Application of DInSAR techniques to the monitoring of ground deformations

The aim of the present thesis has been to test the applicability of the innovative Advanced DInSAR techniques in the natural risk mitigation related to subsidence phenomena. In particular, two test sites have been chosen, both located within alluvial plains and affected by subsidence phenomena: Telese Terme (Italy) where no monitoring network has been installed in spite of the great amount of damaged buildings located in the urban area; Murcia city (Spain) where subsidence has caused damage to structures and infrastructures with an estimated cost of more than 50 million euros. In this second case, the institutions have required studies since '90. For this reason, 20 years of monitoring data are available which have allowed the implementation of an integrated monitoring system based upon satellite DInSAR, conventional field techniques and geotechnical data. Therefore these two areas have been chosen to test different approaches in the use of DInSAR results which can complete a monitoring network where available (as in the case of Murcia city) and replace it where it does not exist (as in the case of Telese Terme). In Murcia case study, the correlation between the temporal evolution of ground surface displacement measures (radar and in situ) and the piezometric groundwater level variation has been analysed to determine mechanisms and critical states of failure; this has permitted to implement a finite element model (FEM) of the phenomenon. Therefore, two models have been carried out: one (called "deep") up to the end of the gravel layer (where the pumping takes place) and one (called "shallow") up to the extensometers' base. The results of the deep model have been compared with DInSAR displacements time series which represent the whole deformation of the stratigraphic column. These comparisons have allowed the individuation of local anomalies of the stiffness values, and have permitted a best model calibration. Moreover, the shallow model results have been compared with the extensometers measurements. These comparisons have showed the occurrence of vertical anisotropies of the permeability. This hypothesis has been verified, analysing the available Lefranc's tests and the most detailed stratigraphic columns and a new model has been proposed. The geotechnical model results have been interpolated through the Ordinary Kriging Radar Errors (OKRE) technique. The achieved deformation maps have been used in the SAR images processing to allow the algorithm to better estimate the no-lineal part of the interferometric phase. In Telese Terme case study, radar measured displacements have allowed to understand the phenomenon spatial extension, its magnitude as same as its historical development. This has permitted the individuation of the causes which provoked damages for some "test buildings". For one of them, a structural model has been implemented; in this case, radar data have been used to verify if its structural response to the displacements detected by SAR corresponded to the overpassing of the limit states. The model results have turned out to have a good correspondence with the forensic analysis achieved in situ. All the proposed approaches could be applied to other scenarios affected by similar phenomena.El objetivo de la presente tesis ha sido probar la aplicabilidad de las técnicas innovadoras de DInSAR Advanced, en la mitigación de los riesgos naturales relacionados con fenómenos de subsidencia. En particular, se han elegido dos sitios de prueba, ambos ubicados en llanuras aluviales y afectados por fenómenos de subsidencia: Telese Terme (Italia) donde no se ha instalado red de vigilancia, a pesar de la gran cantidad de edificios dañados ubicadas en el área urbana y la ciudad de Murcia (España), donde la subsidencia ha causado daños a las estructuras e infraestructuras con un coste estimado de más de 50 millones de euros. En este segundo caso, las instituciones han requerido estudios desde los años 90.Por esta razón, se dispone de 20 años de datos monitorizados los cuales han permitido la implementación de un sistema integrado de vigilancia basado en el satélite dinSAR, técnicas de datos convencionales y datos geotécnicos. Por lo tanto, para probar diferentes enfoques en el uso de los resultados de DInSAR, se han escogidas estas dos áreas de modo que se pueda completar una red de monitoreo donde esté disponible (como en el caso de la ciudad de Murcia) y reemplazarla donde no existe (como en el caso de Telese Terme). En el caso de Murcia, se ha analizado la correlación entre la evolución temporal de las medidas de desplazamiento de la superficie del suelo (radar in situ) y la variación piezométrica del nivel de las aguas subterráneas para determinar los mecanismos y estados críticos de fracaso. Esto ha permitido poner en práctica un modelo de elementos finitos (FEM) del fenómeno. Teniendo en cuenta estos estudios, se han llevado a cabo dos modelos FEM: uno (llamado "(deep) profundo") hasta el extremo del nivel de grava (donde se lleva a cabo el bombeo) y uno (llamado "(shallow) superficial") hasta la base de los extensómetros. Los resultados del modelo de profundidad han sido comparados con las series temporales de deformación DInSAR que representan toda la deformación de la columna estratigráfica. Estas comparaciones han permitido a la individuación de las anomalías locales de los valores de rigidez, y han permitido una mejor calibración del modelo. Por otra parte, los resultados del modelo superficial (shallow), se han comparado con las mediciones extensométricas. Estas comparaciones han mostrado la ocurrencia de anisotropías verticales de la permeabilidad. Esta hipótesis ha sido verificada, analizando las pruebas disponibles de la Lefranc y las columnas estratigráficas más detalladas y se ha propuesto un nuevo modelo. Los resultados del modelo geotécnico han sido interpolados a través de la técnica "Ordinary Kriging Radar Errors" (OKRE). Los mapas de deformación obtenidos han sido utilizados en el procesado de imágenes SAR para permitir al algoritmo una mejor estimación de la parte no lineal de la fase interferométrica. En el caso de Telese Terme, los desplazamientos radar medidos han permitido comprender la extensión espacial del fenómeno, su magnitud y su desarrollo histórico. Esto ha permitido la individuación de las causas que provocaron daños en algunos edificios "de prueba". Para uno de ellos, se ha implementado un modelo estructural; en este caso, se han utilizados, los datos radar para verificar si su respuesta estructural a los desplazamientos detectados por SAR correspondían a la "superación de los estados límite". Los resultados del modelo han resultado tener una buena correspondencia con el análisis forense conseguida in situ. Todos los aproches propuestos se podrían aplicar a otros escenarios afectados por fenómenos similares

