Saline-alkali irrigation area drainage regulation method and system based on salt peak window response

Abstract

The application discloses a salinization irrigation area drainage regulation method and system based on a salt peak window response, and relates to the technical field of irrigation area resource management; the perception layer collects original hydrological and water quality data in real time through a distributed salt monitoring matrix and carries out data preprocessing, the decision layer calculates to obtain characteristic indexes of salt peak window identification, compares the characteristic indexes with preset determination thresholds to identify key nodes of the salt peak window and time periods in which the salt peak window is located, imports a water quality and water level double collaborative optimization scheduling model, solves a comprehensive objective function through a linear weighting method to obtain optimal regulation parameters and regulation modes in combination with constraint conditions, the execution layer switches the regulation modes and adjusts variable frequency pump stations and electric regulating gates, and real-time operation parameters are fed back to the decision layer; the salinization irrigation area drainage regulation method and system based on the salt peak window response are adopted, centralized drainage is carried out in a time window with the highest salt discharge efficiency, and invalid operation time of the pump stations is significantly reduced.

Description

Technical Field

[0001] This invention relates to the field of irrigation area resource management technology, and in particular to a method and system for regulating drainage in saline-alkali irrigation areas based on salt peak window response. Background Technology

[0002] Traditional irrigation district drainage scheduling is mostly based on water level control, that is, when the groundwater level or the drain water level exceeds a set threshold, the pumping station is activated for forced drainage. This results in low salt removal efficiency, and the salt concentration during the drainage process is spatially and temporally uneven. Blindly draining water during periods of low salinity will remove a large amount of freshwater while leaving salt behind. Resource utilization is low, failing to utilize the "low salinity" during the drainage process for interception and reuse or infiltration to compensate for groundwater. The environmental impact is significant, as the indiscriminate discharge of high-concentration saline water causes a serious ecological burden on downstream receiving water bodies. The root cause of these defects is the lack of accurate capture and automated linkage feedback of the peak salt concentration (salt peak) and time window during the drainage process. Summary of the Invention

[0003] The purpose of this invention is to provide a drainage control method and system for saline-alkali irrigation areas based on salt peak window response. This method enables centralized discharge during the time window with the highest salt discharge efficiency, optimizes the salt discharge and desalination process, significantly reduces the ineffective operating time of pumping stations, saves electricity costs, and reduces the salt load discharged into the downstream Yellow River main stream. It also provides a new mode of water quality response scheduling, which is in line with the research and development direction and has broad application prospects.

[0004] To achieve the above objectives, this invention provides a drainage regulation method for salinized irrigation areas based on salt peak window response, comprising the following steps:

[0005] S1. The sensing layer uses a distributed salinity monitoring matrix to collect raw hydrological and water quality data in real time at the main drainage channels and outlets of agricultural ditches at all levels in the irrigation area and performs data preprocessing.

[0006] S2. The decision-making layer calculates the characteristic indicators for salt peak window identification based on the hydrological and water quality data obtained after preprocessing in S1.

[0007] S3. Compare the feature indicators of S2 with the preset judgment threshold, and identify the key nodes and periods of the salt peak window according to the salt peak window judgment rules.

[0008] S4. Import the hydrological and water quality data preprocessed in S1 and the salt peak window determination results in S3 into the water quality and water level dual collaborative optimization scheduling model. Combine the preset constraints and solve the comprehensive objective function by linear weighting method to obtain the optimal control parameters and control mode.

[0009] S5. Based on the optimal control parameters and control mode obtained from S4, the execution layer automatically switches the control mode and precisely adjusts the variable frequency pump station and electric regulating gate.

[0010] In S6 and S5, the execution layer feeds back the real-time operating parameters, gate opening, and equipment operating status of the variable frequency pumping station to the decision-making layer in real time to dynamically track the salt peak window status and changes in irrigation area water quality and water level. At the same time, the sensing layer continuously collects the latest hydrological and water quality data.

[0011] Preferably, the raw hydrological and water quality data collected in S1 includes conductivity values. Water temperature Drainage flow Drainage water level ;

[0012] The preprocessing process is as follows:

[0013] Since water temperature affects the accuracy of conductivity monitoring, the conductivity value needs to be corrected for water temperature to eliminate temperature interference. The compensation formula is as follows:

[0014] ;

[0015] in, This is the standard conductivity value corrected for water temperature at 25°C. This is the conductivity temperature compensation coefficient, calibrated according to the water quality characteristics of the irrigation area, with a value ranging from 0.01 to 0.02 / ℃. This is the original conductivity value. For real-time monitoring of water temperature data;

[0016] At the same time, the collected drainage flow rate Drainage water level Outlier removal is performed using a moving average method for smoothing, as shown in the following formula:

[0017] ;

[0018] in, for Smoothed data at any given time. The length of the sliding window. for The raw monitoring data at any given moment.

