Water resources are all waters of an area that are either used, or can be used, for the economy. They are contained in rivers (there are more than two million rivers in Russia), lakes (Lake Baikal is the world's largest freshwate lake) and storage reservoirs, deep underground aquifers that are not connected with the rivers, and in soil, bogs, swamps, and mountain glaciers. The main type of water resource, however, is a river runoff which is abundant practically everywhere and annually renewable. Other kinds of water resources play an auxiliary role, although in some regions they can have significant importance for the water supply of the population and for some branches of the economy.

The total river runoff is composed of two main components; surface and underground runoffs. The surface river runoff, which is the more dynamic, results from quick running down of both melted and rain waters along the water catchment area, and it mainly forms spring and summer floods. Surface river runoff provides a necessary watering of river floodplains and fish spawning areas and a number of other relevant ecological functions is performed during this process. Underground river runoff results from percolation of meltwater and rainwater into soil and further down to underground horizons, with following drainage of them by rivers. The velocity of underground water flow is much slower than that of surface water. These waters supply the river during the periods when no rains or snowmelt take place, i.e., they provide the river an existence for long rainless periods, during the so-called low water period. The underground component of river runoff is the most valuable for most branches of the economy, as it does not actually need any regulation.

River runoff is measured in cubic kilometers (km³)/year or in millimeters (mm) of layer, i.e., in the water volume, transported by rivers over a year, related to the drainage area. The water volume running through an actual cross-section of the river flow per a time unit is called water discharge. It is usually measured in m³/second.

The Russian Federation is the second country in the world, after Brazil, in mean annual river runoff being formed over its territory as a result of snow melting and rains: 4,043 km³/year. When taking into account an inflow from adjacent territories, the runoff resources become still greater: 4,270 km³/year.

The world’s largest rivers are in Russia. They are the Yenisei (630 km³/year), the Ob (534 km³/year), the Lena (521 km³/year), and the Volga (238 km³/year). However, when calculated per unit of the water catchment area, the river runoff over the Russian Federation territory is more than 1.2 times smaller than the world's average values. The reason is that Russia is, on average, poorer in precipitation than other countries. It is also important also that water resources are very irregularly distributed over the territory. Mean annual values of the river runoff layer vary from practically zero in the southeast regions of European Russia to more than 2,000 mm near the Main Caucasus ridge.

The layer of underground runoff over the Russian territory is 1.7 times smaller than the world's average values. This number is low because the formation of both surface and underground runoff takes place mainly during the spring snowmelt, when water is not absorbed by the soil because of its winter freezing. As for the warm period, the greater part of precipitation is then spent for evaporation rather than for a runoff.

Over the major part of the country, 60–70% of the river runoff runs for a relatively short period of spring high waters. During this time, surface slope runoff is of special interest to agriculture, as it is the main cause of erosion processes on arable land and the main source of water storage for agriculture in dry regions. In general, the uneven distribution of the river runoff in Russia – both over the surface and in time – complicates its use in the economy.

For a long time now, water resources have been affected by human economic activity on water catchments and river valleys. The use of water for economic needs exerts the most essential influence. At the beginning of the 1990s, about 60% of all sources of freshwater was taken for industrial purposes; more than 15%, for irrigation; and about 25%, for agricultural needs. A part of the water taken is never returned into rivers (irreversible water discharge), while another part is discharged into rivers as polluted sewage (wastewaters) and collection-drainage waters. The result is that the river runoff decreases, and water in rivers is polluted. As this takes place, each volume of sewage and collection-drainage waters pollutes a much greater volume of clean water.

Anthropogenic decrease of the runoff is clearly manifested in southern regions of the country. There, the main water user – i.e., irrigated agriculture – is the most developed. Water resources in industrial regions are highly polluted. At present, most river waters of European Russia and many rivers in its Asian part are polluted. The basic part of underground waters, which are the main sources of the drinking water supply, still remain clean.

Bibliography
Water Resources and Water Balance of the Soviet Union Territory. 1967. Reference book, Gidrometeoizdat, Leningrad, 200 pp. [In Russian]

Water Balance in the USSR and Its Transformation. 1969. Reference book, Nauka, Moscow, 338 pp. [In Russian]

Waters in Russia (State, Use, and Protection): 1986–1990. 1991. Reference book, Gidrometeoizdat, Sverdlovsk, 158 pp. [In Russian]

Voskresensky K.P. 1962. Norm and Variability of Annual Runoff of the Soviet Union Rivers. Gidrometeoizdat, Leningrad, 550 pp. [In Russian]

Koronkevich N.I. 1990. Water Balance of the Russian Plain and Its Anthropogenic Changes. Nauka, Moscow, 205 pp. [In Russian]

L’vovich M.I. 1974. World Water Resources and Their Future. “Mysl,” Moscow, 448 pp. [In Russian]

World Water Balance and Water Resources of the Planet Earth. 1974. Reference book, Gidrometeoizdat, Leningrad, 639 pp. [InRussian]

Comprehensive Assessment of the Freshwater Resources of the World: Assessment of Water Resources and Water Availability in the World. 1997. Stockholm Environment Institute, Stockholm, misc. pp.

