Monitoring of the saline wedge in the Po di Goro river

Seawater intrusion in coastal aquifers is a worldwide problem caused, among other factors, by aquifer overexploitaHon related to human acHviHes, such as irrigaHon and drinking water supply, and the reducHon in natural groundwater recharge due to climate change [1]. In order to prevent or limit the degradaHon of both surface water and groundwater quality due to saltwater contaminaHon, research studies have been conducted to gain a comprehensive understanding of the issue, idenHfy fundamental parameters, and assess possible correcHve measures. The territory of the Po Delta is characterized by minimal slopes and it is largely situated below sea level. The elevaHon profile of the territory significantly influences land management. The morphological characterisHcs of the Po Delta make the largest Italian wetland parHcularly unstable and very fragile when subjected to human pressure. Only the applicaHon of careful policies concerning coastal defence, flood miHgaHon, anthropogenic subsidence reducHon and salt wedge intrusion control will allow reducHon of the present or predicted negaHve effects [2]. In order to detect the salinity of the water river, a probe system that measure the water conducHvity (EC) is necessary. Typical monitoring system for EC data involves moving boat acquisiHons, which depict a low resoluHon of the salt wedge detecHon. Moreover, long rivers are not suitable for point acquisiHon approach as they require long acquisiHon Hmes. To overcome these limitaHons, geophysical methods could appear as a good alternaHve for fast mapping and detailed resoluHon. Taking in account these aspects, a monitoring research acHvity was applied along the Po di Goro River by geophysical method. In detail, a FDEM system was used to carry out the in-phase and out-phase components, in order to obtain the ECa distribuHon along the river. The geophysical monitoring began in summer 2022 [3], during the last salt wedge crisis along the Po River, and conHnued this summer. The first results of the Summer 2022 data set highlighted the saline wedge intrusion, on the contrary the Summer 2023 data set showed that saline intrusion was absent in the same invesHgated area. Anyway, the acquired data during last summer permiXed to observe the influence of the Hde on the advance and retreat of the salt wedge along the river (Fig.1). The results highlight the significant potenHal of the proposed geophysical approach to monitor the salt wedge phenomenon during the warmer periods with increased drought but also on a daily basis due to the influence of tides.