Attribution of runoff variance in the alpine basin of Northwest China at multiple timescales

Abstract

ABSTRACT Attributions of runoff variability have been widely conducted under the Budyko framework; however, the effects of snow water equivalent change (∆swe) have not been considered by this framework in alpine basins. Considering the Heihe upstream basin of Northwest China as an example, we derived runoff variance () from the variance and covariance of precipitation (P), soil water storage change (∆soil), ∆swe, potential evapotranspiration (E 0), and land surface condition (represented by Budyko’s parameter, n) on seasonal and annual scales. The results showed that P variance mainly controlled in autumn and winter. The n variance ranked first in spring and summer. The effects of P and n variance on annual were enhanced compared to their seasonal values. However, was alleviated by the interaction between factors, especially by ∆soil and n, P and ∆soil with negative contributions. The effects of ∆swe variance could not be ignored, especially in spring.