Winter streamflow, ground temperature and active‐layer thickness in Northeast China

Seasonal freezing and thawing influence the hydrological regimes of winter streamflow in northeast China where abrupt increases of 1.3° C and 2.8° C in the annual and winter air temperatures have occurred since the 1990s. Correlation between winter discharge and soil freezing is based upon hydrometeorological and geocryological data for the last 40 years. A mountainous watershed is used. The active‐layer temperature is estimated by a statistical model derived from annual air temperature, its annual range and the maximum depth of snow cover in January. Results indicate an asymptotic curve between winter streamflow and both thickness of the active layer and winter temperature. They imply that winter streamflow increases with a thickening of the active layer and a decrease in the depth of seasonal frost penetration in winter.