Deformation analysis of a metropolis from C- to X-band PSI: proof-of-concept with Cosmo-Skymed over Rome, Italy

Stability of monuments and subsidence of residential quarters in Rome (Italy) are depicted based on geospatial analysis of more than 310,000 Persistent Scatterers (PS) obtained from Stanford Method for Persistent Scatterers (StaMPS) processing of 32 COSMO-SkyMed 3m-resolution HH StripMap ascending mode scenes acquired between 21 March 2011 and 10 June 2013. COSMO-SkyMed PS densities and associated displacement velocities are compared with almost 20 years of historical C-band ERS- 1/2, ENVISAT and RADARSAT-1/2 imagery. Accounting for differences in image processing algorithms and satellite acquisition geometries, we assess the feasibility of ground motion monitoring in big cities and metropolitan areas by coupling newly acquired and legacy SAR in full time series. Limitations and operational benefits of the transition from medium resolution C-band to high resolution X-band PS data are discussed, alongside the potential impact on the management of expanding urban environments

Deformation analysis of a metropolis from C- to X-band PSI: proof-of-concept with Cosmo-Skymed over Rome, Italy

Stability of monuments and subsidence of residential quarters in Rome (Italy) are depicted based on geospatial analysis of more than 310,000 Persistent Scatterers (PS) obtained from Stanford Method for Persistent Scatterers (StaMPS) processing of 32 COSMO-SkyMed 3m-resolution HH StripMap ascending mode scenes acquired between 21 March 2011 and 10 June 2013. COSMO-SkyMed PS densities and associated displacement velocities are compared with almost 20 years of historical C-band ERS- 1/2, ENVISAT and RADARSAT-1/2 imagery. Accounting for differences in image processing algorithms and satellite acquisition geometries, we assess the feasibility of ground motion monitoring in big cities and metropolitan areas by coupling newly acquired and legacy SAR in full time series. Limitations and operational benefits of the transition from medium resolution C-band to high resolution X-band PS data are discussed, alongside the potential impact on the management of expanding urban environments

Exploiting satellite SAR for archaeological prospection and heritage site protection

Optical and Synthetic Aperture Radar (SAR) remote sensing has a long history of use and reached a good level of maturity in archaeological and cultural heritage applications, yet further advances are viable through the exploitation of novel sensor data and imaging modes, big data and high-performance computing, advanced and automated analysis methods. This paper showcases the main research avenues in this field, with a focus on archaeological prospection and heritage site protection. Six demonstration use-cases with a wealth of heritage asset types (e.g. excavated and still buried archaeological features, standing monuments, natural reserves, burial mounds, paleo-channels) and respective scientific research objectives are presented: the Ostia-Portus area and the wider Province of Rome (Italy), the city of Wuhan and the Jiuzhaigou National Park (China), and the Siberian “Valley of the Kings” (Russia). Input data encompass both archive and newly tasked medium to very high-resolution imagery acquired over the last decade from satellite (e.g. Copernicus Sentinels and ESA Third Party Missions) and aerial (e.g. Unmanned Aerial Vehicles, UAV) platforms, as well as field-based evidence and ground truth, auxiliary topographic data, Digital Elevation Models (DEM), and monitoring data from geodetic campaigns and networks. The novel results achieved for the use-cases contribute to the discussion on the advantages and limitations of optical and SAR-based archaeological and heritage applications aimed to detect buried and sub-surface archaeological assets across rural and semi-vegetated landscapes, identify threats to cultural heritage assets due to ground instability and urban development in large metropolises, and monitor post-disaster impacts in natural reserves

Structural health monitoring of engineered structures using a space-borne synthetic aperture radar multi-temporal approach: from cultural heritage sites to war zones

Structural health monitoring (SHM) of engineered structures consists of an automated or semi-automated survey system that seeks to assess the structural condition of an anthropogenic structure. The aim of an SHM system is to provide insights into possible induced damage or any inherent signals of deformation affecting the structure in terms of detection, localization, assessment, and prediction. During the last decade there has been a growing interest in using several remote sensing techniques, such as synthetic aperture radar (SAR), for SHM. Constellations of SAR satellites with short repeat time acquisitions permit detailed surveys temporal resolution and millimetric sensitivity to deformation that are at the scales relevant to monitoring large structures. The all-weather multi-temporal characteristics of SAR make its products suitable for SHM systems, especially in areas where in situ measurements are not feasible or not cost effective. To illustrate this capability, we present results from COSMO-SkyMed (CSK) and TerraSAR-X SAR observations applied to the remote sensing of engineered structures. We show how by using multiple-geometry SAR-based products which exploit both phase and amplitude of the SAR signal we can address the main objectives of an SHM system including detection and localization. We highlight that, when external data such as rain or temperature records are available or simple elastic models can be assumed, the SAR-based SHM capability can also provide an interpretation in terms of assessment and prediction. We highlight examples of the potential for such imaging capabilities to enable advances in SHM from space, focusing on dams and cultural heritage areas. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Evaluation of subsidence induced by long-lasting buildings load using InSAR technique and geotechnical data: The case study of a Freight Terminal (Tuscany, Italy)

