River channel parameter construction method and system

Abstract

The invention belongs to the technical field of hydrological and hydrodynamic coupling simulation, and provides a construction method and system for river channel parameters, and the method comprises the steps: obtaining a remote sensing image of a river channel, extracting a central line of the river channel, dividing stable and swing type river reaches according to the change rate, and constructing three-dimensional models respectively. Generalizing the river channel section into a triangle or a power exponent type, obtaining section parameters through regression analysis, and constructing a river channel attribute table; on the premise of uniform convergence of slope water, inputting attribute table data into a WEP model to calculate slope confluence; and then the slope confluence flow is assigned to river lateral inflow, river confluence is calculated in combination with section parameters, the connection relation between river confluence and slope confluence is constructed, and distributed and river hydrodynamic model coupling and river parameter construction are achieved. According to the method, the problem that seamless connection and whole-process simulation calculation are difficult to carry out due to complex and changeable river attributes when the distributed hydrological model and the river hydrodynamic model are coupled can be solved.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of hydrological and hydrodynamic coupling simulation, and particularly relates to a method and system for constructing river channel parameters. Background Art

[0002] For a long time, numerical simulation models have been important tools for solving scientific problems and assisting in decision-making. Among them, distributed hydrological models, as important tools for simulating basin hydrological processes, provide important support for water cycle scientific research and water resource management; river hydrodynamic models are also important tools for simulating, predicting, and making management decision analyses of water flow and its associated processes such as river channel hydrodynamic processes, sediment transport processes, and pollutant transport processes. Due to the huge differences in mechanisms, scales, etc. of research objects, problems to be solved, etc., there are huge differences in the boundary conditions between the two.

[0003] Existing basin water cycle models are mainly based on large-scale DEM data. The digital river system is extracted using the D8 method, and then the runoff generation process calculation of the computational unit and the confluence process calculation based on the upstream-downstream relationship are realized on this basis, so as to realize the simulation of the water cycle process at the basin scale; in the process of extracting the digital river system, due to the limitations of the large-scale DEM grid resolution and the DEM generation principle, it is difficult for the river channel position to be strictly consistent with the actual river channel, and the extracted river channel cross-section morphology is seriously distorted.

[0004] Existing river hydrodynamic models can establish one-dimensional, two-dimensional, and three-dimensional hydrodynamic process simulation models according to the simulation calculation mechanism, specific modeling requirements, and data conditions;

[0005] The establishment of a river channel hydrodynamic model has high requirements for river channel terrain data, and it is difficult to support the river channel positions and cross-section morphologies generated by existing distributed hydrological models.

[0006] When coupling the hydrological process on the land surface (simulated by a distributed hydrological model) with the water flow process in the river channel (simulated by a river channel hydrodynamic model), due to the complex and changeable river channel terrain, it is difficult to meet the requirements of the river channel characteristic parameters required in the calculation process of the hydrodynamic model. Therefore, seamless connection and full-process simulation calculation of different physical processes cannot be realized. Summary of the Invention

[0007] To solve the above problems, the present disclosure provides a method and system for constructing river channel parameters, which uses remote sensing images to obtain river channel information, construct a three-dimensional model, and calculate slope-channel confluence and other technologies, and solves the problem that seamless connection and full-process simulation calculation cannot be realized due to differences in river channel characteristic parameters when coupling existing distributed hydrological models and river channel hydrodynamic models.

[0008] The technology of the present invention is as follows:

[0009] A method for constructing river channel parameters, characterized by comprising:

[0010] Obtain remote sensing images of the river channel during the dry season in different periods, and extract the centerlines of the river channels in different periods from the images; based on the change rate of the centerlines of the river channels, divide the river channel types into stable river reaches and swinging river reaches; construct three-dimensional solid models of the river channels for the stable river reaches and the swinging river reaches respectively;

[0011] Generalize the river channel cross-section into a triangular or power-exponential cross-section according to the three-dimensional solid model, and through regression analysis of the water depth and the cross-sectional area after generalization, obtain the parameters of the generalized river channel cross-section. After cutting the generalized river channel by contour lines according to the contour bands, construct a river channel attribute table using the cross-section parameters of each section of the river channel;

[0012] With the condition that the water on the slope of the river channel contour band flows into the river channel uniformly when it converges, input the data in the river channel attribute table into the WEP model to calculate the slope hydrological runoff generation process. Based on the calculation results of the slope hydrological runoff generation process, use the kinematic wave model to calculate the slope runoff concentration to obtain the slope runoff concentration flow rate Q;

[0013] Assign the slope runoff concentration flow rate Q to the lateral inflow of the river channel in the river channel runoff concentration, and combine the river channel cross-section parameters in the river channel attribute table to realize the calculation of the river channel runoff concentration; realize the construction of the calculation connection relationship between the river channel runoff concentration and the slope runoff concentration;

[0014] The calculation connection relationship between the river channel runoff concentration and the slope runoff concentration is used for the coupling connection between the distributed hydrological model and the river channel hydrodynamic model; and further realize the construction of river channel parameters for the coupling connection between the distributed hydrological model and the river channel hydrodynamic model.

