Deformation and Volumetric Change in a Typical Retrogressive Thaw Slump in Permafrost Regions of the Central Tibetan Plateau, China

Abstract

Ice-rich permafrost in the Qinghai–Tibet Plateau (QTP), China, is becoming susceptible to thermokarst landforms, and the most dramatic among these terrain-altering landforms is retrogressive thaw slump (RTS). Concurrently, RTS development can in turn affect the eco-environment, and especially soil erosion and carbon emission, during their evolution. However, there are still a lack of quantitative methods and comprehensive studies on the deformation and volumetric change in RTS. The purpose of this study is to quantitatively assess the RTS evolution through a novel and feasible simulation framework of the GPU-based discrete element method (DEM) coupled with the finite difference method (FDM). Additionally, the simulation results were calibrated using the time series observation results from September 2021 to August 2022, using the combined methods of terrestrial laser scanning (TLS) and unmanned aerial vehicle (UAV). The results reveal that, over this time, thaw slump mobilized a total volume of 1335 m3 and approximately 1050 m3 moved to a displaced area. Additionally, the estimated soil erosion was about 211 m3. Meanwhile, the corresponding maximum ground subsidence and headwall retrogression were 1.9 m and 3.2 m, respectively. We also found that the amount of mass wasting in RTS development is highly related to the ground ice content. When the volumetric ice content exceeds 10%, there will be obvious mass wasting in the thaw slump development area. Furthermore, this work proposed that the coupled DEM-FDM method and field survey method of TLS-UAV can provide an effective pathway to simulate thaw-induced slope failure problems and complement the research limitations of small-scale RTSs using remote sensing methods. The results are meaningful for assessing the eco-environmental impacts on the QTP.

Quantifying the effect of a retrogressive thaw slump on soil freeze–thaw erosion in permafrost regions on the Qinghai–Tibet Plateau, China

“…Unmanned aerial vehicle (UAV) based orthoimage of the study site and ground‐penetrating RADAR (GPR) survey data. (a) 300 MHz GPR survey inversion result, (b) 70 MHz GPR survey inversion result, (c) UAV‐based orthoimage of the investigated thaw slump and the surrounding area, and (d) the borehole stratigraphy of active layer and top of permafrost (Jiao et al, 2022). The GPR detection line location is illustrated in Figure 3c.…”

“…Among them, three boreholes are near the Ghill-northeast RTS. Based on the GPR survey inversion result (Figure 3b,c) and the core logging information for drilling (Figure 3d) (Jiao et al, 2022), we built a 2D geological information model (physical model). From the detailed stratigraphic information displayed in Figure 3, there are about four layers, including sands, silt and clay, compact clay, and the bedrock.…”

Preliminary Insight into Ice Melting, Surface Subsidence, and Wellhead Instability during Oil and Gas Extraction in Permafrost Region

“…The relative slippage between the wellhead system and the permafrost is 81.54 cm when the development operation lasts 0.05 years. From that time onward, the support force at the bottom end of the wellhead system gradually replaces the adhesion force of permafrost on the pipe wall to support the wellhead system [36]. The wellhead sinks slowly with the permafrost, and the sinking situation during this period is similar to the permafrost's subsidence.…”