University of Alicante participates with the IGME in the first world map of land subsidence by groundwater extraction, published today in Science
The work is a key advance for the security of many areas of the planet by explaining where it can happen
The global map is the result of the research and can be used by anyone free of charge
Its application may be particularly relevant in coastal and riverine areas, where subsidence may increase the risk of flooding
World map of land subsidence (IGME map repository)
Alicante, 1 January 2021
An international team led by researchers of the Spanish Geological and Mining Institute of (IGME), Gerardo Herrera and Pablo Ezquerro, where the University of Alicante participates, have just completed the world's largest study on land subsidence, i.e. land subsidence caused by the extraction of groundwater. The work has been published in the journal Science on 1 January 2021. There, scientists have developed a model that explains where this phenomenon can occur. They have succeeded in drawing up a world map showing the areas susceptible to subsidence.
In particular, the IGME scientific team and its collaborators, including Roberto Tomás from the UA, IGME researchers Marta Béjar-Pizarro, Juan López-Vinielles and Rosa Mateos, and scientists from the UNESCO International Subsidy Initiative, have managed to propose a map that anyone anywhere in the world can consult to find out if the area in which they live, work or intend to live or build may have or may eventually have a problem with subsidence. This map can be particularly relevant in river lines or coastal areas where subsidence can increase the risk of flooding up to ten times faster than the rise in sea level caused by global warming. According to Roberto Tomás, almost 90% of the population exposed to this phenomenon is located in Asia. In Europe, the most dangerous areas are located mainly in the Mediterranean basin.
The deformation of the land due to subsidence has an effect on infrastructure and therefore on people's lives. The sinking of the ground causes cracks in these infrastructures and in the buildings, which might make them become unsafe. These deformations reach extremely high figures in some places, with subsidence of up to 30 centimetres a year, yet in most cases it is a slower process of one or a few centimetres a year. This slow deformation means that they go unnoticed by the people who live there, who will only be aware that the ground is sinking under their feet when the situation is so serious that cracks start to appear, or the floods become increasingly intense and recurrent as in the case of Venice. But this problem is also expected to grow. As Roberto Tomás explains, the increase in the demand for groundwater associated with the supply of the world's population and agricultural production will undoubtedly increase the intensity of this phenomenon in the near future in areas that are already active, and will encourage its development in other susceptible areas where it has not yet occurred.
The map will be public and can be used by anyone interested free of charge. "It is going to be very useful for regional authorities, for example, for those who manage the water basins to see what may happen in their areas and to be able to anticipate the problem, as Gerardo Herrera states.
The work published in Science comes from a research begun by Pablo Ezquerro, who, in 2017, was doing his PhD at the Spanish Geological and Mining Institute (IGME) supervised by Institute's scientist Gerardo Herrera. Ezquerro focused his research on the subsidence of the land caused by the extraction of water from underground aquifers in Lorca (Murcia), a danger known and studied for more than a hundred years. Research on land subsidence had always been local. Scientists in some areas suffering from this analysed what was happening in their regions and sought solutions. Pablo Ezquerro and Gerardo Herrera, from the Spanish Working Group on Land Subsidence, carried out a search for scientific publications on subsidence. They all referred to this subsidence from a local point of view. As reported by Gerardo Herrera, it was then that they thought of a pattern common to all the areas, and they found that pattern: there were conditions common to all areas of the world where this phenomenon of land deformation due to the extraction of water from underground aquifers.
To understand the relevance of this work, we must know that this geological phenomenon has led, for example, to Indonesia's decision to move its capital Jakarta from its current location to a new one on another island. In some areas of the world, the situation caused by land subsidence has become unsustainable, even forcing the relocation of cities, as is the case in Indonesia, whose government is considering moving its capital, Jakarta, to the island of Borneo, Roberto Tomás explained.