Irrigation water distribution numerical simulation method

Abstract

The invention relates to the technical field of irrigation management, in particular to an irrigation water distribution numerical simulation method. Dispersing the physical water channel and generalizing the physical water channel into a digital water channel formed by a binary tree; the motion environment of water in the channel is generalized into physical parameters of channel nodes, physical parameters of gate nodes, gate flow coefficients and fluid mechanics constraints; flow of canal water is generalized into movement of a rectangular strip on a binary tree, a movement equation of the rectangular strip is adopted, the downstream water regimen change condition is predicted, and irrigation production cooperation is organized; through the mode, the water regimen change trend of all downstream channel sections under various constraint conditions can be calculated, so that technical support is provided for formulating a scientific and reasonable irrigation scheduling plan and an irrigation operation scheduling sequence, accurately metering water consumption, collecting water charges, coordinating farmers to supervise each other to save water, guiding river patrol management work and the like.

Description

Technical Field

[0001] The invention relates to the technical field of irrigation management, and in particular to a numerical simulation and emulation method for irrigation water distribution. Background Art

[0002] Generally, due to the relatively rough irrigation management plan of the irrigation area, the irrigation manager needs to go back and forth between the gates day and night during the water flow period of the channel, repeatedly monitoring and operating the gates to ensure the safety of the dam and timely and sufficient irrigation of crops. In modern times, through the channel water condition telemetry equipment, integrated measurement and control gates, etc., real-time monitoring and remote control of water conditions are achieved, which well guarantees the irrigation management tasks; however, the cost of channel construction and operation and maintenance is high, which is unbearable for the government, society and water users.

[0003] Therefore, a numerical simulation and emulation method for irrigation water distribution is proposed. This method can calculate the water regime change trend of all downstream canal sections under various constraints, thereby providing technical support for formulating scientific and reasonable irrigation scheduling plans, scheduling irrigation operations, accurately measuring water consumption, collecting water fees, coordinating farmers to supervise each other in water conservation, and guiding river patrol management. Summary of the invention

[0004] The purpose of the present invention is to provide a numerical simulation and emulation method for irrigation water distribution, aiming to realize the calculation of the water situation change trend of all downstream canal sections under various constraints, so as to provide technical support for formulating scientific and reasonable irrigation scheduling plans, scheduling irrigation operations, accurately measuring water consumption, collecting water fees, coordinating farmers to supervise each other in water conservation, and guiding river patrol management.

[0005] To achieve the above purpose, the present invention adopts an irrigation water distribution numerical simulation and emulation method, comprising the following steps:

[0006] Discretize the physical waterway and generalize it into a digital waterway composed of a binary tree;

[0007] The water movement environment in the channel is generalized into the physical parameters of the channel nodes, the physical parameters of the gate nodes, the gate discharge coefficient, and the fluid mechanics constraints;

[0008] The flow of canal water is generalized as the movement of rectangular strips on a binary tree. The motion equation of the rectangular strips is used to predict changes in downstream water conditions and organize irrigation production cooperation.

[0009] The digital waterway includes: the topological structure of the digital waterway, the discretization of the digital waterway, the constraints of digital water movement, and the water movement equation in the digital waterway;

[0010] The topological structure of the digital waterway is as follows: according to the natural structure of the irrigation area, the channel is generalized into a tree structure;

[0011] The digital waterway is discretized as follows: according to the location of the water intake, the channel is divided into a number of channel sections, each of which has the same constraints and water motion equations;

[0012] The digital water movement constraints include: channel physical parameters, gate physical parameters, gate flow coefficient, and fluid mechanics constraints;

[0013] The water movement equation in the digital waterway includes: generalizing the natural flow of water in the channel into an open channel uniform flow, generalizing the water movement after the control gate is closed into a pool of water storage, and generalizing the flow mode such as the water level raised by the submerged dam into a submerged flow;

[0014] The rectangular strip is the representation of the water condition of the node on the time axis.

