National Initiatives

After more than twenty years' efforts of scientists in fields of radar, remote sensing, geomatics, geophysics and geo-technicians, satellite SAR interferometry (InSAR) has been proven as an operational tool for ground displacement monitoring and can be used for many diverse purposes. Thanks to the development of SAR satellites, InSAR can provide a multi-scale of measurements ranging from wide area mapping to infrastructure monitoring depending on the SAR data and processing technique. Since the launch of "The Chinese National Land Subsidence Monitoring Programme Derived by Satellite InSAR" supported by China Geological Surveying(CGS) in last ten years, which provides the historical and latest national ground subsidence mapping in area has been suffering or prone to subsidence, more and more scientists, engineers and managers began to re-recognize the technique and its powerful abilities.

    This contribution gave a brief review of the national land subsidence monitoring program and introduced the key algorithm for process thousands of SAR scenes to cover the major subsidence zone of the nation as well as the significant applications of InSAR data for hydro-geology research and ground water exploitation control. By comparing the advantage of InSAR data and GPS observation for large coverage monitoring purpose, the capability and condition of InSAR techniques to satisfy the investigation of regional subsidence has been demonstrated. Aiming at the future trends of SAR data and processing techniques, a series of key issues for large volumes of InSAR data processing, deformation data update, big data integration and managing has been presented for further monitoring of the national subsidence, through a case study of Sentinel-1 SAR data for large scale subsidence monitoring. As a summary, we presented the perspective for the full coverage of China national surface deformation by InSAR data based on Sentinel-1 satellite.

Building upon decades of experience with deformation monitoring from repeated precision leveling and GNSS measurements as well as more recent time series analyses of ERS, Envisat, and Sentinel-1 imagery, we are now working towards a nationwide mapping using Sentinel-1 Interferometric Wide Swath (IWS) mode data. The mission’s high spatio-temporal resolution yields multiple new potentials, one of which is the focus of this work: The establishment of an operational service for a nationwide monitoring of vertical land deformations in Denmark.

We present deformation rates over selected test sites, obtained by applying Persistent Scatterer Interferometry to nearly two years of Sentinel-1 IWS data. They clearly demonstrate the potential in using such observations to identify areas undergoing rapid changes, so-called hotspots. Close collaborations with end-users show that the high-resolution information is relevant for, e.g., climate change adaptation and for optimizing renovation works of subsurface pipelines. Other relevant end-users represent road authorities, insurance companies, local authorities, etc. A nationwide mapping therefore is associated with great potentials for optimizing processes in both the public and private sectors. This will inevitably lead to significant economic savings.

The test study makes up part of the foundation for establishing a nationwide service. As such, the results over the test sites will be presented to a broad range of end-users to identify their needs for the full-scale, technical solution. Furthermore, we investigate how to optimally exploit our network of in-situ measurements as well as a national uplift model to generate absolute deformation rates with a mm-accuracy. Combined with the close involvement of end-users, we focus on developing a service tailored to specific needs, which increases the probability of its implementation in both the public and private sectors.

Presenting the results obtained on the road to setting up a nationwide deformation monitoring will clearly demonstrate the potentials arising with the continuous stream of Sentinel-1 IWS data.

SAFETY is a two-year research project funded under the ECHO (European Commission's Humanitarian aid and Civil Protection department) call “Prevention and preparedness projects in Civil Protection and marine pollution”, which started the 1st January 2016. The mission of the project is to improve the efforts in detecting and mapping geohazards (i.e. landslides and subsidence), by assessing their activity and evaluating their impact on built-up areas and infrastructure networks through space-borne radar data. The project goal is based on three key pillars: (I) the performances of the SAR sensor Sentinel-1, both in terms of wide area coverage and high temporal repeatability; (2) the development of a free software tool that fully exploits Sentinel-1 SAR data to periodically detect and monitor ground deformations at regional scale; and (3) the exploitation of the software tools and methods developed in the FP7 LAMPRE project to assess geohazard susceptibility and its impact on urban structures and infrastructures.

This work provides an overview of the project state, after one year of activities. The main goal is to  describe the main expected outcomes of the project and to show the most significant results obtained over the two test sites of the project: the Canary Island (Spain) and the Volterra municipality (Italy).

We present here a pilot project launched by CNES in 2016 to propose PSI-based ground motion measurement service over the French territory.  The objective is to assess the level of interest of the users community (geological surveys, national and local authorities, etc.) for this type of service, in order to better contribute to its definition. The CLS Group, through its company TRE ALTAMIRA, has been appointed to lead the study, taking advantage of the expertise gained over 20 years in the field of SAR Interferometry.

