# A System to Improve Port Navigation Safety and Its Use in Italian Harbours
## 2 Materials and Methods
### Environmental Monitoring in Harbours  
To perform environmental monitoring in Italian harbours, meteo-mareographic stations belonging to the National Tidegauge Network managed by ISPRA (Italian Institute for Environmental Protection and Research) are usually employed. Regarding this work, parameters have been acquired by the ISPRA's measurement stations located in the ports of Livorno and Bari (see Figures 6 and 7).  
A typical measurement station includes several instruments to measure environmental parameters, and among them, the most important for the study described in this article are the hydrometer to acquire sea level and the barometer to measure atmospheric pressure; it is also equipped with a data acquisition system, an Internet connection and a solar panel to provide the power supply.  
Figure 5: Block diagram of bathymetry updating and virtual traffic lights.  
Figure 6: The ISPRA’s monitoring station in the port of Livorno: (**a**) the station (picture from [[https://www.mareografico.it/](https://www.mareografico.it/)]([https://www.mareografico.it/](https://www.mareografico.it/)) (accessed on 25 October 2021)); (**b**) its position (10\({}^{\circ}\)17’57.62” E, 43\({}^{\circ}\)32’46.63” N, image from Google Earth).  
Figure 7: The ISPRA’s monitoring station in the port of Bari: (**a**) the station (picture from [[https://www.mareografico.it/](https://www.mareografico.it/)]([https://www.mareografico.it/](https://www.mareografico.it/)) (accessed on 25 October 2021)); (**b**) its position (16\({}^{\circ}\)51’57.72” E, 41\({}^{\circ}\)08’24.74” N, image from Google Earth).  
Sea level measurements are usually referred to IGM's 0 level. Their typical resolution is \(10^{-2}\) m. The hydrometer essentially consists of a radar transducer positioned above the sea surface. Microwave pulses are sent towards the water/air interface, then, since the speed of the electromagnetic radiation in the air, the time taken by the impulses on the round trip, and the position of the transducer with respect to IGM's 0 level are known, the sea level value is calculated. A typical sampling interval to acquire tide data is greater than or equal to 10 min and, to avoid the disturbance induced by sea waves, the radar transducer is usually placed inside a still-pipe.  
The atmospheric pressure, on the contrary, is measured by means of a barometer based on a capacitive silicon transducer. As the atmospheric pressure varies, both distances between the two plates and electrical capacitance change; measurements are usually made once every hour (atmospheric pressure is characterized by very low-frequency variations), with a typical resolution equal to \(10^{-1}\) hPa (1 hPa is approximately equal to 1 mbar).  
The date and the time of a monitoring station are usually referred to as UTC--Universal Time Coordinates.  
Data acquired can be stored in a memory (to create a local data archive), downloaded in real-time via the Internet on a receiving station (e.g., to implement a remote data storage or to update the bathymetric map of the port), and made available on a website. Data shown in this work and other information regarding the measurement stations are available on [[https://www.mareografico.it/](https://www.mareografico.it/)]([https://www.mareografico.it/](https://www.mareografico.it/)) (accessed on 25 October 2021).