Dynamic regulation and control method for farmland-irrigation area-drainage basin water conservation and drainage system in black soil area

Abstract

The invention relates to the technical field of agricultural water conservancy, and discloses a dynamic regulation and control method for a farmland-irrigation area-drainage basin water conservation and drainage system in a black soil area, which comprises the following steps: S1, collecting basic data including meteorological and hydrological data, irrigation data, environmental data and monitored soil data; s2, analyzing water retention threshold values and soil fitting parameters of the four kinds of soil by applying a naive Bayes method; s3, calculating a function relationship between the water demand and the yield; the soil water retention threshold value serves as input and is input into a management file of a DSSAT model, and the DSSAT model is used for simulating the growth conditions of the four kinds of soil under the condition that multiple crops are planted on the farmland scale; and S4, constructing a dynamic regulation and control framework of a water retention and drainage system of soil-farmland-irrigation area-drainage basin. According to the method, the minimum water retention threshold value and the effective water threshold value of different soil types in the black soil area are quantified, the crop water consumption amount based on the crop growth process is estimated, and a response relation function among soil water, crop water demand and irrigation water is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural water conservancy, and in particular to a method for dynamically regulating a farmland-irrigation area-watershed drainage system in a black soil region. Background Art

[0002] With global climate change and the growing demand for agricultural production, the effective use and management of water resources has become a key challenge for the sustainable development of modern agriculture. Especially in the black soil region, the soil fertility is high and the farming history is long. However, due to unreasonable agricultural practices and frequent extreme weather events, the region faces problems such as water shortage, soil degradation and ecological environment deterioration. Therefore, how to achieve efficient use and management of agricultural water resources in the black soil region and ensure the green and sustainable development of agriculture has become the focus of common concern in academia and industry.

[0003] Traditional agricultural water management methods usually rely on static water resource allocation strategies, lack consideration of multi-scale dynamic systems, cannot accurately quantify the water retention and drainage thresholds of different soil types in black soil areas, do not combine management with the water demand of crop growth processes, and cannot adapt to changes in complex environments such as farmland-irrigation areas-watersheds. Summary of the invention

[0004] In order to overcome or alleviate one or more of the above technical problems, the purpose of the present invention is to provide a method for dynamically regulating the drainage system of farmland-irrigation area-watershed in black soil areas. Through quantitative analysis and simulation technology, the minimum water conservation threshold and effective water threshold of different soil types are accurately quantified, combined with the water demand assessment of the crop growth process; the impact of floods, droughts and waterlogging on the system is studied, and water resource management strategies under these natural disaster conditions are revealed. By introducing the DSSAT model, the model can simulate and evaluate the growth and yield performance of rice, corn and soybeans in various irrigation scenarios under different soil types, thereby providing data support and theoretical basis for optimizing irrigation strategies. While exploring green and efficient agricultural water resources efficient utilization and management technologies, an ecological model of green and sustainable agricultural development is realized.

[0005] The present invention provides the following technical solutions:

[0006] A method for dynamically controlling a farmland-irrigation area-watershed drainage system in a black soil region comprises the following steps:

[0007] S1: Basic data collection, including meteorological and hydrological data, irrigation data, environmental data and soil monitoring data. The soil monitoring data is based on the main soil types of the black soil in the study area, which are divided into four types: meadow soil, white pulp soil, black soil and dark brown soil. Each type of black soil is monitored at a fixed point, and the soil moisture content and porosity-related soil properties of the four soil types are monitored over a long period of time.

