Hydrogeological and Hydrochemical Characterization of Quarry Lakes in the Piedmont Alluvial Plain

Quarry lakes, primarily located in alluvial plains, form as a result of the deepening of quarry excavations beyond the water table of the shallow aquifer.

They allow for full exploitation of the deposit without excessively damaging the landscape, limiting land consumption. Quarry lakes play also an important ecological and landscape role, because they provide (i) habitats for aquatic plants, aquatic animal species and birds, and (ii) recreational opportunities. Additionally, they contribute to management of water resources and mitigation of flood risks.

In the Piedmont region (NW Italy), quarry lakes are numerous and of considerable size due to the high market demand for concrete and aggregates. These quarry lakes are mostly located along the Po River, the main river of the region, and its main tributaries.

This study focused on six active quarry lakes and, primarily, a hydrogeological reconstruction of the surrounding areas was carried out. Lake water samples were collected in the summer and autumn of 2025 and analysed for hydrochemical composition. Field parameters, including pH, electrical conductivity, and water temperature, were also recorded.

The hydrochemical results, compared with data from the regional network of groundwater monitoring wells, reveal a strong correlation between lake waters, the surface aquifer, and watercourses. The chemical characterization of these quarry lakes supports the study of their  photochemical activity, and the assessment of their potential use as nature-based basins for quaternary treatment of water, thus allowing to minimize the overexploitation of groundwater resources in a context of more frequent drought events due to climate change.