Janusz Wasowski(1), Fabio Bovenga(2), Raffaele Nutricato(3), Davide Oscar Nitti(3) and Maria Teresa Chiaradia(4), 2018, High resolution multi-temporal interferometry for monitoring slope instability hazards in open-cast mines_ the strenghts and limitations” G21C-0607, AGU Fall Meeting 2018, Washington (USA), 10-14/12/2018,
URL: http://www.cnr.it/prodotto/i/399218

he new multi-temporal interferometry (MTI) techniques can be profitably used to study land instability hazards. The potential appears great, but the MTI-derived results are yet to be fully explored, especially those based on high spatio-temporal resolution data. Here we focus on the use of MTI for mapping and monitoring of slope and ground instabilities in open-cast mines. They represent a good target for MTI, because they are i) often very large (from few to tens of km2); ii) free of or covered by sparse vegetation; iii) require long-term (years-decades) regular monitoring. Furthermore, given the often large extent of areas affected by surface mining and life span of mines (tens of years), long-term monitoring via traditional in-situ methods can be impractical (economically and technically). However, a review of the recent literature suggests that in comparison to applications to underground mines, MTI has been relatively little exploited to investigate ground instabilities related to surface mining. One reason for this is that some portions of open-cast mines can lack measurable radar targets due to rapid changes of ground surface caused by mining operations (e.g., overburden stripping, waste material damping). We argue that this limitation can now be (in part) mitigated by the higher frequency and regularity of acquisitions provided by the European Space Agency Sentinel-1 (S-1) mission (nominally every 6 days since Oct 2016). Indeed, S-1 medium resolution C-band SAR data acquired at 6 days imply improved time coherence with respect to previous C-band missions, leading to better coverage. We also argue that the initial reconnaissance approaches using S-1 data can be suitably integrated with high spatial resolution MTI (based on e.g., COSMO-SkeyMed or TerraSAR-X imagery) to provide most valuable information for the spatial and temporal analyses of slope deformation and a sound basis for derived products ranging from early slope instability hazard identification to individual landslide monitoring. To illustrate the potential and limitations of MTI for detecting and monitoring ground instabilities induced by surface mining, we present case study examples from two large coal open-cast operations in Europe.

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