How to avoid false interpretations of Sentinel-1A TOPSAR interferometric data in landslide mapping? A case study: recent landslides in Transdanubia, Hungary

Abstract

It is a crucial issue to better understand the usability of Sentinel-1 satellites in geomorphologic applications, since Sentinel-1 and the Copernicus Program are considered to be the workhorse of Earth observation by the European Space Agency during the next decades. Yet, a very limited experience is available on the applicability of Sentinel-1 images in the detection and identification of surface deformations and especially landslide mapping and monitoring in densely vegetated (low-coherence) areas. Few Synthetic Aperture Radar images (not more than 20) are sufficient for a successful run of interferometric stacking algorithms. This number is really low compared to the tremendous data flow of Sentinel-1 images that are available for interferometric analysis nowadays. Despite the availability of acquisitions, only a few papers exist on the accuracy of Sentinel-1 data, signal-to-noise ratio and the value of the acquired imagery for geomorphologic interpretation. Two test sites and a control site-affected by active surface deformations-have been investigated using 40 Sentinel-1A images and conventional persistent scatterers (PSI) method. PSI results have been combined with the geomorphologic information of the studied sites. We verified that the given number of Sentinel-1A acquisitions provide a unique base for surface deformation recognition and mapping in low-coherence areas. We found that scatterers were corrupted by a strong noise if their line of sight (LOS) velocity was below ± 6-7 mm/ year all over the three test sites, although noise can easily be reduced. Noise reduction was achieved by a significant increase of the length of time series, i.e., time range between the first and last image to reduce the effect of atmospheric phase screen (APS).

The Use of Sentinel-1 Synthetic Aperture Radar (SAR) Images and Open-Source Software for Cultural Heritage: An Example from Paphos Area in Cyprus for Mapping Landscape Changes after a 5.6 Magnitude Earthquake

“…In general, D-InSAR favors short baselines (less than 200 m) for C-band systems. Due to the high revisit frequency and the excellent orbital accuracy of Sentinel-1, the perpendicular baseline is usually not a limiting factor, facilitating the application of InSAR in many countries [39]. The perpendicular baseline aspect, though, can be used to select the optimal pair of images [40].…”

Differential SAR Interferometry Using Sentinel-1 Imagery-Limitations in Monitoring Fast Moving Landslides: The Case Study of Cyprus

“…Geosciences 2020, 10, x FOR PEER REVIEW 4 of 26 complex ground displacement phenomena, especially of fast-moving landslides [1,37,38] and slope deformations, cannot be achieved using Sentinel-1 images due to the limitations of the C-band wavelength and the images' medium spatial resolution [39][40][41].…”

“…Additionally, although the moderate spatial resolution of the IW swath images for Level-1 SLC products (2.7 × 22 m to 3.5 × 22 m), which are available for Cyprus, has proven to be satisfactory for the detection of land subsidence and/or uplift [22,23,36], the detailed study and monitoring of more complex ground displacement phenomena, especially of fast-moving landslides [1,37,38] and slope deformations, cannot be achieved using Sentinel-1 images due to the limitations of the C-band wavelength and the images' medium spatial resolution [39][40][41].…”

A Synergetic Analysis of Sentinel-1 and -2 for Mapping Historical Landslides Using Object-Oriented Random Forest in the Hyrcanian Forests

“…Recently, the number of successful studies for mapping landslides through Sentinel-1 [1,2,[42][43][44][45][46][47][48] has been increasing; however, little research has addressed the application of Sentinel-2 [3,41,49], or the combination of Sentinel-1 and -2 [4,50] for this objective. Moreover, most of these studies have applied pixel-based image analysis for detecting landslide events using Sentinel images.…”