Dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape

Abstract

This invention discloses a method for dynamically calculating river width based on intersection analysis of water level and river channel cross-sectional shape, and relates to the technical fields of river hydrological monitoring and river channel morphology analysis. [Solution] The method performs data quality checks and data format standardization on water level and cross-sectional data. A continuous elevation function is constructed by single-cross section interpolation, and the three-dimensional topographic surface of the river channel is reconstructed by spatial interpolation of multiple cross-sections. At a predetermined time, a horizontal water level line is set, and this is solved simultaneously with the cross-sectional elevation function to find the set of intersections, and effective intersections on the left bank and right bank are identified based on the number of intersections and the maximum distance criterion. The water surface width is calculated, geometric correction is performed, and uncertainty is calculated based on error propagation. A river width time series is constructed, and the response relationship with flow rate and water level is established. The present invention employs a dynamic calculation method for river width based on the intersection analysis of water level and river channel cross-sectional shape, and the time resolution can reach the daily or hourly scale, making it suitable for long-term continuous dynamic monitoring of river width.

Description

[Technical Field]

[0001] This invention relates to the technical fields of hydrological monitoring and measurement of rivers and river channel morphology analysis, and more particularly to a method for dynamically calculating river width based on intersection analysis of water level and river channel cross-sectional shape. [Background technology]

[0002] River channel width is an important parameter representing the morphological characteristics of a river channel. Its dynamic changes reflect the regularity of hydrological processes and riverbed changes, and it has significant implications for flood forecasting, water resource management, river channel management, and ecological protection. Conventional methods for obtaining river channel width mainly rely on field surveys, interpretation using remote sensing, or estimation using hydraulic models. Field surveys are highly accurate but costly and do not easily form continuous time series. Remote sensing methods can cover a wide area but are affected by rainfall and clouds, and their temporal resolution is limited by the revisit cycle. Hydraulic models require the identification of numerous parameters, and their applicability is limited in complex river channels.

[0003] Conventional technologies have many challenges, including insufficient temporal resolution, poor data continuity, inconsistencies between accuracy and efficiency, lack of standardized and automated processes, and high long-term monitoring costs, making it particularly difficult to capture rapid changes in river width during floods. [Overview of the project]

[0004] The objective of this invention is to provide a dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape. This solves the problems of insufficient temporal resolution and poor data continuity in the dynamic monitoring of river width in conventional technologies. By realizing an automatic river width calculation method through geometric intersection analysis, it is possible to obtain a continuous time series of river width on a daily or hourly scale, quantitatively evaluate the uncertainty of the controlled object, and enable analysis of the hydrological response.

[0005] To achieve the above objective, the present invention provides a dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape, and includes the following steps. Step S1: Obtain the water level time series H(t) and river channel cross-sectional topographic data of the river under study, and perform data quality checks and data format standardization on the water level time series and cross-sectional topographic data. Here, the cross-sectional topographic data includes the cross-sectional survey point number, the cross-sectional distance x, and the elevation z. Step S2: For each cross-section, use the interpolation method to perform the continuous elevation function z=f s (x) is constructed, and spatial interpolation is performed on multiple cross-sections to reconstruct the three-dimensional topographic surface of the river channel. Step S3: For any time t, set the equation z=H(t) for the horizontal water level line, and solve this simultaneously with the continuous elevation function to find the set of intersections {x} between the water level line and the cross section. i} is obtained. Furthermore, the left bank intersection x is obtained based on the effectiveness determination and selection rules. left and the intersection on the right bank x right Confirm. Step S4:x left and x right Based on this, the river width W(t) is calculated, and geometric correction is performed using the angle between the cross section and the main flow direction, and the uncertainty U of the river width is also calculated. W(t) Output. Step S5: Combine the river width W(t) at each time point to create time-series data of river width, and construct a statistical response relationship with the water level time series H(t) and / or flow rate Q(t), and use it for dynamic change analysis.

[0006] Preferably, the data quality check in step S1 includes detecting abnormal values ​​in the water level, checking the topology consistency of the cross-sectional data, imputing missing data or marking invalid data, and unifying the water level and cross-sectional elevation to the same elevation reference plane and coordinate system.

[0007] Preferably, the interpolation method in step S2 is Lagrangian interpolation, and Lagrangian interpolation satisfies the following equation.

[0008] [Numerical formula]

[0009] Here, f s (x) is the continuous elevation function of the cross-section, L i (x) is a Lagrange interpolation basis function, z i i is the elevation of the i-th measuring point, and n is the number of measuring points.

