Abstract:From the wide range of methods available to landslide researchers and practitioners for monitoring ground displacements, remote sensing techniques have increased in popularity. Radar interferometry methods with their ability to record movements in the order of millimeters have been more frequently applied in recent years. Multi-temporal interferometry can assist in monitoring landslides on the regional and slope scale and thereby assist in assessing related hazards and risks. Our study focuses on the Corvara landslides in the Italian Alps, a complex earthflow with spatially varying displacement patterns. We used radar imagery provided by the COSMO-SkyMed constellation and carried out a validation of the derived time-series data with differential GPS data. Movement rates were assessed using the Permanent Scatterers based Multi-Temporal Interferometry applied to 16 artificial Corner Reflectors installed on the source, track and accumulation zones of the landslide. The overall movement trends were well covered by Permanent Scatterers based Multi-Temporal Interferometry, however, fast acceleration phases and movements along the satellite track could not be assessed with adequate accuracy due to intrinsic limitations of the technique. Overall, despite the intrinsic limitations, Multi-Temporal Interferometry proved to be a promising method to monitor landslides characterized by a linear and relatively slow movement rates.
Active landslides are generally characterized by variations\ud
in displacement rate in response to cumulated precipitation.\ud
Velocities that are only exceeded in a limited number of days\ud
during the year might be considered as critical events, since they\ud
might determine, or prelude to, a significant evolution of the\ud
landslide. The purpose of this paper is to present a novel approach\ud
based on the use of receiver operating characteristic (ROC) curves\ud
for assessing cumulated precipitation thresholds that can provide\ud
early warning for the occurrence of critical events such as the\ud
exceedance of rare displacement rates. The approach has been\ud
developed and tested in the Piagneto landslide, an active complex\ud
rock slide—debris slide in the Northern Apennines of Italy, for\ud
which a 5-year continuous surveying monitoring dataset is available.\ud
On the basis of the first 4 years of monitoring data (training\ud
dataset), threshold curves relating cumulative precipitation (mm)\ud
to precipitation moving windows (days) have been generated by\ud
using different benchmarks that, in literature, are used to estimate\ud
the maximum predictive performance of ROC curves. These\ud
threshold curves have been successfully validated using the last\ud
1 year of monitoring data (validation dataset). They have then\ud
been used to simulate how they might help defining different early\ud
warning levels in due advance. The proposed methodology can be\ud
replicated in any landslide for which a monitoring dataset that\ud
includes recurrent acceleration events in response to precipitation\ud
is available
By computational and experimental means, this work investigates unsteady mixing processes of the wake behind a blunt trailing edge turbine blade. Numerical solutions of the Reynolds averaged Navier Stokes equations have been earned out employing state-of-the-art algorithms in a fully conservative structured multi-block approach.Predicted aerodynamic performance profile and unsteady flow field features compare favorably with a set of measurements carried out on a large scale nozzle guide vane.
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