Total river runoff

Total river runoff is the water volume running in the river bed over a period of time. It is the main type of water resource. Total river runoff is measured in cubic meters (m³)/seconds or cubic kilometers (km³) of water transported by rivers per year, or in a layer of runoff measured in millimeters (mm), i.e., the runoff volume related to the drainage area. Total river runoff consists of components different in their genesis – mainly, surface and underground runoff – and is rather irregularly distributed over the seasons.

The runoff volume being formed over the territory of the Russian Federation exceeds 4,000 km³. The average runoff layer amounts to 237 mm. The distribution of the runoff layer over the country is rather irregular, and it is mainly connected with the amount of precipitation. Zonality (both latitudinal geographical and altitudinal climatic) is clearly manifested. In lowland regions, the highest values of the river runoff are observed in the taiga zone of European Russia: 300–400 mm. In the forest-steppe zone, the river runoff varies from 50 to 150 mm, while in the steppe zone it is within the range of 10–50 mm. In semi-desert regions in the southeast of European Russia, the runoff is close to zero. In lowland regions of Asian Russia, values of the runoff layer are, as a rule, smaller than those in the same latitudes of European Russia, mainly owing to a smaller amount of precipitation.

The runoff reaches its maximum values in mountain regions. Over the northwest part of the Caucasus the runoff layer exceeds 2,000 mm. In regions of the North Urals, the Altai, and in the mountains of Eastern Siberia, it is close to 1,000 mm.

Bibliography
Water Balance in the USSR and Its Transformation. 1969. Reference book, Nauka, Moscow, 338 pp. [In Russian]

Voskresensky K.P. 1962. Norm and Variability of Annual Runoff of the Soviet Union Rivers. Gidrometeoizdat, Leningrad, 550 pp. [In Russian]

Resources of Surface Waters in the USSR: Basic Hydrologic Characteristics. 1966–1967. Reference books, Volumes 1–20. Gidrometeoizdat, Leningrad.

Variability of the total river runoff

The variability of a river runoff is characterized by the degree of the runoff deviation taken for individual years from its climatic value. It is expressed by a coefficient of variation, C_v. The more variable is the runoff, the lower is the C_v value. Thus, the more regulated the runoff, the more applicable it is for use. When the mean climatic value of the runoff increases, the C_v value usually decreases. Over the Russian territory, the runoff is rather variable, and it requires great efforts to use it.

To a degree, the runoff variability in Russia follows the latitudinal geographical zonality. Thus, in the north of European Russia, the C_v values range from 0.15 to 0.3, in the central part they amount to 0.3-0.4, and in the southeast regions they exceed 1.0.

Coefficient C_v depends also on the drainage area. So, the maximal annual runoff of the Enisei river near Igarka town is nearly 1.4 times greater than its minimum, that of the Volga river near the Verhnia Lebiazh’e village is 2 times bigger, and that of the Don near the Razdorskaya village is 4.6 times bigger.

Bibliography
Atlas of Calculated Hydrologic Maps and Nomograms (Attachment 1 for “Textbook for Determination of Calculated Hydrologic Characteristics”). 1986. Reference work, Gidrometeoizdat, Leningrad, 22 sheets of maps. [In Russian]

Voskresensky K.P. 1962. Norm and Variability of Annual Runoff of the Soviet Union Rivers. Gidrometeoizdat, Leningrad, 550 pp. [In Russian]

Guide for Calculation of Hydrologic Characteristics. 1972. Reference work, CH-435-72, Gidrometeoizdat, Leningrad, 20 pp. [In Russian]

Underground runoff

Underground runoff is that part of the total river runoff that is formed in underground soil horizons. It is determined by partitioning discharge hydrographs (graphs of the water discharge time variations) of the total river runoff into its generic components.

In Russia, the underground component accounts for 27% of the total river runoff (on average, for land globally this value amounts to 32%). Russia is 1.7 times worse provided with resources from underground runoff related to unit of an area (52 mm) than is global land as a whole. This fact is explained by the relatively small amount of precipitation and the poor infiltration properties of soils and grounds, especially in the permafrost regions (Eastern Siberia, North of the Far East). Like the total river runoff, distribution of resources of the underground runoff over the territory is mainly zonal. Underground runoff resources are lowest in lowland regions in southeastern European Russia, and also in Central Yakutiya where they are close to zero. They reach the maximal values (more than 100 mm) in the taiga regions of North European Russia. Underground runoff increases in mountain regions as well as those (for instance, karst) with conditions that favor infiltration.