[0010] Preferably, the spatial interpolation of a plurality of cross-sections in said step S2 comprises the following. Grid interpolation is adopted to construct a terrain surface z=F(X,Y), wherein (X,Y) are plane coordinates, and F(X,Y) is an elevation value after interpolation. For grid interpolation, mesh resolutions ΔX and ΔY are set, and the elevation at mesh nodes is estimated by using an inverse distance weighting method or a Kriging model.

[0011] Preferably, the validity determination in said step S3 comprises the following. When the number of intersection points m < 2, the river width result at the current time t is determined as invalid. When m=2, the two intersection points are respectively a left bank intersection point and a right bank intersection point. When m>2, screening of a plurality of intersection points is performed.

[0012] JPEG0007913797000003.jpg19170

[0013] Preferably, in said step S4, the river width is calculated by the following formula.

[0014] [Numerical formula]

[0015] [Numerical formula]

[0016] Alternatively, when projection correction is performed with the main flow direction angle α, the river width is as follows.

[0017] [Formula] .

[0018] JPEG0007913797000007.jpg12170

[0019] [Formula]

[0020] JPEG0007913797000009.jpg9170

[0021] Preferably, the statistical response relationship in step S5 includes a power function or a log-linear model, which is represented by the following formula.

[0022] [Formula]

[0023] The log-linear form thereof is as shown in the following formula.

[0024] [Formula]

[0025] Parameters a, b and c are identified by a regression method.

[0026] Disclosed is a dynamic river width calculation system based on intersection analysis of water level and river channel cross-section shape, comprising a data preprocessing module, a spatial interpolation and three-dimensional reconstruction module, an intersection analysis module, a river width calculation and uncertainty evaluation module, and a dynamic analysis module.

[0027] Therefore, the present invention adopts the dynamic river width calculation method based on intersection analysis of water level and river channel cross-section shape, and has the following beneficial effects. (1) This method makes full use of normal observation data from hydrological observation stations, does not rely on remote sensing images or high-frequency field surveys, is low-cost, and is not affected by weather conditions. (2) This method has high temporal resolution, and can reach the daily scale and even the hourly scale, making it possible to capture rapid changes in river width during floods. (3) Because this method is based on solving intersections by geometric analysis and screening criteria for multiple intersections, it can be applied to complex cross-sections with river core gravel islands. (4) This method uses the uncertainty quantification index U W(t) This service provides data quality checks and helps evaluate the reliability of the results. (5) This method establishes a standardized and automated process from raw observational data to river width time series and even hydrological response analysis, making it suitable for long-term continuous monitoring and batch processing.

[0028] The technical configuration of the present invention will be described in more detail below with reference to the attached drawings and embodiments. [Brief explanation of the drawing]

[0029] [Figure 1] This is a flowchart of the dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape according to the present invention. [Figure 2] This is a schematic diagram illustrating the intersection analysis of the water level line and the cross-sectional shape of the river channel according to the present invention. [Figure 3] This is a schematic diagram illustrating the geometric correction of river width and the error propagation of uncertainty according to the present invention. [Figure 4] This is a schematic diagram showing the time series of river width and its response relationship to flow rate / water level. [Modes for carrying out the invention]

[0030] The technical configuration of the present invention will be further described below with reference to the attached drawings and embodiments. Unless otherwise defined, technical or scientific terms used in this invention shall have the general meanings understood by a person of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention shall not imply any order, quantity, or importance, but shall be used solely to distinguish different components. Similar terms such as “include” or “inclusive” shall mean that the element or object described before the term includes the elements or objects listed after the term and their equivalents, but shall not exclude other elements or objects. Similar terms such as “connect” or “link” may include electrical connections, whether direct or indirect, and may not be limited to physical or mechanical connections. “Up,” “down,” “left,” “right,” etc., indicate only relative positional relationships, and such relative positional relationships shall change accordingly after the absolute position of the object described changes.

[0031] Referring to Figures 1 to 4, the present invention provides a dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape. As shown in Figure 1, the method includes the following steps. Step S1: Data acquisition and preprocessing The water level time series H(t) of the river channel (a topographic area through which water can flow) under study is obtained. The water level time series can be either daily or hourly water levels. Topographic data of the river channel cross section (data including the transverse distance x and elevation z of multiple survey points acquired along the direction transverse of the river channel) is obtained. This data is a collection of discrete topographic survey points collected along a certain cross section survey line, and includes at least the cross section survey point number / distance s, the transverse distance x, and the elevation z. Here, the transverse distance x is assumed to be zero at the cross section starting point and increases along the direction of the cross section survey line, and the elevation z is an elevation value under a unified elevation standard. Topographic data of the river channel cross section can be obtained by total station surveying, bathymetric survey cross section, or laser point cloud extraction. The water level time series and cross-sectional topographic data will undergo data quality checks and data format standardization. Specifically, this includes: detecting outliers and identifying fluctuation points in the water level data; checking the topology and completeness of the cross-sectional topographic data (checking for x-monotonicity, removing duplicate / jump points, imputing missing data, and marking invalid data); and unifying the water level and cross-sectional elevation to the same elevation reference plane and coordinate system to ensure comparability between the water level H(t) and the cross-sectional elevation z, as well as achieving spatial consistency.

