CN109583703B - Method for quantitatively defining starting critical index of non-viscous bottom sand - Google Patents

Abstract

The invention relates to a method for quantitatively defining the starting critical index of non-viscous bottom sand. Under certain bed surface bottom sand and changing water flow conditions, a high-speed camera is used to continuously shoot images of the bed surface sediment, and the color images continuously shot by the high-speed camera are used for Preprocessing, obtains the motion state of sediment particles in each sub-domain in the camera area, identifies the sub-domains that move in the camera area, clarifies the distribution characteristics of the sediment movement in the camera area, and counts the area of all the sub-domains where the sediment movement occurs. The sum is calculated as the percentage of the sub-domain where the sediment starts to occupy the imaging area, so that the water flow intensity when the ratio of the sub-domain where the sediment starts to occupy the imaging area is 0 is taken as the critical hydraulic index for defining the starting of the bottom sand; Accurately and quantitatively define the critical initiating index of bed surface sediment, which solves the problem that the critical initiating indicator of bottom sand is difficult to quantitatively define, and the critical indicator determined by this method can be easily extended and applied to bed sand initiating observation under different water and sediment conditions.

Description

A method to quantitatively define the critical index of non-viscous bottom sand start-up

technical field

The invention relates to a method for quantitatively defining the starting critical index of non-viscous bottom sand, and belongs to the technical field of hydraulic engineering.

Background technique

The critical hydraulic index condition for bottom sand start-up is an important part of the study of estuarine and coastal water and sediment movement, and it is a hot spot of scientific research at this stage. There are various methods for defining the critical hydraulic index of conventional sediment starting. There are methods for reverse estimation using the sediment transport rate, and direct monitoring methods using high-speed camera technology. On the one hand, the measurement of mass and sediment transport is difficult, and on the other hand, the accuracy is poor, and high measurement accuracy can be obtained. However, in field monitoring, on the one hand, due to the complex water and sediment environment on site, the test is difficult, so the test results are greatly affected. interference, thereby reducing the monitoring accuracy.

At this stage, it is a more common method to use the hydraulic index when the sediment transport rate of the bottom sediment is 0 as the critical hydraulic index of the bottom sediment, and it is relatively easy to realize. Mainly by observing the bed sediment transport rate under different hydraulic index conditions, then taking the sediment transport rate as the ordinate and the hydraulic index as the abscissa to draw a scatter diagram to reflect the change of bed load and sediment transport rate with the change of hydraulic index. process. In this way, the hydraulic index corresponding to the bed sediment transport rate of 0 is found as the critical starting index.

Using high-speed camera technology for sediment observation, Miao Wei, Chen Qigang, Li Danxun and others have used high-speed camera technology to study the starting probability of bedding sediment. It is based on the sediment starting experiment carried out in the closed channel. During high-speed image processing, the motion ratio can be extracted without bias through the grayscale difference between two consecutive frames. The moving sediment extracted from two consecutive high-speed images may be in the starting, stopping or gliding state. The time interval divided by the intermediate time scale of bedrock motion.

Obviously, the above two methods, the inverse method of bedrock transport rate, can be used to determine the critical hydraulic index of sediment initiating, but it is limited by the observation accuracy of bedrock transport rate, especially the real-time monitoring and calculation of low bedrock transport rate. The difficulty of stage research greatly limits the accuracy of quantitatively defining the critical hydraulic index; while the high-speed camera method focuses on the movement form of particles and the movement process of bedding bedding, and does not deeply involve the critical hydraulic force of sediment initiation. Research on quantitative definition of indicators.

SUMMARY OF THE INVENTION

The invention provides a method for quantitatively defining the critical index of non-viscous bottom sand start-up, which is suitable for most water flow conditions, including the background of field investigation or indoor test, and solves the problem that it is difficult to quantitatively define the start-up of non-viscous sand in complex water flow environment conveniently and quickly. The problem of critical hydraulic index.

