A high frequency monitoring (HFM) system for the deep subalpine lakes Maggiore, Lugano and Como is under development within the EU INTERREG project SIMILE. The HFM system is designed to i) describe often neglected but potentially relevant processes occurring on short time scale; ii) become a cost-effective source of environmental data; and iii) strengthen the coordinated management of water resources in the subalpine lake district. In this project framework, a first HFM station (LM1) consisting of a monitoring buoy was placed in Lake Maggiore. LM1 represents a pilot experience within the project, aimed at providing the practical know-how needed for the development of the whole HFM system. To increase replicability and transferability, LM1 was developed in-house, and conceived as a low-cost modular system. LM1 is presently equipped with solar panels, a weather station, and sensors for water temperature, pH, dissolved oxygen, conductivity, and chlorophyll-a. In this study, we describe the main features of LM1 (hardware and software) and the adopted Quality Assurance/Quality Control (QA/QC) procedures. To this end, we provide examples from a test period, i.e., the first 9-months of functioning of LM1. A description of the software selected as data management software for the HFM system (IstSOS) is also provided. Data gathered during the study period provided clear evidence that coupling HFM and discrete sampling for QA/QC controls is necessary to produce accurate data and to detect and correct errors, mainly because of sensor fouling and calibration drift. These results also provide essential information to develop further the HFM system and shared protocols adapted to the local environmental (i.e., large subalpine lakes) and technical (expertise availability) context. Next challenge is making HFM not only a source of previously unaffordable information, but also a cost-effective tool for environmental monitoring.

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Precipitation and temperature over the Lake Maggiore watershed greatly influence its water balance. Local communities from both Italy and Switzerland rely on the watershed for agriculture, tourism and hydropower production. Accurate climate projections in this area are vital in dealing with their impacts and yet are still lacking. Future climate was assessed by applying the Statistical DownScaling Model (SDSM) and using CanESM2 predictors. Three scenarios defined by RCP2.6, RCP4.5 and RCP8.5 were adopted. Based on our results, SDSM is to a certain degree applicable for simulating precipitation and temperature in an Alpine area. Results indicate that warming from now until the end of the century will be about 2 to 3 times greater without global mitigation. Temperature is estimated to increase throughout the 21st century, with a stronger warming trend in the northeastern part of the region than in the southwestern part. The strength of the warming at the end of the century highly depends on the scenario considered, with an increase up to 1.7°C for the mitigation scenario RCP2.6 compared to 4.2°C for the unmitigated scenario RCP8.5. Seasonal precipitation is expected to change depending on the future scenarios. Most of the region is expected to display a seasonally positive precipitation change during the cold season and vice versa, resulting in a shift in the peak rainy season from autumn to winter. These findings suggest that the area might be vulnerable to global change and will provide useful insight to develop a better strategy for the management of water resources and to study the adoptive measures to manage flood disasters.