Winter hydrological monitoring in Polistovsky Reserve
Raised bog is a large water body; therefore, observations of hydrological parameters are conducted in Polistovsky reserve all year round. In the summer water levels in the bog and rivers are monitored; and during the winter, observations of snow cover and freezing of the bog massif are held. Monitoring of these parameters was also carried out this winter.
In order to estimate the amount of water in the snow, snow survey is carried out. Three times a month, Reserve staff conduct field measurements at two sites and three routes - bog, forest and meadow, located in the most typical plant communities of the protected area. In each location, 50 measurements of snow depth are carried out using a measuring rod, as well as 10 measurements of snow density on the routes, and 5 - on the sites.
To determine the density of snow, a special hollow measuring cylinder is used - the snow gauge. At first it is immersed into the snow to the full depth and the resulting value in centimeters is fixed on the measuring scale, then it's lifted together with the accumulated snow and weighed. Together with the measurements, they describe the snow cover "relief" and the structure of snow. According to this data, it's possible to calculate the density of snow and the amount of water in it.
Simultaneously with the snow survey, the depth of freezing of the bog massif is measured. To do this, the surface of the bog is cleared of snow, a small hole is made in the frozen layer and its thickness is measured.
At each of the two sites and one swamp route, depth of freezing is measured at 8 fixed points. At the beginning of winter, when the depth of the snow is less than 15 centimeters, the depth of freezing is measured every 5 days, when the snow becomes higher - every 10 days. In the spring, when the air temperature passes through 0°C in the positive direction, the depth of freezing is measured every 5 days again.
This winter was snowy, but it failed to exceed last year’s snow depth level (50 cm). The maximum value (45 cm) was recorded on January 30th. Due to the absence of severe frosts, the bog covered with snow froze slowly, and only in February the maximum depth of freezing reached 23 cm.