The technical scheme adopted by the present invention to solve its technical problems is:

A method for quantitatively defining a critical index for starting non-viscous bottom sand, comprising the following steps:

Step 1: Insert the bracket vertically into the bed surface, install the LED lighting, camera and ADCP on the horizontal bracket of the bracket in sequence, adjust the bracket adjuster, so that the camera, LED lighting and ADCP are in the position that is convenient for videography and hydraulic parameters. detection;

Step 2: The camera performs continuous shooting, obtains at least one color image, preprocesses the captured color image, and divides the camera area into regular sub-domains. The number of sub-domain divisions is a single bed surface sediment horizontal The cross-sectional area is at least twice, and each sub-domain contains at least one sediment particle, and the average gray value of each pixel in the sub-domain is calculated at the same time;

Step 3: Take the color image captured by the camera in the initial state as the original image, and compare at least one color image obtained by the camera with the original image. When the sand moves obviously, compare them in sequence, and finally obtain the motion state of the sediment in each sub-field within the camera's imaging area;

Step 4: Fill the sub-domain with sediment particle movement with red, and fill the sub-domain without sediment particle movement with green to identify the corresponding water flow state, so as to obtain the sub-domain of sediment movement in the camera area. distribution range;

Step 5: Take the dimensionless hydraulic index as the abscissa, and the percentage of the sub-domain area where sediment movement takes place in the area of the camera area as the ordinate, fit the trend line, and extend the trend line to obtain the intersection of the trend line and the abscissa point, the dimensionless hydraulic index corresponding to this point is the critical hydraulic index of bottom sand starting;

As a further preference of the present invention, in step 2,

According to the sediment particle size distribution information obtained from the bed surface and bottom sand sampling results in the corresponding survey area, the median particle size of the bed bottom sand is calculated, and the median particle size is defined as D ₅₀ based on the median particle size. The color image is divided into equal For subdomains with side length and equal area, the division standard of the subdomain is L=ε×D ₅₀ , where L is the side length of the subdomain, and ε is the weight coefficient of the side length of the subdomain, which can be determined according to the corresponding test results, and D ₅₀ is The median particle size of bed bottom sand;

Calculate the gray value of each pixel in the subdomain, that is, convert at least one color image continuously shot by the camera into a gray image in batches, and the conversion formula is F _i =α×R _i +β×G _i +γ×B _i , where , i is the number of the pixel point in the color image, F _i is the gray value of the pixel point i after conversion, R _i , G _i , B _i are the red value, green value and blue value of the i pixel point respectively, α, β and γ are the corresponding weight coefficients, which can be determined according to the corresponding test results;

其中，F_i为编号为j的子域内转换之后的各个像素点i的灰度值，

为编号为j的子域灰度值的算数平均，j为子域编号，n为编号为i的子域内像素点总数；The formula for calculating the average gray value of pixels in each subfield is as follows:

Among them, F _i is the gray value of each pixel point i after conversion in the sub-domain numbered j,

is the arithmetic mean of the gray value of the subfield numbered j, j is the number of the subfield, n is the total number of pixels in the subfield numbered i;

As a further preference of the present invention, in step 3,

其中，

为编号为k的图像中的编号为j的子域平均灰度值之差；

为连续拍摄的编号为k的图像中的j子域平均灰度值；

为原始图像中j子域平均灰度值；The color image captured by the camera in the initial state is used as the original image, and at least one color image obtained by the continuous shooting of the camera is compared with the original image respectively to obtain the gray value difference of the subdomain of the continuous shooting color image. The calculation formula is:

in,

is the difference between the average gray values of the sub-domain j in the image numbered k;

is the average gray value of the j subfield in the image numbered k continuously shot;

is the average gray value of the j subfield in the original image;

其中f为子域泥沙运动状态，当f＝1时表示子域内泥沙处于起动状态，当时f＝0时表示子域内泥沙处于未起动状态，K为设定的临界阈值，其范围为15-20，根据试验确定，

为子域平均灰度值之差；The critical threshold is set, and the formula for judging the sediment state in the subdomain is:

Among them, f is the sediment movement state of the sub-domain. When f=1, it means that the sediment in the sub-domain is in the starting state. When f=0, it means that the sediment in the sub-domain is in the non-starting state. K is the set critical threshold, and its range is 15-20, according to the test,

is the difference between the average gray values of the sub-domains;

