Water supply of rivers and its types. Food and water regime of rivers Which rivers are fed by snow

We all know very well that several of the largest rivers of our planet flow through the territory of Russia, the width of which reaches 50-60 kilometers.


But the source of even the largest river is a thin, inconspicuous stream. Only after running many hundreds of kilometers, having been saturated with the moisture of many large and small tributaries, the river becomes truly powerful and wide. Do you know what river nutrition is, and what are its sources? Yes, the river is also fed, but, of course, not by cutlets with mashed potatoes, but by water from its tributaries.

Nutrition and river regime

How to measure a river? You can measure its length, the width of the channel and the depth of the bottom. Another important characteristic is the water consumption, i.e. the amount of water that flows through a channel per unit of time. If you make these measurements throughout the year, you will find that the level and flow of water in different periods are not the same.

Continuing observations for several years in a row, you can see that in spring and autumn the river becomes more full-flowing, and in summer and winter the amount of water in it decreases. Scientists call these seasonal fluctuations the regime of the river.

It is customary to distinguish three main periods in the regime of any river:

- - a long period when the amount of water reaches a maximum, as a rule, due to the spring melting of snow;

- - periods of lowering the water level, usually occur in summer and winter;

- - short-term and sharp, lasting only a few days, rise in water level due to heavy rains or sudden snowmelt.

It is easy to see that fluctuations in the water level in the river are caused by an increase or decrease in its supply, i.e. water entering the river from tributaries, streams and underground sources. Hydrologists (specialists who study the "behavior" of natural waters and reservoirs) identify four main sources of river nutrition - snow, ice, rain and underground. One of them is usually predominant, but the river does not refuse the rest either.

Rain, snow supply

Rivers fed exclusively by rain are characterized by frequent and sudden floods. As a rule, these are tropical and subtropical rivers flowing from peaks or hills.


In our country, there are also rivers with a predominantly rain source of food. They flow from the peaks of Altai, the Caucasus, the Baikal region and other similar regions. But for our rivers, no less powerful source than rain is snow, or rather, its spring melting. "Snowy" rivers, as a rule, are distinguished by the softness of the water and the low content of salts in it. In spring, they are characterized by abundant floods, after which the river enters its usual banks. A similar picture is observed after heavy rains.

Glacial nutrition

The main source of water in the river may be a mountain glacier, the melting of which replenishes the water level in the channel. Such rivers originate on the high peaks of the mountains, covered with a multi-meter layer of ice. In summer, when the glacier actively melts, the water level in them rises, the flow becomes turbulent and erodes the banks, carrying down fertile soil.

Therefore, as a rule, glacial rivers are not popular with the population, and their banks are deserted and barren. Sometimes a glacial river flowing down from a mountain peak, for many centuries, carves a deep gorge in the rocks, the bottom of which becomes its channel.

underground food

On the plains and in the lowlands there are rivers that feed mainly from underground sources. There are not so many of them, and their diet is still not well understood. It has been established that underground power can be ground, i.e. coming from the upper aquifer, in which rainwater absorbed into the soil accumulates, or artesian, coming from a natural artesian well.


Underground feeding is typical for small streams, but large water flows are supplied mainly from tributaries.

The runoff of rivers and their water regime during the year bears the stamp of zonality, since they are determined primarily by the conditions of nutrition. The first classification of rivers according to feeding conditions and water regime was created by A.I. Voeikov in 1884. Later, it was improved by M.I. Lvovich by quantifying the role of individual sources of river nutrition and the seasonal distribution of runoff. Under certain conditions, each of the food sources can be almost exclusive if its share is more than 80%; may have a predominant value (50-80%) or prevail over others (less than 50%). The same gradations are used by him for the flow of rivers according to the seasons of the year. According to the combination of food sources (rain, snow, underground, glacial) and the seasonal distribution of runoff, they have identified six zonal types of the water regime of rivers on Earth, well expressed on the plains.

Rivers of the equatorial type have abundant rain supply, a large and relatively uniform flow throughout the year, its increase is observed in the autumn of the corresponding hemisphere. Rivers: Amazon. Congo etc.

