Calculation method for sediment transport rate of bed load section

Abstract

The invention discloses a bed load section sediment transport rate modification method. The method comprises the following steps: calculating a plurality of measured bed load section sediment transport rates; calculating the bed load change section sediment transport rate of multiple times of measurement; based on the bed load actually-measured section sediment transport rate and the modified section sediment transport rate which are measured for multiple times, the correlation between the bed load actually-measured section sediment transport rate and the bed load modified section sediment transport rate is established and obtained; and based on the established relationship between the bed load actually measured section sediment transport rate and the modified section sediment transport rate, substituting the bed load actually measured section sediment transport rate of a certain measurement time to obtain the corresponding bed load calculated section sediment transport rate. According to the method, the bed load actually-measured section sediment transport rate is recalculated, the relation between the bed load actually-measured section sediment transport rate and the recalculated section sediment transport rate is established, the bed load recalculated section sediment transport rate is directly obtained, the actually-measured single-width sediment transport rates of all vertical lines of the bed load do not need to be recalculated one by one, the workload is greatly reduced, and the working time is greatly shortened.

Description

Technical Field

[0001] This invention relates to the field of bedload sampling, and more specifically, to a method for recalculating the sediment transport rate of bedload sections. Background Technology

[0002] Bedload sediment is a key component involved in riverbed erosion and deposition, making bedload measurement of great significance. Currently, the most commonly used bedload measurement method in China is the direct measurement method, which is further divided into instrument-based and pit-based methods. However, pit-based methods are rarely used directly for bedload measurement in rivers; instrument-based methods remain the primary approach. Instrument-based methods directly measure river bedload using specialized bedload samplers. When the sampler is placed on the riverbed, a unique flow field, different from the natural flow, is created in front of the sampler inlet due to water resistance within the sampler and the inconsistency between the flow velocity entering the sampler and the natural flow velocity. Within this flow field, the velocity and direction of bedload movement change. Combined with the sampler's adherence to the riverbed and the resistance around the inlet, this results in a difference between the amount of bedload sediment entering the sampler and the amount naturally transported. Therefore, when using bedload samplers, there is a sampling efficiency issue between the measured bedload quantity and the actual quantity under natural conditions.

[0003] To study the sampling efficiency of bedload samplers, calibration is typically performed in a flume before the samplers are put into operation. Generally, compared to actual rivers, flume widths are smaller, and the lateral variation in bedload transport rate is also smaller; it can be generalized to the transport rate along a specific vertical line under natural conditions. Therefore, during sampling efficiency calibration in the flume, the measured unit width transport rate of the sampler along a specific vertical line and the actual unit width transport rate under natural conditions can be obtained. By establishing the correlation between these two rates, the sampling efficiency can be calculated. According to the sampling calibration test data, the sampler's sampling efficiency is not a constant value; it varies with the transport rate.

[0004] Since the bedload transport rate is calculated from the unit width transport rate of multiple vertical lines, and the unit width transport rate of each vertical line varies significantly, the sampling efficiency of the transport rate for each vertical line is inconsistent. Therefore, during the calculation process, the unit width transport rate of each vertical line needs to be recalculated one by one according to different sampling efficiency formulas. However, in rivers with wide sections, there are more than twenty bedload vertical lines. If the transport rate of each vertical line is recalculated one by one, this method is not only extremely labor-intensive but also overly cumbersome. Summary of the Invention

[0005] This invention provides a method for recalculating the sediment transport rate of bedload sections. By recalculating the measured sediment transport rate of bedload sections and establishing the relationship between the measured sediment transport rate and the recalculated sediment transport rate, the recalculated sediment transport rate of bedload sections can be directly obtained. This eliminates the need to recalculate the measured unit width sediment transport rate of all vertical lines of the bedload one by one, greatly saving workload and shortening working time.

[0006] The technical solution adopted in this invention is: A method for recalculating the sediment transport rate of bedload sections includes the following specific steps: S1. Calculate the measured sediment transport rate of the bedload section after multiple measurements; S2. Calculate the sediment transport rate of the bedload alteration section after multiple measurements; S3. Based on the measured and revised sediment transport rates of bedload sections from multiple measurements, establish the correlation between the measured and revised sediment transport rates of bedload sections. S4. Based on the established relationship between the measured sediment transport rate and the revised sediment transport rate of the bedload section, substitute the measured sediment transport rate of the bedload section of a certain measurement to obtain the corresponding estimated sediment transport rate of the bedload section.

