A representative velocity synthesis method for deriving river flow

Abstract

The present invention relates to a representative velocity synthesis method for deriving river flow rates, which solves the problems that the representative measuring points for synthetic representative velocities selected based on manual experience currently have relatively large randomness and cannot well meet the requirements of standardized and accurate flow rate monitoring. The method for synthesizing the representative velocity for flow derivation is divided into 4 steps: (1) consistency transformation of the measuring point velocities; (2) stability analysis of the measuring point velocity series; (3) using the "unit-width flow comparison method" to determine the weights of the velocities of each representative measuring point in the representative velocity for flow derivation; (4) synthesizing the representative velocity according to the weight coefficients of the velocities of each representative measuring point. Based on the consistency transformation of the measuring point velocity series, the present invention optimizes the representative measuring points through the stability analysis of the measuring point velocities, determines the weights of the representative measuring point velocities using the "unit-width flow comparison method", and proposes a representative velocity synthesis method for deriving river flow rates, with higher data reliability and improved accuracy of hydrological data calculation.

Description

Technical Field

[0001] The present invention belongs to the field of hydrological data processing, and relates to a representative velocity synthesis method for deriving river flow Background Art

[0002] River flow refers to the volume of water passing through a river cross-section per unit time and is one of the most important hydrological element characteristics of a river. Discharge measurement is an important basic task in daily hydrological monitoring, and the monitoring results play an irreplaceable role in public water safety guarantee and ecological environment governance. However, the hydrological situation of natural rivers is complex, the water conditions of many small and medium-sized rivers change rapidly, the water environment is diverse, and during high floods, the sediment concentration is high, there are many floating objects, and the water body turbulence is strong. It is relatively difficult to directly measure the flow by traditional velocity-area methods such as the multi-point and multi-line method of rotor current meters and the moving ship ADCP method. The safety of the measurement operation is not high, and it is difficult to achieve online flow monitoring.

[0003] In recent years, the automatic monitoring technology of flow has been continuously developed, and various forms of automatic flow monitoring equipment and methods have been put into practical production applications, but there are still deficiencies. Among the many method theories of automatic flow monitoring, the method of deriving river flow through the representative velocity method and then realizing automatic flow monitoring is one of the most important methods of current automatic flow monitoring. This method mainly automatically monitors hydrological elements such as the water level of the flow measurement cross-section and the velocity of some measuring points. After selecting representative measuring point velocities to synthesize the flow-pushing representative velocity, the correlation between the representative velocity and the measured cross-section average velocity under different flow-pushing water level grades is compared and analyzed. After determining this correlation, the automatic monitoring equipment is used to continuously monitor and calculate the representative velocity online, the cross-section average velocity is derived through the correlation, and then the cross-sectional area of the water passage is derived using the water level monitoring data, and thus the river flow is obtained. In the above method, the synthesis of the representative velocity is a key link. At present, the representative measuring points for synthesizing the representative velocity are generally selected based on artificial experience, lacking quantitative analysis and judgment, with great randomness, and cannot well meet the requirements of standardized and precise flow monitoring. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the selection of representative measuring points for synthesizing the representative velocity based on artificial experience has great randomness and cannot well meet the requirements of standardized and precise flow monitoring, and to provide a representative velocity synthesis method for deriving river flow. On the basis of the consistency transformation of the measuring point velocity sequence, representative measuring points are preferably selected through the stability analysis of the measuring point velocity, the "unit-width flow comparison method" is used to determine the weight of the representative measuring point velocity, and then the representative velocity is synthesized, with higher data reliability and improved accuracy of hydrological data calculation.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a representative velocity synthesis method for deriving river flow, with n measuring points arranged along the river cross-section, including the following steps:

[0006] Step 1, flow velocity consistency transformation at the measuring point;

[0007] Generally, water flow velocity monitoring equipment can continuously measure the water flow velocity at the same spatial position at different time points. However, the water conditions in natural rivers change rapidly, especially during flood seasons, when it is difficult to obtain data sequences of different measurements under the same water conditions. Therefore, it is necessary to perform consistency transformation on the velocity sequences of different measurements at the same measuring point. On this basis, the velocity sequence of the same measuring point under approximately consistent water conditions is obtained to provide basic data for subsequent analysis and calculation. The specific steps are as follows:

