Measuring Snowmelt in Siberia: Causes, Process, and Consequences

Abstract

The soil erosion on arable lands of Siberia is widespread. More than 50 % of all farmlands are subject to erosion to various degrees. Erosion is the main process of soil degradation in West Siberia which can lead to a catastrophic decrease in the fertility of soils, and pose a threat to food security in the region. Studying the causes, the process of soil erosion and its consequences is an important question both for science and for farm production. The purpose of this work is to show the main methods and devices used to define the quantity and quality of surface snowmelt water runoff, and also the damage caused by this in the form of soil erosion. To quantify the overall snowmelt erosion process, the following parameters need to be measured: the total pre-winter water reserve of soil, snow depth, snow water equivalent, depth of soil frost penetration, volume of snowmelt water runoff, runoff coefficient, water stream temperature, and soil loss with surface snowmelt water runoff. Research takes place in 3 stages: (1) preparatory stage, during which the late fall period soil water supply is defined and the runoff and thermometric plots are constructed; (2) studying the process of accumulation of solid atmospheric precipitation, the nature of its distribution over the territory, and also the influences of snow depth on the frost penetration in soils; and (3) monitoring the snowmelt process in spring, during which the intensity of snowmelt, the volumes of a superficial drain of snowmelt waters, and the damage caused by them to a soil cover are defined. One special feature of the Siberian soils during the cold period of the year is the intra-soil ice sheet, which is largely impenetrable to melting water and positive temperatures. This ice sheet in Siberian soils is one of the reasons for snowmelt water runoff forming. Over a period of 45 years we measured a mean annual soil loss of 6 t/ha by snowmelt erosion on arable land in West Siberia.

Appendix 1: Calculation of Hydrological Data from Measurements

Example 1

The length of an experimental runoff plot is 50 m, the width is 10 m. The area of an experimental runoff plot is 500 m². In this case, to transfer the size of an experimental runoff plot to 1 ha, apply the coefficient 20 (500 × 20 = 10,000 m² = 1 ha). The measuring cylinder with a capacity of 1 l was filled with snowmelt water for 5 s. Thus, the intensity of snowmelt runoff from an experimental runoff plot in 500 m² during 1 s is:

• 1 l/5 s = 0.2 l/s.

• During 1 h at this intensity, the flow from this runoff plot was:

• 0.2 l/s × 3600 s = 720 l/h

• During 1 h, the flow from an area of 1 ha was:

• 720 l/h × 20 (coefficient) = 14,400 l/h/ha, or runoff depth = 1.44 mm/h.

Example 2

Data from a snow survey showed that for the cold period of the hydrological year (November–March), 140 mm of water were stored in the snow cover. The snowmelt runoff was 70 mm. The runoff coefficient in this case is 0.5 (70 mm/140 mm = 0.5).

Example 3

The depth of a water stream is 20 cm, the width is 25 cm. The speed of the water stream is 80 cm/s. The watershed area is 10 ha. The current drainage intensity of thawed snow of this watershed is:

$$ \frac{{20\,{\text{cm}} \times 25\,{\text{cm}} \times 80\,{\text{cm/s}}}}{{1000^{*} \times 10\,{\text{ha}}}} = 4\,{\text{l/s ha}}\,\,{\text{or}}\,\, 1. 4 4\;{\text{mm/h}}. $$

*1000—coefficient for transforming the volume of snowmelt runoff measured, in Example 3, in cm³, into liters.

Example 4

Snow water equivalent (SWE)—150 mm. The type of spring weather is radiation, snowmelting period—5 days.

Day 1

• Daily Rd1 (Runoff depth)—3 mm;

• Daily M soil1 (mass of solid phase of the soils in the snowmelt waters)—250 kg/ha.

Day 2

• Daily Rd2—7 mm;

• Daily M soil2—600 kg/ha.

Day 3

• Daily Rd3—56 mm;

• Daily M soil3—1830 kg/ha.

Day 4

• Daily Rd4—24 mm;

• Daily M soil4—1220 kg/ha.

Day 5

• Daily Rd5—4 mm;

• Daily M soil5—370 kg/ha.

• 1.
  $$ \begin{aligned} {\text{Rd}} & = {\text{Rd1}} + {\text{Rd2}} + {\text{Rd3}} + \cdots \ {\text{Rd}} & = 3+ 7+ 5 6+ 2 4+ 4= 9 4\;{\text{mm}} \\ \end{aligned} $$
  $$ {\text{The runoff coefficient (Cr)}} = \frac{\text{Rd}}{\text{SWE}} = \frac{94}{150} = 0.6 $$
• 2.
  $$ \begin{aligned} M\,{\text{soil}} & = M\,{\text{soil1}} + M\,{\text{soil2}} + M\,{\text{soil3}} \cdots \\ M\,{\text{soil}} & = 2 50 + 600 + 1 8 30 + 1 2 20 + 3 70 = 4 2 70{\text{ kg}}/{\text{ha}} \\ \end{aligned} $$