Horizontal strains related to mining-induced subsidence may endanger infrastructure and surface users’ safety. While directional horizontal strains should be well determined, appropriate solutions for a complete assessment of the terrain surface deformation field are still required. As a result, the presented study examined a new method for calculating horizontal strain tensor based on the decomposition of satellite radar interferometry (InSAR) observations into vertical and azimuth look direction (ALD) displacements. Based on a geometric integral model, we tested our method on experimental data before applying it to an underground copper ore mine in Poland. In the case study, the displacement field was determined using the Multi-Temporal InSAR method on Sentinel-1 data. The model data relative error did not exceed 0.02 at σ = ±0.003. For the case study, land subsidence of up to −167 mm and ALD displacements ranging from −110 mm to +62 mm was obtained, whereas the extreme values of horizontal strains ranged from −0.52 mm/m to +0.36 mm/m at σ = ±0.050 mm/m. Our results demonstrate the high accuracy of the method in determining the horizontal strain tensor. As a result, the approach can broaden the assessment of the environmental impact of land subsidence worldwide.
The marine-terminating glaciers are one of the biggest contributors to global sea-level rise. Research on this aspect of the effects of global climate change is developing nowadays in several directions. One of them is monitoring of glaciers movements, especially with satellite data. In addition to well-known analyzes based on radar data from available satellites, the possibility of studying glacier displacements from new sensors, the so-called microsatellites need to be studied. The main purpose of research was evaluation of the possibility of applying new high-resolution ICEYE radar data to observe glacier motion. Stripmap High mode were used to obtain velocities for the Jakobshavn glacier with an Offset-Tracking method. Obtained results were compared with displacements obtained from the Sentinel-1 data. The comparative analysis was performed on displacements in range and azimuth directions and for maximum velocity values. Moreover, correlation plots showed that in different parts of glaciers, a comparison of obtained velocities delivers different correlation coefficients (R2) in a range from 0.52 to 0.97. The analysis showed that the scale of movements is similar from both sensors. However, Sentinel-1 data present underestimation of velocities comparing to ICEYE data. The biggest deviations between results were observed around the maximum velocities, near the Kangia Ice Fjord Bay. In the analysis the amplitude information was used as well. This research presents that data from the ICEYE microsatellites can be successfully used for monitoring glacial areas and it allows for more precise observations of displacement velocity field.
31 January 2025 in Remote Sensing Applications: Society and Environment
The study analyzes the changes in dynamics of the Jakobshavn Glacier in summer and winter in 2017 and 2021. Satellite radar observations and the available database were used for this. Moreover, the influence of the time baseline between SAR images on the quality of the results was also investigated. The velocities computed from Sentinel-1 images and the offset-tracking technique were compared with the MEaSUREs database information. The results showed that Jakobshavn Glacier accelerated in 2021 up to 39.0 m d−1. However, this value may be underestimated due to the resolution of Sentinel-1 data. The results therefore confirm the acceleration of the glacier melting process, which may be a result of the observed climate changes on our planet.
Sinkholes generated above flooded underground mines pose a growing hazard, yet practical precursors remain lacking. We analyse five years (2018–2023) of Sentinel-1 C-band radar and Sentinel-2 multispectral imagery over the abandoned Olkusz–Pomorzany underground zinc-lead mine (Poland), where nineteen sinkholes appeared during groundwater rebound in early 2022. Three hydro-spectral proxies, C-band backscatter coefficient, Moisture Index and Normalised Difference Vegetation Index, were extracted for sinkhole pixels and 500 randomly distributed background control pixels. A control–minus–event difference isolates local effects from regional variability. Welch t, Mann–Whitney U and bootstrap tests all indicate highly significant post-collapse mean shifts in the three hydro-spectral proxies. Breakpoint analysis applied to the 26-month pre-event record reveals a common structural change in mid-2021, approximately six months before the first sinkhole and coincident with rapidly rising groundwater. The Chow test confirms a significant difference in regression coefficients across the detected break. These results demonstrate that freely available hydro-spectral data can supplement Synthetic Aperture Radar Interferometry-based deformation measurements, offering weeks-to-months of lead time for early warning in vegetated, post-mining terrain. The approach is inexpensive, transferable and readily automated within Google Earth Engine and R.