This paper shows the results of the comparison between Multi-temporal Synthetic Aperture Radar (MTInSAR) products derived from different sensors (C-band ERS 1/2, Envisat, Sentinel-1 and X-band COSMO-SkyMed) and geotechnical data to investigate the driving factors of subsidence which affect a freight terminal located along the a coastal plain of Tuscany (central Italy). MTInSAR data have been acquired in a very long period, between 1992 and 2018 and were analyzed in terms of subsidence rates and deformation time series at building scale. The obtained results show that the oldest buildings are still affected by a deformation rate close to −5 mm/yr, whereas recent buildings register rates around −40 mm/yr. Time series of deformation suggest that the deformation rates decrease over time following time-dependent trend that approximates the typical consolidation curve for compressible soils. The geotechnical and stratigraphical analysis of the subsurface data (boreholes, cone penetration tests and dilatometer tests) highlights the presence of a 15 m thick layer formed of clay characterized by poor geotechnical characteristics. The comparison among InSAR data, subsurface geological framework and geotechnical reconstruction suggests a possible evaluation of the timing of the primary and secondary consolidation processes

Prothego : WP2 : harmonisation of PS data, and creation of digital factsheets : deliverable : D.02.01 : available satellite InSAR data for the European WHL sites

PROTHEGO (PROTection of European Cultural HEritage from GeO-hazards) is a collaborative research project funded in 2015–2018 in the framework of the Joint Programming Initiative on Cultural Heritage and Global Change (JPI-CH) – Heritage Plus. The project aims to make an innovative contribution towards the analysis of geohazards in areas of cultural heritage, and uses novel space technology based on Interferometric Synthetic Aperture Radar (InSAR) to retrieve information on ground stability and motion in the UNESCO World Heritage List (WHL) monuments and sites of Europe. This report introduces PROTHEGO’s Work Package (WP) 2: Harmonisation of available PS data, and creation of digital factsheets, led by the Natural Environment Research Council (NERC) – British Geological Survey (BGS) and aimed to define, catalogue and assess the availability of satellite-derived ground motion information from multi-temporal InSAR and Persistent Scatterers (PS) techniques for the UNESCO WHL sites of Europe. WP2 consists of two main tasks: 2.1 – Analysis of satellite InSAR and PS datasets available at European scale; and 2.2 – Harmonisation of InSAR and PS ground motion information and creation of digital factsheets. Their goal is to generate a GIS catalogue of the available satellite InSAR data for the UNESCO WHL sites of Europe, and digital factsheets summarising the observed ground motion velocities and deformation histories of the PS reflectors within each WHL site, alongside two technical reports. This is the first report describing the methodology adopted for, and results obtained from, the analysis of the availability of ground motion information for the WHL sites of Europe (i.e. Task 2.1). This information is based on InSAR processing of satellite radar imagery that was carried out in the framework of ongoing or recent European, national and/or research projects (such as ESA-GMES Terrafirma, and the Italian Extraordinary Plan of Environmental Remote Sensing EPRS-E), as well as those available through published literature (e.g., scientific papers, project reports). Information on data availability for the WHL sites was recorded in an ad hoc catalogue, together with metadata on the retrieved ground stability and motion datasets (e.g., data source, satellite and sensor, monitoring period, acquisition mode). The analysis allowed the delineation of a general overview of the coverage of InSAR datasets for the UNESCO sites at European scale, as well as the identification of data coverage gaps. The results reveal that, as of the end of 2016, 147 sites (i.e. 37% of the analysed 399 sites of PROTHEGO) are covered by existing datasets and/or published literature, whereas there is a data coverage gap for 252 sites (i.e. 63%). Therefore InSAR information can or may be accessible to study geohazards in more than one-third of the total European UNESCO sites. It is to be noted, however, that in addition to the datasets and literature found so far, many other unpublished studies may exist, as well as other digital datasets that could be made available to PROTHEGO via other projects, suggesting that even more sites than the 37% figure provided in this report may be already covered

Trends and perspectives of space-borne SAR remote sensing for archaeological landscape and cultural heritage applications

This paper provides an overview of the opportunities that image analysts, archaeologists and conservation scientists currently have to use space-borne Synthetic Aperture Radar (SAR) imagery for prospection of cultural landscapes and investigation of environmental, land surface and anthropogenic processes that can alter the condition of heritage assets. The benefits of the recent developments in SAR satellite sensors towards higher resolution (up to less than 1 m) and shorter revisiting times (up to a few days) are discussed in relation to established techniques using the two key SAR parameters – amplitude and phase. Selected case studies from Middle East to South America illustrate how SAR can be effectively used to detect subtle archaeological features in modern landscapes, monitor historic sites and assess damage in areas of conflict. These examples form the basis to highlight the current trends in archaeological remote sensing based on space-borne SAR data in the era of the European Space Agency's Sentinel-1 constellation and on-demand high resolution space missions such as TerraSAR-X