[0019] Preferably, the salt peak window in S2 is identified using standard conductivity values. Focusing on the time-varying characteristics, it is characterized through first-order derivative operations. The rate of change of the value, represented by the second derivative operation. By analyzing the trend of salt concentration changes, key nodes in the salt peak window can be accurately identified, enabling precise capture of periods of rapid salt concentration change. The specific calculation process is as follows:

[0020] First derivative The change in standard conductivity per unit time, reflecting the rate of increase or decrease in salt concentration, is calculated using the finite difference method. The specific formula is as follows:

[0021] ;

[0022] in, for The first derivative of the standard conductivity at time t, for Standard conductivity value at time , for Standard conductivity value at time , The time step for collecting raw hydrological and water quality data, when When the salt concentration increases, the concentration tends to rise; when At that time, the salt concentration showed a decreasing trend;

[0023] Second derivative The change in the first derivative reflects the trend of the rate of increase or decrease in salt concentration and is a core indicator for determining the opening and closing of the salt peak window. It is also calculated using the finite difference method, with the following formula:

[0024] ;

[0025] in, for The second derivative of the standard conductivity at time t, , for , The first derivative of the standard conductivity at time t.

[0026] Preferably, the salt peak window determination threshold in S3 is as follows:

[0027] Based on historical monitoring data of the irrigation area and field tests, three judgment thresholds were preset:

[0028] High conductivity threshold The minimum standard electrical conductivity value during the peak salt concentration period in the irrigation area is determined by the soil salinity and irrigation water quality of the irrigation area.

[0029] First derivative positive threshold The minimum rate at which the salt concentration increases significantly is determined as the critical value for the salt peak rising phase.

[0030] Second derivative zero threshold : Take 0, which is the critical value at which the rate of salt concentration change from increasing to decreasing.

[0031] Preferably, the key nodes of the salt peak window identified in S3 include the window opening point, the peak point, and the window closing point; the rules for determining the window opening point, the peak point, and the window closing point are as follows:

[0032] Window opens: When , , When this time, it is determined that the salt peak window is open. This marks the beginning of the peak salt season;

[0033] Peak point: when The moment before The next moment At that time This is the peak point of the salt peak window, where the salt concentration reaches its maximum value;

[0034] Window closed: When or and When the salt peak window is closed, it is determined that the salt peak window is closed. This marks the point where the salt concentration drops, signifying the end of the peak salt season and the beginning of a low-salt period.

[0035] Preferably, in S4, an objective function is constructed to maximize the total amount of salt excreted. The objective function for minimizing freshwater loss For a dual-objective optimization scheduling model, the standard conductivity is used. As a core water quality constraint, the drainage water level As a core hydrological constraint, and taking into account the pump station operating power and downstream ecological salinity load boundary conditions, the objective function is constructed as follows to achieve coordinated regulation of water quality and water level:

[0036] Objective function to maximize total salt excretion as follows:

[0037] ;

[0038] in, This represents the total amount of salt discharged during the peak salt window period. , The opening and closing times of the salt peak window. The conductivity-salt concentration conversion coefficient is determined by water samples from the irrigation area and is a constant.

[0039] freshwater loss minimization objective function as follows:

[0040] ;

[0041] in, To calculate the total freshwater loss during the statistical period, , The start and end times of the statistical period. This is the threshold for determining whether freshwater is usable; water below this value is considered reusable freshwater. This is an indicator function that takes the value 1 when the condition inside the parentheses is true and 0 when it is false.

[0042] The dual-objective problem is transformed into a single-objective optimization problem using a linear weighted method. The optimal scheduling scheme is then solved, and the combined objective function is obtained. as follows:

[0043] ;

[0044] in, To comprehensively optimize the target value, , The weighting coefficients and Salt peak period > Prioritize salt removal and extract salt during periods of low salinity. > Prioritize water conservation. This represents the maximum total amount of salt discharged. This represents the maximum total freshwater loss.

