Coastal karst aquifers and submarine springs: what future for their water resources?

Abstract

This paper is intended to be a reminder of a series of scientific works whose origin is largely attributable to G. de Marsily, without attempting to make an exhaustive overview of submarine springs and coastal karst aquifers. The main results show that coastal karst aquifers with their submarine outlets and the possibility of natural seawater intrusion are particularly fragile and must be studied and managed with appropriate tools. For the coming decades, the evolution of the climate as results from the IPCC scenarios leads us to question the effects of the increase of sea level on this coastal resource, and the effects of frequent and severe droughts, added to an increase in withdrawals from aquifers caused by the coastalisation of the population.Résumé. Cet article a pour objectif de rappeler une série de travaux scientifiques dont l'origine est largement attribuable à G. de Marsily, sans chercher à faire un tour d'horizon exhaustif des sources sous-marines et des aquifères karstiques côtiers. Les principaux résultats montrent que les aquifères karstiques côtiers avec leurs exutoires sous-marins et la possibilité d'intrusion naturelle d'eau de mer sont particulièrement fragiles et doivent être étudiés et gérés avec des outils appropriés. Pour les décennies à venir, l'évolution du climat telle qu'elle résulte des scénarios du GIEC nous conduit à nous interroger sur les effets de l'augmentation du niveau de la mer sur cette ressource côtière, et sur les effets de sécheresses sévères et plus fréquentes et de la montée du niveau marin, ajoutés à une augmentation des prélèvements dans les aquifères causée par la littoralisation de la population.

Impact of connected conduit on pumping-induced seawater intrusion in a coastal karst aquifer

“…Furthermore, water exchange between conduits and the carbonate matrix allows for the expansion of saltwater within the freshwater system (Hu, 2010). During the last decade, researchers have given significant attention to this issue (e.g., Bakalowicz, 2018;Acikel and Ekmekci, 2021;Fleury et al, 2023;Schuler et al, 2019), conducting numerous numerical simulations, lab and field experiments to understand the process of seawater-fresh water interactions, assess aquifer vulnerability, and further apply to the geochemical and nutrient investigations (e.g. Faulkner et al, 2009;Xu et al, 2015;Oehler et al, 2019;Bejannin et al, 2020;Petréet al, 2020;Shokri et al, 2022).…”

A hydrogeological acrostic: in honour of Ghislain de Marsily

“…Submarine springs and karsts are discussed by Fleury et al [2023], who analyze issues for the conservation of the water resources in coastal karst aquifers: they show that the possibility of natural seawater intrusion makes these aquifers particularly fragile, with the combined effect of the increase of sea level, that of more frequent and severe droughts, and that of an increase in withdrawals from aquifers for urban development. Sanz et al [2023] analyze the controversy on the possible salinization mechanisms for coastal brackish springs (which present the puzzling characteristic to be able to discharge high flow rates with significant salinities at elevations of several meters above sea level).…”