Contribution of supra-permafrost discharge to thermokarst lake water balances on the northeastern Qinghai-Tibet Plateau

摘要

Highlights?The precipitation-induced supra-permafrost discharge plays an important role in the water balance of thermokarst lakes on the Qinhai-Tibet Plateau.?The contribution of supra-permafrost discharge to lake water balance can increase nonlinearly with precipitation, based on an exponential precipitation- subsurface runoff relation.?The results provide a novel conceptual model for interpreting the recent lake growth on the Tibetan Plateau.AbstractThe seasonal hydrological mechanisms of two thermokarst lakes on the northeastern Qinghai-Tibet Plateau (QTP) were characterized by three-year intensive field observations and a water balance model. In three ice-free seasons, the supra-permafrost discharge contributed a mean ratio of over 170% of the precipitation. In the ice-cover seasons, the supra-permafrost discharge contribution varied between ?20% and 22% of the water storage change. Results show that a large portion of the lake water storage change is because of the supra-permafrost discharge resulting from pr