[0045] Preferably, the preset constraints in S4 are as follows:

[0046] Water level constraints: The drainage water level must not exceed the warning water level or fall below the ecological minimum water level, as specified in the formula: ,in To achieve the lowest ecological water level in the drainage canal, To set the warning water level for the drainage canal;

[0047] Pump station operation constraints: The pump station's drainage flow rate and operating power are adjustable within the rated range, specifically: , ,in , For the pump station's drainage flow rate and operating power, , The minimum and maximum rated drainage flow rates of the pumping station. , These are the minimum and maximum rated operating power of the pumping station;

[0048] Downstream ecological salt carrying capacity constraint: The salt load discharged downstream per unit time must not exceed the ecological threshold, i.e. ,in This represents the maximum permissible salinity load of the downstream receiving water body;

[0049] Mode switching constraint: determined based on the ratio of real-time standard conductivity value to historical background value. ,in This is the historical average background value of the standard conductivity of the irrigation area, obtained from years of monitoring data.

[0050] Preferably, in S4, the ratio coefficient between the salt peak window determination result and the conductivity is... Based on the optimization results of the water quality and water level dual-coordinated optimization model, the control modes are divided into salinity discharge mode, recharge mode, and water-saving mode. Each control mode adopts differentiated pump station and gate control strategies to achieve adaptive response of high salinity high discharge, low salinity reuse, and appropriate salinity throttling. The judgment criteria for each control mode are as follows:

[0051] Criteria for determining salt discharge mode: The salt peak window is open during the salt peak period. and ;

[0052] Criteria for determining the replenishment mode: The salt peak window is closed during a low-salt period. and The groundwater in the irrigation area needs to be replenished;

[0053] Criteria for determining water-saving mode: The salt peak window is closed and the water level is low. and .

[0054] Preferably, the control strategies formulated by each control mode according to the judgment criteria are as follows;

[0055] The core strategy of the salt discharge mode is to maximize the drainage capacity of the pumping station, quickly discharge high-salt water, and ensure that the total amount of salt discharged is maximized.

[0056] Equipment control in salt discharge mode: Pump station is turned on to rated operating power, and drainage flow is adjusted to the maximum value; main drainage outlet gate is fully open, and freshwater interception channel gate is fully closed.

[0057] The core strategy of the replenishment model is to completely intercept reusable freshwater and replenish the groundwater in the irrigation area through infiltration, thereby minimizing the loss of freshwater.

[0058] Equipment control in replenishment mode: Pump station is shut down or adjusted to the rated operating power for pressure maintenance; main drainage outlet gates are fully closed, and freshwater interception channel gates are fully open;

[0059] The core strategy of the water-saving model is to moderately reduce water flow and discharge, while taking into account both irrigation area water level control and freshwater conservation, and avoiding ineffective discharge.

[0060] Equipment control in water-saving mode: The pumping station is adjusted to a lower-middle rated operating power, and the drainage flow is appropriately reduced; the main drainage outlet gate is partially opened, and the freshwater interception channel gate is opened as needed.

[0061] To achieve the above objectives, the present invention also provides a drainage control system for saline-alkali irrigation areas based on salt peak window response, comprising a sensing layer, a decision-making layer, and an execution layer;

[0062] The sensing layer is responsible for the collection and preprocessing of raw hydrological and water quality data. The distributed salinity monitoring matrix is ​​evenly deployed at the outlets of the main drainage canals and agricultural ditches at all levels to achieve comprehensive and real-time monitoring of drainage salinity and hydrological parameters.

[0063] The decision-making layer has a built-in salt peak window diagnostic algorithm. Based on the sensing layer and the processed hydrological and water quality data, it captures the peak band of salt concentration by analyzing the time change rate of conductivity values ​​in real time. Combined with preset thresholds, it completes the accurate determination of salt peak window and low salt period and outputs clear scheduling instructions to the execution layer. It also stores diagnostic data and instruction records in sync, forming a complete data traceability chain.

[0064] The execution layer receives scheduling instructions from the decision-making layer, including the variable frequency pump station controller and the electric regulating gate. The two work together to achieve flexible adjustment and on / off control of drainage flow.

[0065] Therefore, the drainage control method and system for salinized irrigation areas based on salt peak window response described above has the following advantages compared with the prior art:

[0066] This application enables centralized discharge during the time window with the highest salt discharge efficiency, optimizing the salt discharge and desalination process; it significantly reduces the ineffective operating time of pumping stations, saves electricity costs, and reduces the salt load discharged into the downstream Yellow River main stream; it provides a new mode of water quality response scheduling, which is in line with the research and development direction and has broad application prospects.