[0032] JPEG0007913797000012.jpg34170

[0033]

number

[0034] JPEG0007913797000014.jpg101170

[0035]

number

[0036] JPEG0007913797000016.jpg64170

[0037] JPEG0007913797000017.jpg119170

[0038] JPEG0007913797000018.jpg32170

[0039]

number

[0040] If the cross-section and the direction of the river channel are not perpendicular, a geometric correction is performed based on the angle θ between the cross-section and the direction of the river channel, and the river width after geometric correction is:

[0041]

number

[0042] Alternatively, if projection correction is performed using the main current direction angle α, the river width is:

[0043]

number

[0044] JPEG0007913797000022.jpg16170

[0045]

number

[0046] JPEG0007913797000024.jpg10164

[0047] JPEG0007913797000025.jpg29170

[0048]

number

[0049] The logarithmic linear form is given by the following equation.

[0050]

number

[0051] We will use a regression method to identify parameters a, b, and c.

[0052] A dynamic calculation system for river width based on intersection analysis of water level and river channel cross-sectional shape, comprising a data preprocessing module, a spatial interpolation and three-dimensional reconstruction module, an intersection analysis module, a river width calculation and uncertainty evaluation module, and a dynamic analysis module.

[0053] JPEG0007913797000028.jpg127170

[0054]

number

[0055] JPEG0007913797000030.jpg29170

[0056] JPEG0007913797000031.jpg47170

[0057] Finally, the embodiments described above are used solely to illustrate the technical configuration of the present invention and not to limit it. While the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that modifications or equivalent substitutions can be made to the technical configuration of the present invention, and that these modifications or equivalent substitutions will not cause the modified technical configuration to deviate from the spirit and scope of the technical configuration of the present invention.

Claims

1. A dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape, Step S1: Obtain the water level time series H(t) and river channel cross-sectional topographic data of the river under study, and perform data quality checks and data format standardization on the water level time series and cross-sectional topographic data. Step S2: For each cross-section, use the interpolation method to perform the continuous elevation function z = f ｓ (x) is constructed, and spatial interpolation is performed on multiple cross-sections to reconstruct the three-dimensional topographic surface of the river channel. Step S3: For any time t, set the equation z = H(t) for the horizontal water level line, and solve this simultaneously with the continuous elevation function to find the set of intersections {x} between the water level line and the cross section. ｉ Furthermore, based on the effectiveness determination and selection rules, the left bank intersection x ｌｅｆｔ and the intersection on the right bank x ｒｉｇｈｔ Identify, Step S4: x ｌｅｆｔ and x ｒｉｇｈｔ Based on this, the river width W(t) is calculated, and geometric correction is performed using the angle between the cross section and the main flow direction, and the uncertainty U of the river width is also calculated. Ｗ（ｔ） Output, Step S5: A dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape, characterized by creating time-series data of river width by combining the river width W(t) at each time point, constructing a statistical response relationship with the water level time series H(t) and / or flow rate Q(t), and subjecting it to dynamic change analysis.

2. The method for dynamically calculating river width based on intersection analysis of water level and river channel cross-sectional shape according to claim 1, characterized in that the cross-sectional topographic data in step S1 includes the cross-sectional survey point number, the cross-sectional distance x, and the elevation z.

3. The dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape according to claim 2, characterized in that the data quality check in step S1 includes detecting abnormal values ​​in water level, checking the topology consistency of cross-sectional data, imputing missing data or marking invalid data, and unifying the water level and cross-sectional elevation to the same elevation reference plane and coordinate system.

4.

5. The spatial interpolation of the multiple cross-sections in step S2 includes the following: Grid interpolation is used to construct the terrain surface z = F(X,Y), where (X,Y) is the planar coordinate and F(X,Y) is the interpolated elevation value. The dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape according to claim 4, characterized in that grid interpolation sets mesh resolutions ΔX and ΔY, and estimates elevation at mesh nodes using an inverse distance weighting method or a kriging model.

6. The effectiveness determination in step S3 includes the following: If the number of intersections m < 2, the river width result at time t is marked as invalid. When m=2, the two intersections are designated as the left bank intersection and the right bank intersection, respectively. The dynamic calculation method for river width based on intersection analysis of water level and river channel cross-sectional shape according to claim 5, characterized in that, when m > 2, screening of multiple intersections is performed.

7.

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