Leiria, July 16, 2024 (Lusa) - Climate change has forced managers of an 80-year-old irrigation system in the valley of the River Lis, in west-central Portugal, to make changes to ensure that farmers have water available when they need it, according to the association made up of the system's users.

 "We have a change in the rainfall pattern and that's what we feel most when we talk about climate change. And we need to have an irrigation system that fulfils this purpose," Henrique Damásio, managing director of the Lis Valley Irrigators and Beneficiaries Association, told Lusa.

According to Damásio, this is the great challenge facing the association, which has 3,686 members and covers an area of 2,000 hectares divided into 11,000 plots, from the outskirts of Leiria to Vieira de Leiria, in the municipality of Marinha Grande. The main crops grown in the area are maize and vegetables.

According to the managing director, there has been a major change in rainfall patterns and "it's not just the problem of not having enough water to water the crops at one time and then needing it at another time.

"As the rainfall is much more concentrated, it infiltrates less into the land, because as it is torrential it flows more directly into the water courses and is drained into the sea, and this means that when it's not raining, the water available in the environment is much less," he explained.

Damásio emphasised that, year after year, the River Lis "gets less and less water in the dry season, when it doesn't rain" - so the challenge is to provide the area with an irrigation infrastructure that people can use when they need it, but that requires less water overall than before, because there are fewer inflows.

"If we continue with the same irrigation system as we had in the last eighty years, in a very short time... there will have to be rationing in the distribution of water, because it's not enough for all that people want," he said, noting that there have been years when this has already happened.

"Therefore, we need to adopt irrigation systems that use less water," he said, adding that "it's true that agriculture is only interested in using as little water as possible for crops to have a yield and no more than that" but this requires "more efficient systems, with fewer losses, that people can use whenever they need it with pressure."

Damásio explained that this is what is being implemented in part of the Lis hydro-agricultural perimeter.

"Of the 2,000 hectares, we already have a block of 300 working with this system in which people swipe an identifier (similar to an electronic command to turn off a home alarm) next to the hydrant that supplies them with water" counted by the cubic metre on a meter, he explained, adding that users pay for the amount of water consumed.

This adaptation will now be implemented on another 400-hectare block, work on which is currently underway, with the aim being to extend this system to the remaining 1,300 hectares.

Damásio added that, in the context of climate change, another problem relates to more extreme phenomena, such as strong winds.

"Since we're now very involved in the conversion of the irrigation system, we haven't started that process yet, but we intend to start it in the not too distant future, which is the introduction of hedges," he said.

The delegate noted that the added value of hedges is that they reduce wind speed, divide up the property and, as they are not very tall, they do not cast shade over crops and provide shelter for wildlife.

Meanwhile, Damásio noted that in recent years records have been broken for the amount of rain falling during a period, so another concern is the waterproofed areas around the Vale do Lis hydro-agricultural perimeter.

"When these torrents happen, they cause flooding and thus damage crops," he emphasised, noting that when these areas, from industrial to residential zones, were sealed off, no care was taken to channel this rainwater.

In this sense, "when there are these sharp [downpours], which has been the pattern in recent years", they affect farmers "a lot, because these waters come unduly, most of them into the hydro-agricultural perimeter and then cause damage to the crops.

"This is now, in fact, our biggest negative externality and the one that worries me the most," he said.

SR/ARO // ARO.

Lusa