Impacts of Groundwater Flow on Evolution of a Thermokarst Lake in the Permafrost Region on the Qinghai-Tibet Plateau

Abstract

Thermokarst lakes and permafrost degradation in the Qinghai-Tibet Plateau (QTP) resulting from global warming have been considerably affected the local hydrological and ecological process in recent decades. Simulation with coupled moisture-heat models that follows talik formation in the Beiluhe Basin (BLB) in the hinterland of permafrost regions on the QTP provides insight into the interaction between groundwater flow and freezing-thawing process. A total of 30 modified SUTRA schemes have been established to examine the effect of hydrodynamic forces, permeability and climate. The simulated results show that the hydrodynamic conditions impact the permafrost degradation surrounding the lake, thereby further affecting groundwater flow and late-stage freezing-thawing process. The thickness of the active layer varies with time and location under different permeability conditions, which significantly influences the occurrence of a breakthrough of the lake bottom. Warmer climate accelerates thawing and decreases the required time of formation of the breakthrough zone. Overall, these results indicate that explicit consideration of hydrologic process is critical to improve the understanding of environmental and ecological changes in cold regions.

Study on Shear Characteristics of Herbs Plant Root–Soil Composite System in Beiluhe Permafrost Regions under Freeze–Thaw Cycles, Qinghai–Tibet Highway, China

“…In recent years, due to the influence of global warming, the freeze-thaw (F-T) cycles have been significantly strengthened, leading to changes in soil cohesion in the permafrost regions of the QTP, which affects the shear strength of permafrost, reduces the stability of slopes, and triggers a certain degree of damage and destabilization of infrastructure construction such as highways and railways in the cold region [6]. In particular, in recent years, with the continuous increase in infrastructure construction such as railways and highways in the permafrost region of the QTP, a series of disaster problems such as retrogressive thaw slump, solifluction, and thermokarst have occurred due to permafrost degradation [6][7][8][9][10][11], which has resulted in certain impacts and potential threats on adjacent transportation trunk lines and infrastructure facilities. Based on this, in order to ensure the coordinated development between the construction of infrastructure and the protection of the ecological environment in the region, it is necessary to carry out research on the shear characteristics of soil in permafrost regions under the action of F-T cycles.…”