[0067] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0068] Figure 1 This is an overall flowchart of the drainage regulation method for salinized irrigation areas based on salt peak window response of the present invention;

[0069] Figure 2 This is a structural diagram of the drainage control system for salinized irrigation areas based on salt peak window response, as described in this invention. Detailed Implementation

[0070] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0071] Example

[0072] like Figure 1As shown, the drainage regulation method for salinized irrigation areas based on salt peak window response of the present invention includes the following steps:

[0073] S1. The sensing layer uses a distributed salinity monitoring matrix to collect raw hydrological and water quality data in real time at the main drainage channels and outlets of agricultural ditches at all levels in the irrigation area and performs data preprocessing.

[0074] The raw hydrological and water quality data collected include conductivity values. Water temperature Drainage flow rate Drainage water level ;

[0075] The preprocessing process is as follows:

[0076] Since water temperature affects the accuracy of conductivity monitoring, the conductivity value needs to be corrected for water temperature to eliminate temperature interference. The compensation formula is as follows:

[0077] ;

[0078] in, This is the standard conductivity value corrected for water temperature at 25°C. This is the conductivity temperature compensation coefficient, calibrated according to the water quality characteristics of the irrigation area, with a value ranging from 0.01 to 0.02 / ℃. This is the original conductivity value. For real-time monitoring of water temperature data;

[0079] At the same time, the collected drainage flow rate Drainage water level Outlier removal is performed using a moving average method for smoothing, as shown in the following formula:

[0080] ;

[0081] in, for Smoothed data at any given time. The length of the sliding window. for For the raw monitoring data at any given time, it is recommended to take 3 to 5 times.

[0082] S2. The decision-making layer calculates the characteristic indicators for salt peak window identification based on the hydrological and water quality data obtained after preprocessing in S1.

[0083] The salt peak window is identified using standard conductivity values. Focusing on the time-varying characteristics, it is characterized through first-order derivative operations. The rate of change of the value, represented by the second derivative operation. By analyzing the trend of salt concentration changes, key nodes in the salt peak window can be accurately identified, enabling precise capture of periods of rapid salt concentration change. The specific calculation process is as follows:

[0084] First derivative The change in standard conductivity per unit time, reflecting the rate of increase or decrease in salt concentration, is calculated using the finite difference method. The specific formula is as follows:

[0085] ;

[0086] in, for The first derivative of the standard conductivity at time t, for Standard conductivity value at time , for Standard conductivity value at time , The time step for collecting raw hydrological and water quality data, when When the salt concentration increases, the concentration tends to rise; when At that time, the salt concentration showed a decreasing trend;

[0087] Second derivative The change in the first derivative reflects the trend of the rate of increase or decrease in salt concentration and is a core indicator for determining the opening and closing of the salt peak window. It is also calculated using the finite difference method, with the following formula:

[0088] ;

[0089] in, for The second derivative of the standard conductivity at time t, , for , The first derivative of the standard conductivity at time t;

[0090] S3. Compare the feature indicators of S2 with the preset judgment threshold, identify the key nodes and periods of the salt peak window according to the salt peak window judgment rules, and input the judgment results into the water quality and water level dual collaborative optimization scheduling model.

[0091] The threshold for determining the salt peak window is as follows:

[0092] Based on historical monitoring data of the irrigation area and field tests, three judgment thresholds were preset:

[0093] High conductivity threshold The minimum standard electrical conductivity value during the peak salt concentration period in the irrigation area is determined by the soil salinity and irrigation water quality of the irrigation area.

[0094] First derivative positive threshold The minimum rate at which the salt concentration increases significantly is determined as the critical value for the salt peak rising phase.

[0095] Second derivative zero threshold : Take 0, which is the critical value at which the rate of salt concentration change from increasing to decreasing;

[0096] The key nodes of the salt peak window include the window opening point, the peak value point, and the window closing point; the rules for determining the window opening point, peak value point, and window closing point are as follows:

[0097] Window opens: When , , When this time, it is determined that the salt peak window is open. This marks the beginning of the peak salt season;

[0098] Peak point: when The moment before The next moment At that time This is the peak point of the salt peak window, where the salt concentration reaches its maximum value;

[0099] Window closed: When or and When the salt peak window is closed, it is determined that the salt peak window is closed. This marks the point where the salt concentration drops, the end of the peak salt season, and the beginning of the low-salinity period.

