SPATIO-TEMPORAL PATTERNS OF SNOWMELT PROCESSES IN THE CATCHMENTS OF THE UPPER KAMA

The paper deals with the spatio-temporal dynamics of the snowmelt process in the catchments of the Upper Kama, differing in size and relief features and located both on the plains – gauging station (g/s) Kosa-Kosa (A=6,221 km2), g/s Kama-Gainy (A=27,822 km2) and in a mountainous territory – g/s Vishera-Ryabinino (A=31,084 km2). The calculations were carried out using the method of temperature coefficients integrated into the GIS for years with different meteorological conditions and duration of snowmelt: 2004, 2010, and 2015. An analysis of the calculation results showed that the average duration of snowmelt in the studied catchments is 32 days. The duration of snowmelt and the daily amount of melted snow are influenced by the intensity of the increase in positive air temperatures. The timing of the start of snowmelt varies much less than the timing of its end. The plain catchments are freed from snow cover earlier than the mountain one by an average of 20 days. This is due to the latitudinal and altitudinal zonality, as well as the significant dissection of the relief of the g/s Vishera-Ryabinino catchment. The process of intense snowmelt begins here, on average, 9 days later than in the plain catchments. The g/s Kosa-Kosa catchment is freed from snow cover earlier than the others, which is due to its small area and weak dissection. The influence of latitudinal zonality during the melting of snow cover is best seen in the meridional catchment g/s Kama-Gainy. The southern and central parts of the catchment area are freed from snow first, later followed by the northern part.