CN115824169A - River channel flow shore base automatic measurement and refined calculation method - Google Patents

Abstract

A river flow shore base automatic measurement and fine calculation method comprises the following steps: carrying out terrain self-adaptive piecewise fitting based on actually measured terrain data under and on the bank of the river channel section to obtain a river channel section terrain polynomial set; the current river channel water level is monitored in real time, the river channel land-water junction position and the water depth are determined by combining a river channel terrain polynomial set, and the surface flow velocity of the river channel is measured at a fixed distance by rotating a speed measuring radar through an automatic control device; converting corresponding average flow velocity by using a relational expression of surface flow velocity and section average flow velocity of the open channel, and performing self-adaptive piecewise fitting to obtain a river section average flow velocity polynomial set; dividing the water surface of the river into a plurality of sections by using the vertical lines, and calculating the water depth of the river at the vertical lines and the area between adjacent vertical lines in a segmented manner; and calculating the average flow velocity of the center line of the perpendicular line of each section by using the river cross section average flow velocity formula group, and accumulating and calculating the river cross section flow by the product of the area of each section and the average flow velocity. The method has important practical value for performing shore-based real-time online measurement on the river flow under the complex water regime.

Description

River channel flow shore base automatic measurement and refined calculation method

Technical Field

The invention relates to the technical field of hydrological measurement, in particular to a river flow shore base automatic measurement and fine calculation method.

Background

River course flow is important basic data of river hydrological calculation, water resource evaluation and water ecological environment evaluation, and river course flow test calculation is also important content of hydrological work. At present, the flow measurement is mainly based on a contact flow measurement technology, common methods include a flowmeter method, a volumetric method, a floating mark method, a flow meter method, an ultrasonic time difference method, a Doppler ADCP method and the like, and non-contact measurement is mainly realized by measuring surface flow velocity conversion flow by dragging a radar velocimeter through a river-crossing cable. The flow meter method and the volume method cannot be applied to flow measurement of a wide river channel and a large flow river channel; the buoy method and the current meter method need manual operation, are high in labor intensity, have mechanical inertia, are low in response speed, cannot measure rapidly-changing turbulence, need to be regularly checked and maintained, and cannot measure water when the flow is large; instruments used by the ultrasonic time difference method have high requirements on water quality, the instruments need to work in clear water, and the precision is poor when the instruments are measured in turbid water or narrow channels; the Doppler ADCP method needs to carry out shipborne measurement, needs manual operation, has poor accuracy when measuring water with high sediment or impurity content, cannot measure channels with small width, and has high measuring operation danger when encountering river reach or flood season with complex water conditions. The traditional contact type flow measurement technology has low automation degree, cannot meet the requirement of real-time online long-time monitoring, and the existing non-contact type measurement method needs to install stand columns at two sides of a river channel and erect a cable to pull or fix a flow measurement radar, belongs to fixed measurement and is not convenient for measurement equipment transfer. Therefore, a flow measuring method which is real-time online, full-automatic, high in precision, convenient to disassemble and transfer and low in cost of manpower and material resources is urgently needed to be found.

The river channel flow shore base automatic measurement and the refined calculation method are provided, and the problems of traditional contact type and non-contact type river channel flow measurement are well solved. In the flow measurement of river channels of medium and small rivers, the radar flow measurement technology is paid more and more attention by the characteristics of higher automation, higher accuracy, real-time online monitoring and the like. The patent with publication number CN109060056A discloses a river channel section flow calculation method for non-contact radar flow measurement, which is based on measured section data, fits a section polynomial, calculates the water surface gradient of a river channel section according to the position of a fixed radar probe, the measured water level, the surface flow velocity and the river bed roughness by combining a hydraulics Manning formula, reversely calculates the flow velocity between each vertical line section of the river channel section by using a calculation result, and finally calculates the large section flow of the river channel by an area weighting method. The patent with publication number CN 103792533B discloses a fixed point-based river channel section multipoint flow measurement method, which is based on a radar flow meter fixedly installed above a river channel to measure the altitude of the flow meter, the vertical distance from the river channel section to be measured, and the distance from each measuring point to the river channel section, and the flow measurement is realized by adjusting the horizontal orientation and the vertical inclination angle of the radar flow meter. The patent with publication number CN 206515468U discloses an ultrasonic radar flow measurement system, in which a radar support is arranged above a monitored water body, a plurality of radar probes are fixed on the radar support and connected with a radar station room acquisition controller through a wireless transmission module, so as to realize non-contact on-line measurement. The patent with the publication number of CN 206459711U discloses an unmanned aerial vehicle radar current surveying system, and this system comprises unmanned aerial vehicle, wireless remote control radar current surveying appearance, remote control equipment, positioner, data teletransmission, data processing and auxiliary assembly can hover, measures to appointed current surveying position through artifical remote control unmanned aerial vehicle, and this patent need not to erect the test cable way, can realize non-contact current surveying. The patent with publication number CN 113124941B discloses a non-contact measurement and calculation method for river channel flow, in which a speed measuring radar is dragged to obtain the surface flow velocity and water level of a river channel, the terrain and flow velocity formulas of the river channel are obtained through data fitting respectively, vertical coordinates are divided according to the cross section of the river channel, the sectional area and flow velocity are calculated, and then the river channel flow is calculated.

