Monitoring means checking physical, chemical and biological phenomena over time by using equipment or analytical techniques.
Continuous monitoring may be applied, which is conducted through an instrument that records information seamlessly or at very short intervals.
If recordings are registered at a sufficiently high frequency with regard to the monitored process, it is considered high frequency monitoring.
If the measurements or samples are taken on a daily, monthly, quarterly or any longer basis, it is considered medium-low frequency monitoring.
For this study, all three monitoring techniques were used:
- continuously for rainfall levels
- at high frequency to characterise the spring water in terms of hydrodynamics and certain chemical and physical parameters
- at low frequency for geochemical and isotopic characterisation of spring water
Meteorological data monitoring
For this project, data has been taken into account from automatic rainfall stations and from manual snow stations (snow fields) totalling about one hundred measuring points across Italy and France.
In particular, the following have been taken into consideration:
- rainfall data measured by rain gauges and air temperature data
- data on the height of ground snow measured by snow gauges
Monitoring at springs and surface waterways
The ALIRHYS project has examined various springs supplied under different hydrogeological circumstances:
- porous aquifers (Borello Inferiore and Fontanas springs)
- karst carbonate aquifers (Bandito, Coulomp, Féraud-Meyniers, Fuse, Gréolières, Pesio, Pesio 18 and Riou-Sourcets springs)
- fractured carbonate aquifers (Ray, Tenda, Maira and Beinette springs)
- fractured and karst aquifers (Dragonera, Soma, Borello Superiore and Bossea springs)
The Corsaglia and Gesso torrents were also monitored
The data gathered by instruments include the water level, conductivity and temperature.
Thermographic surveys from drone to monitor sub-riverbed sources
The use of a UAV (Unmanned Aerial Vehicle) to gather data is now common practice in geomatics. A Hexakopter by Mikrokopter was used for the ALIRHYS project, which had been customised for the special data collection requirements. The drone is fitted with a GPS antenna and receives the navigation data set by the control PC via telemetry. During flight it autonomously gathers data through its mounted sensors. For the ALIRHYS project, this piece of equipment gathered data on a section of the Vermenagna torrent in Vernante (CN) by using photographic and thermal sensors to identify any underflow springs.