Using Small Baseline Subset (SBAS)Technology To Monitor Landslides In Xihe Country

In this study, slow-moving landslides in Xihe Country, which is in Gansu Province, were monitored by high-resolution interferometric synthetic aperture radar (InSAR) technology——Small Baseline Subset (SBAS) in regional and local scale respectively. As soon as the variations of the rates of typical landslides in2003-2010were analyzed, this paper has presented anddiscussed the factors related to the creeping of landslides accordingly. The specific conclusions are listed from three aspects as followed:(1) On a regional scale, the surface deformation of landslides of Xihe in2003-2010indicates that landslides of Xihe are concentrated in the Western Hills and southern valleys. Moreover, the slipping rate of landslides in the southern valleys is significantly faster than that of those in the Western Hills area.(2) On the local scale, the research for temporal and spatial change rules of velocity and displacement was developed, which was focused on seven typical landslides in Xihe county.(i)When the conditions about rainfall of these landslides are the same, the velocity of each individual landslide has the similar character that intermediate has an obvious faster rate than front and trailing edges. In addition, there are also some landslides whose leading and trailing edges fraction show displacement and mutation rate due to the collapse in the trailing edge, human activity in the leading edge, fluvial erosion and so on.(ii) Under the different rainfall conditions, for the landslide, the size of displacement fluctuates with rainfall and the most relevant of rain conditions is the number of moderate rain days.(3) What’s more, the correlation between the influence factors, rate and displacement of the seven representative landslides has also been analyzed respectively. The sliding of landslides is the outcome of land use, topography, structural conditions, hydrological conditions as well as weather conditions. For landslides in Xihe, the dominant factor is the structural conditions, especially rock lithology (cohesive, elastic modulus, tensile strength) and these factors show a positive correlativity with the rate of landslides. Followed by hydrological conditions (distance from the river), the factor shows a negative correlativity with the rate of landslides. In addition, the terrain slope, aspect and the land use type of forest also show a significant positive correlativity with the rate of landslides, but the impact is less than that of rock features.