Bibliography
Water Balance in the USSR and Its Transformation. 1969. Reference book, Nauka, Moscow, 338 pp. [In Russian]

Underground Runoff on the USSR Territory. 1966. Reference book, Moscow State University, Moscow, 304 pp. [In Russian]

Runoff for the spring flood period

Spring flood refers to high water flow in rivers during the spring snow melting. It is the basic hydrological phase of the water regime over the greater part of Russia's territory. About 50–70% of the annual runoff runs in the large rivers, usually between April and June. In small rivers in southeast European Russia, the spring floods involve more than 90% of the annual runoff.

Over the lowland territory of Russia (in north European Russia and in West Siberia) the spring flood runoff is maximal (about 200 mm). This is where the largest snow storage has accumulated by the time the flood starts. The flood runoff reaches the greatest values (more than 500 mm) in the mountains of the North Urals and of East Siberia. In Central Yakutiya, the runoff is extremely small (less than 20 mm), owing to very small snow storage.

Bibliography
Atlas of Calculated Hydrologic Maps and Nomograms (Attachment 1 for “Textbook for Determination of Calculated Hydrologic Characteristics”). 1986. Reference work, Gidrometeoizdat, Leningrad, 22 sheets of the maps. [In Russian]

Guide for Calculation of Hydrologic Characteristics. 1972. Reference work, CH-435-72, Gidrometeoizdat, Leningrad, 20 pp. [In Russian]

Spring surface slope runoff from the arable land area

On Russia’s arable lands, surface slope runoff is predominantly formed in spring, during the flood periods. It is the principal reason for erosion on slopes. It is the pathway by which fertilizers and toxic chemicals are transported from fields into rivers and water reservoirs. At the same time, it is an important reserve of water for agriculture in arid regions.

Values of a surface slope runoff are derived from graphs of its correlation with the total river runoff near positions of the water-balance stations where observations of the slope runoff are regularly carried out.

Distribution of the spring surface runoff over the territory of the main agricultural regions of Russia ranges from 60–80 mm in the south of the forest zone to 5–10 mm in the south area of the steppe zone. In the steppe regions, the slope runoff layer can exceed that of the river runoff because in the course of its way to a river, a part of the slope runoff is intercepted by closed negative relief forms.

Bibliography
Koronkevich N.I. 1990. Water Balance of the Russian Plain and Its Anthropogenic Changes. Nauka, Moscow, 205 pp. [In Russian]

Total river runoff in subjects of the Russian Federation

In many respects the total river runoff volume characterizesthe water resources of any region and also represents the current state of and prospects for development of the national/local economy. In administrative units of the Russian Federation, the river runoff is calculated on the basis of the total river runoff maps.

The largest local resources, expressed in km³/year, are in the region Krasnoyarsky Krai (738 km³/year), whose vast territory embraces the greater part of the Enisei river drainage area. The Astrakhan region actually has no local resources.

With respect to the river runoff layer, the Sakhalin region is the best supplied at 701 mm. The largest total river runoff resources are in the Krasnoyarsky Krai, at 901 km³/year, while the smallest ones are in the Republic of Kalmykiya, at 1.06 km³/year. Since the Astrakhan region has no resources of local runoff, the Volga River runoff plays a key role for the water supply of this region.

Bibliography
Water Resources and Water Balance of the Soviet Union Territory. 1967. Reference book, Gidrometeoizdat, Leningrad, 200 pp. [In Russian]

Melioration (Land Improvement) and Water Economy. 1988. Reference book, Vol. 5, Vodnoe Khozyaistvo (Water Economy). Agropromizdat, Moscow, 400 pp. [In Russian]

Anthropogenic impact on the water resources

Anthropogenic effects on the water resources of the Russian Federation are rather various. The main impacts are presented by different types of water use. Any water intake from both surface and underground sources results in reduction of river runoff. The waters returned after human use cause pollution of natural waters. Each unit volume of the wastewater fouls, even after filtration, a much greater volume of clean water. If a 5- to 10-fold dilution of the wastewater within the total river runoff is not provided, then rivers and water reservoirs become greatly polluted. Rivers and water reservoirs are usually relatively clean where the rate of dilution of discharged wastewaters exceeds 500 times.

The greatest quantity of water is taken in southern regions of the Russian Federation, in the basins of the Kuban’ and Terek Rivers. In the Stavropol Krai region, the water intake exceeds total water resources, and this deficit is made up by water delivery from adjacent regions. As for the human intake, it is close to 40% of total water resources. With the advance of urban development, i.e., as metropolitan conglomerates grow, a danger of polluted waters associated with an insufficient rate of dilution of the wastewaters in northern regions increases. Only in regions where the sewage and collector-drainage waters amount to less than 0.2% of the river runoff resources, do waters remain relatively clean.

