assume regarding natural background concentrations.

To download the report, please visit:
http://www.waterfootprint.org/Reports/Report65-GreyWaterFootprint-Guidelines.pdf