Understanding groundwater behaviour in urban environments: thermal and piezometric analysis in the Turin city area (NW Italy)

This study investigated the thermal and piezometric characteristics of the shallow aquifer in the Turin metropolitan area (north-western Italy), focusing on the dynamics and management of groundwater (GW) resources. The analysis includes data collected by the regional monitoring network in Turin and surrounding areas between 2010 and 2022. During this period, an average decrease in the water table of approximately 1 m and an increase in the GW temperature (GWT) of approximately 0.5 °C were observed. The GWT and water table data were also measured during three field campaigns in 2022 using a network of 31 monitoring points in the city of Turin. The data show that GW flows from west to east towards the Po River, with values ranging from 240 m a.s.l. to approximately 210 m a.s.l. Moreover, a decrease in the water table depth throughout the monitored year was observed. The GWT increases from west to east in the flow direction, with values ranging from 13 °C to 17.5 °C. The temperature profiles and the spatial distribution show typical seasonal dynamics following air temperature fluctuations. Seasonal variations are diminished by the saturated and unsaturated zones, with the GWT stabilising below 4–6 m from the water table and 20 m below ground level. This comprehensive analysis highlights the impact of anthropogenic activities and climate change on GWT and emphasises the need for improved monitoring and management strategies to protect GW resources, especially in urban areas.