The green, blue and grey water footprint of crops and derived crop products release_byaxfvra2bhyro6xj7n53kyr3q

by M. M. Mekonnen, A. Y. Hoekstra

Published in Hydrology and Earth System Sciences by Copernicus GmbH.

2011   Volume 15, p1577-1600

Abstract

<strong>Abstract.</strong> This study quantifies the green, blue and grey water footprint of global crop production in a spatially-explicit way for the period 1996–2005. The assessment improves upon earlier research by taking a high-resolution approach, estimating the water footprint of 126 crops at a 5 by 5 arc minute grid. We have used a grid-based dynamic water balance model to calculate crop water use over time, with a time step of one day. The model takes into account the daily soil water balance and climatic conditions for each grid cell. In addition, the water pollution associated with the use of nitrogen fertilizer in crop production is estimated for each grid cell. The crop evapotranspiration of additional 20 minor crops is calculated with the CROPWAT model. In addition, we have calculated the water footprint of more than two hundred derived crop products, including various flours, beverages, fibres and biofuels. We have used the water footprint assessment framework as in the guideline of the Water Footprint Network. <br><br> Considering the water footprints of primary crops, we see that the global average water footprint per ton of crop increases from sugar crops (roughly 200 m<sup>3</sup> ton<sup>−1</sup>), vegetables (300 m<sup>3</sup> ton<sup>−1</sup>), roots and tubers (400 m<sup>3</sup> ton<sup>−1</sup>), fruits (1000 m<sup>3</sup> ton<sup>−1</sup>), cereals (1600 m<sup>3</sup> ton<sup>−1</sup>), oil crops (2400 m<sup>3</sup> ton<sup>−1</sup>) to pulses (4000 m<sup>3</sup> ton<sup>−1</sup>). The water footprint varies, however, across different crops per crop category and per production region as well. Besides, if one considers the water footprint per kcal, the picture changes as well. When considered per ton of product, commodities with relatively large water footprints are: coffee, tea, cocoa, tobacco, spices, nuts, rubber and fibres. The analysis of water footprints of different biofuels shows that bio-ethanol has a lower water footprint (in m<sup>3</sup> GJ<sup>−1</sup>) than biodiesel, which supports earlier analyses. The crop used matters significantly as well: the global average water footprint of bio-ethanol based on sugar beet amounts to 51 m<sup>3</sup> GJ<sup>−1</sup>, while this is 121 m<sup>3</sup> GJ<sup>−1</sup> for maize. <br><br> The global water footprint related to crop production in the period 1996–2005 was 7404 billion cubic meters per year (78 % green, 12 % blue, 10 % grey). A large total water footprint was calculated for wheat (1087 Gm<sup>3</sup> yr<sup>−1</sup>), rice (992 Gm<sup>3</sup> yr<sup>−1</sup>) and maize (770 Gm<sup>3</sup> yr<sup>−1</sup>). Wheat and rice have the largest blue water footprints, together accounting for 45 % of the global blue water footprint. At country level, the total water footprint was largest for India (1047 Gm<sup>3</sup> yr<sup>−1</sup>), China (967 Gm<sup>3</sup> yr<sup>−1</sup>) and the USA (826 Gm<sup>3</sup> yr<sup>−1</sup>). A relatively large total blue water footprint as a result of crop production is observed in the Indus river basin (117 Gm<sup>3</sup> yr<sup>−1</sup>) and the Ganges river basin (108 Gm<sup>3</sup> yr<sup>−1</sup>). The two basins together account for 25 % of the blue water footprint related to global crop production. Globally, rain-fed agriculture has a water footprint of 5173 Gm<sup>3</sup> yr<sup>−1</sup> (91 % green, 9 % grey); irrigated agriculture has a water footprint of 2230 Gm<sup>3</sup> yr<sup>−1</sup> (48 % green, 40 % blue, 12 % grey).
In application/xml+jats format

Archived Files and Locations

application/pdf  1.1 MB
file_6xe4wywvefeavmqcwzbudpvapm
ris.utwente.nl (web)
web.archive.org (webarchive)
application/pdf  2.0 MB
file_sxmrwc6tvvfyxioc6twevpmrr4
web.archive.org (webarchive)
dlc.dlib.indiana.edu (web)
application/pdf  493.1 kB
file_dwz2lieaszao5fpjrn2yvc2zvi
web.archive.org (webarchive)
ris.utwente.nl (web)
application/pdf  1.2 MB
file_a2vjj2josvawzbjx5kxyj6pavi
web.archive.org (webarchive)
web.archive.org (webarchive)
www.worldcocoafoundation.org (web)
www.hydrol-earth-syst-sci.net (web)
web.archive.org (webarchive)
+ 11 more URLs
Read Archived PDF
Preserved and Accessible
Type  article-journal
Stage   published
Date   2011-05-25
Language   en ?
Container Metadata
Open Access Publication
In DOAJ
In ISSN ROAD
In Keepers Registry
ISSN-L:  1027-5606
Work Entity
access all versions, variants, and formats of this works (eg, pre-prints)
Catalog Record
Revision: f469d1d4-78e6-4f9e-a459-03e2e9256e9f
API URL: JSON