[0008] Step 1.1: Use the general area enclosing method or arithmetic mean method to calculate the average water level of each measurement, and use the Manning formula or the previous water level-flow relationship curve to calculate the average flow velocity V of the section corresponding to the average water level. 平均 ;

[0009] Step 1.2: Use the Manning formula or the previous water level flow relationship curve to calculate the average flow velocity V of the section corresponding to each measured water level. i ;

[0010] Step 1.3, calculate the flow velocity consistency transformation correction coefficient for each measurement

[0011] Step 1.4: Perform consistency transformation on the flow velocity at each measuring point in each measurement, V ij变 =α i V ij ; Where: V ij V is the velocity of the jth measuring point in the i-th measuring order; ij变 is the velocity of the corresponding measuring point after consistency transformation at the j-th measuring point of the i-th measuring time;

[0012] Step 2, stability analysis of flow rate sequence at measuring points;

[0013] The stable operation of the flow measurement system is the premise of actual production application, and it is also the key consideration when selecting representative measuring points when applying the representative flow velocity method to push the flow. The stability of the measuring point can be evaluated by the discrete degree of the results of different measurements at the same measuring point under the same water conditions. The coefficient of variation Cv is introduced to analyze the stability of the flow velocity data samples at the measuring point:

[0014] Step 2.1, calculate the flow velocity V at each measuring point after consistency transformation ij变 The coefficient of variation Cv value of the sequence:

[0015]

[0016]

[0017] Where: Cv jThe Cv value of the flow velocity sequence at the j-th measurement point after the consistency transformation;

[0018] V 1j变 、V 2j变 ...V n-1，j变 、V nj变 Are the flow velocities at each measurement time of the j-th measurement point after the consistency transformation;

[0019] —— The average value of the flow velocities at each measurement time of the j-th measurement point after the consistency transformation;

[0020] Step 2.2, Select M measurement points with relatively small corresponding Cv values as representative measurement points or select consecutive measurement points as a representative measurement point segment;

[0021] Step 3, Use the "unit-width flow rate comparison method" to determine the weights of the flow velocities of each representative measurement point or representative measurement point segment in the flow-pushing representative velocity;

[0022] The unit-width flow rate is the flow rate per unit width of the cross-section of flowing water, which is related to the water flow velocity and the cross-sectional area of this unit width. According to the basic theory of hydraulics, the unit-width flow rates at different starting distances of the cross-section of flowing water can reflect the concentration degree of the water flow at that place. In other words, the water flow of the cross-section of flowing water is concentrated at the place with a larger unit-width flow rate, and the proportion of the flow rate near this place in the total flow rate of the cross-section of flowing water is relatively large; Therefore, the hydraulic factors such as the flow velocity at the place with a larger unit-width flow rate are more representative, and it is proposed to use the "unit-width flow rate comparison method" to determine the weights of the flow velocities of each representative measurement point or representative measurement point segment in the flow-pushing representative velocity; The specific steps are as follows:

[0023] Step 3.1, Analyze and calculate the weights of the flow velocities of each representative measurement point or representative measurement point segment in each measurement time based on the measured flow rate data;

[0024] Select the measurement times within the flow-pushing water level segment from the existing measured flow rate results, and calculate the ratio of the unit-width flow rate of each representative measurement point or representative measurement point segment in each measurement time to the sum of the unit-width flow rates of all representative measurement points or representative measurement point segments, which is denoted as β mx :

[0025]

[0026] In the formula:

[0027] Q m单x —— The average unit-width flow rate of the m-th representative measurement point or representative measurement point segment in the x-th measurement time;

[0028] —— The total sum of the average unit-width flow rates of each representative measurement point or representative measurement point segment in the x-th measurement time;

[0029] β mx —— The single-time weight coefficient of the m-th representative measurement point or representative measurement point segment in the x-th measurement time;

