Post-failure evolution analysis of a rainfall-triggered landslide by multi-temporal interferometry SAR approaches integrated with geotechnical analysis

Persistent Scatterers Interferometry (PSI) represents one of the most powerful techniques for Earth's surface deformation processes' monitoring, especially for long-term evolution phenomena. In this work, a dataset of 34 TerraSAR-X StripMap images (October 2013–October 2014) has been processed by two PSI techniques - Coherent Pixel Technique-Temporal Sublook Coherence (CPT-TSC) and Small Baseline Subset (SBAS) - in order to study the evolution of a slow-moving landslide which occurred on February 23, 2012 in the Papanice hamlet (Crotone municipality, southern Italy) and induced by a significant rainfall event (185 mm in three days). The mass movement caused structural damage (buildings' collapse), and destruction of utility lines (gas, water and electricity) and roads. The results showed analogous displacement rates (30–40 mm/yr along the Line of Sight – LOS-of the satellite) with respect to the pre-failure phase (2008–2010) analyzed in previous works. Both approaches allowed detect the landslide-affected area, however the higher density of targets identified by means of CPT-TSC enabled to analyze in detail the slope behavior in order to design possible mitigation interventions. For this aim, a slope stability analysis has been carried out, considering the comparison between groundwater oscillations and time-series of displacement. Hence, the crucial role of the interaction between rainfall and groundwater level has been inferred for the landslide triggering. In conclusion, we showed that the integration of geotechnical and remote sensing approaches can be seen as the best practice to support stakeholders to design remedial works.Peer ReviewedPostprint (author's final draft

Imaging land subsidence in the Guadalentín River Basin (SE Spain) using Advanced Differential SAR Interferometry

Aquifer overexploitation can lead to the irreversible loss of groundwater storage caused by the compaction or consolidation of unconsolidated fine-grained sediments resulting in land subsidence. Advanced Differential SAR Interferometry (A-DINSAR) is particularly efficient to monitor progressive ground movements, making it an appropriate method to study depleting aquifers undergoing overexploitation and land subsidence. The Guadalentín River Basin (Murcia, Spain) is a widely recognized subsiding area that exhibits the highest rates of groundwater-related land subsidence recorded in Europe (>10 cm/yr). The basin covers an extension of more than 500 km2 and is underlain by an overexploited aquifer-system formed by two contiguous hydraulically connected units (Alto Guadalentín and Bajo Guadalentín). Although during the last years the piezometric levels have partially stabilized, the ongoing aquifer-system deformation is evident and significant, as revealed by the A-DInSAR analysis presented. In this work, we submit the first vertical and horizontal (E-W) decomposition results of the LOS velocity and displacement time series of the whole Guadalentín Basin obtained from two datasets of Sentinel-1 SAR acquisitions in ascending and descending modes. The images cover the period from 2015 to 2021 and they were processed using the Parallel Small BAseline Subset (P-SBAS) implemented by CNRIREA in the Geohazards Exploitation Platform (GEP) on-demand web tool, which is funded by the European Space Agency. The output ascending and descending measurement points of P-SBAS lie on the same regular grid, which is particularly suited for the geometrical decomposition. Time series displacements are compared to a permanent GNSS station located in the Bajo Guadalentín basin.This study has received funding in framework of the RESERVOIR project (Sustainable groundwater RESources managEment by integrating eaRth observation deriVed monitoring and flOw modelIng Results), funded by the Partnership for Research and Innovation in the Mediterranean Area (PRIMA) programme supported by the European Union (Grant Agreement 1924; https://reservoir-prima.org/). The study has also been supported by the Grant FPU19/03929 (funded by MCIN/AEI/10.13039/501100011033 and by “FSE invests in your future”); the Project CGL2017-83931-C3-3-P (funded by MCIN/ AEI/10.13039/501100011033 and by “ERDF A way of making Europe”); the ESA-MOST China DRAGON-5 Project (ref. 59339) and the SARAI Project PID2020-116540RB-C22 (funded by MCIN/AEI/10.13039/501100011033). Copernicus Sentinel-1 IW SAR data were provided and processed in ESA’s Geohazards Exploitation Platform (GEP), in the framework of the GEP Early Adopters Programme