Mapping interactions between geology, subsurface resource exploitation and urban development in transforming cities using InSAR Persistent Scatterers: two decades of change in Florence, Italy

Urban expansion and city transformation are increasing reality across the world. Now more than ever it is essential to understand and map at the appropriate scale the processes happening along the verticality and horizontality of cities, to gather robust evidence underpinning strategies for sustainable management of the built environment. This paper explores how established techniques of Persistent Scatterer Interferometry (PSI) can be shaped into a novel dedicated procedure to detect vertical and horizontal urban dynamics including: use and re-use of urban space (new building construction, intentional demolition, renovation projects); exploitation of groundwater resources (induced land subsidence); interactions between new foundations, superficial deposits and bedrock geology (settlement of recent buildings); ground and slope instability affecting settled buildings; susceptibility of heritage assets to structural damages; baseline characterisation prior to planned major infrastructure construction (tunnelling and transportation networks). Florence, central Italy, is used as a demonstration site. This city includes UNESCO World Heritage List historic centre, 20th-century residential, industrial and peri-urban quarters, and is currently in transition to metropolitan area of over 1 million of inhabitants. Velocity decomposition maps were generated based on millimetre-precise estimates of surface displacements retrieved from PSI processing of the full archives of satellite C-band radar images, including 79 ERS-1/2 descending (1992–2000), 70 ENVISAT ASAR ascending and descending (2003–2010) and 101 RADARSAT-1 ascending and descending (2003–2007). 12 macropatterns and 84 micropatterns in the final map of alert areas highlight a dualism which reflects the physical and urban geography of Florence. North-western and south-western quarters show hot spots of new building construction and regeneration projects for residential, business and tertiary service purposes, alongside issues due to groundwater exploitation and induced land subsidence up to 30–40 mm/yr. Local interactions with underlying geology and natural slope instability processes predominate in the southern and north-eastern sectors. At local scale, stable condition was found for the heritage assets and buildings located along the tracks of the planned subway railway and tramway, with motion rates averagely within ±1.5 mm/yr and localised deformation only up to −3.5 mm/yr. Structural assessment based on future PSI monitoring campaign will benefit of this baseline characterisation

Combined InSAR and Terrestrial Structural Monitoring of Bridges

This paper examines advances in InSAR satellite measurement technologies to understand their relevance, utilisation and limitations for bridge monitoring. Waterloo Bridge is presented as a case study to explore how InSAR data sets can be combined with traditional measurement techniques including sensors installed on the bridge and automated total stations. A novel approach to InSAR bridge monitoring was adopted by the installation of physical reflectors at key points of structural interest on the bridge, in order to supplement the bridge’s own reflection characteristics and ensure that the InSAR measurements could be directly compared and combined with insitu measurements. The interpretation and integration of InSAR data sets with civil infrastructure data is more than a trivial task, and a discussion of uncertainty of measurement data is presented. Finally, a strategy for combining and interpreting varied data from multiple sources to provide useful insights into each of these methods is presented, outlining the practical applications of this data analysis to support wider monitoring strategies.Author funding under EPSRC (UK) Award 1636878, co-author funding under Research Council of Norway (RCN Grant no. 237906)

Measuring Urban Subsidence in the Rome Metropolitan Area (Italy) with Sentinel-1 SNAP-StaMPS Persistent Scatterer Interferometry

Land subsidence in urban environments is an increasingly prominent aspect in the monitoring and maintenance of urban infrastructures. In this study we update the subsidence information over Rome and its surroundings (already the subject of past research with other sensors) for the first time using Copernicus Sentinel-1 data and open source tools. With this aim, we have developed a fully automatic processing chain for land deformation monitoring using the European Space Agency (ESA) SentiNel Application Platform (SNAP) and Stanford Method for Persistent Scatterers (StaMPS). We have applied this automatic processing chain to more than 160 Sentinel-1A images over ascending and descending orbits to depict primarily the Line-Of-Sight ground deformation rates. Results of both geometries were then combined to compute the actual vertical motion component, which resulted in more than 2 million point targets, over their common area. Deformation measurements are in agreement with past studies over the city of Rome, identifying main subsidence areas in: (i) Fiumicino; (ii) along the Tiber River; (iii) Ostia and coastal area; (iv) Ostiense quarter; and (v) Tivoli area. Finally, post-processing of Persistent Scatterer Inteferometry (PSI) results, in a Geographical Information System (GIS) environment, for the extraction of ground displacements on urban infrastructures (including road networks, buildings and bridges) is considered