What is the river ratio drop and the reason why the river has a horizontal ratio drop

The height difference between the source of the river and the estuary is called the total drop of the river (for example, the Yangtze River is more than 6,600 meters), and the height difference between the two ends of a specific river section is the drop of the river section, and the drop within the unit length of the river is called the specific drop of the river, expressed in decimal or thousandths. The area of a watershed is one of the important characteristics of a watershed. The amount of water in a river is directly related to the size of the basin.

Except for dry climate areas, the larger the area of the basin, the greater the amount of water in the basin (e.g., the Yangtze River basin covers an area of 1,808,500 km2 and the total annual runoff. The shape of the watershed also has a significant effect on the change of river water volume. In circular or ovoid basins, precipitation is easy to concentrate in the main stream, thus causing huge flood peaks, and in narrow and long basins, flood discharge is relatively uniform, and flood peaks are not easy to concentrate.

The elevation of the watershed mainly affects the formation of precipitation and the temperature in the basin, and the precipitation form and temperature affect the water volume change in the basin.

The specific drop of the river is the slope of the water surface. In the case of constant and uniform flow, the slope of the water surface is exactly equal to the slope of the river bottom. The flood wave is not a constant and uniform flow, and the slope of the water surface changes.

You have to take a section in the upstream and downstream, calculate their kinetic energy, potential energy, and loss along the way between the sections, and calculate the water difference and water level difference between the two sections according to the principle of energy balance, and the water level difference is divided by the section spacing, which is the total water surface slope. The total water surface slope minus the river bottom slope is the additional specific drop.

The specific drop of the river is the slope of the water surface.

In the case of constant and uniform flow, the slope of the water surface is exactly equal to the slope of the river bottom.

The flood wave is not a constant and uniform flow, and the slope of the water surface changes.

You have to take a section in the upstream and downstream, calculate their kinetic energy, potential energy, and loss along the way between the sections, and calculate the head difference and water level difference between the two sections according to the principle of energy balance, and the water level difference is divided by the section spacing, which is the total water surface slope.

The total water surface slope minus the river bottom slope is the additional specific drop.

The reasons for the horizontal ratio drop of rivers are: the influence of inertial centrifugal force, the influence of rapid rise and fall of water level, etcThe rotation of the EarthEffect of eccentric force

The effects of wind.

1. The influence of inertial centrifugal force.

In the curved river channel, when the direction of water flow changes wide orange muffle, the force acting on the water quality point of Shenwan water will produce inertial centrifugal force pointing to the concave bank in addition to gravity, and the combined force of the two forces will promote the water flow to the concave bank to gather, causing the water surface of the concave bank to be higher than the convex bank, forming a transverse water surface ratio drop inclined from the concave bank to the convex bank.

2. The impact of the rapid rise and fall of the water level.

Because the friction resistance in the middle of the riverbed is smaller than that on both banks, when the flow increases sharply and the water level rises sharply, the water surface in the middle of the straight river section is raised, and when the water level falls sharply, the first part of the riverbed has a large flow velocity, small resistance, and the surface of the river center is concave, all forming a horizontal ratio drop.

3. The influence of the eccentricity of the Earth's rotation.

Due to the rotation of the Earth, water points on the Earth's surface are subjected to rotational deflection forces (also known as Coriolis forces).

effect, and produce a drop in aspect ratio.

in the Northern Hemisphere. In the river, the rotational deflection force of the water quality point is always from left to right, resulting in the water surface of the right bank being higher than the water surface of the left bank, and the horizontal ratio drop is directed from the right bank to the left bank, and the water flow washes the right bank for a long time, so most of the right bank is high and steep, the nodes are more defeated, and the left bank is deposited with sand. The Southern Hemisphere is the opposite.

4. The influence of wind.

When the wind direction and flow direction are at a certain angle of intersection, the aspect ratio drop will also occur, and the degree of influence depends on the intersection angle and the magnitude of the wind.

The specific drop of the riverbed refers to the ratio of the drop of the riverbed to its length in any river section, that is, i=(h2-h1) l=(dh l)*100%, where:

i--- River Imperial God tells the bed than to descend and blind and ambush is expressed in thousands; h1, h2 --- the elevation of the riverbed at the beginning and end of the river section (m); DH--- riverbed drop (m); l--- length of river section (m) river

bedgradient riverbed ratio refers to the ratio of the riverbed drop to its length in any river section, i.e., i=(h2-h1) l=(dh l)*100% where:

i--- The ratio of the riverbed is expressed in thousands; h1, h2 --- the elevation of the riverbed at the beginning and end of the river section (m); DH--- riverbed drop (m); l--- length of river section (m).

