The fall and the gradient of the river - what is it? Define the slopes of the rivers: the Volga, Amur, Pechory

The river is a water stream of natural origin, which flows along the channel, which it also produced. It is possible to measure the length of this watercourse, the number of its tributaries, the area of the general catchment, etc. One of the main hydrological indicators is the slope of the river. How correctly to calculate it?

What is the fall of the river?

Any natural watercourse on our planet flows from the top down. The reason for this is the Universal Gravity Law, known to all of us, which was discovered by Isaac Newton in the middle of the 17th century. All rivers, as a rule, start from underground springs or flow from large lakes. Then they carry their waters down (smoothly or swiftly) to the seas and oceans.

The fall of the river shows us how much one or another watercourse loses during the "journey" along the earth's surface. In other words, this is the difference in height between the source point and the point of the river mouth. The fall can be complete or partial (when you need to calculate this indicator for a certain length of the channel).

Calculate the fall of the river is elementary. For this you need to know the height of its source and mouth. For example, we are given a river A with a total length of 2000 km, which begins its journey at 250 m, and flows into the lake at a height of 50 m. The difference between these two marks will be 200 meters. This will be the fall of the river A.

Knowing the fall, you can calculate the slope of the river. How to do it correctly - read in the next section.

How to calculate the gradient of the watercourse?

The slope of the river is the ratio of the value of the fall of the watercourse to its total extent. This indicator can be expressed in percent, ppm (most often), degrees or in m / km.

The slopes of the plains and mountain rivers vary considerably. In the first case, this indicator rarely exceeds 0.1 m / km. The slopes of mountain rivers can be tens or even hundreds of times larger.

Calculate this figure is also easy. Let's return to our river A, the fall of which is 200 meters. To calculate the slope, it is necessary to divide this value by the value of the river length: 200 m / 2000 km = 0.1 m / km. Proceeding from this, we can say that our river A is flat and has an insignificant speed of its current.

The fall and slope of the river can be depicted graphically. To do this, use the so-called longitudinal profiles. The x-axis of such a graph is the length of the river, and the y-axis is the height of the terrain. This profile looks like this:

The fall and the gradient of the Volga

To solve such problems are taught in school, in lessons on geography in the 8th grade. Take as an example the largest watercourse in Europe - the Volga. Let's try to calculate the fall and slope of the river.

The Volga flows in the European part of Russia, within 15 subjects of the federation. She repeatedly changes her direction. This is the most important water artery of the country, the largest river in the world from among those streams that do not flow into the sea or the ocean.

The Volga originates in the Valdai Upland, at an altitude of 228 meters above sea level. Within the Astrakhan region, it flows into the Caspian Sea. At the same time, the mouth is located at a height of -28 meters. Thus, the total fall of the Volga is 256 meters. Now calculate the slope of the river.

The Volga has a total length of 3530 km. At the same time, it collects its water from a huge area of 1.36 million square meters. Km. This is four times more than the area of Germany! To calculate the slope of the Volga, the following mathematical action should be performed: 256 meters / 3530 km = 0.07 m / km.

The fall and slope of the Amur River

One of the main rivers of the Far East, flowing between the two states (Russia and China) is the Amur. Its source is considered to be the site of the merger of Shilka and Argun. The height of this point above the sea level is 304 meters. Further, the Amur flows mainly to the east and flows into the Sea of Okhotsk. The height of its mouth is 0 meters. Thus, the overall fall of the Cupid is 304 meters. Calculate the slope of the river.

Cupid has a total length of 2824 km. The area of the river basin is 1.85 million square meters. Km. To calculate the slope of the Amur, you must perform a simple mathematical action: 304 meters / 2824 km = 0.11 m / km.

This indicator tells us that the Amur River "loses" 11 centimeters in height on a section of the riverbed that is one kilometer long. It is important to note that the general bias of one or another watercourse is not very informative. After all, the geomorphological conditions (relief conditions) in which the river bed is located can vary considerably. Therefore, it is better to calculate this indicator for individual short sections of the river bed.

Fall and slope of the Pechora River

Pechora is a fairly large Russian river flowing within the Komi Republic and the Nenets Autonomous District. It originates in the mountains of the Northern Urals, at an altitude of 630 meters above sea level. Pechora flows into the same name of the Barents Sea lip, forming a vast delta. The height of the mouth is 0 meters. Calculate the fall and slope of the river.

Pechora has a total length of 1809 km. The fall of the river is 630 meters. The area of the river basin of Pechora in comparison with the Volga and the Amur is not large - only 330 thousand square meters. Km. To calculate the slope of the Pechora River, the following mathematical action should be performed: 630 meters / 1809 km = 0.35 m / km.

As we see, among the three rivers considered in this article, the biggest deviation is typical for Pechora. In general, the definition of this indicator helps hydrologists in studying the valley of a particular river, its water regime and channel processes.