[0015] Furthermore,

[0016] The division of the river channel types into stable river reaches and swinging river reaches; includes:

[0017] According to the water body vector range and the centerline of the river channel in different periods, select a river section spacing of 500 m to obtain the water surface width, and obtain the positions at the intersections of the river channel cross-section and the centerline based on the water surface width; measure the migration distance s of the intersections in different periods, and sequentially obtain the migration speed v and the acceleration a; the migration speed is the ratio of the migration distance to the time, and the migration acceleration is the ratio of the migration speed to the time;

[0018] Calculate the relative stability index RSIRR-G: The relative stability index RSIRR-G is a linear combination of the main streamline migration distance s, the migration speed v, and the migration acceleration. The calculation formula is:

[0019] RSIRR-G = β1s + β2v + β3a

[0020] Among them, β1, β2, and β3 are undetermined coefficients, which contain the change information of the river during the time interval Δt;

[0021] Expand RSIRR-G from the cross-section scale to the reach scale. The relative stability index of the reach is equal to the average value of RSIRR-G at all cross-sections of the reach;

[0022] By comparing the relative stability index of the reach with the threshold value, the reach is divided into a stable reach and a meandering reach; if the RSIRR value is greater than the threshold, the reach is a meandering reach, and if the RSIRR value is not greater than the threshold, the reach is a stable reach.

[0023] Furthermore,

[0024] Use cluster analysis to determine the coefficients β1, β2, and β3, which includes:

[0025] Extract morphological indicators, including the main stream migration distance and channel width at N cross-sections, and calculate the values of the main stream line migration distance s, velocity v, and acceleration a;

[0026] According to the main stream line migration distance s, velocity v, and acceleration a, use the hierarchical clustering method to divide the N cross-sections into g groups, and calculate the clustering results according to the similarity distance and natural grouping process between the N cross-sections;

[0027] Calculate the F statistic of the main stream line migration distance s, velocity v, and acceleration a. The F statistic is the ratio of the sum of variances to the sum of between-group error variances, and its calculation formula is:

[0028]

[0029] Among them, SS(TR) is the sum of squares between groups, SSE is the sum of squared errors, g is the degree of freedom, that is, the number of classification groups; ni is the number of cross-sections in the i-th group; xi and x are the average index values of the i-th group and all groups of cross-sections respectively; xij is the index value of the j-th section in the i-th group;

[0030] The index F is the weight of β1, β2, and β3, that is:

[0031] F1:F2:F3 = β1:β2:β3

[0032] Calculate RSIRR-G at each cross-section and select the maximum RSIRR-G max ,i and the minimum RSIRR-G min ,i (i = 1, 2,..., g); the RSIRR-G threshold between two adjacent groups is in the interval [RSIRR-G max ,I, RSIRR-Gmin In the interval [i, i + 1], if the interval is less than the threshold, the true value approximately replacing the threshold with a constant in the interval is given, and the values of β1, β2, and β3 are determined.

[0033] Furthermore,

[0034] Separate three-dimensional solid models of the river channel are constructed for stable river reaches and meandering river reaches, including:

[0035] Remote sensing images of the river channel in the dry season at different times are obtained, and the centerlines of the river channels at different times are extracted from the images; based on the change rate of the centerlines of the river channels, the river channel types are divided.

[0036] According to the hydrological rhythm, high-resolution remote sensing images of the river channel in different months are collected, the water surface vector files are extracted from the remote sensing images, and a sequence of water surface vector files corresponding to the corresponding frequencies is established by referring to the hydrological frequencies.

[0037] Based on the requirements of the river channel hydrodynamic model, the river reaches are divided based on the centerlines of the river channels.

[0038] Using the sequence of water surface vector files, combined with the corresponding water level data, the three-dimensional water body boundaries of the corresponding river reaches are interpolated and generated, and the three-dimensional solid river channel and river channel model are formed by connecting each river reach one by one.

[0039] The river channel topography during the flood period and the upper river channel topography are supplemented and generated using DEM data, and the three-dimensional solid river channel and river channel model, the river channel topography during the flood period and the upper river channel topography are spliced to obtain the three-dimensional solid model of the river channel.

[0040] Furthermore,

[0041] The kinematic wave model is used to calculate overland flow concentration, including:

[0042] Based on the generation of the river network water system and the division of the basin, the river channel data under the contour belts of each sub-basin are obtained, and the contour belt data includes the river channel area, length, width, average elevation, slope, and Manning roughness coefficient.

[0043] The one-dimensional kinematic wave method is used to calculate the overland rainfall runoff concentration from the upstream contour belt to the downstream contour belt, and the overland runoff concentration data of the downstream contour belt are transmitted to the river channels within the corresponding sub-basins to realize the calculation of overland flow concentration.