Compared with a contact type current measuring technology, the non-contact type radar current measuring technology can realize measurement work which cannot be finished manually in a severe environment in the field. Most of the existing river channel section flow measurement calculation methods are based on statistical analysis methods, a certain vertical line with a high correlation coefficient is used for representing the flow velocity of a river channel, or polynomial fitting is adopted for the terrain and the flow velocity data of the river channel section to calculate the flow of the whole river channel section, the methods have the defect of being complete in terms of approximation, a large amount of data are fitted by using a single polynomial, and certain errors exist in the methods; the existing riverway section non-contact flow measuring method realizes fixed section flow measurement by adjusting the angle of a fixed flow measuring instrument, carrying the flow measuring instrument by an unmanned aerial vehicle, and towing a radar by a river-crossing cable or erecting a plurality of flow measuring devices simultaneously, and has poor detachability and portability. The current flow measurement technology and the current calculation method have perfect space, the precision is to be further improved, and the portability and the automation degree are required to be further improved.

Disclosure of Invention

The invention aims to provide a river channel flow shore base automatic measurement and refined calculation method, which comprises the steps of measuring a plurality of groups of river channel surface flow velocity and current water level data, obtaining a river channel section shape and an average flow velocity polynomial group through sectional fitting, then refining a river channel surface in a sectional manner, and solving the problem of refined automatic calculation of river channel section flow by combining with a hydraulic natural river channel flow calculation principle.

The technical scheme adopted by the invention is as follows:

a river flow shore base automatic measurement and fine calculation method comprises the following steps:

step one, self-adaptive piecewise fitting of river channel section terrain: measuring the river bank surface topography and the river channel underwater topography at a certain distance on the river channel section to obtain a relative abscissa and relative elevation data set of measuring points, dividing the data set into a plurality of groups according to a set step length by using a self-adaptive segmented search mode, performing grouping fitting, determining the sequence number and parameters of each group of polynomials to obtain a river channel section topography polynomial group;

secondly, measuring the surface flow velocity of the cross section of the river channel: the speed measuring radar is positioned at the downstream of the water level measuring device, faces the upstream at a certain inclination angle, determines the rotation angle of the speed measuring radar according to the installation position, the relative elevation, the current water level and the measurement step length of the speed measuring radar, and automatically rotates the speed measuring radar back and forth by combining the automatic control device to realize unattended and real-time measurement of the surface flow velocity of the river cross section;

thirdly, self-adaptive piecewise fitting of the average flow velocity of the river cross section: converting the surface flow velocity of the river channel cross section measured in the second step into average flow velocity by using a relation formula of the surface flow velocity of the open channel and the average flow velocity of the cross section, and performing self-adaptive piecewise fitting by using the horizontal coordinate of the flow velocity measuring point and the average flow velocity as a flow velocity data set to obtain a polynomial group of the average flow velocity of the river channel cross section;

fourthly, the sectional area of the river channel section is as follows: uniformly or non-uniformly dividing the fitted river channel section by utilizing the dense vertical lines, enabling two adjacent vertical lines to approximately form a right trapezoid or a right triangle, and calculating the river channel water depth at the vertical lines and the area between the adjacent vertical lines in a segmented manner according to the current water level and the horizontal coordinate set of the vertical lines and by combining the terrain polynomial set of the river channel section obtained in the first step;

fifthly, calculating the cross section flow of the river channel: according to the horizontal coordinates of two adjacent vertical lines, the average flow velocity of the cross section of the river channel obtained in the third step is combined with a piecewise polynomial set, and the average flow velocity of the center line of the adjacent vertical lines is calculated; and (4) multiplying the area between the adjacent vertical lines obtained in the fourth step by the average flow velocity of the central line of the corresponding vertical line, and accumulating to obtain the flow of the whole river channel section.

Further, the first step comprises the steps of:

step 1.1, measuring the underwater topography of the river channel section: carrying out underwater topography measurement on the section of the river channel from a left bank to a right bank at an approximately constant speed by using a sailing Doppler profile current meter or a depth finder, and determining a zero coordinate point of a longitudinal relative elevation of the section to be researched in consideration of the maximum water depth of the section of the river channel;

step 1.2, measuring the surface topography of the river bank: utilizing a level gauge and a distance meter to measure the relative elevations and distances of river banks on two sides outwards by using determined water-land boundary points and relative elevation zero coordinate points along the cross section direction of a river channel until the relative elevations and distances reach the outer side of the historical highest flood level to obtain the surface topography of the river banks, and using a water level meter fixedly installed on the left bank and a speed measuring radar upright post as transverse relative zero coordinate points;

step 1.3, a river channel section terrain data set: converting transverse coordinates and relative elevations of the river bank surface and the underwater topography of the river channel by using the determined transverse zero coordinate points and elevation zero coordinate points, wherein all measuring points jointly form a river channel section topography data set, and the river channel section topography measuring point data set is recorded as (X) _t ，H _t )；

Step 1.4, self-adaptive piecewise polynomial fitting of river channel section terrain: for a complex data set with large sample size, dividing the data set into a plurality of groups progressively every other group of data according to a set segmentation step length by using a self-adaptive segmentation search mode, and performing segmentation fitting to obtain a river channel section terrain polynomial group;

the river channel section terrain data set is subjected to piecewise polynomial fitting by a least square method to obtain a river channel section terrain polynomial set as follows:

wherein h is ₁ (x) The relative elevation m of the section terrain of the ith river channel is shown; x is the cross-sectional coordinate m of the river channel; a is _ij The coefficients of the ith section of equation; j 82301 is an index coefficient;

the data acquisition range required by the self-adaptive piecewise polynomial fitting extends to the outer side of the historical highest flood level on both sides so as to ensure that the method is suitable for flow calculation under different water levels, meanwhile, the step length of the piecewise data and the fitting highest power can be adjusted, the formula group obtained by fitting is checked and evaluated by using the determination coefficient, and the piecewise polynomial group can be ensured to perfectly depict the river terrain.

