A method for calculating the distance across a river channel cross section.

Abstract

The application relates to a river section distance calculation method, which comprises the following specific steps: collecting river terrain data and section data; judging the collected data, and calculating the river section distance under the conditions of existing historical river terrain data and only section data. The application optimizes the value of the distance between adjacent sections in the calculation of the river storage capacity by the traditional section method, and realizes the calculation of the section distance under the conditions of existing historical river terrain and no historical river terrain data.

Description

Technical Field

[0001] This application relates to the field of geographic information system technology, specifically to a method for calculating the distance of a river cross section. Background Technology

[0002] Due to the high time and material costs associated with river topographic surveying, river topographic information is typically collected by measuring river cross sections or by taking multiple cross sections at intervals. River cross sections are usually laid out continuously at appropriate intervals along the river channel, perpendicular to the flow direction, to fully reflect the river's course. In hydrology, river cross section data is frequently used to calculate channel storage capacity. The formula for calculating the channel storage capacity V between two adjacent cross sections is:

[0003] V = [S 上 +S 下 +(S 上 ×S 下 ) 1 / 2 ]d / 3

[0004] In the formula, S 上 S represents the cross-sectional area of ​​the water passage. 下 Let S be the cross-sectional area of ​​the lower section, and d be the distance between two adjacent sections. The cross-sectional area S between the upper and lower sections is... 上 S 下 All of these can be accurately measured and calculated, but the distance between adjacent cross-sections lacks a clear definition and is essentially an equivalent distance. Common methods for determining this distance include: 1. the length of the line connecting the midpoints of the cross-sections; 2. the centroid method; and 3. manual drawing followed by measurement. However, all of these are fixed values. In reality, the cross-sectional distances determined by these methods may deviate significantly from the actual distances. Furthermore, as water levels change, the river channel morphology and length also change. Therefore, the length of the river channel cross-section distance becomes a key source of error in calculating channel storage using the cross-sectional method. Summary of the Invention

[0005] The purpose of this application is to provide a method for calculating the equivalent distance of a river cross section, optimize the value of the distance between adjacent cross sections when calculating the channel storage of the traditional cross section method, and realize the calculation of river scour and sedimentation under the background of having historical river topography and not having historical river topography data.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] This application provides a method for calculating the distance across a river cross section, including the following specific steps:

[0008] Collect river channel topographic data and cross-sectional data;

[0009] The data collected is assessed, and the river cross-sectional distance is calculated separately when historical river topographic data is available and when only cross-sectional data is available.

[0010] Scenario 1: Given existing historical river topographic data, first calculate the channel storage capacity (Vol) of the river topography below the water surface between two adjacent cross-sections using the river topographic data from a specific measurement. 地 The cross-sectional area S below the water surface between the two adjacent cross sections. 上 S 下 Thus, the equivalent distance d between the two cross sections is obtained:

[0011] d = 3Vol 地 / [S 上 +S 下+ (S 上 ×S 下 ) 1 / 2 ]

[0012] Scenario 2: With only cross-sectional data available, extend two adjacent cross-sections. If the two cross-sections intersect at a single point, there will be a fan-shaped area formed by the two cross-sections or their extensions. Calculate the positions AB and CD of the water surface lines of the upper and lower cross-sections, and their midpoints E and F, based on the water level and cross-sectional data. Calculate the two line segments OE and OF formed by the intersection of the midpoints of the water surface lines of the two cross-sections and the cross-sections or their extensions, with lengths R and R respectively. 上 R 下 , with R 上 R 下 Let be the radius and θ form an scalene sector. The arc length d of the sector is the equivalent distance between adjacent cross-sections. The formula for calculating d is:

[0013] d=(R 上 +R 下 )θ / 2,

[0014] If the two cross sections are parallel, then the equivalent distance between the two cross sections is the distance between the parallel lines of the two cross sections.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] (1) With historical river topographic data as a reference, the equivalent distance of the cross section under different water levels can be inferred by using the channel storage volume under different water levels between cross sections, which is closer to the equivalent distance of the cross section when calculating the channel storage volume using the cross section method.

[0017] (2) With only cross-sectional data available, the characteristics of natural river formation and the characteristics of cross-sectional layout reflecting river trend were fully considered. The original cross-sectional distance was changed from a straight line to a curve. Furthermore, the changes in river morphology under different water levels were taken into account, making it closer to the actual distance under natural river conditions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram illustrating the calculation of the distance between adjacent cross sections in the case where only cross section data is available, according to an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will now be described with reference to the accompanying drawings. It should be noted that similar reference numerals and letters in the following drawings indicate similar items; therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0021] The terms “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0022] The terms “first,” “second,” etc., are used only to distinguish one entity or operation from another, and should not be construed as indicating or implying relative importance, nor as requiring or implying any such actual relationship or order between these entities or operations.