[0008] S2: Naive Bayes method was used to analyze the water retention threshold and soil fitting parameters of four soils;

[0009] S3: Calculate the functional relationship between water demand and yield according to the soil water retention threshold and soil fitting parameters obtained in step S2; input the soil water retention threshold into the management file of the DSSAT model as input, and use the DSSAT model to simulate the growth of four types of soils under the condition of planting multiple crops at the farmland scale; set different irrigation scenarios for the DSSAT model; obtain the yield of multiple different crops planted in four types of soils under different irrigation scenarios; use the naive Bayes method to fit the functional relationship between water volume and yield, and the calculation formula for the yield per unit area of ​​each crop is as follows:

[0010]

[0011] Where i is the soil type index, i = 1...4; c is the crop type, c = 1...3; YA ic is the yield per unit area of ​​crop c of soil type i, kg / hm 2 ; IQ ic is the irrigation water quantity for crop c of soil type i, i.e., the decision variable, m 3 / hm 2 ; a ic 、b ic and d ic is the fitting parameter of soil type i and crop c;

[0012] S4: Construct a dynamic control framework for the water conservation and drainage system of soil-farmland-irrigation area-watershed. The dynamic control framework synergistically considers the water delivery time, water delivery and distribution energy consumption, and water delivery loss process, establishes a drainage feedback system that considers soil water conservation thresholds, farmland water demand feedback, and watershed water supply information, and constructs a drainage dynamic control system that automatically adjusts according to the drainage feedback system.

[0013] According to some embodiments, step S3: based on the soil water retention threshold and soil fitting parameters obtained in step S2, the functional relationship between the total water requirement and the total yield can also be calculated, and the specific steps are as follows:

[0014] S31: Prepare the data required for the water demand and yield function, including: 12 sets of yield and water volume correlation coefficients output in step S2; canal system data for water delivery and drainage in the irrigation area, including canal length, canal width, canal depth, design flow, and loss coefficient; sluice-related data, including sluice power consumption, flow through the sluice, and gate parameters; soil and crop properties of the farmland in the irrigation area; and meteorological data related to rainfall, floods, droughts, and waterlogging.

[0015] S32: Irrigation area scale calculation, first select the appropriate yield and water correlation coefficient according to the soil and crop properties of the farmland where the irrigation area is located, and calculate the maximum total yield of various crops:

[0016]

[0017] In the formula, A ic is the area planted with crop c of soil type i, hm 2 ;

[0018] S33: Construct water delivery objective function:

[0019] minWP=WT·CP (3)

[0020] WT=Σq ur t ur +ΣIQ ic ·A ic (4)

[0021] Where WP is the total power loss of canal water distribution system, kWh; WT is the total water loss of canal water distribution system, m 3 CP is the electrical energy consumed by the canal system to transport a single cubic meter of water, m 3 / kWh; u is the number of channel sections; r is the water supply and distribution period; q ur is the water loss flow rate of channel section u during period r, m 3 / s;t ur is the water delivery and distribution time for channel section u and period r, s;

[0022]

[0023] In the formula, β u is the reduction coefficient of the channel bed leakage after anti-seepage measures are taken in channel section u; u is the groundwater support correction factor for channel section u; u is the soil permeability coefficient of the channel bed in channel section u; m u is the soil permeability index of the channel bed in channel section u; l u is the length of channel segment u;

[0024] minTI=(st j +t j ) (6)

[0025] Where j is the field index; TI is the total water distribution time of the canal system, s; st j is the time when water distribution starts in field j, s; t j is the duration of water distribution to field j, s;

[0026] S34: Water transmission and distribution constraints, including:

[0027] Constraints on channel water delivery capacity: The water delivery flow of channels at all levels shall not exceed the design flow;

[0028] WT≤DQ (7)

[0029] Where DQ is the design flow rate of the channel, m 3 / s;

[0030] Irrigation time constraints: water distribution start time and water distribution end time should be within the maximum allowable canal water distribution cycle;

[0031] 0≤st j ≤st j +t j ≤3600T (8)

[0032] Where T is the maximum allowable canal water distribution cycle, h;

[0033] Channel water balance constraints:

[0034]

[0035] In the formula, X ur is a 0-1 variable, X ur =1 means water distribution starts; X ur =0 means no water distribution;

[0036] S35: Construct drainage targets:

[0037] WD=(δ·R+H+G-∑p ur t ur -∑IQ ic ·A ic )·Z (10)