Further, the second step comprises the following steps:

step 2.1, determining river section land and water boundaries: according to the relative height H of the water level measured by the water level meter ₁ Traversing the terrain data set of the river channel section, anchoring two groups of coordinates (X) with the minimum relative elevation difference with the current water level _a ，H _a )、(X _b ，H _b ) Determining the polynomial set of the two sets of coordinates according to the step length set by the piecewise polynomial, and making the polynomial value equal to the current water level value H ₁ Solving to obtain the abscissa (X) _L ，X _R ) The river section land left and right bank boundaries are obtained;

step 2.2, determining the position of the speed measuring radar: the speed measuring radar is close to the water level gauge mounting upright column, so that the zero point of the abscissa of the speed measuring radar is ensured to be the same as the zero point of the relative elevation, and the abscissa of the speed measuring radar is X _V Relative elevation of H ₃ If the vertical column of the speed measuring radar is S away from the vertical column of the water level gauge, the vertical distance between the speed measuring radar and the section of the river channel to be measured is

Step 2.3, measuring the surface flow velocity of the cross section of the river channel: the speed measuring radar faces the water direction, the deviation angle of the speed measuring radar wave is expressed by the angle theta, the calculation is carried out according to the step 2.1, and the horizontal coordinate of the water-land interface is (X) _L ，X _R ) The speed measuring radar rotates through the automatic control device, the distance a is measured once and m times are measured in total,

a rotation angle of

Wherein I is the I-th section, and after one period of measurement is finished, a horizontal coordinate and surface flow velocity data set (X) is obtained _L +a×I，V _{TABLE I} ) The water level meter measures the current water level again to determine a new water-land boundary, and the speed measuring radar measures the surface flow velocity of the river channel at a new angle, so thatAnd (5) circulating and reciprocating.

Further, the third step comprises the following steps:

step 3.1, converting the surface flow velocity of the river channel into an average flow velocity: and (3) converting the surface flow velocity measured in the step (2.3) into the average flow velocity of the corresponding position according to a relation formula of the surface flow velocity of the open channel and the average flow velocity of the cross section, wherein the conversion formula is as follows:

k _s ＝a _n D ₉₀ ＝3.5D ₉₀ (3)

wherein U is the average flow velocity, m/s; u. u _s Surface flow velocity, m/s; k is a radical of _s The roughness of the bed surface; h is the water depth of the vertical line, m; d ₉₀ The sand and sand grains have equal volume grain size; a is _n Taking the coefficient as 3.5; m is a parameter for describing flow conditions, and m =1/6 or m =1/8 is taken;

step 3.2, self-adaptive piecewise fitting of average flow velocity: by measuring the abscissa X of the point _L + axI and corresponding average flow velocity V across section _{Are all I} Performing self-adaptive piecewise fitting as an average flow velocity basic data set to obtain a river cross section average flow velocity polynomial group;

the river cross section average flow velocity data set is subjected to piecewise polynomial fitting by a least square method, and the obtained river cross section average flow velocity polynomial group is as follows:

wherein v is _I (x) The average flow velocity of the section of the river channel at the section I is m/s; x is the cross-sectional coordinate m of the river channel; b is a mixture of _IJ The equation coefficients of the section I; j8230and 1 is an index coefficient.

Further, the fourth step comprises the following steps:

step 4.1, dividing river channel sections: uniform division of fitted river channel section water surface area by utilizing dense verticalsn segments, the number of the vertical lines is n +1, and the vertical line interval is

The abscissa of each perpendicular is X _k ＝X _L - (k-1). Times.b, wherein k is the kth perpendicular;

step 4.2, calculating the water depth of the river channel at the vertical line: two adjacent vertical lines form an approximate right trapezoid or a right triangle, and the abscissa of the kth vertical line is X _k Traversing the river terrain dataset (X) generated in step 1.3 _t ，H _t ) Anchored to X _k The serial number corresponding to the abscissa with the minimum difference is determined, the fitting polynomial of the serial number is the piecewise fitting polynomial corresponding to the kth vertical line, and the X is divided into _k Substituting the polynomial to calculate the relative elevation H of the river cross section at the kth vertical line _k And converted into water depth D _k ＝H ₁ -H _k ；

Step 4.3, determining the horizontal coordinate of the central line of the perpendicular line: according to the abscissas of two adjacent vertical lines, determining the abscissa of the central line of each segment as CX _k ＝X _L +(k-1)×b+0.5b；

Step 4.4, calculating the sectional area of the river channel section: the river course section surface of water regional evenly divide n section, and section 1 and nth are generalized to right triangle, and middle n-2 section is generalized to right trapezoid, according to the river course depth of water and right triangle and the right trapezoid area calculation formula of the perpendicular line department that step 4.2 calculated, obtains adjacent perpendicular line area, river course section segmentation area promptly:

wherein S is _k Is the area of the kth segment in m ² ；D _k The water depth of the kth vertical line is m; b vertical line spacing, unit is m; h _k The topographic elevation of the cross section of the river channel at the kth vertical line is measured by X _k Traversing a terrain data set, determining a polynomial in which the terrain data set is located, and substituting the polynomial for calculation to obtain the unit of m; x _R The unit is m, and the horizontal coordinate of the land boundary line of the right bank of the current water level is the horizontal coordinate of the land boundary line of the right bank of the current water level; x _L Is as followsThe horizontal coordinate of the front water level left bank land and water boundary line is m; and n is the number of segments of the water surface area of the river cross section.

