Preprints
https://doi.org/10.5194/hess-2021-329
https://doi.org/10.5194/hess-2021-329

  27 Jul 2021

27 Jul 2021

Review status: this preprint is currently under review for the journal HESS.

Historical simulation of maize water footprints with a new global gridded crop model ACEA

Oleksandr Mialyk1, Joep F. Schyns1, Martijn J. Booij1, and Rick J. Hogeboom1,2 Oleksandr Mialyk et al.
  • 1Multidisciplinary Water Management group, Faculty of Engineering Technology, University of Twente, Enschede, The Netherlands
  • 2Water Footprint Network, Enschede, The Netherlands

Abstract. Crop water productivity is a key element of water and food security in the world and can be quantified by the water footprint (WF). Previous studies have looked at the spatially explicit distribution of crop WFs but little is known about the temporal dynamics. We develop a new global gridded crop model – AquaCrop-Earth@lternatives (ACEA) – that can simulate three consumptive WF components: green (WFg), blue from irrigation (WFbi), and blue from capillary rise (WFbc) at high temporal and spatial resolutions. The model is applied to analyse global maize production during 1986–2016 at 5 × 5 arc minute grid. Our results show that in 2012–2016, the global average unit WF of maize is 723.2 m3 t−1 y−1 (89.5 % WFg, 8.3 % WFbi, 2.2 % WFbc) with values varying greatly around the world. Regions characterised by high agricultural development generally show a small unit WF and its interannual variation, such as Western Europe and Northern America (WF < 500 m3 t−1 y−1, CV < 15 %). On the contrary, regions with low agricultural development show opposite outcomes, such as Middle and Eastern Africa (WF > 2500 m3 t−1 y−1, CV > 40 %). Since 1986, the global unit WF of maize has reduced by 34.6 % mainly due to the historical decrease in yield gaps. However, due to the rapid expansion of rainfed and irrigated cropland, the global WF of maize production has increased by 48.8 % peaking at 762.9 × 109 m3 y−1 in 2016. As many regions still have a high potential in decreasing yield gaps, the unit WF of maize is likely to continue reducing, whereas the WF of maize production is likely to continue growing as humanity’s rising appetite can lead to further cropland expansion. The simulation of other crops with ACEA is necessary to assess the pressure of overall crop production on ecosystems and freshwater resources worldwide.

Oleksandr Mialyk et al.

Status: open (until 21 Sep 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-329', Anonymous Referee #1, 06 Aug 2021 reply
  • RC2: 'Comment on hess-2021-329', Anonymous Referee #2, 06 Aug 2021 reply
  • RC3: 'Comment on hess-2021-329', Anonymous Referee #3, 01 Sep 2021 reply

Oleksandr Mialyk et al.

Oleksandr Mialyk et al.

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Short summary
The growing demand for crops brings us to sustainable limits of water use. Thus, to stay within these limits, we need to decrease crop water footprints (WF). To see how crop WFs change in time, we develop a new global crop model (called ACEA) and apply it to study maize during 1986–2016. We see that average maize WF has decreased by ~35 %, but total water consumption has increased by ~49 %. Other crops should be studied to see the overall dynamics in WFs of crop production worldwide.