Effect of Snow on Streamflow Variability

With the ongoing climate warming, changes in intra-annual distribution, annual volume, and their inter-annual variability of streamflow have been key research topics of ever-increasing interest. For settling the question of how changing climate shapes streamflow dynamics, here, we used long-term (1950-2010) observations of monthly streamflow (Q) for 2960 global unimpaired catchments, combined with snowfall (SF) and precipitation (P) estimates from ERA5-Land to provide a global assessment of effect of snowfall on streamflow variability. Results showed that precipitation was the main control of intra-annual and inter-annual streamflow variability while the propagation process of variability would be regulated by snow. As the snowfall fraction (sf) decreased, the annual runoff coefficient decreased, while the timing of streamflow got advanced and the intra-annual distribution became more even. Besides, the inter-annual variability of streamflow shows a negative relationship with snowfall fraction. The negative relationship between streamflow inter-annual variability and snowfall fraction may result from the asymmetric hydrological effects of snowfall in the wet and dry years.