Automatic generation of co-seismic displacement maps by using Sentinel-1 interferometric SAR data

Abstract We present a tool for the automatic generation of co-seismic Differential Synthetic Aperture Radar Interferometry (DInSAR) products by using space-borne SAR data. In particular, the implemented tool relies on the large availability of Sentinel-1 SAR data and on-line earthquake catalogues (e.g. USGS, INGV) to generate co-seismic Line Of Sight (LOS) interferograms and displacement maps. The processing is triggered by the occurrence of a main seismic event, according to the accessible earthquake catalogues. The tool automatically retrieves all the needed SAR acquisitions that cover a defined area across the epicentre and generates the DInSAR products that will be then openly available through the European Plate Observing System (EPOS) portal. Moreover, the possibility to implement the presented tool into the upcoming Copernicus Data and Information Access Services (DIAS) will significantly reduce the product processing time, thus implying a faster product generation and delivery. Accordingly, such a tool not only will contribute to expand the use of DInSAR products in the geoscience field, but also will play a key role on the support of the Civil Protection authorities during the management of seismic crisis

Medición de subsidencia del terreno causada por sobreexplotación de acuíferos mediante herramientas GEP: A-DInSAR en la nube

[EN] Groundwater is a vitally important resource for humans. One of the main problems derived from the overexploitation of aquifers is land subsidence, which in turn carries other associated natural risks. Advanced Differential satellite radar interferometry (A-DInSAR) techniques provide valuable information on the surface displacements of the ground, which serve to characterize both the deformational behaviour of the aquifer and its properties. RESERVOIR is a research project belonging to the European PRIMA programme, whose main objective is to design sustainable groundwater management models through the study of four areas of the Mediterranean subjected to water stress. One of the main tasks of the project is the integration of the terrain deformation data obtained with satellite remote sensing techniques in the hydrogeological and geomechanical models of the aquifers. In the present work, a first evaluation of the deformation of the ground in each study area is carried out using the tools contained in the Geohazards Exploitation Platform (GEP). This is a service financed by the European Space Agency (ESA) that allows processing directly on its server, without need to store data or applications locally.[ES] Las aguas subterráneas son un recurso de vital importancia para el ser humano. Una de las principales problemáticas derivadas de la sobreexplotación de acuíferos es la subsidencia del terreno, que a su vez lleva asociados otros riesgos naturales. Las técnicas avanzadas de interferometría radar diferencial de satélite (A-DInSAR) aportan información muy valiosa sobre los desplazamientos superficiales del terreno, que sirven para caracterizar tanto el comportamiento geomecánico del acuífero como sus propiedades. RESERVOIR es un proyecto de investigación perteneciente al programa europeo PRIMA, cuyo principal objetivo es diseñar modelos sostenibles de gestión de aguas subterráneas mediante el estudio de cuatro zonas del Mediterráneo sometidas a estrés hídrico. Una de las principales tareas del proyecto es la integración de los datos de deformación del terreno obtenidos con técnicas de teledetección por satélite en los modelos hidrogeológicos y geomecánicos de los acuíferos. En el presente trabajo se realiza una primera evaluación de la deformación del terreno en cada zona de estudio utilizando las herramientas contenidas en la Geohazards Exploitation Platform (GEP). Este servicio financiado por la Agencia Espacial Europea (ESA) permite realizar procesados directamente en su servidor, sin necesidad de almacenar datos ni aplicaciones en local.This work was supported by RESERVOIR project, which is part of the PRIMA Programme supported under Horizon 2020 the European Union's Framework Programme for Research and Innovation. Grant Agreement number: [1924] [RESERVOIR] [Call 2019 Section 1 Water RIA]. Copernicus Sentinel-1 IW SAR data were provided and processed in ESA’s Geohazards Exploitation Platform (GEP), in the framework of the GEP Early Adopters Programme.Bru, G.; Ezquerro, P.; Guardiola-Albert, C.; Béjar-Pizarro, M.; Herrera, G.; Tomás, R.; Navarro-Hernández, M.... (2021). Land subsidence analysis caused by aquifer overexploitation using GEP tools: A-DInSAR on the cloud. En Proceedings 3rd Congress in Geomatics Engineering. Editorial Universitat Politècnica de València. 127-136. https://doi.org/10.4995/CiGeo2021.2021.12722OCS12713