[0015] In which, each node in the digital waterway is assumed to be a channel section, and the channel section is encoded, and the basic operation rules and graphic representation forms of addition, subtraction and displacement of two adjacent nodes are defined;

[0016] In encoding the canal segment: the parent node of the tree is V n , the child node is V 2n , the second child node is V 2n+1 , V n Yes V 2n The upstream channel section, the second child node V 2n+1 is the water intake gate, and the ascending order indicates the direction of water flow. The main channel {V1, V2, ... V 2n , ...}, the water intake gate is represented by G i ∈{V 2n}, the control gate is represented by P i ∈{V 2n+1};

[0017] The addition is: upstream node water condition V n is the water condition at the downstream node V 2n With water intake gate V 2n+1 The sum of water conditions, graphically represented by the union of two rectangular strips over time period T, mathematically expressed as V n =V 2n +V 2n+1 ;

[0018] The subtraction is the inverse operation of the addition. In a period of time T, the water condition of the downstream node is the difference between the water condition of the upstream node and the water condition of the water intake gate. The graphical representation is the difference operation of two rectangular strips in the period T, and the mathematical expression is V 2n =V n -V 2n+1 ;

[0019] The displacement is: the water condition on the first canal section, after the canal section length L, expressed in the second canal section: V 2n The water condition is V n The rectangular strip on the right is shifted by L n / V n ;

[0020] The water conditions of the two adjacent nodes involve union, intersection and difference operations in two dimensions: time and flow.

[0021] Among them, in the step of generalizing the movement environment of water in the channel into the physical parameters of the channel node, the physical parameters of the gate node and the gate flow coefficient constraint:

[0022] The water flow movement forms at each node in the digital channel include: uniform flow in the open channel, water storage before the gate when the control gate is closed, pressure discharge when the control gate is opened, and submerged flow when the water level is raised by the submerged dam;

[0023] The single-width uniform flow of the open channel is: when the open channel water flows naturally, it is generalized as the uniform flow of the open channel: Q = SV, that is, uniform flow in the channel section; where Q is the flow rate along the way, S is the channel cross-sectional area, and V is the average flow velocity;

[0024] The water storage before the gate is closed is: when the gate opening becomes smaller, the channel section before the gate is filled with water, and the water level gradually rises: R = ΔQT; where R is the water storage capacity, ΔQ is the flow difference between the inflow and outflow channel sections, and T is the duration;

[0025] The control gate P is opened to release water under pressure as follows: when the gate is opened to release water, the gate opening gradually increases, and the water flow motion equation is: Q=F(H, h, a, e, dh / dt, dH / dt, S / s); wherein Q is the gate discharge, H is the water level before the gate, h is the water level after the gate, a is the gate opening, e is the flow coefficient, t is the time, S is the water flow cross-sectional area of ​​the inlet section, and s is the cross-sectional area of ​​the outlet section;

[0026] The submerged flow is: when diverting water to fields with higher terrain, the water level is raised by using a submerged dam, and the water flow motion equation is: ΔZ=F(q, H, b, V, e); where q is the flow rate over the dam, H is the total water head on the top of the submerged dam, b is the top width of the overflow part of the submerged dam, V is the flow velocity, e is the flow coefficient, and Δz is the waterlogging height.

[0027] Among them, in the steps of generalizing the flow of canal water as the movement of rectangular strips on a binary tree, using the motion equation of water flow, predicting the changes in downstream water conditions, and organizing irrigation production cooperation:

[0028] The movement of water flow in the channel is generalized into the movement of rectangular strips on the binary tree, and the water conditions of each node and the water conditions of the upstream nodes, the physical parameters of the channel, the gate opening, and the flow coefficient are calculated:

[0029] V 下游节点水情 =F(V 上游节点水情 , G 闸门开度 );

[0030] Iteratively calculate the display form of the rectangular strips in all downstream nodes and convert them into the water situation information of the node;

[0031] The physical parameters of the canal section are constants, obtained through measurement;

[0032] The gate flow coefficient parameter is a constant, obtained through repeated tests and calibration;

[0033] The relationship between the flow and water level of the canal section is obtained by Xie Cai's formula;

[0034] The water information of the node includes: the flow rate, flow velocity, water level and duration of the node;

[0035] All constants are measured and calibrated before simulation and emulation, with the downstream node water conditions as the dependent variable and the upstream node water conditions and gate opening as the independent variables.

[0036] Among them, in the step of repeatedly iteratively calculating the display form of the rectangular strips in all downstream nodes and converting them into the water situation information of the node:

[0037] The calculation results are presented as a rectangular strip pile, which is smoothed by B-spline curve to form the predicted water regime information;

[0038] Compare the forecast results with the actual monitoring results and revise the parameters of the digital waterway;

[0039] Analyze the historical information between the prediction results and the monitoring results to clarify the flow and energy losses during the water delivery process.