[0044] Furthermore,

[0045] The kinematic wave equation includes:

[0046] The continuity equation, and its calculation formula is:

[0047]

[0048] The motion equation, and its calculation formula is:

[0049] S f = S0

[0050] The Manning formula, whose calculation formula is:

[0051]

[0052] Where: r is the rainfall intensity; f is the infiltration rate; h is the water depth; q is the lateral inflow per unit length, that is, the surface runoff; x is the distance along the river channel; t is the time; S f is the friction slope; S0 is the longitudinal slope of the river channel; n is the Manning roughness coefficient;

[0053] The longitudinal slope S0 of the river channel, the slope length L, the slope width W and the cross-sectional shape are obtained from the three-dimensional solid model of the river channel, and then solved by the finite difference method to obtain the surface runoff discharge Q.

[0054] Furthermore,

[0055] The calculation of the river channel confluence includes:

[0056] Calculate the hydraulic radius R, and perform one-dimensional numerical calculation on the river channel parameters using the kinematic wave equation or the dynamic wave equation; the kinematic wave equation includes:

[0057] Continuity equation:

[0058]

[0059] Motion equation:

[0060] S f = S0

[0061] Manning formula (Manning):

[0062]

[0063] Where: Q is the discharge; A is the cross-sectional area of flow; q is the lateral inflow per unit length; Sf is the friction slope; S0 is the longitudinal slope of the river channel; x is the distance along the river channel; t is the time; R is the hydraulic radius; n is the Manning roughness coefficient.

[0064] Furthermore,

[0065] The dynamic wave equation includes:

[0066] Continuity equation:

[0067]

[0068] Motion equation:

[0069]

[0070] Manning formula:

[0071]

[0072] Where: Q is the flow rate; A is the cross-sectional area of the water flow; q is the lateral inflow per unit length; S f is the friction slope; S0 is the longitudinal slope of the river channel; x is the distance along the river channel; t is the time; R is the hydraulic radius; n is the Manning roughness coefficient; Vx is the component of the unit-width inflow velocity in the x direction.

[0073] A system for constructing river channel parameters, characterized by comprising:

[0074] A model construction module, configured to obtain remote sensing images of the river channel during the dry season in different periods, extract the centerlines of the river channels in different periods from the images; divide the river channel types into stable river reaches and meandering river reaches based on the change rate of the centerlines of the river channels; construct three-dimensional solid models of the river channels for the stable river reaches and meandering river reaches respectively;

[0075] A parameter extraction module, configured to generalize the river channel cross-section into a triangular or power-exponential cross-section according to the three-dimensional solid model, perform regression analysis on the water depth and the cross-sectional area after generalization to obtain the parameters of the generalized river channel cross-section, cut the generalized river channel with contour lines according to the contour bands, and construct a river channel attribute table by using the cross-sectional parameters of each section of the river channel;

[0076] A calculation module, configured to take the condition that the surface water of the river channel contour band flows into the river channel evenly as the condition, input the data of the river channel attribute table into the WEP model, calculate the surface hydrological runoff generation process, and calculate the surface runoff concentration by using the kinematic wave model based on the calculation result of the surface hydrological runoff generation process to obtain the surface runoff concentration flow rate Q;

[0077] Assign the surface runoff concentration flow rate Q to the lateral inflow of the river channel in the river channel runoff concentration, and combine the cross-sectional parameters of the river channel in the river channel attribute table to realize the calculation of the river channel runoff concentration; realize the construction of the calculation connection relationship between the river channel runoff concentration and the surface runoff concentration;

[0078] The calculation connection relationship between the river channel runoff concentration and the surface runoff concentration is used for coupling connection between the distributed hydrological model and the river channel hydrodynamic model; thereby realizing the construction of river channel parameters for coupling connection between the distributed hydrological model and the river channel hydrodynamic model.

[0079] Compared with the prior art, the present disclosure has the following advantages:

[0080] The present invention extracts the centerline of the river channel from remote sensing images in the dry season of different periods, analyzes the change rate to divide the river channel types, and uses the images of different periods to reflect the river channel changes and the change rate of the centerline to reflect the stability, so as to accurately grasp the position and morphological changes of the river channel. High-resolution images are collected according to the hydrological rhythm to extract the water surface vector file and establish a sequence. Combining with the water surface line data sequence, a three-dimensional model is constructed to comprehensively reflect the three-dimensional spatial characteristics of the river channel topography by using the image information at different times and water levels to meet the high-precision requirements of the river channel hydrodynamic model for topographic data;

[0081] Based on the three-dimensional solid model, data is obtained to construct an attribute table. Since the model contains detailed geometric, hydraulic and other information of the river channel, the river channel is uniformly modeled by generalization, and accurate river channel generalization model parameters are calculated to make up for the deficiency that it is difficult to carry out unified hydrological-hydrodynamic coupling due to the complex and changeable shape of the river channel; According to the generalized river channel parameters, the kinematic wave model is used to calculate the overland flow concentration. Based on the reasonable simplification of the overland flow and the approximate reflection of the movement under the action of gravity and resistance, the overland flow concentration result is transmitted to the river channel confluence as lateral inflow, considering that the overland flow is part of the river channel flow to achieve physical connection. On this basis, a connection relationship parameter system is established, and the distributed hydrological model and the river channel hydrodynamic model are made to match each other in terms of river channel characteristic parameters by reasonably setting parameters to solve the problem of seamless connection and full-process simulation calculation caused by parameter differences.

