Societal use of fresh submarine groundwater discharge: An overlooked water resource

Terrestrial groundwater discharging directly into the sea (“fresh submarine groundwater discharge”, fresh SGD) is increasingly recognized as nutrient and pollutant pathway from land to coastal oceans. However, its active use by coastal populations and its role for coastal societies is nearly entirely neglected. Here we present examples from a variety of places and from all available sources around the world to highlight that fresh submarine groundwater discharge is widely valued as a water resource for drinking, hygiene, agriculture, fishing, tourism, culture, or ship navigation. In Peru, fresh SGD is used for drinking, on Tahiti for bathing, in Greece for irrigation, in Bali for blessing, and already Alexander von Humboldt noted the danger for smaller vessels from a submarine spring off Cuba, but at which Manatees gathered and were hunted by fishermen. These are just a few of the presented examples, which document the complex value fresh submarine groundwater discharge has for coastal communities. Because global change will strongly affect this water resource we should assess and understand that value, before the phenomenon will disappear at many locations due to terrestrial groundwater extraction or sea level increase.