Large basins already have their reservoirs less than 80% of their capacity

Summer is affecting Spanish reservoirs. After almost a year of Hydrolyogical recoverysummer goes to the amount of reservoir water, which has been especially reduced in the downtown and north basins.

Two months. Since reaching its annual peak before the start of summer, the amount of water retained in Spanish swamps has descended significantly. If at the end of May the Spanish Water Reserve It was 77.5% of its capacity, nine weeks later It is 68.4%.

At a light pace. The speed at which the swamps are emptying this summer It’s somewhat faster that the average of recent years and considerably faster than in the last two summers. If in their peak the Spanish reservoirs accumulated 43,407 cubic hectometers (HM³), now they have 38,311 hm³, a decrease of 11.74% compared to this maximum (9.1% less compared to the total capacity of the system).

This fall is somewhat greater than usual in this period. If we took the same dates last year, the fall was 8.88%, while the average of the last 5 years was 11.18% for the same dates. 10.98% if we consider the last 10 years.

Different basins, different falls. The basin most affected by this fall is that of the coast of Galicia. The reservoirs of this basin have passed to save 548 to 417 hm³or what is the same, 23.91% less water.

Among the big basins, the largest falls have been seen in the Duero, which went from 7,040 to 6,031 hm³ (a 14.33%drop); and of the Guadalquivir, which passed from 4,905 to 4,206 hm³ (14.25% less).

Less restrictions. Part of the difference can be explained with the end of the drought that threatened our reservation last year at this point, a drought that affected all the basins of the Peninsula. The lack of water led the administrations to introduce Measures to limit consumption water.

Some measures that, as the rains arrived, were being lifted by the different administrations that introduced them. Now, After relaxing the measureswater consumption has been able to increase and, with it, the speed at which our swamps empties.

A June of the most anomalous. Summer is always a time of water stress: rainfall is usually minor and water consumption is greater. This year this is especially true, especially during the month of June.

The summer of 2025 began strongly. June was not only an extremely warm month (the warmest since we have records), it was also a drier month than is usually common on dates. Precipitation was about 68% of the usual in peninsular Spain.

Heat implies greater Evaporation of reservoirs water. A study Posted in 2000 It estimated at 1,400 hm³ the evaporated water in reservoirs and wetlands of Spain. This figure, of course, depends on factors such as temperature, but also on others such as the filling of the reservoirs (more water, more surface; already more surface, more evaporation). Heat makes more water to refresh us, also through greater energy consumption, and the lack of rains in some contexts must be supplied with water from reservoirs.

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Image | Pedro Luis Domínguez Ruiz