SScientists from international research centers, universities and meteorological and space agencies visited the region of Pla d’Urgell in Lleida, northeastern Spain, to study the effects of climate change on water demand for crops.

Organizations such as NASA, the European Space Agency and the French National Meteorological Research Center will spend the summer studying how agriculture in a semi-arid climate affects different weather variables and how weather and climate prediction models for these regions can be improved.

They are also evaluating various Earth observation technologies capable of quantifying crop water consumption and surface soil moisture.

Carried out by the National Center for Meteorological Research (CNRM) and involving several Catalan institutions, including the Institute of Agri-Food Research and Technology (IRTA) and the Meteorological Service of Catalonia (SMC), the mission in question falls within the framework of of the LIAISE (Earth surface interactions with the atmosphere on the semi-arid Iberian environment), which was presented this week in Mollerussa and Linyola.

In the Pla d’Urgell and other semi-arid regions of the Mediterranean basin, water evaporates faster than elsewhere due to the heterogeneity of crop types and irrigation, and can affect the atmosphere , altering precipitation and low cloud formation.

“Current weather forecasting models are not entirely accurate in these semi-arid regions, so we need to know more about how different land uses interact with the atmosphere and assess their impact on the processes that generate clouds and summer storms, ”said Josep Ramon. Miró from the Applied Research and Modeling Division of SMC. In addition, there is a lack of data showing how to manage irrigation in these regions in a future marked by climate change, where fresh water for crops will be more in demand but less available.

“We need to learn how to manage water and we need technological tools that tell us more precisely how much we can use in an increasingly drier future,” said Joaquim Bellvert, researcher in the Efficient Use of Water program. water in IRTA agriculture.

“We also need to assess the effects of dams and river flows on the local climate and what they will be like in a climate change scenario.”
IRTA’s specialist knowledge in irrigation and the involvement of the local population were key factors in choosing Lleida’s agricultural model for the studies involved in the international mission.

“The Pla d’Urgell is a semi-arid region with many types of crops and a wide variety of irrigation systems; it is an ideal framework to improve the models of climate forecasting and irrigation that we need and to extrapolate them on a global scale ”, declared Joan Girona, institutional representative of IRTA in Lleida and in the Pyrenees.

“Catalonia is perfectly suited to international research campaigns of this type because of the density and quality of the MSC’s observation and remote sensing networks,” adds Eliseu Vilaclara, Director of the MSC.

“This underlines the value of the experimental campaigns carried out by the SMC since the beginning of the 20th century; 2021 is in fact the year of our centenary.

“We hope this project will improve our WRF mesoscale working model through better characterization of evapotranspiration and precipitation in transition zones between dry and irrigated lands.”

How to quantify the consumption of water crops?

Images from some satellites can be very useful in quantifying crop water consumption – called evapotranspiration – and soil moisture at the surface.

“Combining climate predictions with information on the amount of water used by crops will provide an essential tool to manage irrigation water more efficiently, both for individual smallholder farms and for communities of water users. irrigation, ”said mission coordinator, CNRM researcher Aaron Boone.

“The campaign will therefore also consist of evaluating different remote sensing techniques to obtain more precise information and achieve even more efficiency in water management, with a view to ensuring the overall sustainability of production and environmental systems.

To this end, NASA, SAFIRE and ESA will fly airplanes equipped with thermal, radar and hyperspectral sensors over the region in the coming days to calculate evapotranspiration, surface soil moisture and photosynthetic levels of plants. cultures.

The information obtained will be used for future space missions. IRTA, meanwhile, will contribute to the validation work by performing ground measurements, in addition to using the images provided to validate the existing satellite image models of the region’s evapotranspiration, in order to be able to then forecast the demand for water.

The other equipment installed in the different study areas of the Pla d’Urgell make it possible to measure the quantity of water used for crops, as well as to characterize the behavior of different meteorological variables at different heights in the atmosphere, from the level of the soil at the boundary layer.

The equipment in question includes the IRTA lysimeter station in Mollerussa, one of the few such installations in the world, which measures the water consumption of crops by means of a weighing system.

There are also a number of eddy covariance flux towers and scintillometers, which can be used to measure water and carbon dioxide fluxes and determine their directions. Other instruments, including WindRASS or UHF equipment, use ultrasound to take vertical measurements of wind and air temperature at different heights.