Flooded road, but development hinders the infiltration of rainwater. | Photo: M. Copa
Andrew EdeJoan J. SerraPalma13/10/2026 19:07
Rainwater infiltration capacity, the maximum rate at which soil can absorb and transmit water from the surface into the ground, has decreased in the Balearics over the past 50 years because of the amount of development and the increasingly irregular patterns of rainfall: there is less frequent but more intense rainfall.
Cels García, a professor of physical geography at the University of the Balearic Islands, calculates that the lost infiltration capacity is approximately equivalent to the amount of desalinated water currently produced in the Balearics on an annual basis - around 20 cubic hectometres.
"The reduction in infiltration is due to increased development, which prevents rainwater from reaching the aquifers, and to increasingly irregular rainfall patterns. Rainfall is becoming less frequent but more intense, which hinders water penetration into the ground. In percentage terms, during the 1970s an average of 25% of rainwater infiltrated the soil in the Balearic Islands; today that figure is below 20%."
The expansion of land that has been built on physically prevents rainwater from soaking into the ground, and while rain can be torrential, the water runs off rapidly across the surface rather than efficiently filtering into the subsoil.
Average production from desalination has hovered around 17–18 cubic hectometres per year, although it has been as high as 27 at times of severe shortage.
García notes that in August, water reserves in the Balearics stood at "a worrying 38%". "In addition to factors such as development and irregular rainfall, the lower the aquifer levels, the harder it is for infiltrating rainwater to reach them, as some is lost as it percolates through the ground, thereby making the recovery of reserves more difficult."