Further, the fifth step comprises the following steps:

step 5.1, calculating the average flow velocity between vertical lines: according to the abscissa of the vertical central line determined in the step 4.3, traversing an abscissa set in the average flow velocity basic data set by adopting the same method as the step 4.2, searching a value closest to the abscissa of the current central line to determine a piecewise fitting polynomial in which the current central line is positioned, substituting the polynomial into the abscissa of the central line, calculating to obtain a corresponding average flow velocity, and calculating average flow velocity values V of all vertical central lines according to the average flow velocity values V _k ＝v _c (CX _k )；

Wherein, V _k Is the average flow speed of the kth section, m/s; CX _k Is the abscissa, m, of the center line of the kth section; v. of _c (x) From CX _k Traversing the average flow velocity data set and determining a polynomial;

step 5.2, calculating the flow of the whole river channel section: segmenting the river channel section area S calculated in the step 4.4 _k Multiplied by the corresponding average flow velocity V _k The flow of the whole river channel section is the sum of all the sectional flows, and the flow of the whole river channel section is obtained after accumulation

The bank-based automatic measurement and refined calculation method for river channel flow, provided by the invention, is based on a hydraulics principle and a data fitting technology, provides a practical operation feasible measurement and calculation method for calculating river channel flow from river channel surface flow velocity and river channel water level for a movable real-time online flow measurement technology, and has the following beneficial effects:

(1) The invention provides a river channel flow shore base automatic measurement and refined calculation method, mainly aiming at solving the problems of high difficulty, high cost, poor precision and difficulty in real-time online monitoring of river channel section flow measurement;

(2) The measuring method provided by the invention combines the set river surface flow velocity measuring interval to calculate the rotation angle of the shore-based speed measuring radar according to the river surface range determined by the current water level, can perform multi-point surface flow velocity measurement to and from the river surface, fully utilizes a large amount of intensive data such as river section terrain, measured surface flow velocity and the like, reduces errors caused by insufficient data quantity, and greatly improves the calculation precision;

(3) The refined calculation method is different from a general data fitting method, aiming at a large amount of measured data, the general data fitting method is difficult to accurately describe the data change trend, and the fitting precision is poor, but the adaptive segmentation fitting method greatly improves the fitting precision by segmenting and fitting a large amount of data, can adaptively determine the fitting formula of the segment where the data is positioned by calculating the data, and simultaneously improves the convenience and the automation degree of data calculation;

(4) According to the measuring method provided by the invention, the measuring device is positioned on the river bank, is easy to install, disassemble and transfer, and can finish automatic cycle measurement by inputting parameters such as relative elevation, relative distance, current water level, measuring interval and the like into the automatic control device; the provided refined calculation method automatically completes the calculation of the sectional average flow velocity and the sectional area by calling the measured topographic data of the river channel, the real-time monitored surface flow velocity and water level data of the river channel, can be suitable for monitoring complex environments and any water period, can identify the water area range of the section of the river channel according to the water level change, and realizes the real-time accurate measurement of the flow under any water level change;

(5) According to the refined calculation method provided by the invention, automatic calculation programs are compiled, the automatic calculation programs comprise a speed measuring radar control module, a river channel section terrain and flow velocity fitting module, an automatic flow calculation module and the like, and refined calculation of river channel section flow under different water level states can be automatically and quickly realized in real time only by inputting information such as actually measured river channel section terrain, relative elevations of a speed measuring radar and a water level gauge, instrument installation positions and the like into a system, so that technical support is provided for river flow monitoring.

Drawings

FIG. 1 is a schematic diagram of an automatic river cross-section flow measurement device on shore base;

FIG. 2 is a flow chart of river cross-section flow shore base automatic measurement and fine calculation according to the present invention;

FIG. 3 is a schematic diagram of the adaptive piecewise polynomial fitting method of the present invention;

fig. 4 (a) is a diagram illustrating a conventional polynomial fitting effect of a river channel cross-sectional terrain according to an embodiment of the present invention;

fig. 4 (b) is a sectional polynomial fitting effect diagram of the river channel section terrain according to the embodiment of the invention;

FIG. 5 is a comparative analysis chart of the measured relative elevation of the river cross section and the piecewise polynomial fit relative elevation according to the embodiment of the present invention;

fig. 6 is a comparative analysis chart of actually measured river cross section flow and calculated flow according to the method of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

According to the method, by acquiring river channel section terrain data, river channel section surface flow velocity, water level data, monitoring equipment positions and the like, polynomial fitting is carried out on the river channel section terrain and the average flow velocity in a self-adaptive segmentation mode, the river channel section is averagely divided into a plurality of sections according to the hydrodynamics natural river flow calculation principle, the area and the average flow velocity of each section are determined through the abscissa of the center line of each section and a segmentation fitting formula group, and finally the whole river channel section flow is obtained through accumulation of the product of the area and the average flow velocity of each section.

The technical solution of the present invention is further described in detail with reference to the following specific examples and the accompanying drawings.