[0030] Step 3.2, fitting and determining the water level - weight correlation;

[0031] For the β values of each representative measuring point or representative measuring point section obtained in Step 3.1 mx and the corresponding water level Z x perform regression analysis to determine the correlation β m = f m (z);

[0032] Step 3.3, calculating the average weight;

[0033]

[0034] In the formula: Z a 、Z b ——The low and high water level ranges of flow pushing corresponding to the calculation of the average weight;

[0035] ——The average weight of the m-th representative measuring point or representative measuring point section;

[0036] Step 3.4, standardizing and scaling the weights;

[0037] To ensure that the sum of the weight coefficients corresponding to each selected representative measuring point or representative measuring point section is 1, perform standardizing and scaling of the weights, and calculate according to the following formula:

[0038] Step 4, synthesizing the representative flow velocity formula for flow pushing;

[0039] The formula for synthesizing the representative flow velocity for flow pushing is expressed as:

[0040]

[0041] In the formula:

[0042] V 代表i ——The synthesized representative flow velocity of the i-th measurement for flow pushing;

[0043] β m定 ——The weight coefficient of the flow velocity of the m-th representative measuring point or representative measuring point section accounting for the representative flow velocity;

[0044] V im ——The flow velocity of the m-th representative measuring point or representative measuring point section at the i-th measurement.

[0045] Based on the consistency transformation of the measured point velocity sequence, this method optimizes representative measurement points through the stability analysis of the measured point velocity, determines the weights of the representative measurement point velocities using the "unit-width flow rate comparison method", and proposes a synthesis method for the representative velocity used to derive the river flow. The synthesis of the representative velocity for flow derivation in this method is divided into 4 steps: (1) Consistency transformation of the measured point velocity; (2) Stability analysis of the measured point velocity sequence; (3) Determining the weights of the representative measurement point velocities in the representative velocity for flow derivation using the "unit-width flow rate comparison method"; (4) Synthesizing the representative velocity according to the weight coefficients of the representative measurement point velocities.

[0046] Preferably, in step 2.2, the proportion of the number of selected representative measurement points is 10% - 30% of the total number of all measurement points.

[0047] Preferably, when the total number of measurement points is small, independent representative measurement points can be selected, and the number of representative measurement points does not exceed 3; when the total number of measurement points is large, representative measurement points continuously distributed are selected to form a representative measurement point section, and the number of representative measurement point sections does not exceed 3.

[0048] Preferably, in step 3.2, the correlation β m = f m (z) can be linear or non-linear, and it is advisable to select the correlation with a larger correlation coefficient; when the water level fluctuation range is large, the correlation can be formulated by section according to the water level grade. The correlation equation is fitted multiple times using linear and non-linear models, and the one with the largest correlation coefficient is selected as the final correlation equation.

[0049] Based on the consistency transformation of the measured point velocity sequence, this invention optimizes representative measurement points through the stability analysis of the measured point velocity, determines the weights of the representative measurement point velocities using the "unit-width flow rate comparison method", and proposes a synthesis method for the representative velocity used to derive the river flow, with higher data reliability and improved accuracy of hydrological data calculation. Brief Description of the Drawings

[0050] The following further describes the present invention with reference to the drawings.

[0051] Figure 1 is a schematic diagram of the measurement point setting of the present invention.

[0052] Figure 2 is a schematic diagram of the river cross-section in Embodiment 2 of the present invention.

[0053] Figure 3 is a graph of the water level change from January to June 2022 in Embodiment 2 of the present invention.

[0054] Figure 4 is a distribution diagram of the Cv value of the measured point velocity sequence along the river width in Embodiment 2 of the present invention.

[0055] Figure 5It is the weight coefficient - water level correlation diagram of one of the representative measuring point segments in Embodiment 2 of the present invention. Detailed implementation manners

[0056] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.