[0007] Further, step S1 includes: S11. Based on a single test using a bedload sampler, determine the two boundaries of the bedload and multiple perpendicular lines between the two boundaries. And obtain the distance between the starting boundary of the transported mass and the first perpendicular line. End point boundary and the first Distance of vertical lines and the distance between each perpendicular line ; S12. Obtain the displacement and corresponding duration for each vertical line, and divide the two to obtain the measured unit width sediment transport rate for each vertical line. ; S13, Distance between the starting boundary of the transported mass and the first perpendicular line End point boundary and the first Distance of vertical lines Distance between each perpendicular line The measured sediment transport rate of each vertical line of the bedload was calculated. S14. Calculate half the sum of the distances between a given vertical line and its left and right adjacent vertical lines, and then multiply this by the measured unit width sediment transport rate of the vertical line. Multiplying these values ​​yields the measured partial sediment transport rate for that vertical line. This process is repeated for all vertical lines, and the measured partial sediment transport rates for each vertical line are then summed to obtain the measured sediment transport rate of a single measurement section. ; S15. Repeat steps S11~S14 to obtain the measured sediment transport rate of the bedload section from multiple measurements. .

[0008] Furthermore, the formula for calculating the sediment transport rate of the bedload measured at the cross-section in a single measurement is as follows:

[0009] In the formula, —Measured sediment transport rate of bedload at a single cross-section, kg / s; — The distance between the starting boundary of the transported mass and the first perpendicular line, in meters; —The endpoint boundary of the transported substance and the first The distance between the perpendicular lines, in meters; , , ..., —The first, second, ..., third article of the transferred substance. The distance between a perpendicular line and its next perpendicular line, in meters (m). , ,..., —Article 1 and Article 2 of the Possession of Substances , No. Measured sediment transport rate per unit width of the vertical line, g / (s·m).

[0010] Further, step S2 includes: S21. Based on a single test using a bedload sampler, obtain the measured unit width sediment transport rate of each vertical line of the bedload. And set a threshold; S22. Determine the measured unit width sediment transport rate of each vertical line of bedload. By setting a threshold value and using the corresponding calculation formula, the modified unit width sediment transport rate of each vertical line of the bedload is obtained. ; S23. Calculated sediment transport rate per unit width based on each vertical line of bedload transport. The sediment transport rate of the bedload change section was calculated for a single measurement. ; S24. Repeat steps S21~S23 to obtain the sediment transport rate of the bedload change section after multiple measurements. .

[0011] Furthermore, the recalculation formula in step S22 is as follows: 1) When the measured sediment transport rate per unit width of the bedload vertical is >3.0 g / (s·m), ; 2) When the measured sediment transport rate per unit width of the bedload vertical is ≤3.0 g / (s·m), .

[0012] Furthermore, the calculation formula in step S23 is as follows: In the formula, —Sediment transport rate at the bedload alteration section, kg / s; — The distance between the starting boundary of the transported mass and the first perpendicular line, in meters; —The endpoint boundary of the transported substance and the first The distance between the perpendicular lines, in meters; , , ..., —Article 11, Article 2, concerning the transfer of substances. , No. The distance between a perpendicular line and its next perpendicular line, in meters (m). , ,..., —Article 1 and Article 2 of the Possession of Substances , No. The revised sediment transport rate per unit width for a vertical line, g / (s·m).

[0013] Furthermore, the correlation in step S3 is a double logarithmic function relationship, as detailed below: 1) When the measured sediment transport rate at the bedload cross section is <1.25 kg / s, ; 2) When the measured sediment transport rate at the bedload section is ≥1.25 kg / s, .