[0082] Other features and advantages of the present disclosure will be described in the following specification, and part of them will be obvious from the specification, or will be understood by implementing the present disclosure. The objectives and other advantages of the present disclosure can be realized and obtained by the structures pointed out in the specification, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0084] Figure 1 Shows a schematic diagram of the method of the present invention;

[0085] Figure 2 Shows a schematic diagram of the generalization of the river channel cross-section;

[0086] Figure 3 Shows a schematic diagram of the generalized triangular cross-section;

[0087] Figure 4 Shows a schematic diagram of the generalized power function type cross-section. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0088] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[0089] Figure 1 The schematic diagram of the method according to the present invention is shown. The specific implementation details of the present invention include:

[0090] 1. Step 1: Collect remote sensing images of the river channel in the dry season at different times, and extract the centerlines of the river channels at different times.

[0091] 2. Step 2: Analyze the change rates of the river channel centerlines at different times, and identify the lateral stability of the river channel; divide the river channel into meandering and stable reaches.

[0092] For meandering reaches, due to the presence of a large amount of easily transportable substances, the river channel morphology is relatively flat and can be directly generalized as a U shape; for stable reaches, which are generally bedrock riverbeds with diverse but relatively stable shapes, they can be directly based on the actual shape.

[0093] Specifically, the method for dividing the river channel stability is as follows:

[0094] 1. Obtain the centerlines of the river channel at different times.

[0095] 2. Calculate the main streamline migration parameters:

[0096] According to the water body vector range and the river channel centerline at different times, select a 500 m river section spacing to obtain the water surface width, and obtain the positions at the intersections of the river channel cross-section and the centerline based on the water surface width; measure the migration distance s of the intersections at different times, and sequentially obtain the migration speed v and acceleration a; the migration speed is the ratio of the migration distance to the time, and the migration acceleration is the ratio of the migration speed to the time.

[0097] 3. Calculate the relative stability index RSIRR-G:

[0098] The RSIRR-G index can be regarded as a linear combination of the main streamline migration distance s, speed v, and acceleration a. The formula is as follows:

[0099] RSIRR-G = β1s + β2v + β3a

[0100] Among them, β1, β2, and β3 are undetermined coefficients, which contain the change information of the river during the time interval Δt.

[0101] Cluster analysis is used to determine the coefficient values in the above formula, and the steps are as follows:

[0102] Step 1: Extract morphological indicators, including the main stream migration distance and channel width at the cross-section (assuming the cross-section is N), and calculate the values of the main stream line migration distance s, velocity v, and acceleration a.

[0103] Step 2: Cluster analysis. Since the number of groups g is unknown, based on the three indicators (main stream line migration distance s, velocity v, and acceleration a), the above N cross-sections are divided into g groups using hierarchical clustering method to estimate the appropriate number of groups g, and then the clustering results are calculated according to the similarity distance and natural grouping process between the N segments.

[0104] Step 3: Calculate the F-statistic of the above three indices. F is defined as the ratio of the sum of variances to the sum of between-group error variances.

[0105]

[0106]

[0107] Among them, SS(TR) is the sum of squares between groups, SSE is the sum of squared errors, g is the degrees of freedom, that is, the number of classification groups; ni is the number of cross-sections in the i-th group; xi and x are the average index values of the i-th group and all groups of cross-sections respectively; xij is the index value of the j-th segment in the i-th group.

[0108] The index F can be regarded as the weights of β1, β2, β3, that is:

[0109] F1:F2:F3 = β1:β2:β3

[0110] Step 4: Threshold determination. After determining the three coefficients, calculate RSIRR-G at each cross-section according to formula (4-7), and select the maximum RSIRR-G max for each group, i and the minimum RSIRR-G min for each group, i (i = 1, 2,..., g). Since the RSIRR-G threshold between two adjacent groups can be considered in the interval [RSIRR-G max for group I, RSIRR-G min for group i+1], if the interval is small, an approximate constant in this interval is given to replace the true value of the threshold.

[0111] 4. Divide the river reach into stable river reaches and meandering river reaches:

[0112] Expand RSIRR-G from the cross-section scale to the river reach scale. The RSIRR at the river reach scale is equal to the average value of RSIRR-G at all cross-sections of the river reach.

[0113]

[0114] It refers to the average value of the relative stability index of the cross-sections included in a certain river reach. By comparing the relative stability index of the river reach with the threshold value, the river reach is divided into a stable river reach and a meandering river reach.

[0115] 3. Step 3: According to the hydrological rhythm, collect high-resolution remote sensing images of different months, or combine the runoff monitoring data of the hydrological station, and select the remote sensing images corresponding to the time according to the hydrological frequency;

[0116] Extract the water surface vector file from the remote sensing image, and establish a sequence of water surface vector files corresponding to the frequency by referring to the hydrological frequency.