[0057] Embodiment 1: A representative velocity synthesis method for deriving river flow rate. There are n measuring points arranged along the cross-section of the river channel, as Figure 1 shown. The horizontal ADCP is used to monitor the flow velocity at each measuring point, including the following steps:

[0058] Step 1, consistency transformation of the measuring point flow velocity;

[0059] Generally, the flow velocity monitoring equipment can continuously measure the flow velocity at the same spatial position at different time points. However, the water regime in natural river channels changes rapidly, especially during the flood season, it is difficult to obtain data sequences of different measurement times under the same water regime conditions. Therefore, it is necessary to perform consistency transformation on the flow velocity sequences of the same measuring point at different measurement times; on this basis, the flow velocity sequence under approximately the same water regime at the same measuring point is obtained, providing basic data for subsequent analysis and calculation. The specific steps are as follows:

[0060] Step 1.1, use the general area enclosure method or arithmetic mean method to calculate the average water level of each measurement time, and use the Manning formula method or the previous water level - flow rate relationship curve to calculate the cross-section average flow velocity V corresponding to the average water level 平均 ;

[0061] Step 1.2, use the Manning formula method or the previous water level - flow rate relationship curve, etc. to calculate the cross-section average flow velocity V corresponding to the water level of each measurement time i ;

[0062] Step 1.3, calculate the correction coefficient for the consistency transformation of the flow velocity of each measurement time

[0063] Step 1.4, perform consistency transformation on the flow velocity of each measurement time at each measuring point, V ij变 =α i V ij ; In the formula: V ij is the flow velocity of the jth measuring point at the ith measurement time; V ij变 is the corresponding measuring point flow velocity of the jth measuring point at the ith measurement time after consistency transformation;

[0064] Step 2, stability analysis of the measuring point flow velocity sequence;

[0065] The stable operation of the flow measurement system is a prerequisite for actual production applications and is also an important aspect to consider when selecting representative measurement points when applying the representative velocity method for flow estimation. The stability of the measurement points can be evaluated by the degree of dispersion of the results of different measurement times at the same measurement point under the same water condition. The coefficient of variation Cv is introduced to analyze the stability of the velocity data samples of the measurement points:

[0066] Step 2.1, calculate the coefficient of variation Cv value of the velocity V of each measurement point after the consistency transformation: ij变 of the sequence:

[0067]

[0068]

[0069] where: Cv j is the Cv value of the velocity sequence of the j-th measurement point after the consistency transformation;

[0070] V 1j变 、V 2j变 ...V n-1，j变 、V nj变 are the measured velocities of each measurement time of the j-th measurement point after the consistency transformation;

[0071] —— the average value of the measured velocities of each measurement time of the j-th measurement point after the consistency transformation;

[0072] Step 2.2, select M measurement points with smaller corresponding Cv values as representative measurement points or select continuous measurement points as a representative measurement point section; the proportion of the number of selected representative measurement points is 10% - 30% of the total number of measurement points. When the total number of measurement points is small, independent representative measurement points can be selected, and the number of representative measurement points does not exceed 3. When the total number of measurement points is large, continuous distributed representative measurement points are selected to form a representative measurement point section, and the number of representative measurement point sections does not exceed 3;

[0073] Step 3, use the "unit-width flow comparison method" to determine the weights of the velocities of each representative measurement point or representative measurement point section in the flow estimation representative velocity;

[0074] The unit-width flow is the flow per unit width of the cross-section of flow, which is related to the water flow velocity and the cross-sectional area of this unit width. According to the basic theory of hydraulics, the unit-width flow at different starting distances of the cross-section of flow can reflect the concentration degree of the water flow at that place. In other words, the water flow of the cross-section of flow is concentrated at the place with a larger unit-width flow, and the proportion of the flow near that place in the total flow of the cross-section of flow is relatively large. Therefore, the hydraulic factors such as the velocity at the place with a larger unit-width flow are more representative. It is proposed to use the "unit-width flow comparison method" to determine the weights of the velocities of each representative measurement point or representative measurement point section in the flow estimation representative velocity. The specific steps are as follows:

[0075] Step 3.1, analyze and calculate the weights of the flow velocities at each representative measuring point or representative measuring point section in each measurement based on the actual flow measurement data.

