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Titre : | Evaluation de la ressource en eaux souterraines (études géologique et hydrogéologique) & étude de l'interface eau douce-eau salée au droit d'une île : Etude de cas de l'île d'Arz (Bretagne, Morbihan) |
Auteurs : | Camille COTREL ; Aimie ROUSSILLON ; Aimie ROUSSILLON |
Type de document : | Mémoire d'initiation à la recherche |
Année de publication : | 2019 |
Concepts : |
POLLUTION
AQUIFERE NAPPE GEOPHYSIQUE RESSOURCE |
Résumé : | The island Arz located in Golfe du Morbihan in Brittany owns 15 watering places declared alongside the municipality. After two weeks of investigations as part of the research introductory memory, 24 private wells in addition of the communal wells have been found. This high number of wells for a small island translate the presence of groundwater and a real need of the people to have access to this resource. Aquifers in Brittany are fractured aquifer because of the geological history of the Armorican massif. An island by its geographical location has an insular aquifer. The island Arz by its definition has a fractured aquifer with the constraints of an insular aquifer. Is the water body really fresh water? Is there an intrusion of salt water in the aquifer of the island? To answer these questions, several methods were set up during the field. Water samplings were realized on wells and the bodies of water on the island. It helped make a full sampling of the island. Back on campus, the samples were analysed in laboratory by ion chromatography. The results indicate the presence in the water of a high chloride and sodium rate in some wells of the island, especially those located near the sea. They are therefore subject to marine pollution. In addition, several geophysical methods such as electrical tomography allows to obtain information on the geological subsoil. The results validate the hypothesis of a seawater intrusion in the island of Arz. All data correlated were used to assess the water resource of the island. This is 6 100 000 m3. |
Spécialité : | Géologie |
Numéro de promo : | 81 |
numéro MIR : | 840 |