Water tables, Issanka source, Inversac: what the latest rains have changed in the Thau basin

Même si l'intrusion d'eau salée est en baisse, les précipitations des 8, 9 et 10 mars n'ont pas permis un arrêt du phénomène inversac dans l'étang de Thau. Midi Libre – DOMINIQUE QUET

Les fortes précipitations du 8 au 10 mars ont fait beaucoup de bien au territoire sans pour autant tout régler, notamment pour les nappes phréatiques et l'inversac.

A blessing. Much hoped for, the heavy rains last weekend brought their share of good news to the Thau basin. The first, and not the least, is that the source of the Vène is flowing again. The Thau Basin Mixed Union (SMBT) confirms "the resurgence of the source, in Cournonsec". And its collateral effect: "The flow rate of the Issanka source, which supplies drinking water to the City of Sète, should increase significantly and allow normal operations to resume for several month."

The effect is also beneficial for the lands. "This rain is gold in bars", recognizes Michel Garcia, vice-president of Sète Agglopôle in charge of agriculture. Who tempers however: "This remains insufficient to recharge the water table, especially since the Thau basin received less water than the hinterland. It should be remembered that before this episode, we were at -64% in annual rainfall and that the two years before had been in deficit! In a normal year, it's 580 mm. Last year, we had 210, less than Algiers or Marrakech!"

Non-uniform precipitation

The precipitation was also not uniform: if 50 to 100 mm of rain fell on the Aumelas plateau, to the north and to the east of the sector, no more than 50 mm were recorded on the Gardiole massif when 12 to 25 mm of water fell in Villeveyrac, Poussan, Balaruc, Sète, and to the west of our territory.

Finally, they did not stop the inversac, which has been going on for 5 months now. But they limit the impact: the SMBT notes that the intrusion flow via the Vise source has decreased from 200 to 137 l/s. Insufficient to counter the pressures and reach the level which allowed the end of the last inversac, just two years ago.

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