An insight in cloud computing solutions for intensive processing of remote sensing data

The investigation of Earth's surface deformation phenomena provides critical insights into several processes of great interest for science and society, especially from the perspective of further understanding the Earth System and the impact of the human activities. Indeed, the study of ground deformation phenomena can be helpful for the comprehension of the geophysical dynamics dominating natural hazards such as earthquakes, volcanoes and landslide. In this context, the microwave space-borne Earth Observation (EO) techniques represent very powerful instruments for the ground deformation estimation. In particular, Small BAseline Subset (SBAS) is regarded as one of the key techniques, for its ability to investigate surface deformation affecting large areas of the Earth with a centimeter to millimeter accuracy in different scenarios (volcanoes, tectonics, landslides, anthropogenic induced land motions). The current Remote Sensing scenario is characterized by the availability of huge archives of radar data that are going to increase with the advent of Sentinel-1 satellites. The effective exploitation of this large amount of data requires both adequate computing resources as well as advanced algorithms able to properly exploit such facilities. In this work we concentrated on the use of the P-SBAS algorithm (a parallel version of SBAS) within HPC infrastructure, to finally investigate the effectiveness of such technologies for EO applications. In particular we demonstrated that the cloud computing solutions represent a valid alternative for scientific application and a promising research scenario, indeed, from all the experiments that we have conducted and from the results obtained performing Parallel Small Baseline Subset (P-SBAS) processing, the cloud technologies and features result to be absolutely competitive in terms of performance with in-house HPC cluster solution

Getting ready for the generation of a nationwide ground motion product for Great Britain using SAR dta stacks: feasibility, data volumes and perspectives

This paper discusses the feasibility of monitoring ground stability and motion across the entire British landmass using satellite InSAR techniques. The ERS-1/2 and ENVISAT archive data availability, topographic visibility and land cover constraints for multi-temporal InSAR techniques to succeed across Britain are analysed. Data volumes, hardware and software requirements for the generation of a nationwide InSAR product are discussed, with a view to both novel processing methods to extend InSAR across unfavourable land covers, and parallel and cloud computing systems to decrease InSAR processing time demands. The P-SBAS method implemented into ESA’s G-POD platform is tested for London and Newcastle using ERS-1/2 1992-2000 and ENVISAT 2002-2008 image stacks, revealing a decrease of the processing time demand from several days to only ~8 hours per image frame

Evaluation of the SBAS InSAR Service of the European Space Agency’s Geohazard Exploitation Platform (GEP)

The analysis of remote sensing data to assess geohazards is being improved by web-based platforms and collaborative projects, such as the Geohazard Exploitation Platform (GEP) of the European Space Agency (ESA). This paper presents the evaluation of a surface velocity map that is generated by this platform. The map was produced through an unsupervised Multi-temporal InSAR (MTI) analysis applying the Parallel-SBAS (P-SBAS) algorithm to 25 ENVISAT satellite images from the South of Spain that were acquired between 2003 and 2008. This analysis was carried out using a service implemented in the GEP called “SBAS InSAR”. Thanks to the map that was generated by the SBAS InSAR service, we identified processes not documented so far; provided new monitoring data in places affected by known ground instabilities; defined the area affected by these instabilities; and, studied a case where GEP could have been able to help in the forecast of a slope movement reactivation. This amply demonstrates the reliability and usefulness of the GEP, and shows how web-based platforms may enhance the capacity to identify, monitor, and assess hazards that are associated to geological processes.Spanish “Juan de la Cierva” grants support part of the work of Jorge P. Galve. The expenses related to the hired researcher contract of Jorge P. Galve and the field surveying were funded by the project CGL2015-67130-C2-1-R (FEDER and Spanish Ministry of Economy and Competitiveness)

Soil deformation analysis through fluid-dynamic modelling and DInSAR measurements: a focus on groundwater withdrawal in the Ravenna area (Italy)

