Empirical models to calculate the snow water equivalent in the high mountain catchments of the Western Carpathians

Abstract

Empirical models based on the relationship between snow depth ( SH ) and density ( ρ ) are used to estimate the snow water equivalent ( SWE ) from SH. However, ρ is poorly correlated with SH while the correlation between SH and SWE which can be directly obtained from snow measurements, is much better. We derived models based on the SH-SWE correlations for two datasets obtained in the high mountain catchments in Slovakia (The Low and Western Tatra Mountains). The models consider time (months from January to April) and elevation zones. Evaluation of the models against independent data showed that they are transferrable to other climatic conditions. About a half of estimated point SWE values was well comparable to measured values, i.e. the differences were approximately within ±15%. Substantial overestimation of measured SWE by more than 35% was obtained for about 10% of the values in January when the same equation was used for all elevation zones. Our final validation employed independent data from the High Tatra Mountains. It showed that about 60% of SWE values calculated for the entire snow courses as an average of 20 values calculated by the derived models from SH compared well (±15%) to values obtained by the traditional approach, i. e. as a product of the snow course mean SH (20 measurements) and ρ (3 measurements). Although the results of our models can be comparable to those provided by models based on snow density, due to recurrent use of SH and almost no correlation between SH and ρ, the models based on the SH-SWE relationship represent in our opinion a more correct approach.