[0023] Please see Figure 1 As shown, this invention provides a method for calculating river channel scour and sedimentation volume using the cross-sectional method, comprising the following specific steps:

[0024] Taking two adjacent fixed cross sections S292 and S293 in the Three Gorges Reservoir as examples, the river section has river topographic data and cross section data in 2016 and 2022. The data is used as an example to verify the effectiveness of the present invention in calculating the channel storage capacity.

[0025] Based on the available data, the coordinates of the two endpoints of sections S292 and S293 can be determined. The length of the line connecting the midpoints of the two sections, the intersection of the two sections or their extensions, and the included angle can then be calculated. Relevant information is shown in Table 1.

[0026] Table 1 Basic Information of Cross-section

[0027]

[0028] Scenario 1: Assuming only 2022 river topographic data is available, based on the 2022 river topographic data, at water levels of 145m and 165m, the cross-sectional distance formula d = 3Vol can be used. 地 / [S 上 +S 下 +(S 上 ×S 下 ) 1 / 2 The equivalent distances between sections S292 and S293 were found to be 2183m and 2115m, respectively. Relevant information is shown in Table 2.

[0029] Table 2 Equivalent Spacing of Cross Sections under Case 1

[0030]

[0031] Based on the 2016 cross-sectional data, the channel storage capacity was calculated using the cross-sectional method. The differences between the channel storage capacity calculated by the original method and the optimized equivalent distance and the true value of the channel storage capacity calculated using the 2016 river channel topography are compared. Relevant information is shown in Table 3.

[0032] Table 3 Comparison of Tank Storage Calculation Accuracy After Optimization in Case 1

[0033]

[0034] Scenario 2: Assuming only the river cross-section data for 2022 is available, calculate the channel storage capacity under the two methods in 2022, and use the channel topographic data of 2022 to calculate the channel storage capacity as the true value for comparison.

[0035] Based on the cross-sectional location information and water level elevation, the coordinates of the left and right endpoints of the water surface line at different water levels can be determined. Furthermore, the coordinates of the intersection point of the cross-section or its extension, and the included angle between the cross-sections can be calculated. Therefore, the distance R between the midpoint of the water surface line and the intersection point of the cross-section or its extension can be determined. S292 At water levels of 145 meters and 165 meters, the depths are 2972 ​​meters and 2955 meters respectively. R S293 The water levels at 145 meters and 165 meters are 2952 meters and 2903 meters respectively. Relevant information is shown in Table 4.

[0036] Table 4 Cross-section Calculation Information Table

[0037]

[0038] Using the cross-sectional distance formula d=(R 上 +R 下Using θ / 2, the equivalent cross-sectional distances at water levels of 145m and 165m are calculated to be 2101m and 2078m, respectively. Based on 2022 river cross-sectional data, the areas of cross-sections S292 and S293 at water levels of 145m and 165m are known. Using the cross-sectional method, the channel storage capacity is calculated using the formula: V=[S 上 +S 下 +(S 上 ×S 下 ) 1 / 2 ]d / 3, the tank storage capacity under the original cross-sectional distance and the optimized equivalent cross-sectional distance can be obtained respectively. Relevant information is shown in Table 5:

[0039] Table 5 Comparison of Tank Storage Accuracy After Optimization in Case 2

[0040]

[0041] Based on the 2022 cross-sectional data, the channel storage capacity was calculated using the cross-sectional method. The differences between the channel storage capacity calculated by the original method and the optimized equivalent distance and the true value of the channel storage capacity calculated using the 2022 river channel topography are compared. Relevant information is shown in Table 6.

[0042] Table 6 shows the equivalent cross-sectional spacing and corresponding tank storage capacity under case 2.

[0043]

[0044] The results show that, in both cases, using the optimized channel cross-sectional distance for channel storage calculation improves accuracy to varying degrees.

[0045] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method of calculating a distance of a river cross section, characterized by, The method comprises the following specific steps: Collecting riverway topographic data and cross section data; Judging the collected data, and calculating the distance between cross sections of the riverway under the condition of existing historical riverway topographic data and under the condition of only having cross section data; Under the condition of existing historical river channel topography data, the slot storage Vol of river channel topography under a water surface between two adjacent sections is calculated by using channel topography data of a survey 地 The section area S between the upper and lower adjacent sections under the water surface 上 , S 下 , and thus the equivalent distance d between the two surveys is obtained: d = 3Vol 地 / [ S 上 +S 下+ (S 上 ×S 下 ) 1 / 2 ] In the case of only cross-section data, the two adjacent cross-section lines are extended, if the two cross-sections intersect at a point, then the fan-shaped area formed by the two cross-sections or the extension lines, according to the calculated water level and cross-section data, the midpoint of the water surface line of the upper and lower cross-sections, the intersection point of the two cross-section water surface line midpoints and the cross-section or its extension line as the radius R 上 , R 下 and its angle θ form an arc, and the length d of the arc is the distance between the adjacent cross-sections, and the calculation formula of d is: d = (R 上 + R 下 ) θ / 2, If the two cross sections are parallel, the distance between the two cross sections is the line connecting the midpoints of the water surface lines of the two cross sections.

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