[0076] Select the measurements within the deduced water level section from the existing actual flow measurement results, and calculate the ratio of the unit width flow of each representative measuring point or representative measuring point section in each measurement to the sum of the unit width flows of all representative measuring points or representative measuring point sections, denoted as β. mx :

[0077]

[0078] In the formula:

[0079] Q m单x —— The average unit width flow of the m-th representative measuring point or representative measuring point section in the x-th measurement.

[0080] —— The total sum of the average unit width flows of each representative measuring point or representative measuring point section in the x-th measurement.

[0081] β mx —— The single-time weight coefficient of the m-th representative measuring point or representative measuring point section in the x-th measurement.

[0082] Step 3.2, fit and determine the water level - weight correlation.

[0083] Perform regression analysis on the β values of each representative measuring point or representative measuring point section obtained in Step 3.1 mx and the corresponding water level Z x to determine the correlation β m = f m (z); The correlation β m = f m (z) can be linear or non-linear, and it is advisable to select the correlation with a larger correlation coefficient; when the water level variation range is large, the correlation can be formulated by dividing the water level into sections.

[0084] Step 3.3, calculate the average weight.

[0085]

[0086] In the formula: Z a 、Z b —— The low and high water level ranges corresponding to the calculation of the average weight.

[0087] —— The average weight of the m-th representative measuring point or representative measuring point section.

[0088] Step 3.4, standardize and scale the weights.

[0089] To ensure that the sum of the weight coefficients corresponding to each selected representative measurement point or representative measurement point segment is 1, weight normalization scaling is performed and calculated according to the following formula:

[0090] Step 4, synthesis of the representative flow velocity formula for flow routing;

[0091] The synthesis formula for the representative flow velocity of flow routing is expressed as:

[0092]

[0093] In the formula:

[0094] V 代表i —— The representative flow velocity of the i-th measurement for synthesis;

[0095] β m定 —— The weight coefficient of the flow velocity of the m-th representative measurement point or representative measurement point segment in the representative flow velocity;

[0096] V im —— The flow velocity of the m-th representative measurement point or representative measurement point segment at the i-th measurement.

[0097] Example 2, A method for synthesizing representative flow velocity for estimating river flow, applied to the Qiaodongcun Hydrological Station in Qingke Village, Jincheng Sub-district, Lin'an District, Hangzhou City, with a catchment area of 233 km 2 , which is a national basic hydrological station, located in the upper reaches of the Dongtaoxi River Basin and is a representative station in an important area for flood control and drought relief in the Taihu Lake water system. Existing monitoring items include precipitation, evaporation, water level, flow, sediment, etc.

[0098] The measured reach of this station is straight, about 300 m in length, about 80 m in width, and the sand and gravel riverbed is basically stable. Flood control dikes are built on both sides. The highest historical water level of the Qiaodongcun Hydrological Station is 5.14 m, and the maximum flow is 1430 m 3 / s. The main flow measurement method of this station is the combination of suspension cableway and rotor current meter method for flow measurement. Since April 2022, the image method system has been applied for flow measurement. The latest large cross-section result diagram in 2022 is as Figure 2 shown. During the period from January to June 2022, the water level change process line is as Figure 3 shown, and the water level change range is 1.45 - 2.88 m; the measured flow by the cableway current meter was carried out 15 times in total, and the measured flow change range is 0.992 - 120 m 3 / s, and the measured cross-section average flow velocity change range is 0.11 - 0.98 m / s. The water level classification of the Qiaodongcun Hydrological Station is shown in Table 1-1.