[0038] Where WD is the total displacement, m 3 ; δ is the rainfall runoff coefficient; R is the total rainfall, m 3 ; H is the flood water volume, m 3 ; G is the total water supply, m 3 ; Z is a drainage 0-1 variable, Z = 1 means drainage starts; Z = 0 means no drainage; p ur is the drainage flow rate m 3 / s;

[0039] S36: Drainage constraints, including:

[0040] When rainfall is greater than crop water demand, and flood damage and water allocation are greater than the sum of crop water demand and loss water consumption, the drainage system begins to drain water;

[0041]

[0042] During irrigation, when the drainage is turned on, the water distribution system is automatically closed, and when the water distribution starts, the drainage is automatically closed; when not irrigating, both the water distribution and drainage are closed;

[0043]

[0044] S37: Output: irrigation water plan for each canal system and field, total amount of irrigation water required, optimal crop yield and water ratio.

[0045] According to some embodiments, step S4 comprises the following steps:

[0046] S41: Prepare the data required for the dynamic control framework of the water conservation and drainage system of soil-farmland-irrigation area-watershed, including: the total amount of irrigation water required according to the output of step S3; meteorological data related to rainfall, floods, droughts, and waterlogging; the total agricultural runoff supplied to the irrigation area; and the amount of surface water and groundwater;

[0047] S42: Basin scale calculation: The input surface water and groundwater are used as the available water volume of the basin, and the overall division is made according to the total amount of irrigation water required output by S3 and the water distribution plan of each irrigation area:

[0048] When the available water volume in the basin is greater than the total water demand in the irrigation area, the operation mode of the constructed dynamic control framework platform for water conservation and drainage systems is S1→S2→S3→S4;

[0049] When the available water volume in the basin is less than the total water demand in the irrigation area, the operation mode of the constructed dynamic control framework platform for water conservation and drainage system is S4→S3→S2→S1;

[0050] When the amount of water from floods, droughts and waterlogging is greater than the threshold set by the dynamic control framework of the water conservation and drainage system of soil-farmland-irrigation area-watershed, the dynamic control framework will adjust the available water volume in the basin according to the feedback of flood, drought and waterlogging information, and then return to the S3 module.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The present invention quantifies the minimum water retention threshold and effective water threshold of different soil types in black soil areas, estimates the crop water consumption based on the crop growth process, and obtains the response relationship function between soil water-crop water demand-irrigation water; it helps to improve the water resource utilization efficiency of agricultural production, provide flexible response plans in the face of climate change and extreme weather events, and promote the green and sustainable development of agriculture.

[0053] (2) By constructing a multi-scale irrigation and drainage system, coordinating the water delivery time, water delivery and distribution energy consumption, and water delivery loss process, a drainage feedback system that takes into account the soil water retention threshold, farmland water demand feedback, and watershed water supply information is established, and a drainage dynamic control system that automatically adjusts according to the drainage feedback information is designed.

[0054] (3) Reveal the impact mechanism of floods, droughts and waterlogging on dynamic systems, and characterize the water conservation and drainage potential of dynamic regulation systems. DETAILED DESCRIPTION

[0055] The present invention is described in detail below in conjunction with the embodiments, but it should be understood that the embodiments are only used to exemplify the present invention and do not constitute any limitation on the protection scope of the present invention. All reasonable changes and combinations included in the scope of the invention spirit of the present invention fall within the protection scope of the present invention.

[0056] The present invention provides a method for dynamically controlling a farmland-irrigation area-watershed drainage system in a black soil region, comprising the following steps:

[0057] S1: Basic data collection, including: meteorological and hydrological data, including effective rainfall, irrigation water utilization coefficient, and crop water demand; irrigation data, including irrigation area and fertilizer, pesticide, and agricultural film usage per unit area, and head loss along the way; environmental data, including surface water supply, groundwater supply, runoff, aquifer permeability, and evapotranspiration; soil monitoring data, including 0.1-1m soil temperature, soil moisture data, and collected snowmelt water data. According to the main soil types contained in the black soil in the study area, the black soil is divided into four types: meadow soil, white pulp soil, black soil, and dark brown soil. Each type of black soil is monitored at a fixed point, and the soil moisture content and porosity-related soil properties of the four soils are monitored over a long period of time.