As a further preference of the present invention, in step 4, the average gray value of the pixels in each sub-domain in the continuously captured color image is replaced with 0 or 1, which is the characteristic value of the sediment movement state, where 0 means that the sediment is in an inactive state, 1 means that the sediment is in the starting state, and at the same time, the sub-domain where the sediment particle movement occurs is filled with red, and the sub-domain where the sediment particle movement occurs is filled with green, and the distribution characteristic map of the sediment starting and non-starting areas is obtained;

其中，P为泥沙处于运动状态的子域面积占比，A_i|f＝1为泥沙处于活动状态的子域面积，A_j|f＝0,1为子域面积，m为每帧图像内泥沙处于活动状态的子域个数，n为每帧图像内子域个数；将前述计算得到的P作为纵坐标；As a further preference of the present invention, in step 5, the setting of the ordinate: carry out statistics on the sediment movement states of all sub-domains in each frame of image, and obtain the sum of the areas of the sub-domains in which the sediment is in a movement state in each frame of image , calculate the proportion of the corresponding sub-domain in each frame of image to the area of each frame of image, the calculation formula is

Among them, P is the proportion of the sub-domain area in which the sediment is in motion, A _i|f=1 is the sub-domain area in which the sediment is in an active state, A _j|f=0,1 is the sub-domain area, and m is each frame The number of sub-fields in which the sediment is active in the image, n is the number of sub-fields in each frame of image; the P calculated above is taken as the ordinate;

The setting of the abscissa: preprocess the flow measurement data of ADCP, analyze the vertical profile of the flow velocity from the water surface and the bed surface at the measurement point, use the logarithmic flow velocity distribution formula, and use the least squares method to fit the vertical flow velocity profile distribution. The combined flow velocity profile, the bottom friction flow velocity U _* is automatically calculated by the program;

The hydraulic index is expressed as a dimensionless hydraulic strength index, and its calculation formula is Φ=ρU _* D, where ρ is the water flow density, D is the bed surface sediment particle size, and U _* is the bottom friction flow velocity; Φ as abscissa;

Draw a scatter diagram, and perform trend fitting on the scatter diagram. The fitting curve is preferably a quadratic polynomial, and the trend line is extended to obtain the intersection point of the trend line and the abscissa. The hydraulic index corresponding to this point is determined as the bottom sand. Start critical hydraulic index;

As a further preference of the present invention, in step 1, the bracket is made of steel material, including a vertical bracket and a horizontal bracket. The vertical bracket is used to insert the bed surface and maintain the stability of the bracket, and the horizontal bracket is used to bind the camera. , LED lighting and ADCP, the adjuster on the vertical bracket can easily adjust the height of the horizontal bracket, which is convenient for the bound device to move up and down.

Through the above technical solutions, with respect to the prior art, the present invention has the following beneficial effects:

The invention is based on the method of accurately and quantitatively defining the critical hydraulic index of non-viscous bottom sand start-up based on the color images continuously shot by the high-speed camera, and the calculation process can be realized by programming. Automatic batch processing can eliminate the interference of human factors as much as possible.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

FIG. 1 is a schematic diagram of the overall structure of a preferred embodiment of the present invention.

In the picture: 1 is the bracket, 2 is the bracket adjuster, 3 is the ADCP, 4 is the camera, 5 is the LED lighting, and 6 is the wire.

Detailed ways

The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are all simplified schematic diagrams, and only illustrate the basic structure of the present invention in a schematic manner, so they only show the structures related to the present invention.

As shown in FIG. 1 , the present invention includes the following characteristic components: 1 is a bracket, 2 is a bracket adjuster, 3 is an ADCP, 4 is a camera, 5 is an LED lighting lamp, and 6 is a wire.

