In several coastal regions simultaneously, a drop in the groundwater table is being observed. This decline is occurring at a rate of 50 cm per year, posing a threat of salinization to these areas and leading to potable water shortages.
Coastal groundwater serves as a vital source of drinking water across numerous global locations, yet it faces risks from over-extraction and saltwater intrusion, issues compounded by rising sea levels. A study conducted by a team of researchers from Johannes Gutenberg University Mainz and the German Climate Service Center in Hamburg, published in the journal Nature Water, utilized data from 480,000 monitoring wells, making it the most extensive dataset on global coastal groundwater to date.
Between 1990 and 2024, a significant shift in groundwater levels was identified in over 20% of the coastal areas examined. In specific locales, the decrease surpassed 50 centimeters annually. Since 2016, specialists have noted an overall acceleration in the speed of this lowering trend. The most pronounced declines were evident along the coasts of the United States and Central America, the Mediterranean, Southern Africa, India, and Southern Australia.
Areas where the groundwater level sits very close to sea level, as well as arid regions with high reliance on groundwater resources, have become particularly susceptible. As water tables fall, seawater infiltration becomes easier, resulting in a substantial risk of contamination with salt.
Over the next fifty years, a shortage of drinking water could potentially affect all coastal zones worldwide. This situation creates considerable hazards for over 30% of the global population residing near the sea. Furthermore, negative impacts will extend to local agricultural activities and existing ecosystems.
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