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Importance of maximum snow accumulation for summer low flows in humid catchments

Type of publication Not peer-reviewed
Publikationsform Original article (non peer-reviewed)
Author Jenicek Michal,
Project Snow resources and the early prediction of hydrological drought in mountainous streams
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Original article (non peer-reviewed)

Journal Hydrol. Earth Syst. Sci. Discuss.
Volume (Issue) 12
Page(s) 7023 - 7056
Title of proceedings Hydrol. Earth Syst. Sci. Discuss.
DOI 10.5194/hessd-12-7023-2015

Open Access

Abstract

The expected increase of air temperature will increase the ratio of liquid to solid precipitation during winter and, thus decrease the amount of snow, especially in midelevation mountain ranges across Europe. The decrease of snow will affect groundwater recharge during spring and might cause low streamflow values in the subsequent summer period. To evaluate these potential climate change impacts, we investigated the effects of inter-annual variations in snow accumulation on summer low flow and addressed the following research questions: (1) how important is snow for summer low flows and how long is the “memory effect” in catchments with different elevations? (2) How sensitive are summer low flows to any change of winter snowpack? To find suitable predictors of summer low flow we used long time series from 14 alpine and prealpine catchments in Switzerland and computed different variables quantifying winter and spring snow conditions. We assessed the sensitivity of individual catchments to the change of maximum snow water equivalent (SWEmax) using the non-parametric Theil–Sen approach as well as an elasticity index. In general, the results indicated that maximum winter snow accumulation influenced summer low flow, but could only partly explain the observed inter-annual variations. One other important factor was the precipitation between maximum snow accumulation and summer low flow. When only the years with below average precipitation amounts during this period were considered,nthe importance of snow accumulation as a predictor of low flows increased. The slope of the regression between SWEmax and summer low flow and the elasticity index both increased with increasing mean catchment elevation. This indicated a higher sensitivity of summer low flow to snow accumulation in alpine catchments compared to lower elevation catchments.
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