Since 1997, 3a has been supplying electronic technology for measuring hydrometric levels in waterways and artificial canals.

The automatic detection station comprises:

• a data acquisition and processing unit
• a local archiving unit
• an alphanumeric keyboard and display enabling an onsite control of equipment functions
• sensors measuring the water height in a body of water
• a power system for the structure
• a transmission module

The data acquisition control unit features analogue and digital inputs, performing the querying of different sensors at preset frequencies. The acquired signals are processed over preset time intervals without altering the accuracy of the sensors' measurements, providing data, averages, and cumulative values. The sampling frequency for each parameter is established in relation to the scope and time variability of the data and management and technical requirements.

Two types of sensors exist for measuring hydrometric levels:

• Piezometric sensor: measures the height of the column of water above a plane, exploiting the pressure exercised by the water (hydrostatic principle).
• Ultrasound sensor: measures the hydrometric level by emitting ultrasonic frequency impulses according to a normal path on the surface of the body of water. The measurement of the time elapsing between the emission of the impulse and the return of the echo provides the measurement of the space between the source and the surface.

The technology supplied respects the high manufacturing standards conforming to the recommendations of the World Meteorological Organization (WMO). The control unit features a photovoltaic power system (20 W solar panel), or as an alternative, can be powered from the grid with a battery acting as a buffer. The data transmission system to the control centre makes use of a GSM/GPRS modem and WI-FI or Ethernet data network.

Monitoring and automation applications developed in-house allow for systems that respond to the real needs of farming estates, rural communities and services operating over the territory. A measurement of the hydrometric level provides data for calculating the capacity of the waterway or canal. Hydrometric level measurement and capacity calculations can be monitored in real time, thanks to a warning system based on identifying threshold values that constitute a quantitative indicator, for the insurgence of risk on a real scale.

The management of data for the above applications is guaranteed by the GPMeteo web application.