Integrating isotope mass balance and water residence time dating: insights of runoff generation in small permafrost watersheds from stable and radioactive isotopes

40 small watersheds in the Source Area of the Yellow River were investigated recently to sample surface waters, groundwater and ground ice, and their water isotopic signatures ( 2 H, 18 O, 3 H, and 222 Rn) have been measured. A novel isotope mass balance approach was developed to estimate annual surface and surface flow discharges in catchment combined water age dating. This approach revealed the changing surface and subsurface runoff patterns were along the hydrological trajectory of progressive permafrost degradation. To build up the linkages between the hydrological indictors and environmental and biological features was recommended, which would benefit a better understanding the significant impacts of permafrost degradation on social, ecological and economic developments in cold regions.