[0117] 4. Step 4: Based on the water level monitoring data of the hydrological station, or the water surface line data sequence generated by the GF-7 satellite, use the sequence of water surface vector files and adopt the interpolation method to construct a three-dimensional river channel model.

[0118] Specifically: According to the modeling requirements of the river channel hydrodynamic model, divide the river reach based on the river channel center line; then use the sequence of water surface vector files, combine with the corresponding water level data, and interpolate to generate the three-dimensional water body boundary of the corresponding river reach. Connecting each river reach one by one forms a three-dimensional river channel and river model; then on this basis, use the DEM data to supplement and generate the flood period / upper river channel topography, and the spliced result is the three-dimensional river channel model.

[0119] 5. Step 5: Based on the three-dimensional river channel model, obtain basic geographical information such as elevation, slope, aspect, and water flow direction, combine with the contour bands to divide the river reaches, obtain basic information such as river reach length, slope drop, top width, and bottom width, construct a river network, divide sub-basins, and generate a water system.

[0120] 6. Step 6: Code the sub-basins, divide the contour bands of the terminal sub-basins, and spatially and temporally distribute meteorological elements such as precipitation.

[0121] 7. Step 7: Calculation of overland flow concentration:

[0122] Use the kinematic wave model to calculate overland flow concentration. On the basis of generating the river network water system and dividing the basin, prepare the data of the contour bands of each sub-basin according to the basic information such as grid cell DEM and land use, including area, length, width, average elevation, slope, and Manning roughness coefficient, etc. Use the one-dimensional kinematic wave method to calculate the overland rainfall concentration from the upstream contour band to the downstream contour band, and transmit the overland flow concentration data of the downstream contour band to the river channel within the corresponding sub-basin.

[0123] The overland flow concentration is calculated using the kinematic wave equation:

[0124] 1) Continuity equation:

[0125]

[0126] 2) Equation of motion:

[0127] S f = S0

[0128] 3) Manning formula:

[0129]

[0130] Where:

[0131] r: rainfall intensity

[0132] f: infiltration rate

[0133] h: water depth (m 2 )

[0134] q: lateral inflow per unit length, i.e., runoff yield from the slope surface (m 2 / s)

[0135] x: distance along the river channel (m)

[0136] t: time (s)

[0137] S f : friction slope

[0138] I0: longitudinal slope of the river channel

[0139] n: Manning roughness coefficient

[0140] Among them, the friction coefficient S0, slope surface length L, slope surface width W and cross-section shape can be obtained from the three-dimensional river channel model, and then solved by the finite difference method to obtain the slope surface confluence flow rate Q and transmitted to the river channel where it is located.

[0141] 8. Step Eight: Calculation of river channel attribute table.

[0142] According to the three-dimensional river channel model, obtain the generalized cross-section shape and corresponding parameters. For a triangle, they are cosθ1 and cosθ2, and for a power exponential type, they are α and β. The parameters are obtained by performing regression fitting on the three-dimensional river channel model.

[0143] Prepare the river channel attribute table. The data in the river channel attribute table includes the longitude, latitude and elevation information of the river channel cross-section. For a triangle, they are cosθ1 and cosθ2, and for a power exponential type, they are α and β.

[0144] Specifically, the present invention adopts a method for generalizing and analyzing the river channel cross-section according to the cross-section shape. The river channel cross-section for flow is generalized into a triangular cross-section (such as Figure 2 a, b in) and a power function type cross-section (such asFigure 2 In the two forms of c), d), and e), a general expression of the functional relationship between the water surface width and the flow rate is established through hydraulic analysis, and the generalized channel model parameters are obtained.

[0145] For an approximately triangular cross-section (such as Figure 3 ), the expressions for the cross-sectional area and the wetted perimeter are:

[0146]

[0147] where A is the cross-sectional area, w is the water surface width, and h is the water depth;

[0148]

[0149] Among them, cosθ1 and cosθ2 can be obtained from the three-dimensional channel model, so the cross-sectional area A and the hydraulic radius R can be expressed in terms of the water surface width w.

[0150] For a cross-section of the power function type (the cross-section is as shown in Figure 4 ), the cross-sectional equation is generalized to:

[0151] y = αx β

[0152] The calculation formula for the cross-sectional area A of the flowing water is:

[0153]

[0154] Since the wetted perimeter χ of a wide and shallow channel is approximately equal to the river width w, the calculation formula for the hydraulic radius R is:

[0155]

[0156] The three-dimensional channel solid model is divided according to the contour bands, and the channel slope S0 at the height difference of each contour band, the channel shape parameters (the expressions of the cross-sectional area A and the hydraulic radius R in terms of w, and the distance x along the channel) are obtained. The above-mentioned channel parameters are assigned to the corresponding hillslope confluence and channel confluence demand parameters, and the corresponding confluence process calculation is carried out. Channel generalization is performed based on the three-dimensional channel solid model.

