Geosci. Model Dev. Discuss., 6, 645-684, 2013
© Author(s) 2013. This work is distributed
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This discussion paper has been under review for the journal Geoscientific Model Development (GMD). Please refer to the corresponding final paper in GMD.
A site-specific agricultural water requirement and footprint estimator (SPARE:WATER 1.0) for irrigation agriculture
S. Multsch1, Y. A. Al-Rumaikhani2, H.-G. Frede1, and L. Breuer1
1Research Centre for BioSystems, Land Use and Nutrition, Institute for Landscape Ecology and Resources Management, Justus-Liebig-University Giessen, Giessen, Germany
2National Centre for Water Technique, King Abdulaziz City for Science and Technology, Riyadh, Kingdom of Saudi Arabia

Abstract. The water footprint accounting method addresses the quantification of water consumption in agriculture, whereby three types of water to grow crops are considered, namely green water (consumed rainfall), blue water (irrigation from surface or groundwater) and grey water (water needed to dilute pollutants). Most of current water footprint assessments focus on global to continental scale. We therefore developed the spatial decision support system SPARE:WATER that allows to quantify green, blue and grey water footprints on regional scale. SPARE:WATER is programmed in VB.NET, with geographic information system functionality implemented by the MapWinGIS library. Water requirement and water footprints are assessed on a grid-basis and can then be aggregated for spatial entities such as political boundaries, catchments or irrigation districts. We assume in-efficient irrigation methods rather than optimal conditions to account for irrigation methods with efficiencies other than 100%. Furthermore, grey water can be defined as the water to leach out salt from the rooting zone in order to maintain soil quality, an important management task in irrigation agriculture. Apart from a thorough representation of the modelling concept we provide a proof of concept where we assess the agricultural water footprint of Saudi Arabia. The entire water footprint is 17.0 km3 yr−1 for 2008 with a blue water dominance of 86%. Using SPARE:WATER we are able to delineate regional hot spots as well as crop types with large water footprints, e.g. sesame or dates. Results differ from previous studies of national-scale resolution, underlining the need for regional water footprint assessments.

Citation: Multsch, S., Al-Rumaikhani, Y. A., Frede, H.-G., and Breuer, L.: A site-specific agricultural water requirement and footprint estimator (SPARE:WATER 1.0) for irrigation agriculture, Geosci. Model Dev. Discuss., 6, 645-684, doi:10.5194/gmdd-6-645-2013, 2013.
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