[0100] S4. Import the hydrological and water quality data preprocessed in S1 and the salt peak window determination results in S3 into the water quality and water level dual collaborative optimization scheduling model. Combine the preset constraints and solve the comprehensive objective function by linear weighting method to obtain the optimal control parameters and control mode.

[0101] The objective function is constructed to maximize the total amount of salt excretion. The objective function for minimizing freshwater loss For a dual-objective optimization scheduling model, the standard conductivity is used. As a core water quality constraint, the drainage water level As a core hydrological constraint, and taking into account the pump station operating power and downstream ecological salinity load boundary conditions, the objective function is constructed as follows to achieve coordinated regulation of water quality and water level:

[0102] Objective function to maximize total salt excretion as follows:

[0103] ;

[0104] in, This represents the total amount of salt discharged during the peak salt window period. , The opening and closing times of the salt peak window. The conductivity-salt concentration conversion coefficient is determined by water samples from the irrigation area and is a constant.

[0105] freshwater loss minimization objective function as follows:

[0106] ;

[0107] in, To calculate the total freshwater loss during the statistical period, , The start and end times of the statistical period. This is the threshold for determining whether freshwater is usable; water below this value is considered reusable freshwater. This is an indicator function that takes the value 1 when the condition inside the parentheses is true and 0 when it is false.

[0108] The dual-objective problem is transformed into a single-objective optimization problem using a linear weighted method. The optimal scheduling scheme is then solved, and the combined objective function is obtained. as follows:

[0109] ;

[0110] in, To comprehensively optimize the target value, , The weighting coefficients and Salt peak period > Prioritize salt removal and extract salt during periods of low salinity. > Prioritize water conservation. This represents the maximum total amount of salt discharged. This represents the maximum total freshwater loss.

[0111] The preset constraints are as follows:

[0112] Water level constraints: The drainage water level must not exceed the warning water level or fall below the ecological minimum water level, as specified in the formula: ,in To achieve the lowest ecological water level in the drainage canal, To set the warning water level for the drainage canal;

[0113] Pump station operation constraints: The pump station's drainage flow rate and operating power are adjustable within the rated range, specifically: , ,in , For the pump station's drainage flow rate and operating power, , The minimum and maximum rated drainage flow rates of the pumping station. , These are the minimum and maximum rated operating power of the pumping station;

[0114] Downstream ecological salt carrying capacity constraint: The salt load discharged downstream per unit time must not exceed the ecological threshold, i.e. ,in This represents the maximum permissible salinity load of the downstream receiving water body;

[0115] Mode switching constraint: determined based on the ratio of real-time standard conductivity value to historical background value. ,in This is the historical average background value of the standard conductivity of the irrigation area, obtained from statistical analysis of monitoring data over many years.

[0116] Based on the salt peak window determination result and the conductivity ratio coefficient Based on the optimization results of the water quality and water level dual-coordinated optimization model, the control modes are divided into salinity discharge mode, recharge mode, and water-saving mode. Each control mode adopts differentiated pump station and gate control strategies to achieve adaptive response of high salinity high discharge, low salinity reuse, and appropriate salinity throttling. The judgment criteria for each control mode are as follows:

[0117] Criteria for determining salt discharge mode: The salt peak window is open during the salt peak period. and ;

[0118] Criteria for determining the replenishment mode: The salt peak window is closed during a low-salt period. and The groundwater in the irrigation area needs to be replenished;

[0119] Criteria for determining water-saving mode: The salt peak window is closed and the water level is low. and ;

[0120] The control strategies formulated by each control model based on the judgment criteria are as follows;

[0121] The core strategy of the salt discharge mode is to maximize the drainage capacity of the pumping station, quickly discharge high-salt water, and ensure that the total amount of salt discharged is maximized.

[0122] Equipment control in salt discharge mode: The pump station is started up to its rated operating power. The drainage flow rate is adjusted to the maximum value. The main drainage outlet gates are fully open (100% opening), and the freshwater interception channel gates are fully closed (0% opening).

[0123] The core strategy of the replenishment model is to completely intercept reusable freshwater and replenish the groundwater in the irrigation area through infiltration, thereby minimizing the loss of freshwater.

[0124] Equipment control: Pump station shutdown Or adjust to the minimum rated operating power for pressure holding. The main drainage outlet gates are all closed (0% opening), and the freshwater interception channel gates are all open (100% opening).

