Attenuation of High-Frequency Interannual Streamflow Variability by Watershed Glacial Cover

Abstract

We used nonparametric statistical and time-series analysis techniques to investigate the effects of watershed glacial cover upon interannual variability in a suite of hydrometric variables describing aspects of the annual hydrograph. Annual time series of eight streamflow-derived metrics were considered for each of five glacier-fed and four nival rivers in the southwestern Canadian subarctic. Our conclusions at p 0.05 are ~1! rank-based coefficients of variation ~CV! in robust measures of freshet-related flow magnitude and timing scale inversely with watershed glacierization; ~2! CVs in extreme events measures do not exhibit a statistically significant relationship to degree of glacial cover; and ~3! CVs in winter baseflow measures also show no glacial moderating influences. The CV results expand substantially upon previous work and are readily physically interpretable. Additionally, spectral analyses tentatively suggest that glacier- ization predominantly attenuates hydroclimatic variability at timescales of about 2-3 years or less.