[0157] The channel parameter acquisition module is used to generalize the measured irregular cross-section into a generalized cross-section (triangular or power-exponential type) required for model calculation, obtain the channel slope S0 at different contour band height differences, and the channel shape parameters (the expressions of the cross-sectional area A and the hydraulic radius R in terms of w, and the distance x along the channel), and form a channel attribute table.

[0158] 9. Step Nine: Channel Confluence Calculation: Calculate the hydraulic radius R according to the channel data table, and perform one-dimensional numerical calculation on the channel parameters using the kinematic wave model or the dynamic wave model as appropriate.

[0159] 1) Kinematic wave equation

[0160] Continuity equation:

[0161]

[0162] Kinematic equation:

[0163] S f = S0

[0164] Manning formula:

[0165]

[0166] Where:

[0167] Q: Discharge (m 3 / s)

[0168] A: Cross-sectional area (m 2 )

[0169] q: Lateral inflow per unit length (m 2 / s)

[0170] S f : Friction slope

[0171] S0: Longitudinal slope of the channel

[0172] x: Distance along the channel (m)

[0173] t: Time (s)

[0174] R: Hydraulic radius

[0175] n: Manning roughness coefficient

[0176] 2) Dynamic wave equation

[0177] Continuity equation:

[0178]

[0179] Kinematic equation:

[0180]

[0181] Manning formula:

[0182]

[0183] Where:

[0184] Q: Discharge (m 3 / s)

[0185] A: Cross-sectional area (m2 )

[0186] q: Lateral inflow per unit length (m 2 / s)

[0187] S f : Friction slope

[0188] S0: Longitudinal slope of the river channel

[0189] x: Distance along the river channel (m)

[0190] t: Time (s)

[0191] R: Hydraulic radius

[0192] n: Manning roughness coefficient

[0193] Vx: Component of the flow velocity per unit width in the x - direction of the inflow

[0194] 10. Step Ten: Generate the corresponding river channel parameters including the friction coefficient S0, slope length L, slope width W and the corresponding cross - section parameters after river channel generalization (cosθ1 and cosθ2 for triangle type, α and β for power - exponential type) based on the generated three - dimensional solid model, calculate the expressions of the cross - section area A and hydraulic radius R with respect to w, the distance x along the river channel, and assign the above river channel parameters to the river channel calculation unit of the WEP model.

[0195] Input the river channel attribute table and other data such as meteorology into the WEP model for hydrological and hydrodynamic calculations. The detailed process is as follows: Assume that the slope water converges into the river channel uniformly when the slope water of the river channel contour band converges into the river channel. First, calculate the hydrological runoff and concentration process on the slope, use the kinematic wave model to calculate the slope runoff, and obtain the slope runoff flow Q;

[0196] Assign the slope runoff flow Q to the lateral inflow in the river channel runoff. The inflow process of the calculation unit in the river channel receives the surrounding runoff evenly, and combines the cross - section parameters of the river channel in the river channel attribute table to realize the calculation of the river channel runoff;

[0197] Establish a connection system for the calculation of river channel runoff and slope runoff based on the calculation relationship between river channel runoff and slope runoff, and realize the construction of river channel parameters for coupling and connection between the distributed hydrological model and the river channel hydrodynamic model.

[0198] Based on the method of the present invention, the embodiments of the present disclosure also provide a system corresponding to the above method, which includes:

[0199] Model construction module, used to obtain the remote sensing images of the river channel in the dry season of different periods, extract the centerlines of the river channels in different periods from the images; divide the river channel types into stable - type river reaches and meandering - type river reaches based on the change rate of the centerlines of the river channels; construct three - dimensional solid models of the river channels for the stable - type river reaches and meandering - type river reaches respectively;

[0200] A parameter extraction module, which is used to generalize the river channel section into a triangular or power exponential section according to the three-dimensional solid model. By performing regression analysis on the water depth and the generalized cross-sectional area, the parameters of the generalized river channel section are obtained. After cutting the generalized river channel by contour lines according to the contour bands, a river channel attribute table is constructed using the cross-sectional parameters of each section of the river channel;

[0201] A calculation module, which is used to input the data in the river channel attribute table into the WEP model on the condition that the surface water of the river channel slope uniformly converges into the river channel when calculating the surface water runoff process of the slope. Based on the calculation results of the surface water runoff process of the slope, the kinematic wave model is used to calculate the surface runoff, and the surface runoff flow rate Q is obtained;

[0202] Assign the surface runoff flow rate Q to the lateral inflow of the river channel in the river channel confluence, and combine the cross-sectional parameters of the river channel in the river channel attribute table to realize the calculation of the river channel confluence; realize the construction of the calculation connection relationship between the river channel confluence and the surface runoff;

[0203] The calculation connection relationship between the river channel confluence and the surface runoff is used for the coupling connection between the distributed hydrological model and the river channel hydrodynamic model; furthermore, the construction of river channel parameters for the coupling connection between the distributed hydrological model and the river channel hydrodynamic model is realized.

