Monitoring of landslide processes by means of l-band radar interferometric observations: Bureya river bank caving case.

The potential of PALSAR-1 (ALOS-1 sat.) and PALSAR-2 (ALOS-2 sat.) L-band radars interferometric observations of the landslide processes is analyzed in this paper with reference to Bureya riverbank landfall occurred in December 2018 when more than 18.5 million m3 of soils crashed into the riverbed. The displacements of the landslide surface were detected and total amplitudes of displacements even on the 2-years time intervals were estimated. Summer images were less informative because of abrupt loss of coherence in the case of heavy precipitations happened during the radar observation. Winter observations made at negative air temperatures are mainly coherent because of temporal stability of dielectric properties of trees and underlying soils. The history of landslide dynamics on decadelong interval is reconstructed. According to our estimations, the velocities of summer displacements are typically higher than wintertime ones. The displacements were low in 20062010 (1.61.9 cm/month), then they increased significantly in 20152016 (4.74.9 cm/month), the maximal measured velocity in summer 2016 reached 10.7 cm/month. It is likely that the activation of the landslide process corresponds to the time of completion of the reservoir filling in 20062009, and it was provoked by both the initial rising and seasonal oscillations of the water level.