Bibliography
Waters in Russia (State, Use, and Protection): 1986–1990. 1991. Reference book, Gidrometeorizdat, Sverdlovsk, 158 pp. [In Russian]

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SNOW COVER AND GLACIERS
Vladimir Kotlyakov

In a northern country like Russia, different phenomena connected with ice play an important role.The snow cover, the river and lake ices, the underground ices and naleds, and glaciers are all important.

The snow cover is the most important as it determines the conditions involving a fall and deposition of a solid precipitation; the appearance, existence, and loss of the snow cover; data on the ice amount precipitating from the atmosphere; and maximal snow storage.

The snow cover is a layer of snow on the Earth's surface that has resulted from snowfalls. Both a temporary snow cover, which melts within several hours or days of its formation, and a stable snow cover, which lies on the surface during the whole winter or with short intervals, exist. The snow cover has a small density which grows with time, especially in spring. Because it does not conduct heat well, it protects the soil from strong cooling and winter crops from freezing. The snow cover reflectivity changes from 70–90% (fresh snow) to 30–40% (old melting snow). The snow cover structure reflects meteorological conditions of the winter that has passed.

Snow cover exerts great influence on climate, relief, hydrological, and soil-forming processes, as well as the life of plants and animals. In Russia, melted waters form a large part of river runoff. The snow cover is widely used for snow land reclamation, i.e., the improvement of the water and heat regimes of soils by regulating the snow accumulation or changing the duration of the snow cover. The main approach here is snow retention (holding), or promoting the snow accumulation on fields to increase the moisture storage in soil and the warming of wintering plants.

The most important characteristics of a snow cover are its duration, stability, thickness, and density, which determine the amount of water contained in it. Generally, snow cover has zonal regularities, but essentially it depends on latitude and also on local conditions, mainly on relief and vegetation.

The duration of the snow cover grows quickly from west to east within the limits of the western part of European Russia. The heat transport of the Atlantic and Mediterranean air masses retards the onset of snow cover in autumn and accelerates its melting in spring. Further eastward, an increase in the snow cover’s duration proceeds rather slowly. Because of that, winter in Eastern Siberia has a small amount of snow. Furthermore, the snow expenditure for evaporation in this region is essential at the end of winter and in early spring.

The snow cover thickness, which is determined as an average from the decade of the thickest winter snow, is connected with the amount of solid precipitation and the snow density. From Russia’s west boundary to the Sea of Okhotsk coast, the thickest snow falls on latitudes 60–65°; this is determined by not only the precipitation amount, but also by the significant duration for which the snow accumulates. A thickness greater than 60 centimeters (cm) is predominant here.

In the Extreme North, the snow cover thickness does not exceed 50 cm despite the long duration of a cold period. The reason is a reduced amount of precipitation and increased snow density by the end of a long winter. To the south, at 58–60°N, the snow cover thickness decreases because the period of solid precipitation accumulation is shortened and its general amount is reduced. In the southern part of European Russia, the snow cover thickness does not exceed 20 cm. Similarly, it is small on the plains of south Zabaikalje: although the winter is long and stable, it has little snow.

In the direction from west to east in the middle latitudes, the snow cover thickness within the limits of the East European Plain increases by a factor of 1.5–2 and reaches its maximum (90–100 cm) in the Pre-Urals. Immediately after the Urals, it decreases down to 60 cm and again increases across the Middle-Siberian tableland up to 80 cm. Further to the east, the snow thickness decreases and in a region of Yakutsk it amounts to only 40 cm. At last, in the Far East – in connection with intensification of cyclonic activity – it increases up to 60–70 cm on the continent coast and 90–100 cm and more on Sakhalin and Kamchatka.

In the high mountains, about a third of annually accumulated snow serves to supply glaciers with snow (serves as a source of glacier nourishment). Aside from those in Arctica, Russia’s modern glaciers exist in the Polar Urals, the north slope of the Caucasus, in Altai, and in some ridges of Siberia and in Kamchatka. They carry a huge storage of fresh water and play an important role in redistributing atmospheric precipitation.

The regulating role of glaciers manifests in long-term, inter-seasonal, and intra-seasonal cycles. The glacier runoff increases in dry years when little precipitation falls on the surface. Runoff from glaciers is concentrated during the summer period, which is dry in many glacier regions. In the beginning of summer, the melted water is accumulated in the snow-firn thickness and in intra-glacier cavities, and then in July and August it runs out. All these changes of the runoff by glaciers are very convenient for irrigation, and long-term regulation is also important for hydro-energetics.