A method for quantitatively defining the critical index for starting non-viscous bottom sand of the present invention comprises the following steps:

Step 1: Insert the bracket vertically into the bed surface, install the LED lighting, camera and ADCP on the horizontal bracket of the bracket in sequence, adjust the bracket adjuster, so that the camera, LED lighting and ADCP are in the position that is convenient for videography and hydraulic parameters. detection;

Step 2: The camera performs continuous shooting, obtains at least one color image, preprocesses the captured color image, and divides the camera area into regular sub-domains. The number of sub-domain divisions is a single bed surface sediment horizontal The cross-sectional area is at least twice, and each sub-domain contains at least one sediment particle, and the average gray value of each pixel in the sub-domain is calculated at the same time;

Step 3: Take the color image captured by the camera in the initial state as the original image, and compare at least one color image obtained by the camera with the original image. When the sand moves obviously, compare them in sequence, and finally obtain the motion state of the sediment in each sub-field within the camera's imaging area;

Step 4: Fill the sub-domain with sediment particle movement with red, and fill the sub-domain without sediment particle movement with green to identify the corresponding water flow state, so as to obtain the sub-domain of sediment movement in the camera area. distribution range;

Step 5: Take the dimensionless hydraulic index as the abscissa, and the percentage of the sub-domain area where sediment movement takes place in the area of the camera area as the ordinate, fit the trend line, and extend the trend line to obtain the intersection of the trend line and the abscissa point, the dimensionless hydraulic index corresponding to this point is the critical hydraulic index of bottom sand starting;

As a further preference of the present invention, in step 2,

According to the sediment particle size distribution information obtained from the bed surface and bottom sand sampling results in the corresponding survey area, the median particle size of the bed bottom sand is calculated, and the median particle size is defined as D ₅₀ based on the median particle size. The color image is divided into equal For subdomains with side length and equal area, the division standard of the subdomain is L=ε×D ₅₀ , where L is the side length of the subdomain, and ε is the weight coefficient of the side length of the subdomain, which can be determined according to the corresponding test results, and D ₅₀ is The median particle size of bed bottom sand;

Calculate the gray value of each pixel in the subdomain, that is, convert at least one color image continuously shot by the camera into a gray image in batches, and the conversion formula is F _i =α×R _i +β×G _i +γ×B _i , where , i is the number of the pixel point in the color image, F _i is the gray value of the pixel point i after conversion, R _i , G _i , B _i are the red value, green value and blue value of the i pixel point respectively, α, β and γ are the corresponding weight coefficients, which can be determined according to the corresponding test results;

其中，F_i为编号为j的子域内转换之后的各个像素点i的灰度值，

为编号为j的子域灰度值的算数平均，j为子域编号，n为编号为i的子域内像素点总数；The formula for calculating the average gray value of pixels in each subfield is as follows:

Among them, F _i is the gray value of each pixel point i after conversion in the sub-domain numbered j,

is the arithmetic mean of the gray value of the subfield numbered j, j is the number of the subfield, n is the total number of pixels in the subfield numbered i;

As a further preference of the present invention, in step 3,

其中，

为编号为k的图像中的编号为j的子域平均灰度值之差；

为连续拍摄的编号为k的图像中的j子域平均灰度值；

为原始图像中j子域平均灰度值；The color image captured by the camera in the initial state is used as the original image, and at least one color image obtained by the continuous shooting of the camera is compared with the original image respectively to obtain the gray value difference of the subdomain of the continuous shooting color image. The calculation formula is:

in,

is the difference between the average gray values of the sub-domain j in the image numbered k;

is the average gray value of the j subfield in the image numbered k continuously shot;

is the average gray value of the j subfield in the original image;

其中f为子域泥沙运动状态，当f＝1时表示子域内泥沙处于起动状态，当时f＝0时表示子域内泥沙处于未起动状态，K为设定的临界阈值，其范围为15-20，,根据试验确定，

为子域平均灰度值之差；The critical threshold is set, and the formula for judging the sediment state in the subdomain is:

Among them, f is the sediment movement state of the sub-domain. When f=1, it means that the sediment in the sub-domain is in the starting state. When f=0, it means that the sediment in the sub-domain is in the non-starting state. K is the set critical threshold, and its range is 15-20,, according to the test,

is the difference between the average gray values of the sub-domains;

As a further preference of the present invention, in step 4, the average gray value of the pixels in each sub-domain in the continuously captured color image is replaced with 0 or 1, which is the characteristic value of the sediment movement state, where 0 means that the sediment is in an inactive state, 1 means that the sediment is in the starting state, and at the same time, the sub-domain where the sediment particle movement occurs is filled with red, and the sub-domain where the sediment particle movement occurs is filled with green, and the distribution characteristic map of the sediment starting and non-starting areas is obtained;