[0125] The core strategy of the water-saving model is to moderately reduce water flow and discharge, while taking into account both irrigation area water level control and freshwater conservation, and avoiding ineffective discharge.

[0126] Water-saving mode equipment control: The pump station is adjusted to a lower-middle rated operating power. The drainage flow rate is appropriately reduced; the main drainage outlet gate is partially opened (opening degree 20%~40%), and the freshwater interception channel gate is opened as needed (opening degree 10%~30%).

[0127] S5. Based on the optimal control parameters and control mode obtained from S4, the execution layer automatically switches the control mode and precisely adjusts the variable frequency pump station and electric regulating gate.

[0128] The data is wirelessly transmitted to the intelligent drainage scheduling terminal at the execution layer. The terminal automatically switches the control mode according to the instructions and makes precise adjustments to the frequency conversion pump station and electric regulating gate: in the salt discharge mode, the equipment is fully opened for forced discharge; in the replenishment mode, the equipment is fully closed for interception; and in the water-saving mode, the equipment is moderately adjusted to throttle the flow, so as to achieve rapid and accurate execution of the instructions.

[0129] In S6 and S5, the execution layer feeds back the real-time operating parameters, gate opening, and equipment operating status of the variable frequency pumping station to the decision-making layer in real time to dynamically track the salt peak window status and changes in irrigation area water quality and water level. At the same time, the sensing layer continuously collects the latest hydrological and water quality data.

[0130] like Figure 2 As shown, the drainage control system for saline-alkali irrigation areas based on salt peak window response includes a sensing layer, a decision-making layer, and an execution layer.

[0131] The sensing layer is responsible for the collection and preprocessing of raw hydrological and water quality data. The distributed salinity monitoring matrix is ​​evenly deployed at the outlets of the main drainage canals and agricultural ditches at all levels to achieve comprehensive and real-time monitoring of drainage salinity and hydrological parameters.

[0132] The decision-making layer has a built-in salt peak window diagnostic algorithm. Based on the sensing layer and the processed hydrological and water quality data, it captures the peak band of salt concentration by analyzing the time change rate of conductivity values ​​in real time. Combined with preset thresholds, it completes the accurate determination of salt peak window and low salt period and outputs clear scheduling instructions to the execution layer. It also stores diagnostic data and instruction records in sync, forming a complete data traceability chain.

[0133] The execution layer receives scheduling instructions from the decision-making layer, including the variable frequency pump station controller and the electric regulating gate. The two work together to achieve flexible adjustment and on / off control of drainage flow.

