How much Water does Swiss Agriculture need now and in the Future?

© Annelie Holzkämper, Agroscope

Water for Irrigation Becoming increasingly Scarce

Due to climate change, summer discharge is decreasing on the Swiss Central Plateau while the potential demand for irrigation is rising. Availability of data on water consumption for irrigation is piecemeal at best. For the early detection and prevention of water-use conflicts, reliable estimates of agricultural water consumption under current and future conditions are therefore needed. Enter the FOEN-funded project ‘SwissIrrigationInfo’, run by Agroscope in cooperation with the University of Agricultural, Forest and Food Sciences HAFL. Agroscope's aim in this project was to develop and test a method that would help bridge existing information gaps as effectively as possible, thereby enabling an estimate of the total annual water consumption for agricultural irrigation in Switzerland.

A model-based attempt to bridge information gaps

The key part of the methodology is the FAO56 approach for estimating the irrigation demands of different crops on the basis of climate and soil characteristics. This model-based approach was parameterised for ten crops or crop groups as part of the project. In addition to knowledge gleaned from the literature and from expert sources, available data on irrigation practices for various sites, crops, and years were used to lend the greatest possible support to the crop-specific parameterisations. The irrigation data used are from the irrigation network of the HAFL as well as from the ‘Efficient Irrigation Vaud’ resources project.

Most irrigation in Switzerland for vegetables, fruits and grassland

The parameterised models were applied using national data on climate, soil and land use to estimate Swiss-wide water consumption for irrigation for 2021–2023 (Figure 1). Estimated consumption was about 9.5 million m³ for 2021, 41 million m³ for 2022 and 31 million m³ for 2023. According to these estimates, the crops with the greatest irrigation consumption were vegetables, fruit, and grassland. Estimated water consumption was particularly high in the southwestern parts of the Central Plateau and in the Valais.

Figure 1: Modelled irrigation volumes at plot level as a function of crop, soil, and climate in 2021, 2022 and 2023 (left to right; background: Swisstopo) from Baumgartner et al. 2025 (https://doi.org/10.34776/as212g)
[Saisonale Bewässerungsmenge [mm] = Seasonal irrigation volume [mm]]

Increased use of irrigation water expected in future

Based on the CH2018 locally downscaled climate projections, model calculations were conducted to estimate future irrigation volumes for all crops or crop groups considered here, then extrapolated to the national scale. Assuming that no climate protection measures are taken (RCP8.5), average annual water consumption was projected to increase by 20% by the end of the century (2077–2099). Assuming that moderate climate protection measures are taken (RCP4.5), consumption was estimated to increase by 5%.

Considerable uncertainties remain – more accurate data may be of help in future

Although the model parameterisations are based not only on knowledge from the literature and from expert sources but also to a large extent on real-world irrigation reference data, model estimates remain imprecise. Farmers’ decision-making behaviour regarding the use of irrigation varies greatly, limiting the ability of the models to accurately predict the volumes applied. At regional scale, the accuracy of the information on irrigated crop areas strongly influences the accuracy of the estimate. Where these data were available, the estimated volumes aligned quite well with the volumes actually withdrawn.

Better data on irrigated crop areas and additional reference information on irrigation and withdrawal volumes will be crucial for improving estimation accuracy in the future.

Further Information

Publications

Project partners

• Frank Liebisch (Agroscope)
• Helge Aasen (Agroscope)
• Andreas Keiser (HAFL)
• Andrea Marti (HAFL)

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