As a further preference of the present invention, in step 5, the setting of the ordinate: carry out statistics on the sediment movement states of all sub-domains in each frame of image, and obtain the sum of the areas of the sub-domains in which the sediment is in a movement state in each frame of image , calculate the proportion of the corresponding sub-domain in each frame of image to the area of each frame of image, the calculation formula is

, where P is the proportion of the sub-domain area in which the sediment is in motion, A _i|f=1 is the sub-domain area in which the sediment is in an active state, A _j|f=0,1 is the sub-domain area, and m is the area of each sub-domain. The number of subfields in which the sediment is active in the frame image, and n is the number of subfields in each frame image; the P calculated above is used as the ordinate;

The setting of the abscissa: preprocess the flow measurement data of ADCP, analyze the vertical profile of the flow velocity from the water surface and the bed surface at the measurement point, use the logarithmic flow velocity distribution formula, and use the least squares method to fit the vertical flow velocity profile distribution. The combined flow velocity profile, the bottom friction flow velocity U _* is automatically calculated by the program;

The hydraulic index is expressed as a dimensionless hydraulic strength index, and its calculation formula is Φ=ρU _* D, where ρ is the water flow density, D is the bed surface sediment particle size, and U _* is the bottom friction flow velocity; Φ as abscissa;

Draw a scatter diagram, and perform trend fitting on the scatter diagram. The fitting curve is preferably a quadratic polynomial, and the trend line is extended to obtain the intersection point of the trend line and the abscissa. The hydraulic index corresponding to this point is determined as the bottom sand. Start critical hydraulic index;

As a further preference of the present invention, in step 1, the bracket is made of steel material, including a vertical bracket and a horizontal bracket. The vertical bracket is used to insert the bed surface and maintain the stability of the bracket, and the horizontal bracket is used to bind the camera. , LED lighting and ADCP, the adjuster on the vertical bracket can easily adjust the height of the horizontal bracket, which is convenient for the bound device to move up and down.

Specifically, as shown in Figure 1, in step 1, insert the vertical support of the support into the bed surface vertically, adjust the support adjuster, so that the camera, LED lighting and ADCP on the horizontal support of the support are in proper positions, which is convenient for videography and hydraulic power Parameter detection; connect the two ends of the wire to the camera, ADCP and computer respectively, the camera's auto focus makes the image obtained the clearest, adjust the LED lighting to illuminate the camera area at the best angle, and adjust the ADCP position to effectively monitor the camera area. vertical velocity profile;

After the support and the corresponding equipment are in place, the real-time continuous high-speed image capture and the collection of the water flow profile data at the corresponding shooting time are started.

In step 2, while the camera automatically shoots continuously at high speed, the ADCP synchronously monitors the water flow profile information, and the two transmit the image and flow profile data to the computer through electrical signals; The image is preprocessed, and the camera area is automatically divided into regular sub-domains according to the median particle size of the sediment obtained from the bed surface sediment sampling results. The gray value of the pixel point and the average value of the gray value of each sub-domain, and according to the logarithmic flow velocity distribution formula, the ADCP profile flow velocity sampling data is used to fit the corresponding flow velocity profile, and the bottom friction flow velocity is reversed. Dimensional hydraulic strength index.

In step 3, the computer uses the program to automatically compare the color images continuously shot by the camera with the original images in batches according to the average gray value of each sub-field within the scope of the camera, and uses the color image in the initial state as the original image. The average gray value deviation is used as the criterion. When the average gray value deviation exceeds the initial set threshold, the computer will automatically determine the obvious movement of the sediment in the sub-field, thereby obtaining the motion status of the sediment in each sub-field in the imaging area. .

In step 4, through the program, the computer fills the sub-domain with sediment particle movement with red, and fills the sub-domain with no sediment movement with green to identify the corresponding water flow state, and give different moments in the form of color graphics. , the distribution range and characteristics of the sub-domains where the sediment movement occurs in the imaging area; at the same time, the processed images are displayed frame by frame in the time series of the captured images, so that researchers can observe the distribution of sediment initiation.

