Effect of Permafrost Degradation on the Development of the Rainfall-controlling Thermokarst Ponds on the Qinghai-Tibet Plateau

Abstract:

Permafrost, as an important index of climate warming, dominates the hydrological ecosystem on the Qinghai-Tibet Plateau (QTP). The relationship between permafrost degradation and development of thermokarst ponds is still unclear. The lack of understanding of the hydrological regimes of the thermokarst ponds in different permafrost regions hinders the prediction of its development, as well as the hydrological responses to climate change. Here we investigate the permafrost features of a shallow thermokarst pond in a rainfall-controlling catchment and the major hydrological processes that influence its development using intensive geotechnical and geophysical surveys like ground-penetrating radar and electrical resistivity tomography. We then characterize its hydrological regime with field observations and reproduce it with a hydrological model - GEOtop. By the end, the effects of permafrost degradation on the development of the rainfall-controlling thermokarst pond are evaluated by projecting an increase in air temperature till 2050 using the latest climate model (CanESM2 from CMIP5) data. These findings suggest that not only thermal regime of thermokarst ponds but also the highly climate-related hydrological regime should be considered in modeling the development of thermokarst ponds on the QTP.