[0040] Among them, after comparing the calculation results with the actual monitoring results and revising the parameters of the digital waterway:

[0041] Establish irrigation scheduling plans, simulate water conditions at water inlets based on multiple information, distribute water to fields, guide the timing of irrigation operations, coordinate farmers’ water-saving irrigation, and perform daily river patrol safety management;

[0042] The irrigation scheduling plan includes: the opening and closing time, opening degree, planned flow, duration, and total water consumption information of all gates;

[0043] The simulated water conditions of the water inlet gate are: estimating the changes in water conditions over a period of time. In actual application, flow and water level curves are usually manually drawn based on upstream hydrological monitoring data, water pumping station plans, precipitation, and mountain torrents.

[0044] The numerical simulation and emulation method of irrigation water distribution of the present invention discretizes and generalizes the physical waterway into a digital waterway composed of a binary tree; generalizes the movement environment of water in the channel into the physical parameters of the channel node, the physical parameters of the gate node, the gate flow coefficient, and the fluid mechanics constraints; generalizes the flow of channel water into the movement of a rectangular strip on a binary tree, and adopts the motion equation of the rectangular strip to predict the change of downstream water conditions, organize irrigation production cooperation, and provide technical support for improving the accuracy of water metering, and provide reference and reference for digital twin irrigation areas. By refining the flow calculation equation of the rectangular strip at each tree node, the water condition change trend of all downstream channel sections under various gate opening constraints is calculated, thereby providing technical support for the formulation of a scientific and reasonable irrigation scheduling plan, irrigation operation scheduling sequence, accurate water consumption measurement, and water fee collection. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 It is a flow chart of the steps of the irrigation water distribution numerical simulation and emulation method of the present invention.

[0047] Figure 2 It is a mapping relationship diagram between the physical channel and the digital channel of the present invention.

[0048] Figure 3 It is the encoding of the physical channel and gate of the present invention.

[0049] Figure 4 Schematic diagram of single channel segmentation of the present invention.

[0050] Figure 5 It is a chart of numerical fitting of water conditions of the present invention.

[0051] Figure 6 It is the interpolation channel section water condition of the present invention. DETAILED DESCRIPTION

[0052] Here, exemplary embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application.

[0053] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0054] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0055] See also Figures 1 to 6 ,in Figure 1 It is a flow chart of the steps of numerical simulation and simulation method of irrigation water distribution. Figure 2 It is a mapping diagram between physical channels and digital channels. Figure 3 It is the encoding of physical channels and gates. Figure 4 This is a schematic diagram of single channel segmentation. Figure 5 is a chart of numerically fitting water conditions, Figure 6 It is to interpolate the water conditions of the canal section.

[0056] In a first aspect, the present invention provides an irrigation water distribution numerical simulation and emulation method, comprising the following steps:

[0057] S100: Discretize the physical waterway and generalize it into a digital waterway composed of a binary tree;

[0058] S200: generalizing the movement environment of water in the channel into physical parameters of channel nodes, physical parameters of gate nodes, gate discharge coefficients, and fluid mechanics constraints;

[0059] S300: The water flow movement in the channel section (assuming it is a constant flow) is generalized as a rectangular strip on the tree node in the digital channel; the water flow movement between channel sections is generalized as operations such as deformation, displacement, union, intersection, and difference of the rectangular strip;

[0060] S400: According to the needs of irrigation area management, establish the functional relationship and iterative calculation method between the water inlet flow, water intake flow, and gate opening; simulate the gate switch operation and simulate the water situation in the downstream channel section;

[0061] S500: "Predicted water conditions" and "monitored water conditions" verify each other, and use "insufficient data to supplement the model, insufficient model to supplement the data" to interpolate the time series of water conditions in each channel section to clarify water loss, water energy loss, etc.

[0062] S600: Provides technical support for formulating scientific and reasonable irrigation scheduling plans, scheduling irrigation operations, accurately measuring water consumption, collecting water fees, coordinating farmers to supervise each other in water conservation, and guiding river patrol management.