This study aims at assessing the deformation processes affecting an area NW of the city of Ravenna (northern Italy), caused by groundwater withdrawal activities. In situ data, geologic and structural maps, piezometric measurements, underground water withdrawal volumes, and satellite C-band SAR data were used to jointly exploit two different techniques: 1) fluid-dynamic and geomechanical modelling (by RSE S.p.A), and 2) Differential Synthetic Aperture Radar Interferometry (DInSAR) analysis (by CNR - IREA). The results of the comparative analysis presented in this work brought new evidence about the contribution of groundwater withdrawal to the total subsidence affecting the area during the 2000-2017 time interval. In particular, they show an increase of the subsidence from year 2000 to 2010 and a decrease from year 2010 to 2017. These results are generally in line with groundwater withdrawal data that report a reduction of the extracted water volumes during the considered temporal interval. Meantime, they show a delay effect in the subsidence process, partially recovered during the 2010-2017 thanks to a stabilisation of the extracted groundwater volumes. The presented results shade new light on the groundwater withdrawal contribution to the subsidence of the analysed zone, although further investigations are foreseen to better clarify the ongoing scenario

A Global Archive of Coseismic DInSAR Products Obtained Through Unsupervised Sentinel-1 Data Processing

We present an automatic and unsupervised tool for the systematic generation of Sentinel-1 (S1) differential synthetic aperture radar interferometry (DInSAR) coseismic products. In particular, the tool first retrieves the location, depth, and magnitude of every seismic event from interoperable online earthquake catalogs (e.g., the United States Geological Survey (USGS) and the Italian National Institute of Geophysics and Volcanology (INGV) and then, for significant (with respect to a set of selected thresholds) earthquakes, it automatically triggers the downloading of S1 data and their interferometric processing over the area affected by the earthquake. The automatic system we developed has also been implemented within a Cloud-Computing (CC) environment, specifically the Amazon Web Services, with the aim of creating a global database of DInSAR S1 coseismic products, which consist of displacement maps and the associated wrapped interferograms and spatial coherences. This information will progressively be made freely available through the European Plate Observing System (EPOS) Research Infrastructure, thus providing the scientific community with a large catalog of DInSAR data that can be helpful for investigating the dynamics of surface deformation in the seismic zones around the Earth. The developed tool can also support national and local authorities during seismic crises by quickly providing information on the surface deformation induced by earthquakes

InSAR-based mapping of ground deformation caused by industrial waste disposals: the case study of the Huelva phosphogypsum stack, SW Spain

Close to the city of Huelva, SW Spain, and near the Atlantic Ocean, there is a phosphogypsum (PG) stack that accumulates 100 Mt of wastes and extends over 1000 ha. The stack lies directly over estuarine unconsolidated sediments with no protective layer in between. Here, we evaluate for the first time the structural stability of the PG stack, monitoring the deformation suffered by the salt-marsh basement. Through the web-based Geohazard Exploitation Platform (GEP) of the European Space Agency (ESA), a specific differential SAR interferometry (DInSAR) algorithm known as arallel Small Baseline Subset (P-SBAS) has been used to process 279 ESA Sentinel-1 images acquired between October 2016 and June 2021. Resulting displacement maps and time-series curves reveal vertical displacements of up to 16 cm/year. This vertical motion has been associated to subsidence. In parallel with subsidence, horizontal movements > 2.5 cm/year have been also accounted and linked to talus destabilization. The analysis also demonstrates that the Huelva PG stack is vulnerable to adverse weather condition. The present study demonstrates that the InSAR-based methods are effective tools for monitoring the stability and ground motion of large waste stockpiles.This work was financed by the ESA thorough a project covered by the NOR Sponsorship Program. The project (ID: Felipe González) was intended to use the Geohazards TEP service (https:// geoha zards- tep. eu/#!) for the analysis of the subsidence of SW Spain. Special thanks are extended to Hervé Caumont (Terradue Programme Manager) who patiently provided technical support during all the analysis. The original manuscript was significantly improved thanks to the valuable suggestions and comments of two anonymous reviewers. Aerial photograph in Figure 1 was provided by the Mesa de la Ría Association. Funding for open access charge: Universidad de Huelva / CBUA