Referring to fig. 1 and fig. 2, an embodiment of the invention provides a river channel flow shore base automatic measurement and fine calculation method, including the following steps:

step one, adaptive piecewise fitting of river channel section terrain

(1) Underwater topography measurement of river cross section: carrying out underwater topography measurement on the section of the researched river channel at intervals of 0.1-1.5M from a left bank to a right bank along the flow direction of vertical water flow by using a sailing type Doppler profile current meter (M9), considering that the maximum water depth of the section of the river channel is measured to be 2.1M, and determining that 0.1M below the maximum water depth of the section of the researched river channel in the longitudinal direction is used as a relative elevation zero coordinate point (2.2M below the current water surface);

(2) Measuring the landform of the river bank: aiming at the surface topography of the river bank, respectively taking land and water junction points of two banks as starting points along the cross section direction of the river channel by using a level gauge and a distance meter, respectively and outwards measuring the relative elevation and the distance of the two banks of the river channel by combining with a determined zero point of the relative elevation, wherein the left side of the vertical column end of the installation instrument is used as a zero point of an abscissa, and the right side of the vertical column end of the installation instrument is used as an outer side end of a historical highest flood level, so that the surface topography of the river bank is obtained (the outermost measuring point of the river bank is higher than the historical highest flood level, and no flooding condition exists);

(3) River section terrain data set: according to the determined zero point of the horizontal coordinate, converting the distance of the river bank measuring point and the distance of the river surface measuring point into a measuring point horizontal coordinate X _t (ii) a According to the determined zero point of the relative elevation, converting the relative elevation of the river bank measuring points and the water depth data of the river channel measuring points into the relative elevation H of the measuring points _t All the measuring points form a river channel section terrain data set together and are recorded as (X) _t ，H _t )；

(4) Adaptive piecewise polynomial fitting of river channel section terrain: in this embodiment, the river channel terrain width is 105.8m, 105 groups of terrain data are collected, the step length of piecewise fitting is set to 3 (when the data volume is less than 3, calculation is performed by using the actual data volume), the highest power is set to 3, a data processing program is written by using python according to the least square principle, and piecewise fitting is performed on a data set of river channel section terrain measuring points to obtain 105 groups of river channel section terrain polynomial groups, the piecewise fitting principle is shown in fig. 3, and the fitting effect is shown in fig. 4 (a), which has a better effect than that of conventional polynomial fitting (fig. 4 (b)).

Step two, measuring the surface flow velocity of the river cross section

(1) River section land and water boundary determination: the current relative water level H of the river section of the embodiment ₁ And (= 2.2 m), determining two groups of coordinates with the minimum relative elevation difference with the current water level as (8.788, 2.115), (97.932, 2.275) by traversing the river channel section terrain data set, determining two groups of polynomials with the serial numbers of 11 and 91 with the two groups of coordinates respectively according to the set step length 3, and enabling the values of the two polynomials to be equal to H ₁ =2.2m, and solving to obtain river section land left and right bank boundary X _L ＝8.22，X _R ＝97.62；

(2) The position of the speed measuring radar is determined: the horizontal coordinate zero point and the relative elevation zero point of the speed measuring radar and the water level gauge are the same, and the horizontal coordinate of the speed measuring radar is X _V =1.0m and a relative elevation of H ₃ =6.2m, S =8.0m from the water level gauge column, and the vertical distance of the speed measuring radar from the cross section of the river channel to be measured is calculated

(3) Measuring the surface flow velocity of the river channel section: the speed measuring radar faces the water inlet direction according to the determined water-land interface horizontal coordinate (X) _L ＝8.22，X _R = 97.62), the speed measuring radar rotates through the automatic control device, the measurement is once at the interval of a =1.788m, the measurement is totally 50 times, and the rotation angle is:

wherein I is the I-th section, and after one period of measurement is finished, a horizontal coordinate and surface flow velocity data set (X) is obtained _L +a×I，V _{TABLE I} ) As shown in fig. 1.

Step three, adaptive piecewise fitting of average flow velocity of river cross section

(1) Converting the surface flow velocity of the river channel into an average flow velocity: and converting the measured surface flow velocity into the vertical line average flow velocity according to a relation formula of the surface flow velocity of the open channel and the section average flow velocity. A relation formula of surface flow velocity and section average flow velocity of an open channel is referred to a result formula derived based on a logarithmic section flow formula in a paper of surface flow detection and deep layer flow inversion algorithm research of a ground wave radar in Wuhan university Li self-supporting, and the result formula is as follows:

k _s ＝a _n D ₉₀ ＝3.5D ₉₀

wherein U is the average flow velocity, m/s; u. of _s Surface flow velocity, m/s; k is a radical of _s The roughness of the bed surface; h is the water depth of the vertical line, m; d ₉₀ The sand and sand grains have equal volume grain size; a is _n Is a coefficient, usually taken as 3.5; m is a parameter for describing the flow condition, and m =1/6 (the relative roughness satisfies 2) is obtained by calculating according to the empirical formula of Manning-strickle in natural river<＝h/k _s <General gravel river of = 1500), engelund recommends m =1/8 (relative roughness satisfies 13/8)<＝h/k _s <=15000 large water depth and small particle size river).

(2) Adaptive piecewise fitting of average flow velocity: to measure the horizontal coordinate X _L + axI and corresponding average flow velocity V across section _{Are all I} And (3) as an average flow velocity basic data set, carrying out self-adaptive piecewise fitting to obtain a river cross section average flow velocity polynomial set: v. of _I (x)＝b _IJ x ^J +b _I(J-1) x ^J-1 +……+b _I1 x+b _I0 Wherein v is _I (x) The average flow velocity of the section of the river channel at the section I is m/s; x is the cross-sectional abscissa of the river channel, m; b _IJ The equation coefficients of the section I; j8230and 1 is an index coefficient.

