The groundwater overexplotation is a worldwide problem and it causes serious consequences such as land subsidence, saltwater intrusion, devastating effects on natural streamflow, groundwater fed wetlands and related ecosystems.The Maggiore Valley (NW Italy) was analysed in this paper because it is considered as a clear example of overexploitation in Italy. In this area a decrease of the piezometric level of more than 40 m and a large reduction of an artesian area were registered, due to a high increase of groundwater withdrawal from the beginning of XX century. Because the exploited confined aquifer is the only source of water for human consumption in the area, Maggiore Valley wellfield is considered of regional importance and numerous actions have been launched to protect and preserve it. After a detailed hydrogeologic reconstruction of the area, a groundwater flow model was implemented. Then, the simulation of new groundwater withdrawal configurations (groundwater extraction decrease, redistribution of the well location and a combination of both of them) were investigated, in order to simulate a different quantitative management of the groundwater resources. The results of all the simulations highlighted a positive impact on the piezometric level. Consequently, a reduction of groundwater withdrawal from Maggiore Valley wellfield and a concurrent supplementary feed (interconnection, 100 L/s) from the Monferrato Aqueduct, were realized. This operation leads to a partial rising of the piezometric level up to 8 m from 2012 and 2016.In addition, geophysical studies were conducted to identify the best area for some wells relocation. A combined use of Electric Resistivity Tomography (ERT) sections and Time Domain Electromagnetic (TDEM) soundings permitted to depict the depth and lateral continuity of the uppermost part of the Quaternary deposits, hosting the near surface aquifers, and to choose the most suitable zone from a hydrogeological point of view.
Aquifer protection from overexploitation: example of actions and mitigation activities used in the Maggiore Valley (Asti Province, NW Italy)
Lasagna, M;Mancini, S;De Luca, D. A.
2019-01-01
Abstract
The groundwater overexplotation is a worldwide problem and it causes serious consequences such as land subsidence, saltwater intrusion, devastating effects on natural streamflow, groundwater fed wetlands and related ecosystems.The Maggiore Valley (NW Italy) was analysed in this paper because it is considered as a clear example of overexploitation in Italy. In this area a decrease of the piezometric level of more than 40 m and a large reduction of an artesian area were registered, due to a high increase of groundwater withdrawal from the beginning of XX century. Because the exploited confined aquifer is the only source of water for human consumption in the area, Maggiore Valley wellfield is considered of regional importance and numerous actions have been launched to protect and preserve it. After a detailed hydrogeologic reconstruction of the area, a groundwater flow model was implemented. Then, the simulation of new groundwater withdrawal configurations (groundwater extraction decrease, redistribution of the well location and a combination of both of them) were investigated, in order to simulate a different quantitative management of the groundwater resources. The results of all the simulations highlighted a positive impact on the piezometric level. Consequently, a reduction of groundwater withdrawal from Maggiore Valley wellfield and a concurrent supplementary feed (interconnection, 100 L/s) from the Monferrato Aqueduct, were realized. This operation leads to a partial rising of the piezometric level up to 8 m from 2012 and 2016.In addition, geophysical studies were conducted to identify the best area for some wells relocation. A combined use of Electric Resistivity Tomography (ERT) sections and Time Domain Electromagnetic (TDEM) soundings permitted to depict the depth and lateral continuity of the uppermost part of the Quaternary deposits, hosting the near surface aquifers, and to choose the most suitable zone from a hydrogeological point of view.
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