Snow water equivalent in the Western Sudetes and its changes in the light of a changing climate

Abstract

Study region

The Western Sudetes.

Study focus

This paper characterises changes in snow water equivalent (SWE) in the Western Sudetes. SWE was linked to the exposure and altitude of the study area. The analysis was made for the winter seasons (November-April) 1961–2020, based on 16 measurement stations from Poland and the Czech Republic.

SWE is strongly positively correlated with snow depth (HS). The adopted method for estimating SWE (SWEi) by simple regression equations is a good and easily applicable method for climatological SWE studies. The method shows point average differences from actual SWE values in the range of 3–29 %. The overall average difference was 16.8 % and is comparable to the average difference for other mountain areas in Europe.

New hydrological insights for the region

The average snow depth and its SWEi gradually increase during the season, reaching maximum values in February or March, after which they decrease markedly. Meanwhile, snow density usually reaches an average monthly maximum in April. The mean and maximum seasonal SWEi values show negative trends, ranging from approximately −0.1 to −1.3 cm / decade and −0.2 to −2.5 cm / decade, respectively. These are statistically significant at many locations. SWEi values, at locations at similar altitudes, are greater at stations with a southern macro-exposure than a northern one. The rate of change of SWEi with altitude is similar on slopes with northern and southern macro-exposure. SWEi values are characterised by a positive asymmetry of differences with respect to the actual SWE. Hence, the actual SWE values are slightly smaller than the estimated values and the amount of water contributed to the environment by the snow cover decreases.

The results correspond with those from other mountainous areas in Europe, indicating decreasing SWE due to decreasing trends in snow cover thickness and duration. They are symptomatic of a warming climate, particularly intense in recent decades.