In step 5, through the program, the computer automatically draws the scatter points corresponding to each frame of color images with the dimensionless hydraulic index as the abscissa and the percentage of the sub-domain area where the sediment movement takes place in the area of the camera area as the ordinate; , with the continuous shooting of images by the camera and the batch processing of ADCP sampling data, the program automatically uses the least squares method to automatically fit the trend line, and extends the trend line to obtain the intersection point between the trend line and the abscissa, which is the instantaneous non-viscous point. Quantitative definition value of critical hydraulic index for bottom sand start-up.

In step 6, a period of time is continuously monitored, and the computer automatically obtains the quantitative definition value of the critical hydraulic index of instantaneous non-viscous bottom sand start-up obtained by the extension of multiple trend lines through the program; The difference between the quantitative limit value of the instantaneous non-viscous bottom sand start-up critical hydraulic index and the current quantitative limit value of the critical hydraulic index of the instantaneous non-viscous bottom sand start-up, but when the difference is less than a certain critical index, the obtained quantitative definition value of the critical hydraulic index of the instantaneous non-viscous bottom sand start-up is The final value of the critical hydraulic index for inviscid bottom sand start-up quantitatively determined for a single measurement. At this point, the single measurement ends.

It will be understood by one of ordinary skill in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as herein, are not to be taken in an idealized or overly formal sense. explain.

The meaning of "and/or" described in this application means that each of them exists alone or both are included.

The meaning of "connection" described in this application may be a direct connection between components or an indirect connection between components through other components.

Taking the above ideal embodiments according to the present invention as inspiration, and through the above description, relevant personnel can make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the contents in the specification, and the technical scope must be determined according to the scope of the claims.

Claims (6)

1. A method for quantitatively defining a non-sticky bottom sand start-up threshold index, characterized by: the method comprises the following steps:

the first step is as follows: the support is vertically inserted into the bed surface, the LED illuminating lamp, the camera and the ADCP are sequentially arranged on the transverse support of the support, and the support regulator is adjusted to enable the positions of the camera, the LED illuminating lamp and the ADCP to be convenient for shooting and detecting hydraulic parameters;

the second step is that: continuously shooting by a camera to obtain at least one color image, preprocessing the shot color image, regularly dividing a shooting area of the camera into sub-areas, wherein the sub-areas are divided by at least one time of the cross section area of the silt of a single bed surface, each sub-area contains at least one silt particle, and meanwhile, the average gray value of each pixel point in each sub-area is calculated;

the third step: taking a color image shot by a camera in an initial state as an original image, comparing at least one color image obtained by continuous shooting of the camera with the original image respectively, determining that the sediment in each sub-domain moves obviously when the deviation of the gray value exceeds a limited threshold value, and comparing the color images in sequence to finally obtain the movement state of the sediment in each sub-domain in a shooting area of the camera;

the fourth step: filling the sub-region in which the sediment particles move in red, filling the sub-region in which the sediment particles do not move in green, and marking the corresponding water flow state, so as to obtain the sub-region distribution range of the sediment movement in the camera shooting region;

the fifth step: and fitting a trend line by taking the dimensionless hydraulic index as an abscissa, wherein the percentage of the sub-domain area with sediment movement in the area of the shooting region is an ordinate, extending the trend line to obtain a point where the trend line and the abscissa intersect, and the dimensionless hydraulic index corresponding to the point is the bottom sediment starting critical hydraulic index.

2. The method of quantitatively defining a non-sticky bottom sand start-up threshold indicator according to claim 1, characterized in that: in the second step, the first step is carried out,

calculating the median diameter of the bed surface bottom sand according to the bottom sand particle size grading information obtained from the bed surface bottom sand sampling result of the corresponding measuring area, and defining the median diameter as D by taking the median diameter as the reference₅₀Dividing the color image into equal-length and equal-area sub-fields, wherein the division standard of the sub-fields is L ═ epsilon × D₅₀Wherein L is the sub-field side length, epsilon is the sub-field side length weight coefficient, which can be determined according to the corresponding test result, D₅₀The median diameter of bed surface bottom sand;

calculating gray value of each pixel point in sub-domainConverting at least one color image continuously shot by a camera into a gray scale image in batch by using a conversion formula F_i＝α×R_i+β×G_i+γ×B_iWherein i is the number of pixel points in the color image, F_iIs the gray value, R, of the pixel point i after conversion_i、G_i、B_iThe red value, the green value and the blue value of the i pixel point are respectively, alpha, beta and gamma are corresponding weight coefficients and can be determined according to corresponding test results;

the calculation formula of the average gray value of the pixel points in each sub-domain is

Wherein, F_iThe gray value of each pixel point i after the conversion in the subfield numbered j,

the number is the arithmetic mean of the gray value of the sub-domain with the number j, j is the number of the sub-domain, and n is the total number of the pixel points in the sub-domain with the number i.