[0099] Table 1-1 Water level classification of the Qiaodongcun Hydrological Station

[0100] Water level during high water period / m Water level during medium water period / m Water level during low water period / m Water level during dry season / m Z≥2.75 2.75＞Z≥2.00 2.00＞Z≥1.85 Z＜1.85

[0101] The steps of Comparative Example 1 are described for this example:

[0102] Step 1, transformation of the measured point flow velocity for consistency;

[0103] According to the actual situation of the site, considering two cases of day and night, select the periods from 15:00 to 17:50 on June 5 (daytime) and from 19:00 to 20:40 on June 5 (nighttime) when the water level is relatively high and stable during the flow measurement period for the transformation of the measured point flow velocity for consistency. The corresponding water level fluctuations are 2.79 - 2.88 m and 2.60 - 2.71 m respectively. Since there is a large amount of data, in this example, the daytime period is mainly used as an example for data display, and the nighttime period can be operated analogously.

[0104] From 15:00 to 17:50 on June 5 (daytime): The average water level is 2.84 m. According to the measured cross-section data and the water level - flow relationship in 2021, the average flow velocity of the corresponding cross-section is calculated to be 1.01 m / s. During this period, the image - based flow measurement system monitors the surface flow field of the cross-section every 5 minutes, with a total of 35 measurement times. The results of the transformation of the measured point flow velocity for consistency in each measurement are shown in Tables 2 - 1 and 2 - 2.

[0105] Table 2 - 1 Calculation Table of the Consistency Transformation Coefficient for Each Measurement from 15:00 to 17:50 on June 5 (Daytime)

[0106]

[0107] Table 2 - 2(1) Results Table of the Transformation of the Measured Point Flow Velocity for Consistency in Each Measurement from 15:00 to 17:50 on June 5 (Daytime)

[0108]

[0109] Table 2 - 2(2) Results Table of the Transformation of the Measured Point Flow Velocity for Consistency in Each Measurement from 15:00 to 17:50 on June 5 (Daytime)

[0110]

[0111] Table 2 - 2(3) Results Table of the Transformation of the Measured Point Flow Velocity for Consistency in Each Measurement from 15:00 to 17:50 on June 5 (Daytime)

[0112]

[0113] Table 2 - 2(4) Results Table of the Transformation of the Measured Point Flow Velocity for Consistency in Each Measurement from 15:00 to 17:50 on June 5 (Daytime)

[0114]

[0115] Table 2 - 2(5) Results Table of the Transformation of the Measured Point Flow Velocity for Consistency in Each Measurement from 15:00 to 17:50 on June 5 (Daytime)

[0116]

[0117] Table 2-2(6) Results of the consistency transformation of the measured point flow velocities at each measurement time from 15:00 to 17:50 on June 5 (daytime)

[0118]

[0119] Table 2-2(7) Results of the consistency transformation of the measured point flow velocities at each measurement time from 15:00 to 17:50 on June 5 (daytime)

[0120]

[0121] Table 2-2(8) Results of the consistency transformation of the measured point flow velocities at each measurement time from 15:00 to 17:50 on June 5 (daytime)

[0122]

[0123] Table 2-2(9) Results of the consistency transformation of the measured point flow velocities at each measurement time from 15:00 to 17:50 on June 5 (daytime)

[0124]

[0125] Table 2-2(10) Results of the consistency transformation of the measured point flow velocities at each measurement time from 15:00 to 17:50 on June 5 (daytime)

[0126]

[0127] Step 2, stability analysis of the measured point flow velocity sequence;

[0128] Calculate the coefficient of variation Cv value of the measured point flow velocity sequences after the consistency transformation. The calculation results are shown in Table 2-3:

[0129] Table 2-3 Calculation results of the Cv values of the measured point flow velocity sequences

[0130]

[0131]

[0132] Plot the change of the Cv value of the measured point flow velocity sequences as Figure 4As shown in the figure, during the daytime, the low-value areas of Cv are located at starting distances of 35 - 44m and 57 - 58m, and the proportion of the number of measurement points is 18.1%. Considering eliminating the random error of the measured velocity of the measurement points to the greatest extent, the measured velocities corresponding to starting distances of 35 - 44m and 57 - 58m are all used in the synthesis of the representative velocity. During the night, the low-value area of Cv for the entire cross-section is at starting distances of 22 - 28m, and the low-value area of Cv for the thalweg section of the entire cross-section is at 57 - 58m. Considering eliminating the random error of the measured velocity of the measurement points to the greatest extent and improving the representativeness level of the selection of measurement points, the measured velocities corresponding to starting distances of 22 - 28m and 57 - 58m are all used in the synthesis of the representative velocity, and the proportion of the number of measurement points is 13.6%.

