In situ and satellite monitoring of a landslide and of a drainage system

A very complex landslide system in Miocene formations affects the national railway in the territory of Calciano, southern Italian Apennines. The analysis of inclinometer data provided the landslide depth and mechanism of movements, and allowed the interpretation of satellite Envisat, COSMO-SkyMed (CSK) and Sentinel-1 data. A long time series (20 years) of displacements was thus obtained for the slow part of the landslide; the series was also used to evaluate the effectiveness of deep drainage systems built to reduce the landslide risk for the national railroad. DinSAR data show a decrease in the landslide displacement rates after the construction, in 2016-2017, of a new drainage well system. A numerical model constructed by the FD MODFLOW 3D code shows that the deceleration is consistent with the progressive decrease in pore water pressures in the landslide body and in the slip zone recorded by the piezometers installed in the zone.