[0014] Compared with the prior art, the present invention has the following advantages: This invention establishes a direct relationship between the measured sediment transport rate of bedload sections and the recalculated sediment transport rate, avoiding the traditional method of recalculating the measured unit width sediment transport rate for all vertical lines. This significantly reduces the computational workload and shortens the data processing time. In practical applications, this recalculation method can obtain the bedload sediment transport rate more quickly and accurately, providing a more efficient technical means for river sediment transport research, channel evolution analysis, and water conservancy project design and operation management. Furthermore, by setting reasonable thresholds and using different recalculation formulas, this method can adapt to the recalculation needs under different measured unit width sediment transport rate conditions, further improving its applicability and accuracy. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments: Figure 1 This is a flowchart illustrating a method for recalculating the sediment transport rate of a bedload section according to the present invention. Figure 2 This is a graph showing the relationship between the measured sediment transport rate and the revised sediment transport rate at a certain hydrological station in this invention. Detailed Implementation

[0016] Example

[0017] like Figures 1 to 2 As shown, a method for recalculating the sediment transport rate of a bedload section includes the following specific steps: A method for recalculating the sediment transport rate of bedload sections includes the following specific steps: S1. Calculate the measured sediment transport rate of the bedload section after multiple measurements; Specifically, S11, based on a single test using a bedload sampler, determines the two boundaries of the bedload and multiple perpendicular lines between the two boundaries. And obtain the distance between the starting boundary of the transported mass and the first perpendicular line. End point boundary and the first Distance of vertical lines and the distance between each perpendicular line ; S12. Obtain the displacement and corresponding duration for each vertical line, and divide the two to obtain the measured unit width sediment transport rate for each vertical line. ; S13, Distance between the starting boundary of the transported mass and the first perpendicular line End point boundary and the first Distance of vertical lines Distance between each perpendicular line The measured sediment transport rate of each vertical line of the bedload was calculated. S14. Calculate half the sum of the distances between a given vertical line and its left and right adjacent vertical lines, and then multiply this by the measured unit width sediment transport rate of the vertical line. Multiplying these values ​​yields the measured partial sediment transport rate for that vertical line. This process is repeated for all vertical lines, and the measured partial sediment transport rates for each vertical line are then summed to obtain the measured sediment transport rate of a single measurement section. ; The formula for calculating the bedload transport rate of a single measured section is as follows:

[0018] In the formula, —Measured sediment transport rate of bedload at a single cross-section, kg / s; — The distance between the starting boundary of the transported mass and the first perpendicular line, in meters; —The endpoint boundary of the transported substance and the first The distance between the perpendicular lines, in meters; , , ..., —The first, second, ..., third article of the transferred substance. The distance between a perpendicular line and its next perpendicular line, in meters (m). , ,..., —Article 1 and Article 2 of the Possession of Substances , No. Measured sediment transport rate per unit width of the vertical line, g / (s·m); S15. Repeat steps S11~S14 to obtain the measured sediment transport rate of the bedload section from multiple measurements. .

[0019] Note: Calculating the measured bedload transport rate is to accurately obtain the actual measured transport status of bedload sediment in the river. It is also a prerequisite for establishing the relationship between the measured bedload transport rate and the revised bedload transport rate. Only by accurately obtaining the measured transport rate can the revised transport rate be further calculated, thereby obtaining the relationship between the measured bedload transport rate and the revised bedload transport rate more quickly and accurately.

[0020] S2. Calculate the sediment transport rate of the bedload alteration section after multiple measurements; Specifically, S21, based on a single test using a bedload sampler, obtains the measured unit width sediment transport rate of each vertical line of the bedload. And set a threshold; S22. Determine the measured unit width sediment transport rate of each vertical line of bedload. By setting a threshold value and using the corresponding calculation formula, the modified unit width sediment transport rate of each vertical line of the bedload is obtained. ; S23. Calculated sediment transport rate per unit width based on each vertical line of bedload transport. The sediment transport rate of the bedload change section was calculated for a single measurement. ; S24. Repeat steps S21~S23 to obtain the sediment transport rate of the bedload change section after multiple measurements. .