[0204] Although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A method for constructing river channel parameters, characterized in that, Including: Obtain remote sensing images of the dry-season river channels in different periods, and extract the centerlines of the river channels in different periods from the images; based on the change rate of the river channel centerlines, divide the river channel types into stable reaches and meandering reaches; construct three-dimensional solid models of the river channels for the stable reaches and meandering reaches respectively; Generalize the river channel cross-sections into triangular or power-exponential cross-sections according to the three-dimensional solid models. Through regression analysis of the water depth and the cross-sectional area after generalization, obtain the parameters of the generalized river channel cross-sections. After cutting the generalized river channel by contour lines according to the contour bands, construct a river channel attribute table using the cross-sectional parameters of each section of the river channel; With the condition that the water on the slope of the river channel contour band uniformly converges into the river channel when it enters the river channel, input the data in the river channel attribute table into the WEP model to calculate the overland hydrological runoff generation process. Based on the calculation results of the overland hydrological runoff generation process, use the kinematic wave model to calculate the overland flow concentration and obtain the overland flow concentration discharge Q; Assign the overland flow concentration discharge Q to the lateral inflow of the river channel in the river channel flow concentration, and combine the cross-sectional parameters of the river channel in the river channel attribute table to realize the calculation of the river channel flow concentration; realize the construction of the calculation connection relationship between the river channel flow concentration and the overland flow concentration; The calculation connection relationship between the river channel flow concentration and the overland flow concentration is used for the coupling connection between the distributed hydrological model and the river channel hydrodynamic model; furthermore, realize the construction of river channel parameters for the coupling connection between the distributed hydrological model and the river channel hydrodynamic model.

2. The construction method of a river channel parameter according to claim 1, characterized in that The division of the river channel types into stable reaches and meandering reaches includes: According to the water body vector ranges and river channel centerlines in different periods, select a 500m river reach spacing to obtain the water surface width, and obtain the positions at the intersections of the river channel cross-sections and the centerlines based on the water surface width; measure the migration distances s of the intersections in different periods, and sequentially obtain the migration velocities v and accelerations a; the migration velocity is the ratio of the migration distance to the time, and the migration acceleration is the ratio of the migration velocity to the time; Calculate the relative stability index RSIRR-G: The relative stability index RSIRR-G is a linear combination of the main streamline migration distance s, migration velocity v, and migration acceleration, and the calculation formula is: RSIRR-G = β1s + β2v + β3a where β1, β2, and β3 are undetermined coefficients, including the change information of the river during the time interval Δt; The RSIRR-G is extended from the cross-section scale to the reach scale to obtain the relative stability index of the reach. Relative stability index of the reach It is equal to the average value of RSIRR-G on all cross-sections of the reach. By comparing the relative stability index of the river reach with the threshold value, the river reach is divided into a stable river reach and a meandering river reach; if the value is greater than the threshold value, the river reach is a meandering river reach, if the value is not greater than the threshold value, the river reach is a stable river reach.

3. The construction method of a river channel parameter according to claim 2, characterized in that, Use cluster analysis to determine the coefficients β1, β2, and β3, which includes: Extract morphological indicators, including the main stream migration distances and river channel widths at N cross-sections, and calculate the values of the main streamline migration distance s, velocity v, and acceleration a; According to the main streamline migration distance s, velocity v, and acceleration a, use the hierarchical clustering method to divide the N cross-sections into g groups, and calculate the clustering results according to the similarity distances and natural grouping processes among the N cross-sections; Calculate the F statistic of the main streamline migration distance s, velocity v, and acceleration a. The F statistic is the ratio of the sum of variances to the sum of between-group error variances, and its calculation formula is: where SS(TR) is the sum of squares between groups, SSE is the sum of squared errors, g is the degree of freedom, that is, the number of classification groups; ni is the number of cross-sections in the i-th group; xi and x are the average index values of the i-th group and all groups of cross-sections respectively; xij is the index value of the j-th section in the i-th group; The index F is the weight of β1, β2, and β3, that is: F1:F2:F3 = β1:β2:β3 Calculate RSIRR-G on each cross-section and select the maximum RSIRR-G for each group max , i and the minimum RSIRR-G min , i (i = 1, 2,..., g); the RSIRR-G threshold between two adjacent groups is in the interval [RSIRR-G max , I, RSIRR-G min , i+1]. If the interval is less than the threshold, give the true value of the approximate constant replacing the threshold in this interval, and determine the values of β1, β2, and β3.