3. The method of quantitatively defining a non-sticky bottom sand start-up threshold indicator according to claim 1, characterized in that:

in the third step, the first step is that,

taking a color image shot by a camera in an initial state as an original image, respectively comparing at least one color image obtained by continuous shooting of the camera with the original image to obtain a gray value difference value of a subdomain of the continuously shot color image, wherein the calculation formula is

Wherein,

is the difference of the subfield average gray value with the number j in the image with the number k;

the average gray value of a sub field j in the continuously shot images with the number of k is obtained;

the average gray value of j subdomain in the original image is obtained;

setting a critical threshold value, and determining the silt state in the subdomain by the formula

Wherein f is the sub-region silt movement state, when f is 1, the silt in the sub-region is in the starting state, when f is 0, the silt in the sub-region is in the non-starting state, K is a set critical threshold value, the range of K is 15-20, determined according to the test,

is the difference between the average gray values of the subfields.

4. The method of quantitatively defining a non-sticky bottom sand start-up threshold indicator according to claim 1, characterized in that:

and in the fourth step, replacing the average gray value of the pixel points in each sub-domain in the continuously shot color image by the characteristic value 0 or 1 of the movement state of the silt, wherein 0 is that the silt is in the non-starting state, 1 is that the silt is in the starting state, filling the sub-domain in which the movement of the silt particles occurs in red, and filling the sub-domain in which the movement of the silt particles occurs in green, thereby obtaining the distribution characteristic diagram of the silt starting and non-starting regions.

5. The method of quantitatively defining a non-sticky bottom sand start-up threshold indicator according to claim 1, characterized in that:

in the fifth step, setting a vertical coordinate: counting the silt movement state of all sub-fields in each frame of image to obtain the total area of the sub-fields with silt in the movement state in each frame of image, and calculating the proportion of the corresponding sub-fields in each frame of image to the area of each frame of image, wherein the calculation formula is

Wherein P is the sub-domain area ratio of the silt in motion state, A_i|_f＝1For the sub-zone area of the sand in active state, A_j|_f＝0,1The area of each sub-field is m, the number of the sub-fields of the sediment in each frame of image in the active state is m, and the number of the sub-fields in each frame of image is n; taking the calculated P as a vertical coordinate;

setting of the abscissa: preprocessing the flow measurement data of ADCP, analyzing the flow velocity vertical section from water surface and bed surface at the measurement point, fitting the flow velocity vertical section distribution by using logarithmic flow velocity distribution formula and least square method, and automatically calculating the bottom friction flow velocity U by program according to the fitted flow velocity section_*；

The hydraulic index is expressed by dimensionless hydraulic strength index, and its calculation formula is phi ═ rho U_*D, wherein rho is the density of water flow, D is the particle size of sediment on the bed surface, and U_*The bottom friction flow rate; taking phi obtained by the calculation as a horizontal coordinate;

and drawing a scatter diagram, performing trend fitting on the scatter diagram, wherein a fitting curve is preferably a quadratic polynomial, extending a trend line to obtain a point of intersection of the trend line and a horizontal coordinate, and determining a hydraulic index corresponding to the point as a bottom sand starting critical hydraulic index.

6. The method of quantitatively defining a non-sticky bottom sand start-up threshold indicator according to claim 1, characterized in that: in the first step, the support is made of steel materials and comprises a vertical support and a transverse support, the vertical support is used for being inserted into a bed surface and maintaining the stability of the support, the transverse support is used for binding a camera, an LED illuminating lamp and an ADCP, the height of the transverse support can be conveniently adjusted by an adjuster on the vertical support, and the bound equipment can conveniently move up and down.

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