Tropical rivers. The flow of these rivers is formed due to monsoonal summer rains in the subequatorial climatic zone and mainly summer rains on the eastern coasts of the tropical zone, so the flood is summer. Rivers: Zambezi, Orinoco, etc.

Subtropical rivers in general, they are predominantly rain-fed, but according to the seasonal distribution of runoff, two subtypes are distinguished: on the western coasts of the continents in a Mediterranean climate, the main winter runoff (Guadiana, Guadalquivir, Duero, Tajo, etc.), on the eastern coasts in a monsoon climate, summer runoff (tributaries of the Yangtze , Huanghe).

Rivers of a moderate type. Within the temperate climate zone, four subtypes of rivers are distinguished according to their sources of food and the seasonal distribution of runoff. On the western coasts, in a maritime climate near rivers, it is predominantly rain fed with a uniform distribution of runoff throughout the year with some increase in winter due to reduced evaporation (Seine, Thames, etc.); in areas with a transitional climate from maritime to continental near rivers, mixed feeding with a predominance of rain over snow, with a low spring flood (Elbe, Oder, Vistula, etc.); in areas with a continental climate near rivers, snow is predominantly fed and spring floods (Volga, Ob, Yenisei, Lena, etc.); on the eastern coasts with a monsoon climate near the rivers, it is mainly rain fed and summer floods (Amur).

Scheme of classification of rivers by sources of food (according to M.I. Lvovich).

Rivers of the subarctic type They are mainly fed by snow with an almost complete absence of underground due to permafrost. Therefore, many small rivers freeze to the bottom in winter and have no flow. High water on the rivers is mainly summer, as they break up in late May - early June (Yana, Indigirka, Khatanga, etc.).

Polar type rivers in a short period of summer they have glacial nutrition and runoff, but for most of the year they are frozen.

Similar types and subtypes of the water regime are characteristic of lowland rivers, the flow of which is formed in more or less the same type of climatic conditions. The regime of large transit rivers crossing several climatic zones is more complicated.

The rivers of mountain regions are characterized by vertical zonality patterns. With an increase in the height of the mountains near the rivers, the share of snow, and then glacial nutrition, increases. Moreover, in an arid climate near rivers, glacial nutrition is the main one (Amu Darya and others), in a humid climate, along with glacial climate, rain nutrition is also carried out (Ron and others). Mountain, especially high-mountain, rivers are characterized by summer floods.

The most intense and even catastrophic summer floods are on rivers that begin high in the mountains, and in the middle and lower reaches are abundantly fed from monsoon rains: the Indus, the Ganges, the Brahmaputra, the Mekong, the Irrawaddy, the Yangtze, the Yellow River, and others.

Classification of rivers by B. D. Zaikov

Along with the classification of rivers by M. I. Lvovich, typification of rivers according to the hydrological regime of B. D. Zaikov is popular in Russia. In this case, the hydrological regime refers to the distribution and nature of the passage of various phases of the water regime: high water, low water, floods, etc. According to this typification, all rivers in Russia and the CIS are divided into three groups:

1. with spring flood;
2. with summer floods and floods;
3. with flood regime.

Within these groups, according to the nature of the hydrograph, rivers with different types of regime are distinguished.

Among the rivers with spring flood rivers stand out: Kazakhstani type (sharply pronounced short flood and almost dry low water for most of the year); Eastern European type (high short flood, summer and winter low water); West Siberian type (low extended flood, increased runoff in summer, low water in winter); East Siberian type (high flood, summer low water with rain floods, very low winter low water); Altai type (low uneven stretched flood, increased summer runoff, winter low water).

Among the rivers with summer flood rivers are distinguished: the Far Eastern type (low extended flood with floods of monsoon genesis, low winter low water); Tien Shan type (low extended flood of glacial genesis).

FROM flood regime rivers stand out: Black Sea type (floods throughout the year); Crimean type (floods in winter and spring, summer and autumn low water); North Caucasian type (floods in summer, low water in winter).

The forecast of the water content of rivers and their regime during the year is of great importance for resolving questions about the reasonable use of the water resources of countries. The forecast of runoff during floods is very important, which in some years are extremely high (for example, on the rivers of Primorsky Krai in August 2000) and lead to negative consequences.

