Radio-based monitoring provides early warning of natural disasters

Protection from natural hazards is a particular priority in the Alps. Monitoring systems of the kind developed by the Zurich-based company Geopraevent offer an alternative to costly physical barriers. The company specialises in the deployment of sensors which are able to provide real-time warnings of falling rock faces or overflowing glacial lakes before they occur. If there is an immediate danger of such an event, a chain of alarms is activated. Roads and tunnels are automatically closed and, in inhabited areas, sirens are sounded – all in the space of a few seconds.

Radio-based system trumps mobile phone network

It is of course in the nature of such hazards that they sometimes occur in places where no electricity supply or mobile telephony connections are available. To address this problem, the ZHAW School of Engineering’s Centre for Signal Processing and Communications Engineering (ZSN) joined forces with Geopraevent to develop a secure radio-transmission system as part of a project supported by Innosuisse (former CTI). As the ZSN’s Roland Küng explains, “The mobile telephony network is often either too weak or dependent on one single transmitter mast, while satellite connections are very expensive. Laying kilometres of cabling is also expensive and the cables can break.” A secure radio connection, on the other hand, with its own licensed channel provides a standalone solution which is less vulnerable to interruptions by third parties or outside events.

Engineers fly in

Two MSc graduates at the ZSN developed both the communications protocol for the software and the hardware modules for the radio network. Their specifications took account of such factors as the extremely low temperatures prevailing in mountain regions at 3,000 metres above sea level. They also had to ensure that the hardware had a very high degree of operational reliability, given the significant logistical effort required to install and maintain the transmitters in remote terrain. To set up their test system, the engineers flew by helicopter to the various transmitter sites. In order to test the equipment under extreme parameters, this work was carried out in tough winter conditions. The transmission distances were deliberately kept close to each transmitter’s maximum range so that the periodic shutdown of individual transmitters and their automatic rejoining of the network could be tested.

Test phase successfully completed

A test version of the ZSN system has been in operation on the Plaine Morte Glacier above Lenk since January 2013. When ice and snow melt, glacial lakes in this area fill up and can overflow beneath the glacier. This results in a rapid increase in water levels down in the valley. Sensors are therefore used to monitor the water levels in the lakes, activating an alarm if they suddenly diminish. The tests carried out in Lenk were successful, demonstrating that the system is reliable in real-life conditions. As Lorenz Meier, Geopraevent’s CEO, puts it “We are very pleased with the results and with the friendly and professional nature of our collaboration with the ZSN.” In addition to municipalities and cantons, Geopraevent’s customers include electricity-generating companies and pipeline operators across the globe.