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.