Mapping and characterizing displacements of active loess slopes along the upstream Yellow River with multi-temporal InSAR datasets.

Landslides and debris flows in the Loess Plateau pose great threats to human lives and man-made infrastructure, such as buildings and expressways. Thus, the detection and monitoring of the stability of slopes are crucial in geohazard prevention and management. In this study, the time series synthetic aperture radar interferometry (InSAR) analysis method that combines persistent scatters (PSs) and distributed scatters (DSs) is employed to detect and map active slopes along the upstream Yellow River from the Longyang Gorge dam to the Lijia Gorge dam using one ALOS PALSAR data stack from 2006 to 2011 and two Sentinel-1 data stacks from 2015 to 2017. More than 100 active slopes in a total coverage of 222.5 km were identified. Through a time series displacement analysis of active slopes, we found that changes in the water content of loess slopes induced by rainfall or reservoir impoundment might be a major factor that can activate unstable slopes or accelerate the movement of active slopes.