Abstract
We discuss enhanced processing methods for high resolution Synthetic Aperture Radar(SAR) interferometry (InSAR) to monitor small landslides with difficult spatial characteristics,such as very steep and rugged terrain, strong spatially heterogeneous surface motion,and coherence-compromising factors, including vegetation and seasonal snow cover. The enhancedmethods mitigate phase bias induced by atmospheric effects, as well as topographic phase errorsin coherent regions of layover, and due to inaccurate blending of high resolution discontinuouswith lower resolution background Digital Surface Models (DSM). We demonstrate the proposedmethods using TerraSAR-X (TSX) Staring Spotlight InSAR data for three test sites reflecting diversechallenging landslide-prone mountain terrains in British Columbia, Canada. Comparisons withcorresponding standard processing methods show significant improvements with resultingdisplacement residuals that reveal additional movement hotspots and unprecedented spatial detailfor active landslides/rockfalls at the investigated sites.
Highlights
Recent years have witnessed a widespread increase in landslide activity due to climate warning
The TSX Staring Spotlight (TSX-ST) mode is currently the best data source on the market for monitoring small-scale landslides; compared to classic spotlight imaging, which has a rotation center located below the scene, TSX-ST improves resolution in azimuth from 1 m to 0.25 m by means of an azimuth steering the antenna to a rotation center within the imaged scene, which allows for a significantly lower InSAR phase noise compared to other TSX modes [6,7]
This study presents three enhanced processing methods developed for high resolution InSAR data to improve the estimation of surface deformation
Summary
Recent years have witnessed a widespread increase in landslide activity due to climate warning (deglaciation, thaw of alpine permafrost). This affects urban areas and anthropogenic activities in the proximity of landslide-prone areas by posing a serious threat to human life, infrastructure and transportation networks (roads, pipelines, etc.) [1]. TerraSAR-X (TSX) is ideal for regional-scale landslide investigations, as it can provide high spatial resolution repeat-pass InSAR measurements with wide-area coverage and short repeat intervals [5]. The short repeat interval of 11 days allows capturing of temporal details in the mass movement time series, while the magnitude of spatial displacement gradients for faster slides, preventing aliasing in the corresponding interferograms. Given that most landslides occur in heterogeneous areas (e.g., close to forests oRremuortebSaenns. s20e1t8t,l1e0m, x eFOnRtsP)EaERndREaVrIEeWaffected by pronounced seasonal weather changes, T2SofX1-8ST data further provide the added benefit of increased spatial and temporal coherences
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