Additional studies on drillings in the Aff valley: re-interpretation of pumping tests, physical-chemical and isotopic analyses - Final report

This study aimed at assessing the influence on the Aff river flow rate on the exploitation of 3 drillings for drinking water on the territory of two communes of the Morbihan and Ille-et-Vilaine districts. Thus, the authors report a re-interpretation of pumping tests performed on different works in 2007 and 2010 in order to highlight whether there is a potential relationship between the caught aquifer and the Aff river, as pumping were suspected to drain a part of the river. They also report physical-chemical, isotopic and dating analyses of waters on the three drillings, on the Aff river, and on another drilling catching the same aquifer but away from the Aff river. Results confirmed the site complexity: atypical strontium signature, unusual river losses, exceptionally high underground flow rates, and very much partitioned aquifer.