[0021] In this embodiment, a hydrological bureau conducted three gravel bedload tests on a river in 1967, 1968, and 1973 using a sampler. The test data showed that the sampler's sampling efficiency varied with the gravel bedload transport rate, exhibiting a significant inflection point around 3.0 g / (s·m). The recalculated unit width sediment transport rate for each vertical line of the gravel bedload was calculated using the following formula: 1) When the measured sediment transport rate per unit width of the bedload vertical is >3.0 g / (s·m), ; 2) When the measured sediment transport rate per unit width of the bedload vertical is ≤3.0 g / (s·m), ; The calculation formula in step S23 is as follows: In the formula, —Sediment transport rate at the bedload alteration section, kg / s; — The distance between the starting boundary of the transported mass and the first perpendicular line, in meters; —The endpoint boundary of the transported substance and the first The distance between the perpendicular lines, in meters; , , ..., —Article 11, Article 2, concerning the transfer of substances. , No. The distance between a perpendicular line and its next perpendicular line, in meters (m). , ,..., —Article 1 and Article 2 of the Possession of Substances , No. The revised sediment transport rate per unit width for a vertical line, g / (s·m).

[0022] Note: In practical river sediment transport research, relying solely on measured cross-sectional sediment transport rate data is often constrained by numerous factors, such as the number of sampling points, sampling frequency, and the accuracy of sampling equipment. These factors can easily prevent the measured data from comprehensively and accurately representing the bedload transport situation across the entire cross-section. Therefore, by establishing a correlation between the measured bedload cross-sectional sediment transport rate and the recalculated cross-sectional sediment transport rate, and by performing recalculation based on the measured unit width sediment transport rate of each vertical line, we can more effectively utilize existing measured data to make reasonable inferences about areas that have not been directly measured, thereby obtaining a more comprehensive and accurate recalculated bedload cross-sectional sediment transport rate.

[0023] S3. Based on the measured and revised sediment transport rates of bedload sections from multiple measurements, establish the correlation between the measured and revised sediment transport rates of bedload sections. The correlation in step S3 is a double logarithmic function relationship, as detailed below: 1) When the measured sediment transport rate at the bedload cross section is <1.25 kg / s, ; 2) When the measured sediment transport rate at the bedload section is ≥1.25 kg / s, ; Note: Considering the significant randomness and pulsation of bedload transport, the measured cross-sectional sediment transport rate was established to improve the correlation of the functional relationship. With the revised cross-sectional sediment transport rate The relationship is a double logarithmic function. Analysis revealed that the measured sediment transport rate at a certain hydrological station's gravel bedload section... With the revised cross-sectional sediment transport rate The functional relationship is a double logarithmic function. In actual river sediment transport studies, due to the complexity and variability of field conditions, measured data often only reflect the bedload transport at a specific time and location, making it difficult to comprehensively and accurately characterize the bedload transport characteristics of the entire cross-section. However, by establishing such a functional relationship, it is possible to deeply reveal the intrinsic connection and variation law between the measured cross-sectional sediment transport rate and the revised cross-sectional sediment transport rate. When the measured unit width sediment transport rate of the bedload vertical falls within different ranges, using different functional relationships for fitting can more accurately describe the relationship between the two.

[0024] S4. Based on the established relationship between the measured sediment transport rate and the revised sediment transport rate of the bedload section, substitute the measured sediment transport rate of the bedload section of a certain measurement to obtain the corresponding estimated sediment transport rate of the bedload section.

[0025] Note: By establishing a close relationship between the measured and recalculated sediment transport rates of bedload sections in the early stages, once the measured sediment transport rate data for each measurement are obtained, the recalculated sediment transport rate for each measurement can be accurately calculated based on this relationship. This eliminates the need for large-scale, high-frequency field measurements, allowing for more comprehensive and abundant data on bedload section sediment transport rates, and greatly expanding the data coverage and time span.

[0026] To verify the effectiveness of the method of the present invention, a single-test pebble bedload transport experiment was conducted. The specific calculation results are shown in Tables 1 and 2. Table 1 shows the calculated results of the measured partial sediment transport rate and the measured cross-sectional sediment transport rate of the single-test pebble bedload transport experiment; Table 2 shows the calculated results of the modified unit width sediment transport rate and the modified cross-sectional sediment transport rate of the single-test pebble bedload transport experiment. Table 1. Calculation results of measured sediment transport rate of gravel bedload from a single measurement and the measured cross-sectional sediment transport rate.