4. The construction method of a river channel parameter according to claim 1, characterized in that, For the stable river section and the meandering river section, a three-dimensional river channel model is constructed respectively; it includes: Obtain remote sensing images of the river channel in the dry season at different times, and extract the centerlines of the river channels at different times from the images; based on the change rate of the centerlines of the river channels, divide the river channel types; According to the hydrological rhythm, collect high-resolution remote sensing images of the river channel in different months, extract the water surface vector files from the remote sensing images, and establish a sequence of water surface vector files corresponding to the corresponding frequencies by referring to the hydrological frequencies; Based on the requirements of the river channel hydrodynamic model, divide the river sections based on the centerlines of the river channels; Use the sequence of water surface vector files, combined with the corresponding water level data, to interpolate and generate the three-dimensional water body boundaries of the corresponding river sections, and connect each river section one by one to form a three-dimensional river channel and river model; Use DEM data to supplement and generate the river channel topography during the flood period and the upper river channel topography, and splice the three-dimensional river channel and river model, the river channel topography during the flood period and the upper river channel topography to obtain the three-dimensional river channel model.

5. The construction method of a river channel parameter according to claim 1, characterized in that, The calculation of slope runoff using the kinematic wave model includes: On the basis of the generation of the river network water system and the division of the basin, obtain the river channel data under the contour belts of each sub-basin. The contour belt data includes the river channel area, length, width, average elevation, slope, and Manning roughness coefficient; Use the one-dimensional kinematic wave method to calculate the slope rainfall runoff from the upstream contour belt to the downstream contour belt, and transmit the slope runoff data of the downstream contour belt to the river channels within the corresponding sub-basins to achieve the calculation of slope runoff.

6. The construction method of a river channel parameter according to claim 5, characterized in that, The kinematic wave equation of the one-dimensional kinematic wave method includes: The continuity equation, and its calculation formula is: The motion equation, and its calculation formula is: S f = S0 The Manning formula, and its calculation formula is: where: r is the rainfall intensity; f is the infiltration rate; h is the water depth; q is the lateral inflow per unit length, i.e., the runoff generated on the slope; x is the distance along the river channel; t is the time; S f is the friction slope; S0 is the longitudinal slope of the river channel; n is the Manning roughness coefficient; The longitudinal slope S0 of the river channel, the slope length L, the slope width W, and the cross-sectional shape are obtained from the three-dimensional river channel model, and the kinematic wave equation is solved by the finite difference method to obtain the slope runoff flow rate Q.

7. A method for constructing river channel parameters according to claim 1, characterized in that, The calculation of river channel confluence includes: Calculate the hydraulic radius R, and perform one-dimensional numerical calculation on the river channel parameters using the kinematic wave equation or the dynamic wave equation; the kinematic wave equation includes: The continuity equation: The motion equation: S f = S0 The Manning formula (Manning): Where: Q is the flow rate; A is the cross-sectional area of the flowing water; q is the lateral inflow per unit length; Sf is the friction slope; S0 is the longitudinal slope of the river channel; x is the distance along the river channel; t is the time; R is the hydraulic radius; n is the Manning roughness coefficient.

8. A method for constructing river channel parameters according to claim 7, characterized in that, The dynamic wave equation includes: The continuity equation: The motion equation: The Manning formula (Manning): Where: Q is the flow rate; A is the cross-sectional area of flow; q is the lateral inflow per unit length; S f is the friction slope; S0 is the longitudinal slope of the river channel; x is the distance along the river channel; t is the time; R is the hydraulic radius; n is the Manning roughness coefficient; Vx is the component of the flow velocity per unit width in the x direction.

9. The construction method of a river channel parameter according to claim 1, characterized in that When the slope runoff flow rate Q is assigned to the lateral inflow of the river channel in the river channel confluence, the inflow process of the calculation units in the river channel is to uniformly receive the surrounding runoff.

10. A construction system for river channel parameters, characterized in that, It includes: The model construction module is used to obtain remote sensing images of the river channel in the dry season at different times, extract the centerlines of the river channels at different times from the images; based on the change rate of the centerlines of the river channels, divide the river channel types into stable river sections and meandering river sections; construct three-dimensional river channel models for the stable river sections and meandering river sections respectively; The parameter extraction module is used to generalize the river channel cross-section into a triangular or power-exponential cross-section according to the three-dimensional solid model. By performing a regression analysis on the water depth and the cross-sectional area after generalization, the cross-sectional parameters of the generalized river channel are obtained. After cutting the generalized river channel with contour lines according to the contour bands, a river channel attribute table is constructed using the cross-sectional parameters of each section of the river channel; The calculation module is used to input the data in the river channel attribute table into the WEP model on the condition that the water on the slope of the river channel contour band uniformly flows into the river channel when calculating the hydrological runoff process on the slope. Based on the calculation results of the hydrological runoff process on the slope, the kinematic wave model is used to calculate the slope runoff, and the slope runoff flow rate Q is obtained; The slope runoff flow rate Q is assigned to the lateral inflow of the river channel in the river channel confluence. Combining the cross-sectional parameters of the river channel in the river channel attribute table, the calculation of the river channel confluence is realized; the construction of the calculation connection relationship between the river channel confluence and the slope runoff is realized; The calculation connection relationship between the river channel confluence and the slope runoff is used for the coupling connection between the distributed hydrological model and the river channel hydrodynamic model; furthermore, the construction of river channel parameters for the coupling connection between the distributed hydrological model and the river channel hydrodynamic model is realized.

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