[0063] In this embodiment, the physical waterway is first discretized and generalized into a digital waterway composed of a binary tree; then the movement environment of water in the channel is generalized into the physical parameters of the digital channel node, the physical parameters of the gate node, and the gate flow coefficient constraint; then the flow of channel water is generalized into the movement of a rectangular strip on a binary tree, and the motion equation of the rectangular strip is used to predict the change of downstream water conditions and organize irrigation production cooperation. Through the above method, the water conditions of water flow in each channel section are simulated, such as time, flow, and water level, and all gates are simulated in various switch operations, such as operation time and gate opening, and the water condition change trend of all channel sections in the basin is predicted, such as numerical simulation, in order to accurately establish the irrigation scheduling plan for the entire irrigation area, guide the switch operation of each gate, coordinate the progress of irrigation operations, and provide technical support for improving the accuracy of water metering, and provide reference and reference for the digital twin irrigation area. Through the above method, the water condition change trend of all downstream channel sections under various constraints is calculated, thereby providing technical support for the formulation of scientific and reasonable irrigation scheduling plans, irrigation operation scheduling sequences, accurate water consumption measurement, and water fee collection.

[0064] Furthermore, the digital waterway includes: a topological structure of the waterway, discretization of the waterway, water motion constraints, and water motion equations;

[0065] The topological structure of the waterway is as follows: according to the natural structure of the irrigation area, the channel is generalized into a tree structure;

[0066] The waterway is discretized as follows: the channel is divided into a number of sections according to the location of the water intake, and each section has the same constraints and water motion equations;

[0067] The water movement constraints include: channel physical parameters, gate physical parameters, and gate discharge coefficient;

[0068] The water motion equation includes: generalizing the natural flow of water in the channel into uniform open channel flow, generalizing the water movement after the control gate is closed into uniform pressure in the pool, and generalizing the flow mode such as the water level raised by the submerged dam into submerged flow;

[0069] The rectangular strip is the representation of the water condition of the node on the time axis.

[0070] Furthermore, after the channel is discretized into channel segments, the water flow motion forms on the tree nodes are divided into four forms: open channel uniform flow, water storage before the gate is closed, pressure discharge of the gate is opened, and submerged flow when the water level is raised by the submerged dam. The present invention assumes that the water flow in a small period of time Δt along each small section (Δd) can be approximated into a constant motion equation, that is, the expression of flow Q = F(t) and water level L = G(t), which can be generalized into the motion equation of a rectangular strip on the flow-time diagram.

[0071] Furthermore, the water flow diversion, convergence, backwatering, and water storage between tree nodes can be summarized as the addition, subtraction, stacking, binning, and packing of rectangular strips. The flow of the main canal inlet is distributed to each field mouth through iteration.

[0072] Furthermore, when mapping the "rectangular strips in the digital channel" back to the "water flow in the physical channel" for verification, it is necessary to comprehensively consider constraints such as the canal water utilization coefficient, and adopt methods such as filling in the data when the model is insufficient and supplementing the model when the data is insufficient, so as to transform the "rectangular strip pile" into a "flow-water level curve".

[0073] 1) If the channel section to be verified has flow, water level and other monitoring instruments, the prediction results should be numerically fitted based on the monitoring values.

[0074] 2) If there is no monitoring equipment in the channel section to be verified, the three characteristic points on the rectangular strip pile are used as the basis to smooth it into a B-spline curve.

[0075] Furthermore, after comparing the calculated results with the actual monitoring results and revising the parameters of the digital waterway:

[0076] Establish irrigation scheduling plan, simulate water conditions at water inlets based on multiple information, and distribute water to fields;

[0077] The irrigation scheduling plan includes: the opening and closing time, opening degree, planned flow, duration, and total water consumption information of all gates;

[0078] The simulated water conditions of the water inlet gate are: estimating the changes in water conditions over a period of time. The system defaults that the water inlet flow and water level remain unchanged. In actual application, the flow and water level curves are usually manually drawn based on upstream hydrological monitoring data, water pumping station plans, precipitation, and mountain torrents.

