Why is there so little water in the Siurana and Riudecanyes reservoirs?

TarragonaThe rains in March have caused significant growth the Catalan marshes, which are already exceeding, on average, 62% of their capacity. The Baells reservoir in Berguedà has even had to release water because it already exceeded 95% of its total capacity, which is 109 hm³. However, looking at the reservoir data, the Siurana reservoir in Priorat is striking, with a modest 23.38% capacity, equivalent to 2.86 hm³, while the Riudecanyes reservoir, which is connected to the Siurana reservoir, is at 51% (2.74 hm³). Why haven't these two reservoirs absorbed as much water as the others?

The reason is twofold: first, this month's rainfall has been much more concentrated in the regions of Ripollès, Vallès Oriental, Baix Ebre, and Berguedà than in Priorat and Baix Camp. These two regions have also seen much more rainfall than in the same period last year, and thanks to this, they have managed to accumulate much more water. The Siurana reservoir, for example, despite not reaching a quarter of its capacity, was at a critical 2.93% a year ago.

However, the main reason why these reservoirs haven't received as much water as the others is due to the drained area, that is, the area of land that ultimately conveys water to the reservoirs. Continuing with the Siurana reservoir, its drainage area is only 60 km². The Riudecanyes reservoir drains even less: just 31 km². "It practically has to rain on the reservoirs for them to fill, because their basin is very small," explains Xavi Segura, head of Meteorology at the newspaper ARA. To give you an idea, the Sau reservoir, which accumulates 113 hm³, has a drained basin area of 1,564 km².

The Siurana reservoir is connected to the Riudecanyes reservoir, and its water comes from the Riudecanyes Irrigation Community, which holds a concession until 2060. The community is made up of farmers and also the municipalities of Reus, Selva del Camp, and Riudoms, as well as some industries. Since the drought was declared, the water from these reservoirs has been unusable, although a meeting is planned for the end of the month that could change things: "Until the Reservoir Commission meets at the end of April, we won't know what supply we'll have for irrigation, but obviously, some irrigation will be possible."

Controversial concession

This concession, approved during the Franco regime, causes significant tension in the region. The most significant concern is the Siurana River, which, due to the lack of rainfall and the fact that much of its water is diverted to the reservoir, lacks sufficient flow. Activists from the Group for the Study and Protection of Catalan Ecosystems (GEPEC) constantly denounce "the deplorable situation of the Siurana River" despite it being "a natural area of great ecological importance that enjoys legal protection" (PEIN and Natura 2000 Network). In 2001, the Catalan Water Agency (ACA) agreed with irrigators to guarantee a minimum flow of 20 liters per second, but a year ago, the Ebro Hydrographic Confederation (which depends on the State and is responsible for the river's flow) established that it should be lowered. The measure was applauded by environmentalists but criticized by the Irrigation Community. "Thanks to this new flow, which has been respected, we have saved the river," celebrates Andreu Escolà, a member of GEPEC who has been sued twice by the Irrigation Community and for whom they were seeking up to eight years in prison. The first complaint, which has since been dismissed, was for having stolen the Francoist plaque stating that the reservoir is the property of the Irrigation Community, while the second, which is still ongoing, is for having blocked the passage of water from the Siurana River to the reservoir, allowing more water to flow down the river.

New transfer

In January of last year, during a visit to Falset, the then Climate Action Councillor, David Mascort, announced that The Government plans a transfer from the Ebro to carry water to the Guiamets and Siurana reservoirs to guarantee irrigation in Priorat. Environmentalists consider the first transfer "justifiable and viable," provided the Ebro's flow allows it, but warn that if the Generalitat carries water to the Siurana reservoir, it could become "a new covert transfer of the Ebro River's waters to the Camp de Tarragona region."

At the same time, is already underway The construction of a new regeneration plant so that the Reus wastewater treatment plant can improve water quality. For thirty years, the water used by the people of Reus has been treated at the wastewater treatment plant and then returned to the sea. Each year, 6 cubic hectometers of water are released, which, with the new treatment plant cycle, could be used for irrigation.