The fall of the Amur River from the source to the mouth

The main river of the Far Eastern District is Amur. In terms of its hydrological parameters, it stands on the 4th place among the 10 largest Russian rivers. In front of him only the Ob, Yenisei and Lena, carrying their waters from the south of Siberia to the seas of the Arctic Ocean. Unlike them, Cupid chose another pool - the Pacific, and flows from west to east. A watercourse begins in the mountain plain of Transbaikalia from the confluence of Shilka and Argun. Passing 2,824 km, the river waters of the Amur River flow into the Pacific Ocean near the city of Nikolaevsk-on-Amur, stretching along the coast of the Tatar Strait. The drainage area of the river basin is 1855 sq.km. The fall and slope of the Amur River depends on the terrain: in the upper reaches it is mountainous, in the lower reaches it is flat.

Hydrological terms

The property of water to flow along an inclined surface is reflected in terms such as a river drop and a longitudinal slope. To determine these parameters, it is necessary to know the elevation marks of the water surface (urez) at the determined points and the distance between them, measured along the watercourse. The water level marks are determined in the period of the lowest standing of the waters - in the low water.

The fall of the river is the elevation of the mark at the point of the downstream over a point that is upstream. Measured in linear units of length - in meters or centimeters.

The slope of the river is an estimated numerical value, determined by the fact that the river falls along its length between the points being determined. It is expressed in ‰ - per mil (thousandth part of the number) or in% (hundredths of a number).

The slope of the river is expressed by the formula I = h1 - h2 / L, where:

I - longitudinal slope of the channel,% or ‰;

H1 - mark the level of the river at the upper point of the specified segment, m;

H2 - the same, at the bottom point, m;

L - length of the river between the determined points, in m or in km.

The total fall of the river is the difference in altitude marks in the source and in the mouth. It does not matter what the marks will be - relative or absolute.

The averaged deviation of the river is the result of dividing the total fall by its total length.

By the value of the slope of the river, you can determine which type it refers to. For mountain rivers are characterized by large slopes, measured from tens of centimeters to the first tens of m. For plains slopes are insignificant, measured in centimeters. The slope characterizes the rate of flow of river water.

Amur river

The fall from its beginning to the mouth is 304 m. This number is the difference between the elevations in the estuary (0 m is the sea level) and at the source of the river.

The beginning of the Amur is the merger of Shilka with Argun. The mark of the surface at this point with coordinates of 53 degrees is 21.5 minutes equal to 304 m. Consequently, the total fall of the Amur River will be: 304 - 0 = 304 m.

Knowing the length of the river and the fall, we find the average longitudinal slope of the watercourse, it is equal to:

I = 304/2824 = 0.107 ‰ or with a rounding off of 0.11 .

This means that depending on the direction in which to travel (by terrain or on a map), for each kilometer of the length of the river the water surface in it changes by 11 cm. If the movement downstream, the fall of the Amur River with each kilometer decreases At 11 cm. But this value is approximate, as if the watercourse flowed over the surface at the same angle of inclination.

In fact, there are no such conditions for the rivers of the globe anywhere. They are laid in various geomorphological conditions. They affect the variability of the parameters of the fall and bias even during a single river.

On 3 parts (conditionally), depending on the terrain and the nature of the current, the Amur River is divided. The fall and biases in the Upper, Middle and Lower Amur are different.

Upper Amur

Its source begins from the merger of Argun and Shilka. The place is determined by the point of the eastern shore of the island of Mad, with a mark of 304 m. The end of the river is the mouth of the Zeya River, a left tributary flowing 1936 km from the mouth of the Amur River. Consequently, the length of the Lower Amur is 888 km. The altitude is 125 m. The fall and slope of the Amur River in this area will be 179 m and 0.2 ‰, respectively. The nature of the current is close to the mountain current - the current velocity is an average of 1.5 m / s. The width of the riverbed is between 420 m and 1 km.

Medium Amur

The plot is bounded by points: the upper part is the mouth of the Zeya river (Blagoveshchensk town) with a height of 125 m, the lower one is the mouth of the Ussuri river (near the village of Kazakevichevo) - the height of the edge is 41 m. The length of the section is 970 km. The fall of the Amur River here is 84 m, and the slope (84/970) is 0.086 ‰. This means a decrease in the altitude marks of the 8.6 cm margin per 1 km of the river. The current velocity is 5.5 km / h or 1, 47 m / s. The width of the channel is from 530 to 1170 m.

Lower Amur

The distance between the points of the definition along the river is 966 km (from the mouth of the Amur to the confluence of the Ussuri tributary). Elevation marks: the upper point is 41 m, the lower point is the sea level, 0 m. Hence, the fall of the Amur River in this area is 41 m. The slope is 0.042 . The speed of the current in the low water is 0.9 m / s, in the high water up to 1.2 m / s. The width of the channel is from 2 km (in some places) to 11 km, and in the mouth - up to 16 km.

Hydrological regime of the river

Amur is characterized by high rates of water availability: an average annual flow of 403 cubic km, an average annual discharge at the mouth of 12800 cubic meters per second.

The main source of food (up to 80% of the runoff) is summer and autumn rain showers. The remaining 20% falls on the share of thawed and groundwater, approximately equal in percentage terms.

Meltwater feeds the river from April to May, so the high water is stretched and a small amount of runoff does not cause rise of high levels. The flood period is usually from year to year in July-August. At this time, sometimes account for 75% of the annual flow.

Concerning the marks of low levels (megacities), it should be noted that the floods exceed them by 10-15 m in the upper and middle reaches, and in the lower reaches - up to 6-8 m. Severe showers cause spills of the Middle and Lower Cupids to 25 km and high levels are retained On a flooded area of up to 70 days.

The multi-day monsoon rains of August 2013 caused a catastrophic flood in the Amur basin, flooded settlements and agricultural lands.

Summer low water after the descent of "indigenous" water (melting snow in the mountains) - in late June. Autumn - in late September or early October. Ledostav occurs in the last days of October - early November. Opening of ice - after the first decade of April and until May.