A landslide forecasting model using ground based SAR data: The Portalet case study

This paper presents a kinematic study of the Portalet landslide (Salient de Gallego, Central Spanish Pyrenees), which was triggered by the construction of a big parking area at the toe of the slope. A description of the landslide from a geomorphological point of view is first introduced. The measurements of displacement performed by conventional (total station, inclinometers; and differential GPS) and advanced (GB-SAR) ground monitoring techniques are presented and GB-SAR and DGPS datasets are compared. The correlation between measured displacements and rainfall series indicates that the landslide is very sensitive to rainfall. The continuous GB-SAR measurements from the 5th of October 2006 to the 21st of November 2006 at a rate of 1/h were used to calibrate a simple 1 D infinite model by back analysis. The model includes a viscoplastic behaviour and takes into account directly the known daily rainfall intensity and the dissipation of the excess pore-fluid through a simple consolidation equation. Prediction was made in an extended period of time, from May 2006 to July 2007, and compared to the DGPS measurements. (C) 2009 Elsevier B.V. All rights reserved.