[0079] Secondly, after discretizing the channel into segments and forming a binary tree, the water flow movement in each small segment (on the tree node) is generalized to the movement of rectangular strips; the water flow movement between segments (between tree nodes) is generalized to the unpacking and packing of rectangular strips. As follows:

[0080] The water flow movement forms in each channel section (on the tree node) are divided into: uniform flow in the open channel, water storage before the gate is closed, pressure discharge when the gate is opened, and submerged flow when the water level is raised by the submerged dam;

[0081] The open channel uniform flow is: when the open channel water flows naturally, it is generalized as the open channel uniform flow: Q = SV, that is, uniform flow in the channel section; where Q is the flow rate, S is the channel cross-sectional area, and V is the average flow velocity;

[0082] The water storage before the gate is closed is: when the gate opening becomes smaller, the channel section before the gate is filled with water, and the water level gradually rises: ΔR = ΔQT; that is, the flow difference between the inflow and outflow channel sections; where ΔR is the water storage, ΔQ is the flow, and T is the duration;

[0083] The gate opening pressure water discharge is: when the gate is opened to release water, the gate opening gradually increases, and the water flow movement mode is divided into two modes: unpressurized flow before the gate and pressurized flow before the gate. The equation is: Q=F(H, h, a, e, dh / dt, dH / dt, S / s); where Q is the gate discharge, H is the water level before the gate, h is the water level after the gate, a is the gate opening, e is the flow coefficient, t is time, S is the water flow cross-sectional area of ​​the inlet section, and s is the cross-sectional area of ​​the outlet section;

[0084] The submerged flow is: when diverting water to fields with higher terrain, the water level is raised by using a submerged dam, and the water flow motion equation is: ΔZ=F(q, H, b, V, e); where q is the flow rate over the dam, H is the total water head on the top of the submerged dam, b is the top width of the overflow part of the submerged dam, V is the flow velocity, e is the flow coefficient, and Δz is the waterlogging height.

[0085] The water flow movement between adjacent nodes in the digital channel can be summarized as follows:

[0086] 1) After the water flow in the upstream channel section of the digital channel flows into the downstream channel section, the average flow velocity and water level must be recalculated based on the physical parameters and hydraulic formulas of the downstream channel section, and the corresponding rectangular strip must be shifted to the right by ΔT=L / V.

[0087] 2) When water is stored, discharged or backed up, backflow often occurs (i.e., channel section V 2n The water conditions at the node often affect V n Node water flow movement), so when calculating V 2n After the water level, flow, water storage capacity, and water level change rate are calculated, V n The representation of the upper rectangular strip.

[0088] 3) When diversion or confluence occurs, the addition and subtraction of rectangular strips should satisfy the properties of water flow, such as flow addition and time shift.

[0089] The physical parameters of the above channel sections are constants and obtained through measurements;

[0090] The above gate flow coefficient parameters are constants, obtained through repeated tests and calibration;

[0091] In the above open channel uniform flow, the relationship between flow rate and water level is obtained by Xie Cai's formula;

[0092] The water information of the above nodes includes: the flow rate, flow velocity, water level and duration of the node;

[0093] Thirdly, when the water flows through the water intake gate, the calculation of the flow rate is similar to the unpacking and packing of rectangular strips, which is further abstracted into a mathematical problem, and the significance of solving the equation is discussed.

[0094] Encode all hydraulic structures, the parent node of the tree is V n , child node V 2n , the second child node is V 2n+1 , V n Yes V 2n The upstream channel section, the second child node V 2n+1 For water intake gates, main canal {V1, V2, ... V 2n , ...} The water intake gate is represented by G i ∈{V 2n}, the ascending order indicates the direction of water flow, and the control gate is represented by P i ∈{V 2n+1 If the water condition at the water inlet V06 is {V 0，601 V 0， 602 ...V 0，630}; Gate G opening

[0095]

[0096] Branch Canal V 2i+1 Flow V (2i+1，j) as follows

[0097]

[0098] 1) Equation V (2i+1，j) =F(V 0j , G ij ) is used to calculate the flow distribution plan of the branch canal corresponding to different water inlet flows and gate opening and closing plans. In the future, it will be used to innovate the flow measurement method, verify with flow monitoring equipment, and provide auxiliary evidence for collecting water fees.

[0099] 2) Equation G ij =F(V 0i , V (2i+1，j) ) is used to calculate the gate operation timing and gate opening of each branch canal. In the future, it will be used to plan gate operation time, reasonably arrange the shifts of river patrol personnel, and reduce the frequency of river patrols.

[0100] 3) Equation V ij =F(V (2i+1，j) , G ij ) is used to calculate when the peak irrigation flow reaches each canal section and the duration of the peak. In the future, it can be used for dam safety reminders and peak-shifting irrigation.