Number of days with snow cover

Duration of the snow cover lying is determined by the number of days in a year when, in the morning hours, more than half of the visible land surface is covered with snow. Although the number of days with a snow cover depends on the heat-moisture relation, it is chiefly related to thermal conditions. Over the greater part of Russia, the land is snow-covered about 100–200 days a year. In the East European Plain, the latitudinal gradient of a number of days with snow cover amounts to about 8 days per 1° of latitude. The main regularities of the snow cover duration on plains are presented in the table that follows.

Number of days with snow cover

In the European part of the country, warm oceanic air masses coming from the west noticeably moderate winter temperature conditions. This results in the shortening of the period in which snow lies on the ground – down to 170–200 days.

In northern Eurasia, snow cover lasting for 250–300 days is observed in the northern part of the West Siberian Lowland and on plains of Eastern Siberia beyond the Polar Circle. In regions where permafrost exists, snow cover endures 10% longer than under similar conditions without a permafrost.

In the southern half of the West Siberian Lowland and in southern Siberia (in latitude belt 50–55°) the snow cover lasts for 150–200 days. Due to intensive evaporation in late winter and early spring, the snow cover lies in East Zabaikalie for an even shorter time than it does in the same latitudes in southern West Siberia. On the Far East coast, which is influenced by a cold east periphery of the continental anticyclone, the snow cover duration is the same as it is in Siberia.

With an increase in the absolute elevation, the snow cover duration grows everywhere in connection with the temperature drop and the increase in solid precipitation. Vertical gradients of the duration depend on the relief forms, slope expositions, and other local features.

Dates of a steady snow cover formation

Over vast areas of Russia, the dates of a steady snow cover formation fall in the broad range: from the middle of September on the Arctic coast of Siberia to late December in the southern European part of the country. The basic factors for dates of the formation are a stretch of cold weather and geographical latitude, and to a significantly lesser degree it is a norm of maximal snow storage.

Steady snow cover is not formed at once. Even in the Arctic zone, where permanent snowfalls are already beginning in August, the final formation of snow cover is shifted by 10–15 days. The earlier dates of the formation, which are in the last of August or early September, are typical for islands in the Arctic.

Isolines of dates of the snow cover formation essentially deviate from latitudinal direction due to the influence of the marine climate of the European part of Russia and the extreme continental climate in the center of its Asian part. Mean rates of the autumn southward advance of the steady snow cover boundary in the sub-Arctic zone and in the north of the moderate zone are equal to 2–2.5 days per 1° of latitude. In the southern regions, the latitudinal gradients increase up to 4 days on the central plains, and up to 6 days in coastal regions.

In Russia, a steady snow cover is formed in all mountain systems. In the southern regions of European Russia, foothills can be snowless, and in the lower parts of the slopes, the snow cover lies off and on. In this case, the altitude of the lower (limiting) boundary of a steady snow cover, and the dates of its formation, depend on the climate “continentality” as well as on a snowiness of individual parts of a mountain system.

Dates of steady snow cover destruction

In the southern European part of Russia, destruction of the snow cover begins already in February, but in southern Siberia, snow lies on the ground until June. As it is destroyed, a boundary of steady snow cover moves from north to south. Basic factors determining dates of the snow cover destruction are the length of the cold period and a norm of maximal snow storage.

In the southern part of Russia, huge snow-free areas frequently appear as early as middle February. However, a return of the winter cold and individual snowfalls retard destruction of the steady snow cover until the end of this month. In March, the rate of the northward movement of the boundary of seasonal snow is small; on the average, the latitudinal gradient is equal to 5–7 days. During this time, the steady snow cover is destroyed over a significant area of the southern East European Plain.

In April, solar radiation drastically increases, and the rate of the northward moving of the seasonal snow boundary increases too, on the average, for 2.5–3 days it is shifted by 1° of latitude. During this period, a greater part of the mid-latitudinal zone becomes free from snow. On the eastern border part of the continent, however, the steady snow cover is destroyed later because of the increased snowiness of this territory. It becomes free from snow only in May, when a boundary of its seasonal spreading moves into the sub-Arctic zone. The rate of its retreat is slightly decreased here; this has mainly to do with the pervasive existence of permafrost.

Because of local climate features in many regions of the plain territories, dates of the steady snow-cover destruction deviate from a latitudinal spreading. Due to differences in the snow accumulation, in some parts of mountain systems, there is an increase both in the range of terms of the snow cover destruction and in an asymmetry in spring positions of the seasonal snow boundary on windward, leeward and screened slopes.

Maximal snow storage

A snow storage is a mass of both solid and liquid water existing at a given time in a snow cover. It is defined by multiplying the snow thickness by its density. The maximal snow storage is measured when the snow cover reaches the greatest mass over a winter.

In the Arctic zone, dominated by the Arctic air masses with their low water content, and where the cold season lasts for more than eight months, the snow storage amount is determined by only the solid precipitation amount, which varies within limits from 50–200 millimeters (mm). On Pechorskaya and the West Siberian lowlands as well as on plains of the Pre-Urals, the snow storage amounts to 100–150 mm.