[0133] Step 3: Use the "unit-width discharge comparison method" to determine the weights of the velocities of each representative measurement point or representative measurement point section in the representative velocity for flow pushing;

[0134] The calculation formula for synthesizing the representative velocity for flow pushing during the daytime can be expressed as the formula:

[0135] V 代表i =β (35～44m) V i(35～44m) +β (57～58m) V i(57～58m)

[0136] In the above formula: V 代表i is the synthesized representative velocity for the i-th measurement; β (35～44m) is the weight coefficient of the average velocity of the measurement points at starting distances of 35 - 44m in the index velocity, V i(35～44m) is the average velocity of each measurement point within starting distances of 35 - 44m for the i-th measurement, β (57～58m) , V i(57～58m) and so on by analogy.

[0137] The weight coefficients in the above formula are determined according to the "unit-width discharge comparison method". Using the routine flow measurement results of the station, calculate and statistically analyze the unit-width discharges at 35 - 44m and 57 - 58m under different water level grades of the station, and calculate the weight coefficients through the following two formulas:

[0138] β (35～44m) =Q (35～44m)单 / (Q (35～44m)单 +Q (57～58m)单 )

[0139] β (35～44m) =Q (35～44m)单 / (Q (35～44m)单 +Q (57～58m)单 )

[0140] In the formula: Q (35～44m)单 is the average unit-width discharge at starting distances of 35 - 44m; Q (57～58m)单 is the average unit-width discharge at starting distances of 57 - 58m.

[0141] This flow release mainly targets the medium and high water periods, taking into account the low water as much as possible. The lowest water level for flow release is set at 1.90 m, and the water level range for flow release is 1.90 - 2.88 m. The latest 15 conventional measured flow results of cableway current meters in 2022 are used to participate in the calculation of the weight coefficient. The calculation results are shown in Table 2-4. In Table 2-4, in order to calculate the unit-width flow weight coefficient more accurately, data near the representative measurement point section are introduced when calculating the unit-width flow to improve data accuracy.

[0142] Table 2-4 Calculation results of weight coefficients at each water level based on the measured data of cableway current meters

[0143]

[0144] Plot the β (57～58m) ~Z correlation relationship, where Z is the water level, as Figure 5 shown. The fitting formula of the correlation relationship is: β (57～58m) = 1.5033Z -0.824 .

[0145] During the day period, the water level range for flow release is 1.90 - 2.88 m. According to the method in Step 3, the mean value (57～58m) of β is 0.741. Referring to the above process, the obtained is 0.257. After standardization and scaling, β (57～58m)定 and β (35～44m) are finally determined to be 0.742 and 0.258 respectively.

[0146] Step 4, the formula for synthesizing the index flow velocity during the day period is obtained as:

[0147] V 代表i = 0.258V i(35～44m) + 0.742V i(57～58m) (corresponding water level: 1.90 - 2.88 m).

[0148] By analogy with the calculation method during the day period, analyze and calculate to determine the formula for synthesizing the representative flow velocity during the night period as:

[0149] V 代表i = 0.139V i(22～28m) + 0.861V i(57～58m) (corresponding water level: 1.90 - 2.60 m);

[0150] V 代表i = 0.246V i(22～28m) + 0.754V i(57～58m) (corresponding water level: 2.60 - 2.78 m).

