A Wireless Sensor Network (WSN) for the landslide in Castelnuovo di Campli (TERAMO)

Once more, we are talking about landslides. Last February, a landslide occurred in the Municipality of Castelnuovo di Campli, in the province of Teramo. Unlike the landslide occurred in Ponzano, which was translational, the landslide in Castelnuovo di Campli caused the slope along the stream Siccagno to collapse, with a front of approximately 80 meters. That was a sudden sinking resulting from the rainfall episodes occurred after the melting of the heavy snowfalls of the last period. Because of this landslide movement, a stretch of fence of a commercial area collapsed, as well as a medium-voltage cabinet of the national electric service (Enel) that was approximately 6 meters high, two garages and a stretch of municipal street of approximately 25 meters. This dramatic situation occurred just a few meters from some houses.

After performing a Feasibility Study, CAE provided the Region of Abruzzo with a full-scale and modern "turnkey" monitoring and alert system that uses self-configuring wireless networks thanks to the WSN technology (Wireless Sensor Network). The collapse of the above-mentioned Enel cabinet caused a blackout that left all the buildings of the area without electricity; therefore, in order to face any other similar situation and avoid any possible malfunction, every element in the supplied system is self-functioning from an energetic point of view; moreover, the use of solar panels and buffer batteries allows the system to self-function up to 30 days and more.

More in detail, as far as the composition of the system, in order to monitor the micro-movements occurring deeply in the soil, we used multipoint extensometers located in inclined holes along the ridge of the southern mountainside, specifically at 12 and 25 meters in depth. As far as the surface movements, we used clinometers that measure the inclination variations of the structures where they are fixed; in detail, they allow us to monitor the inclination variations both on a single axis and on two planes perpendicular to the surface where they are fixed.

While monitoring soil movements, the system is also equipped with a thermo-pluviometric Mhaster station that allows us to associate the evolution of the instability to the rainfalls on the spot; at this purpose, we can distinguish among 3 phases:

• normality: no intense rainfalls or landslide movements have been detected;
• pre-alarm: rainfalls exceed a determined threshold of intensity, therefore the number safety measures are increased and the headquarters can send a warning notification;
• alarm: the movement of the geological sensors (significant inclinations) involve the need to send alert notifications via vocal synthesis message, SMS and FAX.

This system must guarantee the maximum level of reliability in terms of:

• availability of data: this will allow the operators to intervene in an extremely short time, in case of anomalies;
• alert in real time: when the conditions of the system change and the pluviometric and geotechnical alert thresholds are exceeded, the system must communicate via vocal messages, SMS or e-mails, with the competent Authority.

All this is possible thanks to the automatic diagnostic functionalities of the system, as well as to its duplex communication system (a GPRS/UMTS modem and a UHF band radio device connected to the remote measuring radio network of the regional monitoring service); this system sends the collected data both to the Municipal Operative Centre and the Functional Centre of the Civil Protection System. In such situations, the availability of the collected data is essential; therefore, apart from the traditional hardware and software devices, CAE provides the competent Authorities with a valid support to decision making, thanks to a data visualisation service that uses a WEB platform which is 24h mobile-accessible from an internet browser.