12 Jan 2022
12 Jan 2022
Status: a revised version of this preprint is currently under review for the journal HESS.

Net irrigation requirement under different climate scenarios using AquaCrop over Europe

Louise Busschaert1, Shannon de Roos1, Wim Thiery2, Dirk Raes1, and Gabriëlle J. M. De Lannoy1 Louise Busschaert et al.
  • 1Department of Earth and Environmental Sciences, KU Leuven, Heverlee, B-3001, Belgium
  • 2Department of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, Brussels, B-1050, Belgium

Abstract. Global soil water availability is challenged by the effects of climate change and a growing population. On average 70 % of freshwater extraction is attributed to agriculture, and the demand is increasing. In this study, the effects of climate change on the evolution of the irrigation water requirement to sustain current crop productivity are assessed by using the FAO crop growth model AquaCrop version 6.1. The model is run at 0.5° lat × 0.5° lon resolution over the European mainland, assuming a general C3-type of crop, and forced by climate input data from the Inter-Sectoral Impact Model Intercomparison Project phase three (ISIMIP3).

First, the performance of AquaCrop surface soil moisture (SSM) simulations using historical meteorological input from two ISIMIP3 forcing datasets is evaluated with satellite-based SSM estimates. When driven by ISIMIP3a reanalysis meteorology for the years 2011–2016, daily simulated SSM values have an unbiased root-mean-square difference of 0.08 and 0.06 m3m−3 with SSM retrievals from the Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) missions, respectively. When forced with ISIMIP3b meteorology from five Global Climate Models (GCM) for the years 2011–2020, the historical simulated SSM climatology closely agrees with the climatology of the reanalysis-driven AquaCrop SSM climatology as well as the satellite-based SSM climatologies.

Second, the evaluated AquaCrop model is run to quantify the future irrigation requirement, for an ensemble of five GCMs and three different emission scenarios. The simulated net irrigation requirement (Inet) of the three summer months for a near and far future climate period (2031–2060 and 2071–2100) is compared to the baseline period of 1985–2014, to assess changes in the mean and interannual variability of the irrigation demand. Averaged over the continent and the model ensemble, the far future Inet is expected to increase by 67 mm year–1 (+30 %) under a high emission scenario Shared Socioeconomic Pathway (SSP) 3-7.0. Central and southern Europe are the most impacted with larger Inet increases. The interannual variability of Inet is likely to increase in northern and central Europe, whereas the variability is expected to decrease in southern regions. Under a high mitigation scenario (SSP1-2.6), the increase in Inet will stabilize around 40 mm year–1 towards the end of the century and interannual variability will still increase but to a smaller extent. The results emphasize a large uncertainty in the Inet projected by various GCMs.

Louise Busschaert et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-631', Anonymous Referee #1, 10 Feb 2022
  • RC2: 'Comment on hess-2021-631', Anonymous Referee #2, 16 Feb 2022

Louise Busschaert et al.

Louise Busschaert et al.


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Short summary
Increasing amounts of water are being used for agriculture. Therefore, we looked into how the irrigation requirement will evolve under a changing climate over Europe. Our results show that, for the end of the century and under high emissions, the irrigation water will increase by 30 % compared to the year 2000. Moreover, the irrigation requirement is likely to vary more from one year to another. However, if emissions are mitigated, these effects are reduced.