Carbonate aquifers represent a significant fraction of all groundwater resources used globally, due to the high quantity and quality of stored water within them. Aquifers developed in carbonate rocks are often characterized by the high complexity of the water circulation path, varying from slow and diffuse matrix flow to fast and concentrated conduit flow. High complexity, karstification, reduced soil cover, high infiltration coefficient, and reduced auto-depuration capability make carbonate aquifers particularly vulnerable to contamination. The Apuan Alps (Tuscany, Italy), due to their geology (thick and karstified carbonate tectonic succession) and rainy climate (mean annual rainfall up to 3000 mm), host large amounts of groundwater resources in complex and highly karstified aquifers. The Baccatoio Stream catchment, located on the southwestern side of the Apuan Alps, was subjected to numerous investigations linked to the presence of abandoned mines and related acid mine drainages, which also involved springs captured for drinking water. This study aims to achieve new insights into water circulation in carbonate aquifers feeding one of the most important spring system of the area (Moresco springs: VSMOA, VSMOS, VSMOG). VSMOA (natural spring) and VSMOS (artificial spring) show evidence of hydraulic connection with the Baccatoio stream, which is contaminated by acid mine drainages, not recognized in VSMOG (an artificial spring consisting in a tunnel draining several little springs). The study focused on groundwater chemical and isotopic variations induced by a rainfall event. A hydrogeological conceptual model was developed from the interpretation of multiple geological cross-sections and subsequently validated through geochemistry, hydrological-hydrodynamic, and isotopic analyses. The conceptual model was proved to be a reliable description of the natural karst system, from which some general conclusions can be drawn: (i) the hydraulic connection between the Baccatoio stream and VSMOA-VSMOS springs seems to be confirmed; (ii) during rainfall events, infiltrated rainwater seems to directly contribute to the perturbation of VSMOA-VSMOS; (iii) different flow fractions feeding VSMOA-VSMOS after rainfall infiltration were quantified; (iv) VSMOG did not show any significant perturbation linked to the rainfall.
Hydrodynamic and geochemical behavior of a karst aquifer system exposed to contamination: analysis of the response of the Moresco Springs (Apuan Alps, Italy) to rainfall
Matteo Nigro
Primo
;Linda Franceschi;Stefano Natali;Marco Doveri;Roberto Giannecchini
2023-01-01
Abstract
Carbonate aquifers represent a significant fraction of all groundwater resources used globally, due to the high quantity and quality of stored water within them. Aquifers developed in carbonate rocks are often characterized by the high complexity of the water circulation path, varying from slow and diffuse matrix flow to fast and concentrated conduit flow. High complexity, karstification, reduced soil cover, high infiltration coefficient, and reduced auto-depuration capability make carbonate aquifers particularly vulnerable to contamination. The Apuan Alps (Tuscany, Italy), due to their geology (thick and karstified carbonate tectonic succession) and rainy climate (mean annual rainfall up to 3000 mm), host large amounts of groundwater resources in complex and highly karstified aquifers. The Baccatoio Stream catchment, located on the southwestern side of the Apuan Alps, was subjected to numerous investigations linked to the presence of abandoned mines and related acid mine drainages, which also involved springs captured for drinking water. This study aims to achieve new insights into water circulation in carbonate aquifers feeding one of the most important spring system of the area (Moresco springs: VSMOA, VSMOS, VSMOG). VSMOA (natural spring) and VSMOS (artificial spring) show evidence of hydraulic connection with the Baccatoio stream, which is contaminated by acid mine drainages, not recognized in VSMOG (an artificial spring consisting in a tunnel draining several little springs). The study focused on groundwater chemical and isotopic variations induced by a rainfall event. A hydrogeological conceptual model was developed from the interpretation of multiple geological cross-sections and subsequently validated through geochemistry, hydrological-hydrodynamic, and isotopic analyses. The conceptual model was proved to be a reliable description of the natural karst system, from which some general conclusions can be drawn: (i) the hydraulic connection between the Baccatoio stream and VSMOA-VSMOS springs seems to be confirmed; (ii) during rainfall events, infiltrated rainwater seems to directly contribute to the perturbation of VSMOA-VSMOS; (iii) different flow fractions feeding VSMOA-VSMOS after rainfall infiltration were quantified; (iv) VSMOG did not show any significant perturbation linked to the rainfall.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
