LAUSR

Abstract Snow water equivalent (SWE) exactly reflects the hydrological importance of accumulated snow cover. Taking manual measurement is both time consuming and laborious, and one major disadvantage of them is the sporadic information they give about SWE trends during the winter season. This disadvantage is eliminated through the use of an automated device capable of monitoring temporal changes of SWE practically continuously. This study investigated the testing of a new SWE monitoring device installed at three study locations over three winter seasons (2014–2017). The device measures SWE by weighing snow cover and is equipped with a fencing component expected to reduce measurement errors due to snow bridging. It is also equipped with an ultrasonic snow depth and a snowmelt seepage sensors. The evaluation indicated that an hourly interval for collecting SWE data may not be sufficient for providing an accurate description of snow cover trends and for tracking winter hydrology during rain-on-snow events. Changeable winters increase the chance of measurement errors and complicate making evaluations of snow cover. The installed component did not fully prevent snow bridging, and the occurrence of predisposed climatic conditions was site specific. Apart from snow bridging events, the measurement errors did not exceed 7 mm, i.e. maximally from 7 to 26% of SWE. Snowmelt at each device was accelerated by up to one day. The risk of the influence of ground freeze on the snowmelt seepage sensor and measurement apparatus was seen during low snow cover and occurred mainly at the lowest altitude. The calculated evaporation from snow in each particular season ranged between 3.9% and 8.3%; the average values of evaporation increased with decreasing altitude.