[0134] Therefore, the present invention adopts the above-mentioned method and system for regulating drainage in saline-alkali irrigation areas based on salt peak window response, which realizes centralized discharge during the time window with the highest salt discharge efficiency, optimizes the salt discharge and desalination process, significantly reduces the ineffective operating time of pumping stations, saves electricity costs, and reduces the salt load discharged into the downstream Yellow River main stream; it provides a new mode of water quality response scheduling, which is in line with the research and development direction and has broad application prospects.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A drainage regulation method for saline-alkali irrigation areas based on salt peak window response, characterized in that, Includes the following steps: S1. The sensing layer uses a distributed salinity monitoring matrix to collect raw hydrological and water quality data in real time at the main drainage channels and outlets of agricultural ditches at all levels in the irrigation area and performs data preprocessing. S2. The decision-making layer calculates the characteristic indicators for salt peak window identification based on the hydrological and water quality data obtained after preprocessing in S1. S3. Compare the feature indicators of S2 with the preset judgment threshold, and identify the key nodes and periods of the salt peak window according to the salt peak window judgment rules. The threshold for determining the salt peak window in S3 is as follows: Based on historical monitoring data of the irrigation area and field tests, three judgment thresholds were preset: High conductivity threshold The minimum standard electrical conductivity value during the peak salt concentration period in the irrigation area is determined by the soil salinity and irrigation water quality of the irrigation area. First derivative positive threshold The minimum rate at which the salt concentration increases significantly is determined as the critical value for the salt peak rising phase. Second derivative zero threshold : Take 0, which is the critical value at which the rate of salt concentration change from increasing to decreasing; The key nodes of the salt peak window identified in S3 include the window opening point, peak point, and window closing point; the rules for determining the window opening point, peak point, and window closing point are as follows: Window opens: When , , When this time, it is determined that the salt peak window is open. This marks the beginning of the peak salt season; Peak point: when The moment before The next moment At this time This is the peak point of the salt peak window, where the salt concentration reaches its maximum value; Window closed: When or and When the salt peak window is closed, it is determined that the salt peak window is closed. S1 is the point where the salt peak falls back, the salt peak period ends, and the low salt period begins; S4, the hydrological and water quality data preprocessed in S1 and the salt peak window determination results in S3 are imported into the water quality and water level dual collaborative optimization scheduling model. Combined with the preset constraints, the comprehensive objective function is solved by the linear weighting method to obtain the optimal control parameters and control mode. In S4, construct the objective function that maximizes the total amount of salt excretion. The objective function for minimizing freshwater loss For a dual-objective optimization scheduling model, the standard conductivity is used. As a core water quality constraint, the drainage water level As a core hydrological constraint, and taking into account the pump station operating power and downstream ecological salinity load boundary conditions, the objective function is constructed as follows to achieve coordinated regulation of water quality and water level: Objective function to maximize total salt excretion as follows: ； in, This represents the total amount of salt discharged during the peak salt window period. , The opening and closing times of the salt peak window. The conductivity-salt concentration conversion coefficient is determined by water samples from the irrigation area and is a constant. freshwater loss minimization objective function as follows: ； in, To calculate the total freshwater loss during the statistical period, , The start and end times of the statistical period. This is the threshold for determining whether freshwater is usable; water below this value is considered reusable. This is an indicator function that takes the value 1 when the condition inside the parentheses is true and 0 when it is false. The dual-objective problem is transformed into a single-objective optimization problem using a linear weighted method. The optimal scheduling scheme is then solved, and the combined objective function is obtained. as follows: ； in, To comprehensively optimize the target value, , The weighting coefficients and Salt peak period > Prioritize salt removal and extract salt during low-salinity periods. > Prioritize water conservation. This represents the maximum total amount of salt discharged. This represents the maximum total freshwater loss. S5. Based on the optimal control parameters and control mode obtained from S4, the execution layer automatically switches the control mode and precisely adjusts the variable frequency pump station and electric regulating gate. In S6 and S5, the execution layer feeds back the real-time operating parameters, gate opening, and equipment operating status of the variable frequency pumping station to the decision-making layer in real time to dynamically track the salt peak window status and changes in irrigation area water quality and water level. At the same time, the sensing layer continuously collects the latest hydrological and water quality data.

2. The method for regulating drainage in saline-alkali irrigation areas based on salt peak window response according to claim 1, characterized in that: The raw hydrological and water quality data collected in S1 include conductivity values. Water temperature Drainage flow rate Drainage water level ; The preprocessing process is as follows: Since water temperature affects the accuracy of conductivity monitoring, the conductivity value needs to be corrected for water temperature to eliminate temperature interference. The compensation formula is as follows: ； in, This is the standard conductivity value corrected for water temperature at 25°C. This is the conductivity temperature compensation coefficient, calibrated according to the water quality characteristics of the irrigation area, with a value ranging from 0.01 to 0.02 / ℃. This is the original conductivity value. For real-time monitoring of water temperature data; At the same time, the collected drainage flow rate Drainage water level Outlier removal is performed using a moving average method for smoothing, as shown in the following formula: ； in, for Smoothed data at any given time. The length of the sliding window. for The raw monitoring data at any given moment.

3. The method for regulating drainage in saline-alkali irrigation areas based on salt peak window response according to claim 2, characterized in that: The identification of the salt peak window in S2 is based on the standard conductivity value. Focusing on the time-varying characteristics, it is characterized through first-order derivative operations. The rate of change of the value, represented by the second derivative operation. By analyzing the trend of salt concentration changes, key nodes in the salt peak window can be accurately identified, enabling precise capture of periods of rapid salt concentration change. The specific calculation process is as follows: First derivative The change in standard conductivity per unit time, reflecting the rate of increase or decrease in salt concentration, is calculated using the finite difference method. The specific formula is as follows: ； in, for The first derivative of the standard conductivity at time t, for Standard conductivity value at time 10:00 for Standard conductivity value at time 10:00 The time step for collecting raw hydrological and water quality data, when When the salt concentration increases, the concentration tends to rise; when At that time, the salt concentration showed a decreasing trend; Second derivative The change in the first derivative reflects the trend of the rate of increase or decrease in salt concentration and is a core indicator for determining the opening and closing of the salt peak window. It is also calculated using the finite difference method, with the following formula: ； in, for The second derivative of the standard conductivity at time t, , for , The first derivative of the standard conductivity at time t.

