The main river of the Far Eastern District is the Amur. According to its hydrological parameters, it ranks 4th among the 10 largest Russian rivers. Ahead of him are only the Ob, Yenisei and Lena, carrying their waters from the south of Siberia to the seas of the Arctic Ocean. Unlike them, the Amur chose another basin - the Pacific, and flows from west to east. The watercourse begins in the mountainous plain of Transbaikalia from the confluence of Shilka and Argun. After passing 2824 km, the river waters of the Amur flow into the Pacific Ocean in the area of the city of Nikolaevsk-on-Amur, which stretches along the coast of the Tatar Strait. The catchment 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 down an inclined surface is reflected in terms such as the fall of a river and the longitudinal slope. To determine these parameters, it is necessary to know the height marks of the water surface (cutoffs) at the determined points and the distance between them, measured along the watercourse. Water level marks are determined during the period of the lowest water standing - in low water.
Fall of the river - exceeding the mark at the point downstream above the point locatedupstream. It is measured in linear units of length - in meters or centimeters.
Slope of the river - the calculated numerical value, determined by dividing the fall of the river by its length between the determined points. It is expressed in ‰ - ppm (a thousandth of a number) or in% (hundredths).
The slope of the river is expressed by the formula I=h1 - h2 /L, where:
I - longitudinal slope of the channel, % or ‰;
h1 - river level mark at the top of the defined segment, m;
h2 - the same, at the bottom point, m;
L - length of the river between defined points, in m or km.
Full fall of the river - the difference in altitude marks at the source and mouth. It doesn't matter if the marks are relative or absolute.
The average slope of a 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 what type it belongs to. Mountain rivers are characterized by large slopes, measured from tens of cm to a few tens of meters. For flat slopes, they are insignificant, measured in centimeters. The slope characterizes the speed of the flow of river waters.
Amur River
The drop from its beginning to the mouth is 304 m. This number is the difference between the height marks at the mouth (0 m - sea level) and at the source of the river.
The beginning of the Amur is the confluence of the Shilka with the Argun. The elevation of the surface at this point with coordinates 53 degrees 21.5 minutes is 304 m. Therefore, the total fall of the Amur River will be: 304 - 0=304 m.
Knowingthe 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 rounded 0.11‰.
This means that depending on which direction to move (along the terrain or on the map), for every kilometer of the length of the river, the level of the water surface in it changes by 11 cm. If the movement is downstream, then the fall of the river The Cupid decreases by 11 cm with each kilometer. But this value is approximate, as if the watercourse flowed along the surface at one angle of inclination.
In reality, there are no such conditions for the rivers of the globe anywhere. Their channels are laid in various geomorphological conditions. They affect the variability of dip and slope parameters even along the same river.
The Amur River is divided into 3 parts (conditionally), depending on the terrain and the nature of the flow. The fall and slopes on the Upper, Middle and Lower Amur are different.
Upper Amur
Its source starts from the confluence of Argun and Shilka. The place is determined by the point of the eastern coast of the island Bezumny with a shore mark of 304 m. The mouth of the Zeya River, the left tributary, which flows 1936 km from the mouth of the Amur, is taken as the end. Consequently, the length of the Lower Amur is 888 km. The height mark has been leveled with a value of 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 a mountain stream - the current speed here is on average 1.5 m/s. The width of the channel in low water is from 420 m to 1 km.
Middle Amur
The site is limited by points: upstream - the mouth of the Zeya River (Blagoveshchensk) with a height mark of 125 m, the lower one - 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 height marks of the shoreline by 8.6 cm per 1 km of the river. The current speed is 5.5 km/h or 1.47 m/s. Channel width from 530 to 1170 m.
Lower Amur
The distance between the points 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 sea level, 0 m. This means that the fall of the Amur River in this area is 41 m. The slope is 0.042‰. The flow velocity in low water is 0.9 m/s, in high water up to 1.2 m/s. The width of the channel is from 2 km (in places) to 11 km, and at the mouth - up to 16 km.
Hydrological regime of the river
The Amur is characterized by high levels of water abundance: the average annual flow is 403 km3, the average annual flow at the mouth is 12800 m3/s.
The main source of food (up to 80% of runoff) is summer and autumn heavy rains. The remaining 20% is accounted for by melt and groundwater, which are approximately equal in percentage terms.
Thaw water feeds the river from April to May, so the flood is extended and the small amount of runoff does not cause high levels to rise. The flood period usually falls on July-August from year to year. This time sometimes accounts for 75% of the annual flow.
Regarding the marks of low levels (low levels), it should be noted that floodsexceed them by 10-15 m in the upper and middle reaches, and in the lower reaches - up to 6-8 m.
Days of monsoon rains in August 2013 caused catastrophic flooding in the Amur basin, flooding settlements and agricultural land.
Summer low water after the descent of the "root" water (melting snow in the mountains) - at the end of June. Autumn - in late September-early October. Freezing occurs in the last days of October - early November. Ice break - after the first decade of April and before May.