Fourthly, the sectional area of the river channel section

(1) Dividing river channel sections: evenly dividing the fitted river channel section water surface area into n =405 sections by using dense vertical lines, wherein the total number of the n =405 sections is 406 vertical lines, and the vertical line intervals are

The abscissa X of the kth perpendicular _k ＝X _L +(k-1)×b＝8.22+0.22074(k-1)；

(2) Calculating the water depth of the vertical line: the abscissa of the kth vertical line is X _k Go across the river course landShape data set (X) _t ，H _t ) Determining the sum of X _k The serial number corresponding to the abscissa with the minimum difference is determined, the fitting polynomial of the serial number is the piecewise fitting polynomial corresponding to the kth vertical line, and the X is divided into _k Substituting the polynomial to calculate the relative elevation H of the river cross section at the kth vertical line _k And converted into water depth D _k ＝H ₁ -H _k ；

(3) And (3) determining the horizontal coordinate of the vertical line center line: according to the abscissas of two adjacent vertical lines, determining the abscissa of the central line of each segment as CX _k ＝X _L +(k-1)×b+0.5b＝8.10964+0.22074k；

(4) Calculating the sectional area of the river channel: in the divided 405 refined sections, the 1 st and 405 th sections are generalized to right-angled triangles, the other 403 sections are generalized to right-angled trapezoids, and the area of each section between vertical lines is obtained according to the area calculation formulas of the right-angled triangles and the right-angled trapezoids:

wherein H _k Is the topographic elevation of the river channel section at the kth vertical line and is measured by X _k And traversing the terrain data set, determining a polynomial in which the terrain data set is located, and substituting the polynomial for calculation to obtain the terrain data set.

Step five, river cross section flow calculation

(1) Calculation of average flow velocity between vertical lines: using determined vertical centre line abscissa CX _k Traversing the abscissa set in the average flow velocity basic data set in sequence, searching a value closest to the abscissa of the current center line, determining a piecewise fitting polynomial in which the current center line is positioned according to the sequence number, substituting the polynomial into the abscissa of the center line, and calculating to obtain the corresponding average flow velocity: v _k ＝v _c (CX _k ) Wherein, V _k The average flow velocity of the k section is m/s; CX _k Is the abscissa, m, of the center line of the kth section; v. of _c (x) From CX _k And traversing the average flow velocity data set to determine the located polynomial.

(2) Calculating the flow of the whole river channel section: according to the calculation principle of the hydraulic natural river flow, the flow of each sectionThe average flow velocity is multiplied by the corresponding area, and the area of the right trapezoid or the triangle is multiplied by the corresponding average flow velocity, so that the whole river cross section flow is the sum of all the sectional flows, and the whole river cross section flow is obtained after the sum

Example testing

The method comprises the steps of researching the smoothness and the stability of a river reach, erecting two upright columns on the upper and lower positions of the left bank of a river channel, installing an automatic control device, a speed measuring radar, a water level meter and other equipment, measuring a group of data at intervals of 1.788m according to a calculated rotation angle by rotating the speed measuring radar through the automatic control device, obtaining the surface flow velocity of the cross section of the river channel, and measuring the current water level by using the water level meter; measuring basic data such as cross-sectional flow velocity, flow (used for verification) and water depth along a river section by using a sailing Doppler profile current meter; a Python programming program is utilized, the horizontal coordinate is taken as a variable, the terrain of the river channel cross section and the average flow velocity of the river channel cross section are subjected to sectional fitting, the average error of the terrain fitting of the river channel cross section is less than 0.03m through calculation (the comparison analysis of the actually measured relative elevation of the river channel cross section and the sectional polynomial fitting relative elevation is shown in FIG. 5), and the average error of the fitting of the average flow velocity of the river channel cross section is less than 0.03m/s; setting 405 calculation time segments, wherein the interval of each segment is 0.22074m, respectively traversing the terrain data set and the average flow velocity data set, finding out a serial number corresponding to the nearest value of an abscissa in the data set, determining a polynomial where each abscissa is located, respectively substituting each abscissa, calculating the corresponding area and the central line flow velocity, and obtaining the whole section flow of 24.28m by a hydraulic natural river flow calculation method ³ The measured river cross-section flow is 24.20m ³ (s), relative error is less than 0.4%; in order to further verify the precision of the invention, the actually measured flow and the calculated flow of each section are compared and analyzed, and the difference of the flow is 0.014m at most ³ And/s, the relative error is less than 10 percent (the comparison analysis of the measured flow of the river cross section and the flow calculated by the method is shown in figure 6).