4. The method for regulating drainage in saline-alkali irrigation areas based on salt peak window response according to claim 1, characterized in that: The preset constraints in S4 are as follows: Water level constraints: The drainage water level must not exceed the warning water level or fall below the ecological minimum water level, as specified in the formula: ,in To achieve the lowest ecological water level in the drainage canal, To set the warning water level for the drainage canal; Pump station operation constraints: The pump station's drainage flow rate and operating power are adjustable within the rated range, specifically: , ,in , For the pump station's drainage flow rate and operating power, , The minimum and maximum rated drainage flow rates of the pumping station. , These are the minimum and maximum rated operating power of the pumping station; Downstream ecological salt carrying capacity constraint: The salt load discharged downstream per unit time must not exceed the ecological threshold, i.e. ,in This represents the maximum permissible salinity load of the downstream receiving water body; Mode switching constraint: determined based on the ratio of real-time standard conductivity value to historical background value. ,in This is the historical average background value of the standard conductivity of the irrigation area, obtained from years of monitoring data.

5. The method for regulating drainage in saline-alkali irrigation areas based on salt peak window response according to claim 4, characterized in that: S4 is based on the ratio of the salt peak window determination result to the conductivity coefficient. Based on the optimization results of the water quality and water level dual-coordinated optimization model, the control modes are divided into salinity discharge mode, recharge mode, and water-saving mode. Each control mode adopts differentiated pump station and gate control strategies to achieve adaptive response of high salinity high discharge, low salinity reuse, and appropriate salinity throttling. The judgment criteria for each control mode are as follows: Criteria for determining salt discharge mode: The salt peak window is open during the salt peak period. and ; Criteria for determining the replenishment mode: The salt peak window is closed during a low-salt period. and The groundwater in the irrigation area needs to be replenished; Criteria for determining water-saving mode: The salt peak window is closed and the water level is low. and .

6. The method for regulating drainage in saline-alkali irrigation areas based on salt peak window response according to claim 5, characterized in that: The control strategies formulated by each control model based on the judgment criteria are as follows; The core strategy of the salt discharge mode is to maximize the drainage capacity of the pumping station, quickly discharge high-salt water, and ensure that the total amount of salt discharged is maximized. Equipment control in salt discharge mode: Pump station is turned on to rated operating power, and drainage flow is adjusted to the maximum value; main drainage outlet gate is fully open, and freshwater interception channel gate is fully closed. The core strategy of the replenishment model is to completely intercept reusable freshwater and replenish the groundwater in the irrigation area through infiltration, thereby minimizing the loss of freshwater. Equipment control in replenishment mode: Pump station is shut down or adjusted to the rated operating power for pressure maintenance; main drainage outlet gates are fully closed, and freshwater interception channel gates are fully open; The core strategy of the water-saving model is to moderately reduce water flow and discharge, while taking into account both irrigation area water level control and freshwater conservation, and avoiding ineffective discharge. Equipment control in water-saving mode: The pumping station is adjusted to a lower-middle rated operating power, and the drainage flow is appropriately reduced; the main drainage outlet gate is partially opened, and the freshwater interception channel gate is opened as needed.

7. A drainage control system for saline-alkali irrigation areas based on salt peak window response, characterized in that: The system, which uses the salt peak window response-based drainage control method for saline-alkali irrigation areas as described in any one of claims 1-6, includes a perception layer, a decision layer, and an execution layer. The sensing layer is responsible for the collection and preprocessing of raw hydrological and water quality data. The distributed salinity monitoring matrix is ​​evenly deployed at the outlets of the main drainage canals and agricultural ditches at all levels to achieve comprehensive and real-time monitoring of drainage salinity and hydrological parameters. The decision-making layer has a built-in salt peak window diagnostic algorithm. Based on the sensing layer and the processed hydrological and water quality data, it captures the peak band of salt concentration by analyzing the time change rate of conductivity values ​​in real time. Combined with preset thresholds, it completes the accurate determination of salt peak window and low salt period and outputs clear scheduling instructions to the execution layer. It also stores diagnostic data and instruction records in sync, forming a complete data traceability chain. The execution layer receives scheduling instructions from the decision-making layer, including the variable frequency pump station controller and the electric regulating gate. The two work together to achieve flexible adjustment and on / off control of drainage flow.

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