Understanding Earth’s Polar Challenges:International Polar Year 2007-2008. Summary by the IPY Joint Committee.

The International Polar Year (IPY) 2007–2008, co-sponsored by ICSU and WMO, became the largest coordinated research program in the Earth’s polar regions, following in the footsteps of its predecessor, the first and second International Polar Years in 1881-1883 and 1932-1933 and the International Geophysical Year 1957–1958. The summary "Understanding Earth's Polar Challenges: International Polar Year 2007-2008" captures the context, motivations, initiation, planning, implementation and the outcomes of the International Polar Year (IPY) 2007–2008, as well as the lessons derived from this key undertaking

Understanding Earth's Polar Challenges: International Polar Year 2007-2008 - Summary by the IPY Joint Committee

The International Polar Year (IPY) 2007–2008, co-sponsored by ICSU and WMO, became the largest coordinated research program in the Earth’s polar regions, following in the footsteps of its predecessor, the first and second International Polar Years in 1881-1883 and 1932-1933 and the International Geophysical Year 1957–1958. An estimated 50,000 researchers, local observers, educators, students, and support personnel from more than 60 nations were involved in the 228 international IPY projects (170 in science, 1 in data management, and 57 in education and outreach) and related national efforts. IPY generated intensive research and observations in the Arctic and Antarctica over a two-year period, 1 March 2007–1 March 2009, with many activities continuing beyond that date. The summary "Understanding Earth's Polar Challenges: International Polar Year 2007-2008" captures the context, motivations, initiation, planning, implementation and the outcomes of the International Polar Year (IPY) 2007–2008, as well as the lessons derived from this key undertaking

Progress in Landslide Research and Technology, Volume 1 Issue 1, 2022

This open access book provides an overview of the progress in landslide research and technology and is part of a book series of the International Consortium on Landslides (ICL). The book provides a common platform for the publication of recent progress in landslide research and technology for practical applications and the benefit for the society contributing to the Kyoto Landslide Commitment 2020, which is expected to continue up to 2030 and even beyond to globally promote the understanding and reduction of landslide disaster risk, as well as to address the 2030 Agenda Sustainable Development Goals

Groß-skalige 2D-hydraulische Modellierung: Verbesserung der Analyse der Flutdynamik mit remote sensing und freien geographischen Informationen