[0101] The calculation steps are as described above. The graphical representation is a rectangular strip that passes through each tree node and is repacked or split into a small rectangle.

[0102] Since the physical parameters of the channel, the water movement environment, and the gate coefficient remain unchanged throughout the year, the rectangular strip motion constraint parameters can be calibrated in advance, and the flow distribution of each branch canal only depends on the two independent variables of the water condition at the water inlet and the gate opening. By simulating the independent variables through random functions, the present invention is used to predict the temporal and spatial distribution of downstream water volume, analyze whether the irrigation operation can meet the needs of crops in a timely manner, whether the scheduling workload is reasonable, whether the gate opening and closing sequence conforms to the river patrol route, etc.; when the monitored flow does not match the planned flow, it can also find the congested location in time, analyze the area of ​​abnormal water use, and verify the flow monitoring equipment; urge farmers to irrigate according to the plan to make the irrigation operation orderly as a whole; it is a data accumulation and verification tool for the study of irrigation scheduling operation scheduling algorithms, and an important part of the intelligent irrigation area.

[0103] The present invention can dynamically predict the temporal and spatial distribution of canal water: use "rectangular strip piles" at the head of the canal to establish an irrigation operation schedule (conducive to gate scheduling management); numerically fit the water delivery process in the middle reaches (intuitively display water situation changes); predict each flow at the water intake, improve the metering accuracy of the flow meter, and improve the irrigation management service model of modern irrigation areas. Long-term operation and maintenance of this simulation system can reduce the construction cost of modern irrigation areas and improve the efficiency of water resource utilization.

[0104] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the contents disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application.

[0105] It should be understood that the present application is not limited to the exact construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims

1. A numerical simulation and emulation method for irrigation water distribution, characterized in that: The steps include: Discretize the physical waterway and generalize it into a digital waterway composed of a binary tree; The water movement environment in the channel is generalized into the physical parameters of the channel nodes, the physical parameters of the gate nodes, the gate discharge coefficient, and the fluid mechanics constraints; The flow of canal water is generalized as the movement of rectangular strips on a binary tree. The motion equation of the rectangular strips is used to predict changes in downstream water conditions and organize irrigation production cooperation.

2. The irrigation water distribution numerical simulation and emulation method according to claim 1, characterized in that: The digital waterway includes: a topological structure of the digital waterway, discretization of the digital waterway, digital water motion constraints, and water motion equations in the digital waterway; The topological structure of the digital waterway is as follows: according to the natural structure of the irrigation area, the channel is generalized into a tree structure; The digital waterway is discretized as follows: according to the location of the water intake, the channel is divided into a number of channel sections, each of which has the same constraints and water motion equations; The digital water movement constraints include: channel physical parameters, gate physical parameters, gate flow coefficient, and fluid mechanics constraints; The water movement equation in the digital waterway includes: generalizing the natural flow of water in the channel into an open channel uniform flow, generalizing the water movement after the control gate is closed into a pool of water storage, and generalizing the flow mode such as the water level raised by the submerged dam into a submerged flow; The rectangular strip is the representation of the water condition of the node on the time axis.

3. The irrigation water distribution numerical simulation and emulation method according to claim 2, characterized in that: Assume that each node in the digital waterway is a channel segment, encode the channel segment, and define the basic operation rules and graphic representation of addition, subtraction and displacement of two adjacent nodes; In encoding the canal segment: the parent node of the tree is V n , the child node is V 2n , the second child node is V 2n+1 , V n Yes V 2n The upstream channel section, the second child node V 2n+1 is the water intake gate, and the ascending order indicates the direction of water flow. The main channel {V1, V2, ... V 2n , ...}, the water intake gate is represented by G i ∈{V 2n }, the control gate is represented by P i ∈{V 2n+1 }; The addition is: upstream node water condition V n is the water condition at the downstream node V 2n With water intake gate V 2n+1 The sum of water conditions, graphically represented by the union of two rectangular strips over time period T, mathematically expressed as V n =V 2n +V 2n+1 ; The subtraction is the inverse operation of the addition. In a period of time T, the water condition of the downstream node is the difference between the water condition of the upstream node and the water condition of the water intake gate. The graphical representation is the difference operation of two rectangular strips in the period T, and the mathematical expression is V 2n =V n -V 2n+1 ; The displacement is: the water condition on the first canal section, after the canal section length L, expressed in the second canal section: V 2n The water condition is V n The rectangular strip on the right is shifted by L n / V n ; The water conditions of the two adjacent nodes involve union, intersection and difference operations in two dimensions: time and flow.