Claims

1. A representative velocity synthesis method for deriving river flow rates. There are n measuring points arranged along the cross-section of the river channel. Characterized in that: It includes the following steps: Step 1, consistency transformation of the measuring point velocities; Step 1.1: Use the general area enclosing method or arithmetic mean method to calculate the average water level of each measurement, and use the Manning formula or the previous water level-flow relationship curve to calculate the average flow velocity V of the section corresponding to the average water level. 平均 ; Step 1.2, use the Manning formula method or the past water level-discharge relationship curve to calculate the cross-sectional average velocity V corresponding to the water level of each measurement i ; Step 1.3, calculate the correction coefficient for the consistency transformation of flow velocities at each measurement Step 1.4, perform a consistency transformation on the flow velocities of each measuring point for each measuring time, V ij变 = α i V ij ; where: V ij is the flow velocity of the j-th measuring point in the i-th measuring time; V ij变 is the corresponding measuring point flow velocity after the consistency transformation of the j-th measuring point in the i-th measuring time; Step 2, stability analysis of the measuring point velocity sequences; Introduce the coefficient of variation Cv for stability analysis of the measuring point velocity data samples: Step 2.1, calculate the flow velocity V of each measuring point after the consistency transformation ij变 Coefficient of variation Cv value of the sequence: Where: Cv j is the Cv value of the flow velocity sequence at the jth measuring point after the consistency transformation; V 1j变 、V 2j变 …V n-1,j变 、V nj变 are the measured point flow velocities at each measurement time for the jth measured point after the consistency transformation; —— The average measured point flow velocity of each measurement at the j-th measured point after the consistency transformation; Step 2.2, Select M measuring points with relatively small Cv values as representative measuring points or select continuous measuring points as representative measuring point segments; Step 3, Use the "unit-width flow comparison method" to determine the weights of the velocities of each representative measuring point or representative measuring point segment in the flow-deducing representative velocity; Step 3.1, Analyze and calculate the weights of the velocities of each representative measuring point or representative measuring point segment in each measurement based on the measured flow rate data; Select the measurement times within the push flow water level section from the existing measured flow results, and calculate the ratio of the unit width flow of each representative measuring point or representative measuring point section in each measurement time to the sum of the unit width flows of all representative measuring points or representative measuring point sections, which is denoted as β mx : Where: Q m单x —— The average discharge per unit width at the x-th measurement of the m-th representative measuring point or representative measuring point section; —— The sum of the average unit-width discharges of each representative measuring point or representative measuring point section at the x-th measurement; β mx —— The single weight coefficient of the m-th representative measuring point or the x-th measurement of the representative measuring point section; Step 3.2, Fit and determine the water level - weight correlation; For the β of each representative measuring point or representative measuring point segment obtained in Step 3.1 mx and the corresponding water level Z x perform a regression analysis to determine the correlation β m = f m (z); Step 3.3, Calculate the mean weight; where: Z a , Z b —— the low and high water level ranges for calculating the weighted mean corresponding to the flow —— The weighted mean of the m-th representative measurement point or representative measurement point segment; Step 3.4, Standardize and scale the weights; To ensure that the sum of the weight coefficients corresponding to each selected representative measurement point or representative measurement point segment is 1, weight normalization scaling is performed and calculated according to the following formula: Step 4, Synthesis of the flow-deducing representative velocity formula; The flow-deducing representative velocity synthesis formula is expressed as: Where: V 代表i —— The representative flow velocity of the i-th synthetic flow measurement β m定 —— Weight coefficient of the flow velocity of the m-th representative measurement point or representative measurement point section in the representative flow velocity; V im —— Flow velocity at the m-th representative measuring point or representative measuring point section in the i-th measurement sequence.

2. A representative velocity synthesis method for deriving river flow rates according to claim 1, Characterized in that: In step 2.2, the proportion of the number of selected representative measuring points is 10% - 30% of the total number of all measuring points.

3. A representative velocity synthesis method for deriving river flow rates according to claim 2, Characterized in that: For the total number of measuring points, select independent representative measuring points, and the number of representative measuring points does not exceed 3; or for the total number of measuring points, select continuously distributed representative measuring points to form representative measuring point segments, and the number of representative measuring point segments does not exceed 3 segments.

4. A representative velocity synthesis method for deriving river flow rates according to claim 1, Characterized in that: In step 3.2, the correlation β m = f m (z) is linear or non-linear, and it is advisable to select the correlation with a large correlation coefficient; when the water level amplitude varies greatly, the correlation is determined section by section according to the water level grades.

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