[0027] Table 1 shows that in the single-test pebble bedload test, the left and right boundaries of the bedload and 16 vertical lines were determined, and the measured unit width sediment transport rate was obtained using a bedload sampler; the measured sediment transport rate of the first vertical line in Table 1 is... g / s; The measured cross-sectional sediment transport rate is obtained by calculating the sediment transport rate per unit width of the bedload vertical using the corresponding formula. It is 1.74 kg / s.

[0028] Table 2 Calculation results of sediment transport rate per unit width and sediment transport rate per cross section based on single-measurement bedload transport

[0029] Table 2 shows that in the single-test pebble bedload transport experiment, the left and right boundaries of the bedload and 16 vertical lines were determined, and the measured unit width sediment transport rate was obtained using a bedload sampler; the measured sediment transport rate of the first vertical line in Table 2 is... g / s; the corresponding modified unit width sediment transport rate is obtained through the calculation formula. g / (s·m); revised partial sediment transport rate g / s; based on the revised unit width sediment transport rate The sediment transport rate of the modified section was calculated. It is 24.4 kg / s.

[0030] In this embodiment, gravel bedload transport data from 32 different sediment transport rates at a hydrological station between 2011 and 2024 were randomly selected. Steps S1 and S2 were repeated to calculate the measured cross-sectional sediment transport rate for each of the 32 measurements. With the revised cross-sectional sediment transport rate The specific results are shown in Table 3: Table 3. Calculation results of measured and revised sediment transport rates at multiple bedload measurements sections.

[0031] Table 3 shows that, based on 32 randomly selected gravel bedload transport test samples from different measured cross-sectional sediment transport rates at a hydrological station between 2011 and 2024, the corresponding revised cross-sectional sediment transport rates were obtained using the revised formula. The measured cross-sectional sediment transport rate of 1.74 kg / s and the revised cross-sectional sediment transport rate of 24.4 kg / s in the 20th measurement are the final results obtained in Table 1 and Table 2, respectively.

[0032] To verify the accuracy of the method of the present invention, the modified cross-sectional sediment transport rate of each bedload measurement and the inferred cross-sectional sediment transport rate calculated from the measured cross-sectional sediment transport rate of each bedload measurement using the corresponding calculation formula were compared. Error comparison was performed, and the specific results are shown in Table 4: Table 4. Calculation results of the error between the estimated sediment transport rate and the revised sediment transport rate at each measurement section.

[0033] Table 4 shows that the relative errors of the calculated bedload transport rates for each measurement range from -13.1% to 23.9%, with an average relative error of 2.5% and a standard deviation of 10.5%. These errors and standard deviations meet the specifications. This indicates that by establishing the relationship between the measured bedload transport rate and the calculated bedload transport rate, it is unnecessary to recalculate the measured unit width transport rate individually, significantly reducing the recalculation time. It also improves accuracy and reduces the error between the measured and calculated bedload transport rates under natural conditions.

[0034] The method of this invention is not only reflected in the improvement of computational efficiency, but also in its scientific nature and practicality. Specifically, this method divides the measured unit width sediment transport rate of the bedload vertical into two intervals by precisely setting a threshold, and uses corresponding recalculation formulas for different intervals to ensure the accuracy and reliability of the recalculation results. When the measured unit width sediment transport rate is less than the threshold, a specific formula is used for recalculation, which can fully consider the special cases under low sediment transport rate conditions; while when the measured unit width sediment transport rate is greater than or equal to the threshold, another set of formulas is used for recalculation to adapt to the complex cases under high sediment transport rate conditions. This segmented processing method makes the recalculation method more flexible and scientific, and can better meet the needs of actual engineering. In addition, this method simplifies the calculation process and improves data processing efficiency by establishing a direct relationship between the measured cross-sectional sediment transport rate and the recalculated cross-sectional sediment transport rate, providing strong technical support for river sediment transport research, river channel evolution analysis, and water conservancy project design and operation management.