4. The irrigation water distribution numerical simulation and emulation method according to claim 3, characterized in that: In the step of generalizing the water movement environment in the channel into the physical parameters of the channel node, the physical parameters of the gate node, and the gate discharge coefficient constraints: The water flow movement forms at each node in the digital channel include: uniform flow in the open channel, water storage before the gate when the control gate is closed, pressure discharge when the control gate is opened, and submerged flow when the water level is raised by the submerged dam; The single-width uniform flow of the open channel is: when the open channel water flows naturally, it is generalized as the uniform flow of the open channel: Q = SV, that is, uniform flow in the channel section; where Q is the flow rate along the way, S is the channel cross-sectional area, and V is the average flow velocity; The water storage before the gate is closed is: when the gate opening becomes smaller, the channel section before the gate is filled with water, and the water level gradually rises: R = ΔQT; where R is the water storage capacity, ΔQ is the flow difference between the inflow and outflow channel sections, and T is the duration; The control gate P is opened to release water under pressure as follows: when the gate is opened to release water, the gate opening gradually increases, and the water flow motion equation is: Q=F(H, h, a, e, dh / dt, dH / dt, S / s); wherein Q is the gate discharge, H is the water level before the gate, h is the water level after the gate, a is the gate opening, e is the flow coefficient, t is the time, S is the water flow cross-sectional area of ​​the inlet section, and s is the cross-sectional area of ​​the outlet section; The submerged flow is: when diverting water to fields with higher terrain, the water level is raised by using a submerged dam, and the water flow motion equation is: ΔZ=F(q, H, b, V, e); where q is the flow rate over the dam, H is the total water head on the top of the submerged dam, b is the top width of the overflow part of the submerged dam, V is the flow velocity, e is the flow coefficient, and Δz is the waterlogging height.

5. The irrigation water distribution numerical simulation and emulation method according to claim 4, characterized in that: In the steps of generalizing the flow of canal water as the movement of rectangular strips on a binary tree, using the motion equation of water flow, predicting the changes in downstream water conditions, and organizing irrigation production cooperation: The movement of water flow in the channel is generalized into the movement of rectangular strips on the binary tree, and the water conditions of each node and the water conditions of the upstream nodes, the physical parameters of the channel, the gate opening, and the flow coefficient are calculated: V 下游节点水情 =F(V 上游节点水情 ,G 闸门开度 ); Iteratively calculate the display form of the rectangular strips in all downstream nodes and convert them into the water situation information of the node; The physical parameters of the canal section are constants, obtained through measurement; The gate flow coefficient parameter is a constant, obtained through repeated tests and calibration; The relationship between the flow and water level of the canal section is obtained by Xie Cai's formula; The water information of the node includes: the flow rate, flow velocity, water level and duration of the node; All constants are measured and calibrated before simulation and emulation, with the downstream node water conditions as the dependent variable and the upstream node water conditions and gate opening as the independent variables.

6. The irrigation water distribution numerical simulation and emulation method according to claim 5, characterized in that: In the step of repeatedly iteratively calculating the display form of the rectangular strips in all downstream nodes and converting them into the water situation information of the node: The calculation results are presented as a rectangular strip pile, which is smoothed by B-spline curve to form the predicted water regime information; Compare the forecast results with the actual monitoring results and revise the parameters of the digital waterway; Analyze the historical information between the prediction results and the monitoring results to clarify the flow and energy losses during the water delivery process.

7. The irrigation water distribution numerical simulation and emulation method according to claim 6, characterized in that: After comparing the calculated results with the actual monitoring results and revising the parameters of the digital waterway: Establish irrigation scheduling plans, simulate water conditions at water inlets based on multiple information, distribute water to fields, guide the timing of irrigation operations, coordinate farmers’ water-saving irrigation, and perform daily river patrol safety management; The irrigation scheduling plan includes: the opening and closing time, opening degree, planned flow, duration, and total water consumption information of all gates; The simulated water conditions of the water inlet gate are: estimating the changes in water conditions over a period of time. In actual application, flow and water level curves are usually manually drawn based on upstream hydrological monitoring data, water pumping station plans, precipitation, and mountain torrents.

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