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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - GIMS (Geodetic Integrated Monitoring System)

Teaser

Summary

Geological, hydrological, geotechnical, and environmental phenomena causing deformation of the Earth surface (subsidence, landslides, floods, sinking, tectonic activity) are happening at an increasing rate, also due to extreme events likely to be driven by climate change, as well as rarer geophysical phenomena (earthquakes and volcanic eruptions). These phenomena govern negative and sometimes destructive impacts on land, structures (dams, bridges, buildings), infrastructures (roads, railways, channels, pipelines, energy infrastructures, etc.), and ancient structures of artistic and cultural value (churches, ruins, archaeological sites, etc.); in addition, structures and infrastructures can undergo an obsolescence process, eventually leading to a collapse.

The sensitivity of many areas in Europe to different hazards as well as around the world, as the recent landslides events related to the earthquake in Marche Region in Italy show, puts forward the need for an integrated and cost-effective geodetic monitoring capability. The purpose is to have detailed and timely knowledge of the geophysical behaviour of parts of the Earth surface, and its hindrances on structures, in order to mitigate casualties and injuries to the population, and better plan maintenance intervention. To set up such a geodetic monitoring capability of a portion of ground / structures, we need to be able to determine the time history of the coordinates of a number of its relevant points.

The advent of the Galileo and Sentinel satellites, and their integration with miniaturized in-situ sensors, enables new advanced monitoring solutions which are both cost-effective and highly accurate. Recent experiences showed that a millimetric accuracy on a daily basis is achievable using mass market single frequency GPS receivers when in particular operational conditions, such as large visibility of the sky and the presence of a reference station very close to these receivers. With the advent of Galileo, such conditions can be considerably softened because a larger number of visible satellites increases the geometry of the positioning.

Moreover, the availability of the Sentinel 1A and 1B SAR data, which are provided with an open and free access policy, allows the usage of SAR images for ground monitoring purposes at a lower cost compared to a few years ago.
Finally, the miniaturization of sensors like linear accelerometers, angular rate sensors, thermometers, etc. allows for the deployment of a large number of measuring devices provided that their observations, usually highly affected by severe drifts but moderate noise, can be properly processed.
The main objective of the GIMS project is to build and commercialize an advanced low-cost system based on EGNSS, Copernicus SAR and other in-situ sensors, like inertial measurement units, for the purpose of monitoring ground deformations with a focus on landslides and subsidence. The system will recover deformations with millimetric level accuracies and daily acquisition rate. Moreover, the integration of in-situ accelerometers will give real-time alerts in case of sudden movements.

Work performed

The GIMS project activities started with a thorough analysis of the user needs and requirements, carried out by the Geological Survey of Slovenia (GeoZS), in collaboration with all the other partners. The various types of landslides were overviewed, as well as the currently used monitoring technologies. The characteristics of the geodetic techniques implemented in GIMS as regards landslide monitoring were outlined by the competent partners. Based on all this information, two experiment sites for GIMS were selected, both in Slovenia.

GReD implemented an ad-hoc GNSS software able to exploit the new dual-frequency EGNSS receivers for geodetic monitoring, achieving millimeter-level precision. Saphyrion designed and produced the GIMS stations, including the dual-frequency low-cost EGNSS receiver, a low-cost inclinometer, a low-cost IMU and all needed components (e.g. photovoltaic panels, batteries, modems, etc). GeoNumerics developed the IMU analysis software component of the GIMS system. CTTC designed and developed a new low-cost active SAR transponder and enhanced their SAR processing tools for the estimation of land deformation maps. GeoZS brings to the project a direct user needs and evaluates practical capabilities and limitations of GIMS units by field implementation and validation of the data. CNXT, as an innovation-oriented science and technology park, supports the coordinator GReD in administration tasks and leads the dissemination and communications activities. The exploitation phase, concerning the business plan update and IPR management, has just started.

GIMS units comprising 7 EGNSS receivers+antennas, 7 IMUs, 7 inclinometers and 2 active SAR transponders have been installed at the first test site, in SW Slovenia.

Final results

The state-of-the-art before GIMS, regarding EGNSS, SAR and IMU/MEMS technologies for landslide monitoring, is that GNSS (actually GPS) and InSAR are typically used in a separate fashion, and deploying high-level instrumentation, with a relatively high cost. A first experiment had been conducted before the beginning of the GIMS project (it was the I2GPS project, by a group lead by TU Delft) in the framework of the H2020 program, to unify GPS and InSAR techniques for landslide monitoring, yet still applying tools of geodetic level and high cost.

The GIMS project builds on this idea but with the following improved characteristics:
- a new low-cost EGNSS monitoring station (receiver + antenna + transmission + photovoltaic power) has been developed, capable of tracking not only GPS but all systems, specially including Galileo, on two frequencies;
- a new low-cost SAR active antenna has been designed, produced and tested;
- a new open source GNSS processing software has been produced, specifically for the GIMS purposes;
- low-cost MEMS have been integrated into the monitoring unit, and the corresponding sudden motion alarm software is under development;
- the prospect of developing an integrated monitoring system taking advantage of all three technologies, producing alarms, continuous displacement monitoring and weekly snapshots of the areal deformation patterns.

The refinement of the system to make a pre-marketable solution will be finalized within the project timeframe.

After validation, the GIMS system will be released to the market for potential customers to use in geohazard monitoring and could serve as an early-warning system. GIMS units will contribute to the detailed and timely knowledge of the landslides motion behaviour, improved planning maintenance intervention and mitigation of casualties and injuries caused to the population and better plan maintenance intervention.

The combination of monitoring of both landslides and infrastructures has, of course, an important socio-economic impact to mitigate risks related to catastrophic failures. This is true not only for landslides and bridges, as demonstrated by GIMS, but in a much wider frame including for example dams, penstocks, pipelines, land subsidence, river embankments, etc.