Under the conditions of the predominant anticyclonic regime to the west of the Verkhoyansky mountain range, the maximal snow storage falls to 50–100 mm. Mountain ranges of the Chersky and Verkhoyansky ridges obstruct movement of the moisture-carrying west air flows and thus intensify the anticyclonic climate of the Yano-Indigirskaya and Kolymskaya lowlands. Only on the Pacific coast and the Chukotka valleys does the snow storage grow again: up to 200 mm.

In the north area of the temperate belt, i.e., in the Pre-Urals region, the snow storage grows up to 200–250 mm. This is a result of the influence of the Urals mountain range, which stimulates atmospheric fronts. On all uplands within the limits of lowlands, even with a difference of height of several hundred meters, the snow storage noticeably increases. This characteristic feature is clearly evident in the beginning and at the end of winter, when white snow caps on the uplands are in contrast with a dark, snowfree surface of the surrounding lowlands.

In the south area of the moderate belt, the duration of the cold period decreases, and the amount of solid precipitation is sharply reduced down to 50–200 mm; therefore the snow storage drops from north to south. Increasing evaporation from the snow cover, which amounts to about 30 mm on lowlands of Russia's moderate belt, promotes this effect. The snow storage value decreases from west to east, but this effect is rather ambiguous, as the eastward reduction of solid precipitation is followed with a lengthening of the cold period duration.

On the whole, the lowlands of the European part of Russia are characterized by a small spatial variability of the snow storage. Everywhere, except the coastal and extremely south dry regions, the snow storage is equal to 50–100 mm. In the Asian area of the country, dry snowless areas are present in centers of strong anticyclones, and the complicated morphography results in great spatial variability of snow storage. The area with minimal snow storage for these latitudes, i.e., 15–20 mm, is located here, in the center of the Siberian anticyclone activity in the Zabaikalje. On the lowlands of the Far East (Primorje), normal values of maximal snow storage amounts to 50–100 mm.

Variability of maximal snow storage over time

Temporal variability of the maximal snow storage C_v is determined by joint manifestation of variations of both the solid precipitation amount and the thermal conditions during annual formation of the snow cover. The temporal snow storage variability regularly decreases from south to north and along with intensification of climate continentality. The variability C_v decreases from 1.0 near the south boundary of the snow cover down to 0.2–0.3 on the lowlands of Siberia. Here, the small snow storage variability over time is conditioned by the regular formation of the “Siberian High.”

Under conditions that are either marine or transitional to the continental climate, the autumn-winter precipitation is connected with cyclonic and monsoon processes. The weather here is changeable, with frequent thaws and rains. Under such conditions, the C_v values are rather high. Stability of snow accumulation grows outward from the oceans, and this proceeds smoothly on the plain territories and quickly in regions of coastal mountain ranges.

Increase of the snow accumulation stability with elevation is characteristic for any mountain area, but in well-moistened mountain systems the C_v value is larger than it is in more dry mountain regions. For instance, variability of the maximal snow storage in the Altai changes from 0.35–0.40 in the lower parts of the slopes, where the snow storage is close to 100–250 mm, down to 0.15–0.20 in the high mountains, where the snow storage reaches 700–1,000 mm.

Fraction of the snowmelt runoff in the annual volume

The resource of the snowmelt runoff is a volume of mean annual runoff formed after melting of snow and ice. This part of an annual runoff is equal to the amount of solid precipitation, except for a volume of evaporated moisture during the time of snow cover occurrence and melting, and the water flowing down into a river channel.

Distribution of river runoff and its melted component over plains of the European part of Russia and West Siberia is mainly zonal in nature. It is disrupted under the influence of highlands, where the snow accumulation is larger and the melted component is respectively greater. Usually, from north to south from the Arctic Ocean coast to the foothills of the Caucasus, the fraction of the snowmelt runoff in the annual runoff increases from 50% to 90%. In the direction from west to east, the snowmelt component of the runoff changes on the East European Plain from 50% to 70%.

In the Asian part of Russia, the zonal nature of the snowmelt runoff portion is typical for only West Siberia, and within its territory this value increases from 50% to 90%. In the east, relative volumes of snowmelt runoff are determined by a relief. If, on the plain area of the Arctic Ocean coast, the snowmelt runoff part amounts to 50%, so on the plain of Central Yakutiya and the Near Lena plateau it increases up to 80%. In contrast, within closed depressions in the south of Siberia (i.e., Minusinskaya and Tuvinskaya) this fraction does not exceed 40%.

It is rather difficult to isolate the snowmelt fraction in the Far East (Primorje), as in spring time a relatively small flood wave is superimposed with rain floods, and snow alternates with rain. Here, we estimate that the snowmelt component of the runoff changes from 40% to 10%.

