Dip and river regime are key hydrological parameters. According to them, one can get an idea of the water content, the nature and speed of the flow of a particular watercourse. What is the fall of the river? How to correctly calculate its slope? What determines the regime of a particular river? We will consider the answers to all these questions in our article.
Hydrology and relief
Every river is unique. It is very difficult to find two streams in nature that will be exactly the same. They differ from each other in length, water content, chemical composition of water, regime, and so on.
The nature and speed of the flow of the river largely depend on the terrain in which it flows. In the mountains you can see some streams, and on the plains - completely different. Mountain streams carry their waters quickly and swiftly. Their channels are stony and full of rapids and waterfalls. Floods often occur on such rivers. Some of them are disastrous.
Plain rivers, on the contrary, are calm and measured. Themthe channels gently curve and often have solid depths. The flow velocity is minimal.
The fall of the river and the slope - these are exactly the indicators by which you can determine the type of channel processes in the watercourse. How to calculate them will be discussed later.
River fall and slope - what is it?
All watercourses on our planet flow from top to bottom, according to the law of universal gravitation. The point at which a stream begins is called its source, and the end point is called its mouth. What is the fall of the river? What is commonly called her bias?
The fall of a river is the difference in meters between the height of its source and the height of its mouth. The slope is the ratio of the fall to the length of the stream. This parameter can be expressed as a percentage, ppm, degrees, or m/km.
The slope of lowland rivers, as a rule, does not exceed 0.1-0.2 m/km (or 10-20 ppm). For mountain streams, this figure can be tens or even hundreds of times higher. In some segments, it can reach several tens of meters per kilometer. Such areas are a series of cascades and waterfalls.
The slope of the watercourse can be longitudinal or transverse when there is a horizontal skew of the channel.
How to calculate the slope and dip of a stream?
So, what is the fall of the river and its slope, we have determined. It remains to be seen how these indicators are calculated.
Calculating the fall and slope of a river is very simple. To do this, you need to know only three values: the total length of the watercourse, the height of its source and mouth. Knowing the height difference(absolute) between the last two points, we get the fall value. If the river flows into the sea or ocean, then the absolute height of its mouth should be considered the mark of 0 meters. The slope of the river is calculated as follows: the value of the fall should be divided by the total length of the watercourse.
Assume that the length of the river "X" is 800 km. Its source is at an altitude of 1450 m, and the mouth - at around 650 m. The fall of a given river is: 1450 m - 650 m=800 meters. From this it follows that the slope will be equal to: 800 m / 800 km=1 m / km (or 100 ppm).
River regime and factors that determine it
Under the regime of the river is understood the whole complex of changes in its state, due to the geography and climate of a particular area. These changes may be daily or seasonal. The regime of the river is manifested in fluctuations in temperature, flow and water level in the channel.
The three main phases of the water regime of watercourses include low water, high water and floods. High water is a period of increase in the water content of the river and the maximum level of water in its channel. A flood is a sharp and rapid increase in the water level in rivers due to heavy rainfall. Low water is the minimum water level in the channel of the watercourse (this phase of the water regime is illustrated below in the photo).
The phases of the water regime of the river (except for floods) are consistently repeated in the same season of the year.
The water regime of the river depends on many environmental factors. First of all it is:
- geographic locationregion;
- climatic conditions;
- character feeding the river;
- relief and vegetation;
- availability of changing seasons;
- anthropogenic factors.
The fall and slope of the largest rivers of the Earth
Below are the slope and dip values of the ten largest river systems on our planet:
| Name | Length, in km | Fall, in meters | Slope, ppm |
| Amazon | 6992 | 110 | 1, 6 |
| Nile | 6853 | 350 | 5, 1 |
| Mississippi | 6420 | 450 | 7, 0 |
| Yangtze | 6300 | 5600 | 88, 0 |
| Huanghe | 5464 | 4500 | 82, 0 |
| Ob | 5410 | 215 | 4, 0 |
| Yenisei | 5238 | 450 | 8, 5 |
| Lena | 5100 | 1650 | 32, 0 |
| Cupid | 5052 | 300 | 5, 9 |
| Congo | 4374 | 1590 | 36, 0 |
In closing
What is the fall of the river? This is the difference in height between the source and mouth of a particular stream. The slope of a river is the ratio of the fall to its total length. Based on these two parameters, we can draw a conclusion about the nature, as well as the speed of the flow of a river.