This work investigates the integration of hydro-geomorphic models, traditional data (static stage gages) and novel data sources, such as remotely sensed images and Crowdsourced data (Volunteering Geographic Information or VGI), for observation-driven improvements of hydro-modelling tools. The Tiber river basin, was selected as case study with a focus domain on the approximately 120 km channel upstream of Rome for its strategic importance in the protection of the historical city centre and the coastal urbanized zone. A parsimonious hydrological modelling algorithm was implemented, calibrated and validated for calculating the flow hydrographs of the ungauged small basins contributing to the study area. Furthermore, to delineate the boundaries computational domain of the hydraulic model for the Data Assimilation application, a DEM-based hydro-geomorphic floodplain delineation algorithm adapted from literature was tested with different DEMs and considering also its parametrization varying the stream orders. The adopted DA methodology is the Ensemble Kalman Filter (EnKF) that requires multiple simulations for representing the uncertainties related to the model and the observations errors. New approaches were proposed for integrating, as observations in the DA method, traditional static sensors, and simultaneously remotely sensed images and VGI data. Despite the static sensor have already been adopted in literature as observations in a DA framework, some new technical measures were necessary for integrating them in Quasi-2D hydraulic model. The assimilation of satellite images resulted to be effective, since the whole computational domain is interested by the water levels correction, although the improvement of the model performance persisted for only some hours of simulation. The usefulness of VGI have been investigated considering the uncertainties related to their reliability mostly in terms of accuracy and time allocation. Results show the potential of new data for improving the performance of the flood model, partially overcoming the limitations and the potential scarce availability of the traditional sensors. Finally, the simultaneous integration of all the three types of observations gave promising results, improving the performance of the model compared to the ones obtained assimilating only Satellite images or VGI observations.Diese Arbeit untersucht die Integration von hydro-geomorphen Modellen, traditionellen Daten (statische Stufenpegeln) und neuartigen Datenquellen wie Remote-Sensing-Bildern und Crowdsourced-Daten (volunteering Geographic Information oder VGI), um beobachtungsorientierte Verbesserungen von Hydromodellierungswerkzeugen zu erreichen. Das Tiber-Flusseinzugsgebiet wurde als Fallstudie mit einem Schwerpunkt auf dem etwa 120 km stromaufwärts von Rom gelegenen Kanal ausgewählt und zwar wegen seiner strategischen Bedeutung für den Schutz des historischen Stadtzentrums und der urbanisierten Küstenregion. Ein sparsamer hydrologischer Modellierungsalgorithmus wurde implementiert, kalibriert und validiert, um die Fluss-Hydrographen der durch Pegel nicht erfassten kleinen Becken zu berechnen, die zum Untersuchungsgebiet beitragen. Um die Grenzen des rechnerischen Bereichs des Hydraulikmodells für die Data-Assimilation-Anwendung abzugrenzen, wurde außerdem ein DEM-basierter, aus der Literatur angepasster Algorithmus zur Abgrenzung von hydrogeomorphen Flutebenen mit verschiedenen DEMs getestet, wobei auch die Parametrisierung der Stream-Reihenfolge berücksichtigt wurde. Die angenommene DA-Methode ist der Ensemble Kalman Filter (EnKF), der mehrere Simulationen zur Darstellung der mit dem Modell verbundenen Unsicherheiten und Beobachtungsfehler erfordert. Es wurden neue Ansätze für die Integration herkömmlicher statischer Sensoren, von Fernerkundungs-Bildern und von VGI-Daten als Beobachtungen für das DA-Verfahren vorgeschlagen. Obwohl die statischen Sensoren bereits in der Literatur als Beobachtungen in einem DA-Rahmen verwendet wurden, waren einige technische Maßnahmen erforderlich, um sie in das Quasi-2D-Hydraulikmodell zu integrieren. Die Assimilation von Satellitenbildern erwies sich als effektiv, da der gesamte rechnerische Bereich an der Korrektur des Wasserstandes interessiert ist; die Verbesserung der Modellleistung dauerte allerdings nur einige Stunden in der Simulation an. Die Nützlichkeit von VGI wurde unter Berücksichtigung der mit ihrer Zuverlässigkeit verbundenen Unsicherheiten hauptsächlich hinsichtlich Genauigkeit und Zeitzuordnung untersucht. Die Ergebnisse zeigen das Potenzial neuer Daten zur Verbesserung der Leistung des Flutmodells, wobei teilweise die Einschränkungen und die oftmals knappe Verfügbarkeit herkömmlicher Sensoren überwunden werden. Schließlich ergab die gleichzeitige Integration aller drei Arten von Beobachtungen vielversprechende Ergebnisse und verbesserte die Leistung des Modells im Vergleich zur Nutzung nur von Satellitenbilder oder VGI-Beobachtungen