Fresh water resources in glaciers

Glaciers exist because of yearly accumulation of solid precipitation on their surfaces. The annual mass of the seasonal snow on glaciers (220 mm) exceeds a corresponding value typical for continents as a whole (150 mm). In the polar regions of Russia, glaciers occur right down to the point of sea level. In sub-polar regions, they are developed on low mountains and plateaus. To the south, they are confined to the middle-altitude plateaus and further south, to high mountains.

Snowdrifting and accumulation

A snowstorm refers to snow being borne by a strong wind above the land surface. Most snow transport takes place in the ground air layer. We con distinguish: (1) a near-ground snowdrifting, when snow is transported directly above the snow cover; (2) a blowing snow, when snow is lifted high above the surface; and (3) a total snowstorm, when the snow being lifted from the surface and that precipitating from clouds are simultaneously transported.

The snowstorm intensity depends on the wind velocity, the rate of snow fall (when it is snowing), and on the state of the snow cover surface above which the snow transport takes place. During a snowstorm, the snow particles are torn off from the surface: there is reduced pressure within the boundary vortex layer owing to diffusion of suspended material in the air.

The surface layer of the reduced pressure reaches a thickness of 8–10 mm at a wind velocity up to 20–25 meters/second (m/s) and several centimeters when the wind velocity is 30–35 m/s. The surface snow particles are “sucked” by this layer and thrown vertically up, and then transit into a smooth descent. This kind of snowflake motion is called saltation.

As the flow becomes saturated with snow, its transporting capability reduces, but it still can lift new portions of snow. Such a snowstorm is called nonsaturated. After the flow is saturated with snow it can not “suck” new snow particles, and the excessive snow is deposited on the snow cover surface.

As a rule, the precipitation of snow from such a flow takes place behind obstacles, the wind velocity drops in front of them. Snowdrifts are formed in such places.

Snowstorm transport is accompanied by a strong snow evaporation that exerts essential influence upon the economic activity in the regions where the occurrence of this phenomenon is frequent. After a virgin land is plowed up, its hydrological regime is changed, because in the course of a snowstorm a significant part of snow transits into a gaseous state, thus leading to great irretrievable losses. Because the snowstorm evaporates snow, the snowstorm particles cannot be transported over great distances.

Over the greater part of Russia's territory the snowstorm transport mechanism results in snowdrifts, which make the life and transportation in villages and settlements rather difficult. Volumes of snow transported by winter storms vary in different regions of Russia: they range from tens to 2,000 and more cubic meters (m³) per running meter of the flow front.

Here we present two maps that reflect the wind bearing of snow over Russia's territory. The map “Maximal volumes of the snow transports” shows a distribution of maximal volumes of snow transported for a winter, possible to occur once in 20 years, as well as the frequency of the wind directions for snowstorms for individual points. A mass of snow transport was calculated from yearly data for 300 stations for 1936–1980. A volume of transported snow q (m³ per 1 running meter) was calculated with the following formula: q = cv³t, where v is the wind velocity, t is the snowstorm duration, and c is the proportionality factor.

The snow transport volume is relatively small on the western and southern parts of Russia's European territory, West Siberia, Central Yakutiya, and in mountains to the south of East Siberia. In contrast, the snow transport volumes reach great values on the north of the European territory, in the southern part of the Urals and Zauralje, on the northern coastal lowlands of Siberia, and in Kamchatka and Sakhalin.

The map “Possible volumes of snowdrifts near obstacles” shows regions with maximal annual values of volumes of snow accumulated near obstructions (with 5% confidence). The mapping was based on data obtained by calculations using the method of balances, which makes it possible to take into account efficient sizes of snow-accumulating basins, their actual sizes, lengths of zones of the snowstorm accelerations up to complete saturation of them with a drifting snow, retardation of snow by vegetation and orographic obstacles and depressions, and losses of snow via evaporation and melting. These calculations also used data from a network of hydrometric stations, along with mean climatic values of a precipitation amount for the cold period, velocities of storm winds, and mean winter air temperatures.

Possible volumes of snow deposits near obstructions (in m³ per 1 running meter) were calculated using values of efficient distance of the transport, which depends on the drifted snow evaporation; solid precipitation amount; coefficient of snow blowing away; a sum of the snow cover losses for evaporation; its melting and retardation by soil roughness, vegetation, etc.; the snow density in deposits near obstructions; and the air moisture deficit. Gradation of the scale was developed on the basis of a snow-accumulating capability of different forms of protection used to prevent snowdrifts.

