Climatic impact on thermal and hydraulic subsurface processes in permafrost regions in the tibetan plateau

M.Sc. Radhakrishna Bangalore Lakshmiprasad, Prof. Dr. Thomas Graf

The Qinghai-Tibet Plateau, also known as the "Water tower of Asia", is threatened by climate warming. The influence of climate change is greater at high latitudes and elevations, and the trend is expected to continue in the coming decades. Due to the high elevation (average 4000 m.a.s.l) of the Qinghai-Tibet Plateau, it experiences temperatures twice the global average, due to which the permafrost degradation has been recorded. The subsurface thermal and hydrological environment in cold regions is influenced by the change in permafrost distribution.

The permafrost thaws and freezes seasonally due to the influx of heat energy from the ground surface. This dynamic change in permafrost alters the thermal and hydraulic parameters of the subsurface. As the temperature increases, the permafrost thaws, giving rise to an active layer. The groundwater flow increases as the hydraulic conductivity in the active layer increases. The pore water phase change from liquid to ice causes variation in the thermal parameters of the soil, making it a non-linear process. These processes promote a complex interaction between the permafrost, groundwater, and surface water. Research efforts to better understand the cryohydrogeological processes by collecting field observation data are difficult. Due to these reasons, studying permafrost groundwater systems is one of the most challenging fields to study in hydrogeology. Therefore, researchers call for modeling studies and field data collection to better understand the groundwater conditions in cold-region.

We plan to conduct the research work in the Yakou catchment [North-Eastern tip of the Qinghai-Tibet plateau], which is one of the headwater basins of the Heihe River. The Heihe river basin is facing a shortage of water resources in the middle and lower reaches. Our approach is to develop cryohydrogeological models and carry out fieldwork to characterize the permafrost-groundwater-surface water dynamics.