Suprapermafrost groundwater flow and exchange around a thermokarst lake on the Qinghai–Tibet Plateau, China

•Suprapermafrost groundwater (SG) tables were measured in the QTP.•The dynamics of SG were influenced by thawing depth and rainfall events.•The thermokarst lake water balance was evaluated.•The contribution of SG to thermokarst lake water was often less than 1.4 mm d−1. The dynamics of suprapermafrost groundwater regulate hydrological processes, including the fate and transport of carbon and nutrients, suitability of aquatic habitats, and evolution of permafrost in Arctic, boreal, and high-altitude regions. Nevertheless, relatively few studies have focused on these dynamics on the Qinghai–Tibet Plateau (QTP). In this study, soil hydraulic conductivities, saturated thicknesses, and related hydrological processes were observed in situ around a typical thermokarst lake during the warm season. The results showed that the water table in the active layer fluctuated markedly from June to October and at depths of up to 1.0 m. The discharge of suprapermafrost groundwater was often