[0035] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the principles and essence of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for converting the sediment transport rate of a bed load cross section, characterized by, Comprise the following steps: S1, calculate the sediment transport rate of the moving bed measured section of multiple measurements; S2, calculate the sediment transport rate of the moving bed converted section of multiple measurements; S3, based on the sediment transport rate of the moving bed measured section and the sediment transport rate of the moving bed converted section of multiple measurements, the correlation between the sediment transport rate of the moving bed measured section and the sediment transport rate of the moving bed converted section is established; S4, based on the established relationship between the sediment transport rate of the moving bed measured section and the sediment transport rate of the moving bed converted section, the sediment transport rate of the moving bed converted section corresponding to the sediment transport rate of the moving bed measured section is obtained.

2. The method according to claim 1, wherein, The step S1 comprises: S11, determining two boundaries of the bedload and a plurality of perpendicular lines between the two boundaries based on a single test of the bedload sampler , and obtaining the distance between the starting boundary of the bedload and the first perpendicular line , the distance between the ending boundary and the first perpendicular line , and the distance between the perpendicular lines ;​ S12, obtain the displacement amount and the corresponding duration of each vertical line, and divide the two to obtain the measured single-width sediment discharge rate of each vertical line of the displacement mass ; S13, distance between the starting boundary of the bed load and the first vertical line , distance between the ending boundary of the bed load and the second vertical line , distance between the vertical lines , distance between the vertical lines , the measured portion of the sediment discharge rate of each vertical line of the bed load is calculated S14, the half of the sum of the distances between the vertical line and its left and right adjacent vertical lines and the measured single-width sediment discharge rate of the vertical line are multiplied to obtain the measured partial sediment discharge rate of the vertical line, and the measured partial sediment discharge rates corresponding to all the vertical lines are sequentially obtained and summed to obtain the measured bed load section sediment discharge rate of a single measurement ; S15, repeating steps S11-S14 to obtain the sediment transport rate of the multiple measured cross sections .

3. The method according to claim 2, wherein, The calculation formula of the sediment transport rate of the moving bed measured section of the single measurement is as follows: In the formula, - the measured sediment transport rate of the cross section, kg / s; - distance of the origin boundary of the sediment to the first vertical line, m; - the distance of the end boundary of the sediment from the vertical line, m - the distance of the end boundary of the sediment from the vertical line, m , , ..., —The first, second, ..., third article of the transferred substance. The distance between a perpendicular line and its next perpendicular line, in meters (m). , ,..., - 1st and 2nd bars of bed load, , 3rd measured single-width sediment discharge rate of the vertical line, g / (s·m).

4. The method according to claim 1, wherein, The step S2 comprises: S21, based on the single test of the push load sampler, the measured single-width sediment discharge of each vertical line of the push load is obtained and set a threshold value; S22, judging the measured single-width sediment discharge of each vertical line of the moving sediment and using the corresponding conversion formula to convert, to obtain the converted single-width sediment discharge of each vertical line of the moving sediment ; S23, the corrected single-width sediment discharge rate of each vertical line of the bed load The corrected cross-section sediment discharge rate of the bed load in each survey is calculated ; S24, repeating steps S21-S23 to obtain the multiple-time cross- material conversion section sediment discharge rate .

5. The method according to claim 4, wherein, The conversion formula in the step S22 is as follows: 1) when the measured single-width sediment transport rate of the moving bed vertical line is > 3.0 g / (s·m), ； 2) when the measured single-width sediment transport rate of the moving bed vertical line is ≦ 3.0 g / (s·m), 。 6. The method according to claim 4, wherein, The calculation formula in the step S23 is as follows: In the formula, - the bed load correction cross-sectional sediment discharge, kg / s; - distance of the origin boundary of the sediment to the first vertical line, m; —The endpoint boundary of the transported substance and the first The distance between the perpendicular lines, in meters; , , - 11th item of the bed load, 2nd item, , distance of the 11th item of the bed load from the 2nd item, m; , , - 1st and 2nd order of bed load, , converted single-width sediment discharge rate of vertical line, g / (s·m).

7. The method according to claim 1, wherein, The correlation in the step S3 is a double-logarithmic function relationship, which is as follows: 1) when the sediment transport rate of the moving bed measured section is < 1.25 kg / s, ； 2) when the sediment transport rate of the moving bed measured section is ≧ 1.25 kg / s, 。

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