Over the greater part of the European territory of Russia, except the middle area of the Volga basin, the snow transport volume does not exceed 100 m³ per 1 running meter, and snow fences or a one-row forest belt (windbreak) are recommended as snow protection. On the Privolzhskaya highland and in the Middle and South Urals, the volume of snow deposits reaches – and in some places exceeds – 200 m³ per 1 running meter, and here two-row forest belts are recommended as snow protection. Over the greater part of the West Siberian Lowland, Middle-Siberian Tableland, mountains of Zabaikalje, and East Siberia, the volume of snow deposits is small, i.e., from 50 to 100 m³ per 1 running meter. The mechanical removal of snow is expedient here, while in South Siberia, shield lines and fences up to 3 m high are used. The largest volumes of snow deposits are common in near-Arctic lowlands, in Kamchatka, as well as the Altai steppes, i.e., from 200 to 1,000 m³ per 1 running meter.

Possibilities of ice formation

Formation of ice in nature is performed by two processes: (1) the sublimation in the atmosphere and (2) the congelation in the hydrosphere or on a boundary of “water-air.” An artificial freezing of ice due to storage of natural cold is quite possible in the latter case.

If the artificial ice freezing is made by a thin-layer spilling of water or the watering of a solid surface with its thickness up to 8 millimeters (mm), the ice formation runs immediately throughout the whole volume. As the thickness increases the rate of freezing drops. Under the best conditions, 1–2 centimeters (cm) of ice per a degree of a mean daily negative air temperature can be frozen. By means of low-pressure dams, it is possible to remove the water onto a flood-plain, thus creating on it an ice cover of significant area but of small thickness. But, when it is necessary to create a rather high but compact ice block, then liquid water should be splashed on its surface. By this method, the basic heat exchange takes place on a surface of the water layer.

Artificial ice freezing by means of winter water application uses as a heat exchanger a drop plume created by far-reaching sprinklers. The higher and wider the plume is, the smaller are the drops and the more intensive is the air exchange (owing to the wind velocity or motion of the cone itself), the more intensive is the ice formation. Medium sprinklers with the water discharge up to 100 horse power (h.p.), the plume height of 20–25 meters (m), and a distance of the drop sprinkling up to 100 m all allow the freezing to proceed at a rate tens times greater than that from the method of the thin-layer water spilling. When artificial ice is created, a mass of grainy material is formed; its properties are very close to the natural firn. In its wet state it is easily formed, and after it is frozen it has sufficient strength for many purposes.

Such a mass has one more property – a quick filtration and runoff of excessive water – which allows it to be used as a desalter for mineralized waters. Such a mass prepared in winter will give fresh water as it melts in summer. If a monolithic piece of ice is needed for a building purpose (ice bridges, dams, platforms, islands), then – as is done in the method of the thin-layer spilling – a water-ice mix is put onto a surface, and it is frozen in a form of whitish massive ice. Its density and strength are the same as those of the transparent ice.

Not only dense materials – i.e., ice and firn – are produced by means of the water sprinkling in a frosty air. Loose ones can also be made for the purpose of thermally insulating constructions or a stretch of ground. Before the water is sprinkled, it is aerated and saturated with tiny bubbles of air in so-called “snow guns.” The material that is formed is like snow with a density of 200–300 kilograms/cubic meter (kg/m³⁾. It is particularly suitable for creating skiing routes. The density of the material can be further reduced – improving its heat-insulating efficiency – by using a water charged with surfaciants, as well as by saturating the water with the air bubbles.

“Artificial glaciers” can be used in the most complex and efficient way in regions with a sharply continental climate involving frosty winters and hot summers, and which also experience a permanent deficit or a full absence of fresh water. Consuming only highly mineralized underground or lake water and using the ice formation method in a plume of artificial rain, one can obtain a good water-climatic resource in a form of desalted firn massif. With its area of 1 square kilometer (km²), average thickness of 30 m, and a mass of 15x10⁶ tons (t), such a massif will change the surrounding landscape of dry steppes or semi-deserts and its possibilities for economic development.

The maximal possible freezing of ice depends on winter climatic conditions, first of all, on resources of cold. Over Russia's territory these possibilities change regularly from southwest to northeast in conformity with characteristics of climate.

Over the European part of Russia from south to north a potential freezing varies from less than 500 grams of H₂O/square centimeter (g/cm²) in Ciscaucasian and Near-Caspian regions up to more than 2,000 g/cm². In West Siberia from south to north the possibility of freezing of ice falls into the range 1,700–4,000 g/cm².

The most favorable regions for the artificial freezing of ice are Middle and East Siberia. About 2,500–3,500 g/cm² of ice can be frozen for a winter in the south of this territory, while in Central Yakutiya and on ranges Verkhoyansky and Chersky, 5000–6000 g/cm² and larger.

The conditions for the freezing of ice are much worse in the Far East, owing to the great influence of oceanic air masses. Although generally cold conditions occur here, the freezing of ice does not exceed 2,000 g/cm².

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