Author: Louise Busschaert, PhD candidate at KU Leuven

Water is precious and essential for optimal agricultural production. Its availability is threatened in a changing climate, and therefore irrigation is increasingly monitored. Even if irrigation is becoming more and more efficient, will it be enough? The first question we could address is: how much water will we need to sustain optimal crop production in the future? I started exploring this topic for the European continent as part of my MSc thesis at KU Leuven, while majoring in soils and water systems. Now, I am continuing this research as part of my PhD. How did I get there? During my BSc and MSc degree (in bioscience engineering), many courses focused on field and plant-scale processes. After acquiring the necessary knowledge about these small-scale processes, I learned to look at the bigger picture in other courses, in which they addressed soil and water problems at larger scales. This led to the choice of a MSc thesis subject in this direction.

I used the newly developed spatial version of AquaCrop, developed by Shannon de Roos (Work Package 3), and applied it to a concrete research question: ‘What are the future trends in net irrigation requirements in Europe?’. Basically, I used the spatial AquaCrop to ‘look into the future’. To this end, consistent future climate data was required. Having an idea of the uncertainty of future predictions is also a challenge. To meet these requirements, I used meteorological data from the Inter-Sectoral Intercomparison Project (ISIMIP). ISIMIP aims to provide consistent climate input datasets. The model, with this new input data, performs well by comparing AquaCrop estimations of surface soil moisture to various satellite products, proving the model can be used to estimate future net irrigation requirements.

I generated maps showing the evolution of net irrigation requirements depending on the future emission scenario. The values presented on the maps compare the future requirements (during June, July and August) to the requirements of a reference period. This change is called . Results are clear: under high emission scenarios, more water will be required in the future. Future climate will not only have an influence on future water amounts, but it will also alter the variability of irrigation requirements. Irrigation needs will vary highly from one year to another in countries such as France, Belgium, and Germany. A paper describing this research is expected to be published next year. I will also present my findings in a 3-minute lightning poster presentation at the AGU Fall Meeting 2021.

The different research aspects gathered in this research allowed me to work closely with the KU Leuven team, specialized in modeling and remote sensing, and also to collaborate with Prof. Wim Thiery from the VUB (Brussels) to get a better understanding of climate change scenarios. But most importantly, it ultimately opened doors to a new adventure for me, namely a PhD.

What’s next? AquaCrop, has been upgraded to a newer version (from version 6 to 7), enabling the use of more functionalities. A big novelty is the inclusion of perennial crops in the model. This new version has been successfully implemented in the spatial AquaCrop system. We are also working on implementing AquaCrop into a data assimilation system, hoping to improve model predictions. As part of my PhD, I will keep on contributing to these new tools.