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are also within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (6)

1. A river flow shore base automatic measurement and fine calculation method is characterized by comprising the following steps: the method comprises the following steps:

step one, self-adaptive piecewise fitting of river channel section terrain: measuring the surface topography of a river bank and the underwater topography of the river channel at a certain distance on the cross section of the river channel to obtain a data set of relative horizontal coordinates and relative elevations of measuring points, dividing the data set into a plurality of groups according to a set step length by using a self-adaptive segmented search mode, performing grouping fitting, determining the serial number and parameters of each group of polynomials to obtain a polynomial group of the topography of the cross section of the river channel;

secondly, measuring the surface flow velocity of the cross section of the river channel: the speed measuring radar is positioned at the downstream of the water level measuring device, faces the upstream at a certain inclination angle, determines the rotation angle of the speed measuring radar according to the installation position, the relative elevation, the current water level and the measurement step length of the speed measuring radar, and automatically rotates the speed measuring radar back and forth by combining the automatic control device to realize unattended and real-time measurement of the surface flow velocity of the river cross section;

thirdly, self-adaptive piecewise fitting of the average flow velocity of the river cross section: converting the surface flow velocity of the river channel cross section measured in the second step into average flow velocity by using a relation formula of the surface flow velocity of the open channel and the average flow velocity of the cross section, and performing self-adaptive piecewise fitting by using the horizontal coordinate of the flow velocity measuring point and the average flow velocity as a flow velocity data set to obtain a polynomial group of the average flow velocity of the river channel cross section;

fourthly, the sectional area of the river channel section is as follows: uniformly or non-uniformly dividing the fitted river channel section by utilizing the dense vertical lines, enabling two adjacent vertical lines to approximately form a right trapezoid or a right triangle, and calculating the river channel water depth at the vertical lines and the area between the adjacent vertical lines in a segmented manner according to the current water level and the horizontal coordinate set of the vertical lines and by combining the terrain polynomial set of the river channel section obtained in the first step;

fifthly, calculating the cross section flow of the river channel: according to the abscissa of two adjacent vertical lines, combining the piecewise polynomial group of the average flow velocity of the cross section of the river channel obtained in the third step, and calculating the average flow velocity of the center line of the adjacent vertical lines; and (4) multiplying the area between the adjacent vertical lines obtained in the fourth step by the average flow velocity of the central line of the corresponding vertical line, and accumulating to obtain the flow of the whole river channel section.

2. The method for automatically measuring and refining the river channel flow shore-based calculation according to claim 1, wherein: the first step comprises the following steps:

step 1.1, underwater topography measurement of river cross section: carrying out underwater topography measurement on the section of the river channel from a left bank to a right bank at an approximately constant speed by using a sailing Doppler profile current meter or a depth finder, and determining a zero coordinate point of a longitudinal relative elevation of the section to be researched in consideration of the maximum water depth of the section of the river channel;

step 1.2, measuring the surface topography of the river bank: utilizing a level gauge and a distance meter to measure the relative elevations and distances of river banks on two sides outwards by using determined water-land boundary points and relative elevation zero coordinate points along the cross section direction of a river channel until the relative elevations and distances reach the outer side of the historical highest flood level to obtain the surface topography of the river banks, and using a water level meter fixedly installed on the left bank and a speed measuring radar upright post as transverse relative zero coordinate points;

step 1.3, a river section terrain data set: converting transverse coordinates and relative elevations of the river bank surface and the underwater topography of the river channel by using the determined transverse zero coordinate points and elevation zero coordinate points, wherein all measuring points jointly form a river channel section topography data set, and the river channel section topography measuring point data set is recorded as (X) _t ，H _t )；

Step 1.4, adaptive piecewise polynomial fitting of river cross section terrain: for a complex data set with large sample size, dividing the data set into a plurality of groups progressively every other group of data according to a set segmentation step length by using a self-adaptive segmentation search mode, and performing segmentation fitting to obtain a river channel section terrain polynomial group;

the river channel section terrain data set is subjected to piecewise polynomial fitting by a least square method to obtain a river channel section terrain polynomial set as follows:

wherein h is ₁ (x) The relative elevation m of the section terrain of the ith river channel is shown; x is the cross-sectional abscissa of the river channel, m; a is _ij The coefficients of the ith section of equation; j\8230where1 is an index coefficient;

the data acquisition range required by the self-adaptive piecewise polynomial fitting extends to the outer side of the historical highest flood level on both sides so as to ensure that the method is suitable for flow calculation under different water levels, meanwhile, the step length of the piecewise data and the fitting highest power can be adjusted, the formula group obtained by fitting is checked and evaluated by using the determination coefficient, and the piecewise polynomial group can be ensured to perfectly depict the river terrain.

3. The method for automatically measuring and refining the river channel flow shore-based according to claim 2, wherein: the second step comprises the following steps:

step 2.1, determining river section land and water boundaries: according to the relative height H of the water level measured by the water level gauge ₁ Traversing the terrain data set of the river channel section, anchoring two groups of coordinates (X) with the minimum relative elevation difference with the current water level _a ，H _a )、(X _b ，H _b ) Determining the polynomial set of the two sets of coordinates according to the step length set by the piecewise polynomial, and making the polynomial value equal to the current water level value H ₁ Solving to obtain the abscissa (X) _L ，X _R ) The river section land left and right bank boundaries are obtained;

step 2.2, determining the position of the speed measuring radar: the speed measuring radar is close to the water level gauge mounting upright column, so that the zero point of the abscissa of the speed measuring radar is ensured to be the same as the zero point of the relative elevation, and the abscissa of the speed measuring radar is X _V Relative elevation of H ₃ If the distance between the vertical column of the speed measuring radar and the vertical column of the water level gauge is S, the vertical distance between the speed measuring radar and the cross section of the river channel to be measured is S

Step 2.3, measuring the surface flow velocity of the river cross section: the speed measuring radar faces the water direction, the deviation angle of the speed measuring radar wave is expressed by the angle theta, the calculation is carried out according to the step 2.1, and the horizontal coordinate of the water-land interface is (X) _L ，X _R ) The speed measuring radar rotates through the automatic control device, the distance a is measured once and m times are measured in total,

a rotation angle of

Wherein I is the I-th section, and after one period of measurement is finished, a horizontal coordinate and surface flow velocity data set (X) is obtained _L +a×I，V _{TABLE I} ) And the water level meter measures the current water level again to determine a new water-land boundary, and the speed measuring radar measures the surface flow velocity of the river channel at a new angle, so that the operation is repeated in a circulating mode.