Categories: Education, Science, >> Science & Technology.

Problem description: What is the riverbed ratio?

Analysis: The specific drop of the riverbed refers to the ratio of the drop of the riverbed to its length in any section of the river, i.e.

i=(h2-h1) l=(dh l)*100%: i--- riverbed ratio is expressed in thousands;

H1, H2 --- the height of the riverbed at the beginning and end of the river section (m); Tsaiga.

DH--- riverbed drop (m);

l--- length of river section (m).

Answer]: The elevation difference (δh) of any section of the river (water surface or river bottom) is called the drop. The drop per unit of river length is called the longitudinal drop of the river channel, which is generally called the river slope drop, and is expressed as a percentage (%) or a thousand ( ).

The river has a water surface ratio than the water surface and the river bottom. The longitudinal profile slope of the river (river valley, channel, etc.) is a morphological index of the kihuminben that reflects the steps at all levels, and it indirectly reflects the potential energy.

Generally speaking, the average specific drop of a river is the ratio of the total drop of a river (the difference in height from the source to the estuary) to the total length of the river, that is, the drop within the unit length of the river

For example, if a river is 3,000 kilometers long and has a total drop of 3,000 meters, the average specific drop of the river is 1, that is, 1 meter for every kilometer of height.

In fact, the average specific drop of the river is the average slope of the water surface, and in the case of constant uniform flow, the slope of the water surface is exactly equal to the slope of the river bottom.

Simply put, it refers to the longitudinal slope of the river, the longitudinal section of the river, which can form a body shape from the source and the estuary, and then according to the principle of area thinking, the ratio of the non-right-angled hypotenuse and the right-angled hypotenuse of the trapezoidal shape is calculated, which is the average longitudinal slope, that is, the average specific drop.

Mathematically, Manning's formula is: c=(1 n)r1 6, and v= c, i.e., c=(1 n)r2 3s1 2, there is n=(1 v) r2 3s1 2.

According to Manning's resistance formula, the relationship between water depth and flow velocity is the same when the specific drop is the same, indicating that the roughness n value is equal. In natural river channels, the sudden rise and fall of flood peaks is the main reason for the dispersion of the relationship between water depth and flow velocity.

The positive (negative) additional ratio drop during the rising (falling) period causes the flow velocity of the same water depth (or flow) to be too large (too small). In the main stream and tributaries of the Yellow River, the additional specific drop often exceeds the longitudinal drop of the riverbed.

The difference between the elevation of the river bottom at both ends of the river section (h) is called the drop, the difference between the elevation of the river bottom from the source to the mouth of the river is called the total drop, and the specific drop of the river channel (the specific drop of the river bed) refers to the difference in the elevation of the river bed along the direction of the water flow.

Mathematically, Manning's formula is: c=(1 n)r1 6, and v= c, i.e., c=(1 n)r2 3s1 2, there is n=(1 v) r2 3s1 2.

In water level measurement, v, r, and s can all be measured, so n can also be calculated. r is the hydraulic radius of the riverbed, which also reflects the characteristics of the riverbed cross-section. v is the flow rate, which also contains the concept of flow q; s is the riverbed slope; n represents the resistance coefficient between the water flow and the contact surface of the riverbed during the flow of water, that is, the roughness coefficient in hydraulics.

Summary. Hello, when the elevation of the river bottom changes along the way, you can make an oblique line from the lower section of the riverbed on the profile diagram, so that the area below the slope line is equal to the area below the original river bottom line, the slope of the oblique line is the average ratio of the river channel, and the calculation formula is:

j (he +h,)4+(h+h)++h-:+h,) where hh-from downstream to upstream along the river bottom elevation, m;

The distance between two adjacent points, m;

l -- the full length of the river section, m

Hello, I am inquiring for you here, please wait a while, I will reply to you immediately Hello Qinhan Town, when the elevation of the river bottom changes along the way, you can make an oblique line from the lower section of the riverbed on the longitudinal section of the spring rough map, so that the area below the oblique line is equal to the area below the original river bottom line, the slope of the slope is the average ratio of the river channel, the calculation formula is: j (he +h,)4+(h+h)++h-:+h,) where hh-from the downstream to the upstream along the point of the river bottom elevation, m; The distance between two adjacent points, m; l -- the full length of the river section, m