Remote Monitoring of Ground Motion Hazards in High Mountain Terrain Using InSAR: A Case Study of the Lake Sarez Area, Tajikistan

Abstract

High mountain terrains, with steep slopes and deep valleys, are generally challenging areas to monitor using satellite earth observation techniques since the terrain creates perspective distortions and differences in illumination that can occlude or obfuscate a significant proportion of the land. This is particularly prominent in synthetic aperture radar (SAR) data, where the oblique geometry can result in large areas of layover and shadow, which must be excluded from any analysis. Interferometric SAR (InSAR) is an established technique for monitoring ground motion and this study assesses its potential for geohazard monitoring in mountainous areas using Lake Sarez in Tajikistan as a case study, applying SAR data from the Sentinel-1 mission. It is shown that, although the effect of layover and shadow is severe, a judicious combination of ascending and descending satellite passes is still capable of surveying 88% of the land surface. It is also demonstrated that, through the use of an advanced InSAR technique (the APSIS™ Intermittent Small Baseline Subset technique), near-complete coverage of ground motion measurements is possible, despite intermittent snow cover. Moreover, this is achieved without the need for ground control, which can be hazardous to establish in such areas. It is concluded that a combination of satellite passes and advanced InSAR techniques greatly facilitates the remote monitoring of ground motion hazards in high mountain areas.

Complex Monitoring of Vertical Land Motions Corresponding to Geological Structure of Coastal and River Areas in Northwestern Poland

“…Segment II Measurement method GNSS, precision levelling GNSS, precision levelling Frequency of observation 1/year to 5/year 2 months Accuracy of displacement determination ±(0.5-5) mm ±(0.5-5) mm Similar GNSS-based systems have been successfully implemented in 3D deformation studies of several significant engineering objects and geodynamic polygons [1][2][3]. Other systems used Interferometry Synthetic Aperture Radar (InSAR) [4,5] or satellite altimetry to monitor regional vertical motions [6]. In [5], it was demonstrated that, through the use of an advanced InSAR technique (the APSIS™ Intermittent Small Baseline Subset technique), the near-complete coverage of ground motion measurements is possible, despite intermittent snow cover.…”

“…Other systems used Interferometry Synthetic Aperture Radar (InSAR) [4,5] or satellite altimetry to monitor regional vertical motions [6]. In [5], it was demonstrated that, through the use of an advanced InSAR technique (the APSIS™ Intermittent Small Baseline Subset technique), the near-complete coverage of ground motion measurements is possible, despite intermittent snow cover. However, the underlying geological structure was not taken into account in these systems, nor was the methodology used, causing the field work involved in an additional levelling survey to be labor-intensive, time-consuming, and expensive, with the final accuracy of measurements degraded.…”

Analysis of BDS/GPS Deformation Monitoring for the Lake Sarez Dam

“…The findings reveal that the Lake Sarez landslide region has exhibited annual movement rates reaching a magnitude of 100 mm [9]. Grebby confirmed the presence of ground motion in the coastal landslide area of Lake Sarez, including the right bank landslide area, via the use of Interferometric Synthetic Aperture Radar (InSAR) technology [10]. With the development of differential interferometric synthetic aperture radar (DInSAR) technology, radar line-of-sight deformation can be obtained up to the millimeter level [11][12][13][14][15][16].…”

Chlorophyll-a Detection Algorithms at Different Depths Using In Situ, Meteorological, and Remote Sensing Data in a Chilean Lake

“…Remote lakes, defined as bodies of water located in geographically isolated or inaccessible areas [1], are typically found in mountainous regions, polar landscapes, tropical rainforests, or anywhere with significant natural barriers, such as steep terrain or dense vegetation [2,3]. Their defining characteristics include their remoteness from urbanized areas and limited exposure to human activity [4].…”