Global groundwater resources are being depleted due to climate change and an increasing population. This is leading to a reliance on groundwater for farming and urban use. However, pumping groundwater can cause the ground above to sink, as the underground water is drained and the ground collapses. A new study has now mapped this loss of groundwater storage capacity around the world.
The study, published in the journal Nature Communications, examined how groundwater extraction is causing land subsidence and aquifer collapse. The researchers found that approximately 17 km³ of aquifer storage capacity is disappearing each year, equivalent to the size of 7,000 Great Pyramids of Giza. This loss is permanent and reduces the amount of water that can be captured and stored. Around 75% of this subsidence is happening in cropland and urban areas, highlighting the need for better groundwater management globally.
To identify areas where data was not available, the team used advanced machine learning techniques. They collected all publicly available information and built a computer model to predict subsidence using factors like land use and climate data. The model’s accuracy was tested in regions where subsidence has already been observed, allowing the study to be expanded to include rural and understudied areas.
The study found that the United States, China, and Iran have the highest groundwater storage loss. California and Arizona experience significant land subsidence due to their reliance on groundwater for irrigation. In urban areas like Mexico City, subsidence is strongly linked to groundwater use.
The study also predicts high subsidence rates in regions like Afghanistan, Uzbekistan, Azerbaijan, and Syria, where there is a lack of previous data. Even regions with low subsidence rates, such as Europe, still face infrastructure damage and coastal issues. Arsenic contamination and saltwater intrusion are additional consequences of land subsidence.
The problem is not limited to arid regions, as even humid areas like Bangladesh, India, and Vietnam heavily rely on groundwater. The researchers hope their data can help water managers understand the extent of groundwater storage loss in their regions.
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