For this demonstration project, CLS has proposed to CNES an area of interest located in the South-West of France, extending over about 20,000 km². In the past, the CLS Group has already carried out interferometric studies for public and private actors over this area, which will make it easier, for the evaluation of the results of the service, to involve users familiar with the InSAR technique. During this pilot project, different problematics will be addressed, namely:

-           Impact of climate extreme events, and climate change on land movement: winter storms and floods that have repeatedly affected the Basque Country since 2013 have multiplied landslide events and originated ground motions in the urbanized areas located along the Atlantic Coast and the Adour and Gaves rivers. Subsidence along coastal areas has to be monitored as well.

-            Abandoned-mine and flood risk management: since 2009, InSAR has been used for monitoring ground motion over the city of Dax. The city is built on a diapir operated in the 19^th century by salt mining companies. This municipality is crossed by the Adour river and was already affected by significant floods (TRI for Territoires à risque important d'Inondation). The CLS group has already generated flood extent maps using satellite radar images following the events in 2013, 2014 and 2015.

-            Gas storage monitoring: different sites over the area of interest are exploited by gas companies. Natural gas, stored during summer time, is extracted during winter. Surface deformation phenomena must be monitored to meet regulatory obligations. InSAR is a possible option currently under assessment.

-            Industrial site development: in Béarn, in Lacq, exploitation of gas reservoirs, started in 1957, originated subsidence phenomena extensively studied in the scientific literature. Extraction activities stopped in 2013. Nowadays this industrial site has become a chemical cluster, hosting many important companies. Land motion is still an important issue.

For this pilot project, more than 100 Sentinel-1 images acquired from October 2014 to October 2016 have been processed. Ascending and descending data have been properly combined to extract vertical and East-West displacement components, making it easy any comparison with GPS-GNSS data.

The results obtained will allow users to assess the information content and the usability of the deliverables, before starting a possible extension of the service to national and/or European level. In a first step, the French Geological Survey (BRGM) will be in involved in data validation and evaluation.

Other players, familiar with InSAR results, will be involved in a second phase of the project. Based on the results obtained in this proof of concept, the CNES and the CLS Group will decide on a possible involvement of Local Authorities.

The Geohazards Exploitation Platform (GEP) is a European Space Agency (ESA) initiative within the ecosystem of Thematic Exploitation Platforms (TEP) focuses on the integration of Ground Segment capabilities and ICT technologies to maximize the exploitation of EO data from past and future missions. A TEP refers to a computing platform that deals with a set of user scenarios involving scientists, data providers and ICT developers, aggregated around an Earth Science thematic area. The Exploitation Platforms are targeted to cover different capacities and they define, implement and validate a platform for effective EO data exploitation in a given thematic area.

In this framework, the GEP aims at providing on-demand and systematic processing services to address the need of the geohazards community for common information layers and to integrate newly developed processors for scientists and other expert users.

The GEP offers this expanding community a unique set of tools to forge new applications in direct collaboration with a large number of players. In particular, the community will benefit from a cloud-based workspace, allowing advanced EO data exploitation activities and offering access to a broad range of shared processing tools. Each partner brings their own tools and processing chains, but also has access in the same workspace to large data sets and shared processing tools.

The GEP has now on-boarded over 70+ early adopters and is entered in the pre-operations phase during 2016 by developing new Pilot applications that will significantly augment the Platform’s capabilities for systematic production and community building. Each project on the Platform is concerned with either integrating an application, running on demand processing using an application available in the platform or systematically generating a new product collection.

Under a Consortium lead by Terradue Srl, six new pilot projects have been taken on board: time-series stereo-photogrammetric processing using optical images for landslides and tectonics movement monitoring with CNRS/EOST (FR), optical based processing method for volcanic hazard monitoring with INGV (IT), systematic generation of deformation time-series with Sentinel-1 data with CNR-IREA (IT), systematic processing of Sentinel-1 interferometric imagery with DLR (DE), terrain motion velocity map generation based on PSI processing by TRE-ALTAMIRA (ES) and a campaign to test and employ GEP applications with the Corinth Rift EPOS Near Fault Observatory.

Finally, GEP is significantly contributing to the development of the satellite component of the European Plate Observing System (EPOS), a long-term plan to facilitate the integrated use of data, data products, and facilities from distributed research infrastructures for solid Earth science in Europe. In particular, GEP has been identified as gateway for the Thematic Core Service “Satellite Data” of EPOS, namely the platform through which the satellite EPOS services will be delivered.


In this work we show how the GEO Geohazards Supersites community can fully benefit from availability of an advanced IT infrastructure, where satellite and in-situ data, advanced satellite processing tools and web-based visualization instruments (Figure 1) are at the disposal of users to address scientific questions. In particular, we focus on the contributions provided by GEP for the management of EO data, for the implementation of a European e-infrastructure, and for the monitoring and modelling of ground deformations (Figure 2) and seismic activity (Figure 3).