Variability in the Water Footprint of Arable Crop Production across European Regions

Abstract

Crop growth and yield are affected by water use during the season: the green water footprint (WF) accounts for rain water, the blue WF for irrigation and the grey WF for diluting agri-chemicals. We calibrated crop yield for FAO's water balance model "Aquacrop" at field level. We collected weather, soil and crop inputs for 45 locations for the period 1992-2012. Calibrated model runs were conducted for wheat, barley, grain maize, oilseed rape, potato and sugar beet. The WF of cereals could be up to 20 times larger than the WF of tuber and root crops; the largest share was attributed to the green WF. The green and blue WF compared favourably with global benchmark values (R 2 = 0.64-0.80; d = 0.91-0.95). The variability in the WF of arable crops across different regions in Europe is mainly due to variability in crop yield (cv = 45%) and to a lesser extent to variability in crop water use (cv = 21%). The WF variability between countries (cv = 14%) is lower than the variability between seasons (cv = 22%) and between crops (cv = 46%). Though modelled yields increased up to 50% under sprinkler irrigation, the water footprint still increased between 1% and 25%. Confronted with drainage and runoff, the grey WF tended to overestimate the contribution of nitrogen to the surface and groundwater. The results showed that the water footprint provides a measurable indicator that may support European water governance.

Advancing Water Footprint Assessment Research: Challenges in Monitoring Progress towards Sustainable Development Goal 6

“…Early WF studies often focused on accounting (quantifying WFs), without adequate consideration of variabilities and uncertainties and without putting numbers in the wider environmental, economic, or social context. The studies by Gobin et al [14] and Evangelou et al [15] focus on showing the variability in WFs of crop production, while Kersebaum et al [16] quantify uncertainties in WF estimations. Some of the papers focus on understanding the driving forces behind increasing WFs [19][20][21][22][23].…”

“…Thirteen of the fourteen papers in this special issue consider green and blue WFs [14][15][16][17][18][19][20][21][22][23][24][25][26], while eight papers include grey WF estimation. All papers that include the grey WF specifically focus on pollution through nitrogen [14,15,17,19,21,22,25,27].…”

“…All papers that include the grey WF specifically focus on pollution through nitrogen [14,15,17,19,21,22,25,27]. The only paper that exclusively focuses on the grey WF is the one by Brueck and Lammel [27].…”

“…Gobin et al [14] estimate green, blue and grey WFs for 6 crops in 45 different fields in 15 different European countries over a period of 11 years. Evangelou et al [15] estimate green, blue and grey WFs of tomato production at 24 farms in the Pinios river basin in Greece over a period of three years.…”

Assessment of wheat’s water footprint and virtual water trade: a case study for Turkey

“…On the other hand, Gobin et al (2017) provided a variability analysis of the water footprint of arable crop production in Europe. Also, the temporal variability of the water footprint of cereal production in Canada was studied by Zhao et al (2019).…”