Mode means order, control. This term is used to denote order in many areas of human activity, as well as in the nature around us. One example of this is the river regime. But if in everyday life a person adheres to a certain routine, then in the regime of a river, he more often takes an observational position - states the fluctuations that occur in the life of the river, and only in some cases can intervene in the regime of the watercourse in order to change it.

Any object of the surrounding world can be described by giving it a characteristic. Including a characteristic is given to surface water bodies - oceans, seas, lakes, rivers, swamps. This characteristic is called hydrological. It necessarily includes the hydrological regime of the river - a set of characteristic features that change the state of the river over time.

The hydrological regime is manifested in daily, seasonal and long-term fluctuations in the water level and water content (together this constitutes the water regime), ice phenomena, water temperatures, the amount of suspensions in the stream, water hydrochemistry, changes in the river bed, flow rates, waves and other phenomena and processes, occurring continuously in the life of the river. All of the above and other elements of the hydrological regime together determine the regime of the river.

Depending on whether or not there is a hydraulic structure on the river that can influence the hydrological regime, rivers have a regulated regime or a natural (domestic) regime. Of all the elements of the river regime, river runoff is of great practical importance. Its value determines the watering of the territory, hydropower territorial reserves, the size of waterways in this territory.

The river regime depends on many factors: climate, land relief, water supply, and others. The main factor is that rivers receive water from the process of the water cycle in nature. The waters supplying food to the rivers are divided into glacial, snow, rain and underground. The same terms are used when defining rivers. In some cases, it is difficult to clearly define the dominance of one river (the type of river feeding), and then the term “mixed type of feeding” is used.

Phases (periods) of the water regime are divided into high water, low water and floods according to characteristic features. The flood occurs annually in a certain season of the year, is marked by a long rise in the level with high marks and the largest water content in comparison with other phases. Low water is also seasonal in nature and is characterized by a low level and the least water content; at this time, the river is fed mainly by groundwater. Floods are characterized by rapid and short-term high levels with a large flow of water; they occur as a result of rains, snowmelt.

Characteristics of the Nile River: the length of the river with the rivers that form it in the Rukakara-Kager-Nile river system is 6852 km - this is the second longest of the Earth's rivers. The Nile flows from south to north towards the Mediterranean Sea. The course of the river is stormy in the upper and middle parts, slow in the lower part; to the mouth of the Nile is divided into numerous branches and near the Mediterranean Sea forms the greatest delta. The Nile is the source of life in the Sahara Desert. Almost all (97%) settled along its coast. The constant flow of the Nile is provided by year-round equatorial rains (the Blue Nile catchment area) and rains in the southern regions (the White Nile catchment area), and rains in the Abyssinian Highlands, washing away loose soils. The river flow carries suspensions, depositing nutrient silt in the delta, on the fields of which the Egyptians harvest up to 3 times a year. To combat floods, in which the area of ​​Cairo rose by 8 m, which threatened disaster for the population, the famous Aswan Dam was built. And now the regime of the Nile River in the lower reaches is regulated. But although the Nile is 3 times longer than the Volga, in its channel it carries a volume of water 2 times less.

The other part evaporates. However, with the unity of the atmospheric origin, in the final analysis, of all river waters, the direct ways in which water enters the rivers may be different. There are four types (or sources) of water supply of rivers: rain, snow, glacial and underground. For rivers in a warm climate, the main type of food is rain. The flow of such major rivers as the Amazon, the Ganges and the Brahmaputra, the Mekong, is formed mainly by rainwater. This type of river nutrition is the most important on a global scale: it accounts for more than a third of the total river water flow. The second most important is snow nutrition. Its role is very large in the feeding of rivers in a temperate climate (at least 1/3 of the water flow). The third place in terms of the volume of water entering the rivers is occupied by groundwater (on average, it accounts for about 30% of the volume of river water runoff). It is underground nutrition that determines the constancy or long duration of the river flow throughout the year, which ultimately creates the river. The last place in terms of importance in the water supply of rivers is occupied by glacial nutrition (about 1% of the flow of the world's rivers).

rain food

Each rain is characterized by a layer of precipitation (mm), duration (minutes, hours, days), intensity of precipitation (mm per minute, mm per hour) and area of ​​distribution (km 2). Depending on these characteristics, rains can be subdivided, for example, into showers and showers.

