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Source sous-marine de la Vise

La Source de la Vise, a freshwater exsurgence of the karstic aquifer flowing into the Étang de Thau, subject to inversac and fitted with a valve in July 2025.

Balaruc-les-Bains 3m 3m

La Source de la Vise, a freshwater exsurgence of the karstic aquifer flowing into the Étang de Thau, subject to inversac and fitted with a valve in July 2025.

Characteristics

Location

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Entrances

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  1. Source sous-marine de la Vise

    43.443580, 3.672560
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Description

Hydrology

The Source functions as a freshwater exsurgence of the surrounding karstic aquifer that discharges into the brackish water of the Étang de Thau.

When certain conditions are met, an inversac phenomenon occurs: the water of the Étang de Thau flows back into the aquifer, causing salinization of the groundwater table. In order to measure this phenomenon and its impacts, the BRGM of France and the University of Neuchâtel in Switzerland installed measuring instruments at the Source.

To prevent this phenomenon, a valve system was installed in July 2025 at the Source: when the pressure of the brackish water increases to the point of triggering an inversac, a valve closes the device, preventing salt water from entering the aquifer. This unprecedented installation is being monitored for three years before possibly being installed at other similar sites.

Other details

Sources:
* Article "Source de la Vise" from the collaborative encyclopedia Wikipédia en français: https://fr.wikipedia.org/wiki/Source_de_la_Vise
* BRGM, "L’inversac de Thau expliqué : des perspectives pour une meilleure gestion", 26 August 2025: https://www.brgm.fr/fr/actualite/actualite/inversac-thau-explique-perspectives-meilleure-gestion
* LHB Hydroscience Journal, "Suivi hydrologique de la source sous-marine de la Vise : questions techniques et scientifiques": https://www.tandfonline.com/doi/full/10.1080/27678490.2026.2664592#d1e364

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Contains information from Grottocenter (Wikicaves), grottocenter.org, made available under the Open Database License (ODbL 1.0, https://opendatacommons.org/licenses/odbl/1-0/), modified. · https://grottocenter.org/ui/entrances/160016 · The derived data is available on request under the ODbL: [email protected] · data as of 2026 · Source: Grottocenter (Association Wikicaves), worldwide collaborative cave database (grottocenter.org), modified. CC BY-SA 3.0, https://creativecommons.org/licenses/by-sa/3.0/ Grottocenter (Wikicaves) · Text by BTH (Description générale) · adapted by Espeleoworld (normalized, translated); the adaptation is licensed CC BY-SA 3.0, https://creativecommons.org/licenses/by-sa/3.0/ · https://grottocenter.org/ui/entrances/160016 · data as of 2026