Antonio Collados Lara

Transboundary aquifers are groundwater reserves that extend across the territory of two or more countries, as is the case between Spain and Portugal. Globally, these aquifers supply 35 per cent of farmland irrigated with groundwater, but few are covered by international cooperation agreements. A study published in the journal PNAS has analysed water use in the 426 known transboundary aquifers. The results find no evidence that these aquifers, on average, suffer greater depletion than those located within a single country, although depletion tends to be concentrated near borders.

A new report from the United Nations University Institute for Water, Environment and Health (UNU-INWEH) toughens the discourse on the current water emergency by referring to an era of "global water bankruptcy". According to the report, the terms "water stress" or "water crisis" are no longer sufficient, as we find ourselves in a situation that goes beyond a temporary crisis, characterised by irreversible losses of natural water resources and the inability to return to historical levels. The report points out that, although not all basins are in water bankruptcy, "enough critical systems around the world have crossed these thresholds" and are interconnected through trade, migration, climate or geopolitics.