4. The method for automatically measuring and refining the river channel flow shore base according to claim 3, wherein: the third step comprises the following steps:

step 3.1, converting the surface flow velocity of the river channel into an average flow velocity: and (3) converting the surface flow velocity measured in the step (2.3) into the average flow velocity of the corresponding position according to a relation formula of the surface flow velocity of the open channel and the average flow velocity of the cross section, wherein the conversion formula is as follows:

k _s ＝a _n D ₉₀ ＝3.5D ₉₀ (3)

wherein U is the average flow velocity, m/s; u. of _s Surface flow velocity, m/s; k is a radical of formula _s The roughness of the bed surface; h is the water depth of the vertical line m; d ₉₀ The sand and sand grains have equal volume grain size; a is _n Taking 3.5 as a coefficient; m is a parameter for describing flow conditions, and m =1/6 or m =1/8 is taken;

step 3.2, self-adaptive piecewise fitting of average flow velocity: to measure the horizontal coordinate X _L + axI and corresponding average flow velocity V across section _{Are all I} Performing self-adaptive piecewise fitting to obtain a river cross section average flow velocity polynomial set as an average flow velocity basic data set;

the river cross section average flow velocity data set is subjected to piecewise polynomial fitting by a least square method, and the obtained river cross section average flow velocity polynomial group is as follows:

wherein v is _I (x) The average flow velocity of the section of the river channel at the section I is m/s; x is the cross-sectional coordinate m of the river channel; b _IJ The equation coefficients of the section I; j8230and 1 is an index coefficient.

5. The method for automatically measuring and refining the river channel flow shore base according to claim 4, wherein: the fourth step comprises the following steps:

step 4.1, dividing river channel sections: evenly dividing the fitted river channel section water surface area into n sections by utilizing dense vertical lines, wherein the number of the vertical lines is n +1, and the vertical line interval is

The abscissa of each perpendicular is X _k ＝X _L - (k-1). Times.b, wherein k is the kth perpendicular;

step 4.2, calculating the water depth of the river channel at the vertical line: two adjacent vertical lines form an approximate right trapezoid or a right triangle, and the abscissa of the kth vertical line is X _k Traversing the river terrain dataset (X) generated in step 1.3 _t ，H _t ) Anchored to X _k The serial number corresponding to the abscissa with the minimum difference is determined, the fitting polynomial of the serial number is the piecewise fitting polynomial corresponding to the kth vertical line, and the X is divided into _k Substituting the polynomial to calculate the relative elevation H of the river cross section at the kth vertical line _k And converted into water depth D _k ＝H ₁ -H _k ；

Step 4.3, determining the horizontal coordinate of the center line of the perpendicular lineDetermining: according to the abscissas of two adjacent vertical lines, determining the abscissa of the central line of each segment as CX _k ＝X _L +(k-1)×b+0.5b；

Step 4.4, calculating the sectional area of the river channel section: the river course section surface of water regional evenly divided n section, section 1 and nth section, generalize to right angled triangle, and middle n-2 section is generalized to right trapezoid, according to the perpendicular line department river depth of water and right angled triangle and the right trapezoid area calculation formula of step 4.2 calculation, obtains adjacent perpendicular line area, river course section segmentation area promptly:

wherein S is _k Is the area of the kth segment in m ² ；D _k The water depth of the kth vertical line is m; b vertical line spacing, unit is m; h _k Is the topographic elevation of the river channel section at the kth vertical line and is measured by X _k Traversing a terrain data set, determining a polynomial in which the terrain data set is located, and substituting the polynomial for calculation to obtain the unit of m; x _R The unit is m, and the horizontal coordinate of the land boundary line of the right bank of the current water level is the horizontal coordinate of the land boundary line of the right bank of the current water level; x _L The unit is m, and the horizontal coordinate of the left bank land and water boundary line of the current water level is shown as the horizontal coordinate of the left bank land and water boundary line of the current water level; and n is the number of segments of the water surface area of the river cross section.

6. The method for automatically measuring and refining the river channel flow shore base according to claim 5, wherein: the fifth step comprises the following steps:

step 5.1, calculating the average flow velocity between vertical lines: according to the abscissa of the vertical central line determined in the step 4.3, traversing an abscissa set in the average flow velocity basic data set by adopting the same method as the step 4.2, searching a value closest to the abscissa of the current central line to determine a piecewise fitting polynomial in which the current central line is positioned, substituting the polynomial into the abscissa of the central line, calculating to obtain a corresponding average flow velocity, and calculating average flow velocity values V of all vertical central lines according to the average flow velocity values V _k ＝v _c (CX _k )；

Wherein, V _k The average flow speed of the kth section is m/s; CX _k Is the abscissa, m, of the center line of the kth section; v. of _c (x) From CX _k Traversing the average flow velocity data set and determining a polynomial;

step 5.2, calculating the flow of the whole river channel section: segmenting the river channel section area S calculated in the step 4.4 _k Multiplied by the corresponding average flow velocity V _k The flow of the whole river channel section is the sum of all the sectional flows, and the flow of the whole river channel section is obtained after accumulation

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