The intensity, distribution area and duration of rainfall determine many features of the formation of river water runoff and groundwater replenishment. The greater the intensity, distribution area and duration of the rain, the greater the magnitude of the rain flood. The greater the ratio between the area of ​​distribution of rain and the area of ​​the entire river basin, the greater the magnitude of the possible flood. Extreme floods occur for these reasons, usually only on small and medium-sized rivers. Replenishment of groundwater, as a rule, occurs during prolonged rains. The lower the humidity of the air and the drier the soil during the period of rain, the greater the cost of water for evaporation and infiltration, and the lower the amount of rain runoff. On the contrary, rains falling on moist soil at low air temperatures give a large amount of rain runoff. Thus, the same rain, depending on the state of the underlying surface and air humidity, can in some cases be runoff-forming, and in others - almost no runoff.

snow food

In temperate latitudes, the main source of water supply for rivers is water accumulating in the snow cover. Snow, depending on its density and the thickness of the snow cover, can give a different layer of water when melting. Water reserves in snow (a value that is very important for predicting the volume of melt runoff during a flood) is determined using snow surveys. Water reserves in the snow in the river basin depend on the amount of winter precipitation, which in turn is determined by climatic conditions. Water reserves in the snow cover are usually distributed unevenly over the area of ​​the river basin - depending on the height of the terrain, exposure of slopes, uneven terrain, the influence of vegetation, etc. It is necessary to distinguish between the processes of snowmelt and water loss of the snow cover, i.e. the flow of water not retained by snow to the soil surface. Snow melting begins after the air temperature reaches positive values ​​and under the condition of a positive thermal balance on the snow surface. Water loss begins later than the beginning of snowmelt and depends on the physical properties of snow - grain size, capillary properties, etc. Runoff occurs only after the start of water loss.

underground food

It is determined by the nature of the interaction of underground (ground) and river waters. The direction and intensity of this interaction depend on the relative position of the water level in the river, the height of the roof of the water-resistant layer of soil and the level of groundwater, which in turn depends on the phase of the river's water regime and hydrogeological conditions. Underground feeding of rivers is usually greatest during low water, when groundwater enters the river. During high water, the water level in the river is usually higher than the groundwater level and therefore at this time the river feeds the groundwater.

Glacial nutrition

Only rivers flowing from regions with high mountain glaciers and snowfields have such food. The contribution of glacial nutrition to river water runoff is the greater, the greater the proportion of the total area of ​​the river basin is occupied by glaciers. This contribution is greatest in the uppermost parts of mountain rivers.

For each river, the proportion of individual types of water supply may be different. Determining the contribution of various types of nutrition to river water runoff in each specific case is an extremely difficult task. It can be most accurately solved either with the use of "tagged atoms", i.e. by radioactive "marking" of waters of various origins, or by analyzing the isotopic composition of natural waters. A simpler, but approximate way to distinguish between different types of food is a graphical division of a river hydrograph.

Currently, the most common classification of rivers is by type (or source) of food. To determine the degree of predominance of one or another type of nutrition, three gradations were adopted. If one of the types of food provides more than 80% of the annual water flow of the river, we should talk about the exceptional importance of this type of food (the contribution of other types of food is not taken into account). If the share of this type of food accounts for from 50 to 80% of the water runoff, then this type of food is given priority (other types of food are mentioned if each of them accounts for more than 10% of the annual water runoff). If none of the types of food provides more than 50% of the annual flow, then such food is called mixed and sometimes some types of food are indicated in descending order of their contribution to the river flow. The specified ranges of gradations (80 and 50%) refer to all types of nutrition, except for glacial. For glacial feeding, the corresponding gradation ranges are reduced to 50 and 25%.

Most of the rivers in the territory of the former USSR are predominantly fed by snow. The rivers of Northern Kazakhstan and the Trans-Volga region have almost exclusive snow supply. Rain-fed rivers occupy the southern part of the territory east of Baikal, as well as the Yana and Indigirka basins, the Black Sea coast of the Caucasus, the Crimea and the North Caucasus. Rivers in the Caucasus and Central Asia are fed by glaciers.

V.N. Mikhailov, M.V. Mikhailova