[0058] S2: The Naive Bayes method is used to analyze the water retention thresholds of the four soils, so that the water retention thresholds of the soils can be used as output to the farmland scale.

[0059] S3: Soil water retention threshold is used as input to the management file of the DSSAT model. For example, the DSSAT model is used at the farmland scale to simulate the growth of four types of soils under the conditions of planting three crops: rice, corn and soybeans. The DSSAT model is set to different irrigation scenarios. The irrigation scenario for rice is 0-4500m 3 / hm 2 , each scenario increases by 50m 3 / hm 2 There are 90 scenarios for irrigation water volume; the irrigation scenarios for corn and soybeans are 0-2500m 3 / hm 2 , each scenario increases by 25m 3 / hm 2The irrigation water volume was 100 scenarios in total. The yields of three different crops, rice, corn and soybean, planted in four soils under different irrigation scenarios were obtained. The naive Bayes method was used to fit the functional relationship between water volume and yield. The calculation formula for the yield per unit area of ​​each crop is as follows:

[0060]

[0061] Where i is the soil type index, i = 1...4; c is the crop type, c = 1...3; YA ic is the yield per unit area of ​​crop c of soil type i, kg / hm 2 ; IQ ic is the irrigation water quantity for crop c of soil type i, i.e., the decision variable, m 3 / hm 2 ; a ic 、b ic and d ic are the fitting parameters for soil type i and crop c.

[0062] S4: Construct a dynamic control framework for the water conservation and drainage system of soil-farmland-irrigation area-watershed. This dynamic control framework synergistically considers the water delivery time, water delivery and distribution energy consumption, and water delivery loss process, establishes a drainage feedback system that considers soil water conservation thresholds, farmland water demand feedback, and watershed water supply information, and constructs a drainage dynamic control system that automatically adjusts according to the drainage feedback system.

[0063] The present invention is further described below in the form of examples.

[0064] Example 1

[0065] S1, collect basic data. The basic data are as follows:

[0066] Soil types: meadow soil, white pulp soil, black soil and dark brown soil;

[0067] Crops grown: rice, corn, soybeans;

[0068] Fixed-point monitoring equipment: meadow soil-rice, meadow soil-corn, meadow soil-soybean; white soil-rice, white soil-corn, white soil-soybean; black soil-rice, black soil-corn, black soil-soybean; dark brown soil-rice, dark brown soil-corn, dark brown soil-soybean. A total of 12 fixed-point collection equipment to monitor soil moisture content and porosity;

[0069] S2, based on the collected basic data, calculate the corresponding soil water retention threshold under different scenarios.

[0070] Calculation and output: The long-term series data monitored by S1 are used for soil-scale calculation to obtain soil water retention thresholds for different scenarios monitored by 12 fixed-point equipment.

[0071] The details are as follows:

[0072] Data preparation: Based on the output of the water retention thresholds for 12 scenarios, meteorological remote sensing data, soil type data, and crop management data, the lowest soil moisture content is set as the water retention threshold for the medium scenario.

[0073] Scenario settings: 90 irrigation schemes for meadow soil-rice, 100 irrigation schemes for meadow soil-corn, and 100 irrigation schemes for meadow soil-soybean; 90 irrigation schemes for white soil-rice, 100 irrigation schemes for white soil-corn, and 100 irrigation schemes for white soil-soybean; 90 irrigation schemes for black soil-rice, 100 irrigation schemes for black soil-corn, and 100 irrigation schemes for black soil-soybean; 90 irrigation schemes for dark brown soil-rice, 100 irrigation schemes for dark brown soil-corn, and 100 irrigation schemes for dark brown soil-soybean. A total of 1,160 scenarios.

[0074] Farmland-scale smart platform calculation module: The input data is calculated through the platform to generate 1,160 meteorological files, soil files and management files. The DSSAT program is called to generate yield and water data for 1,160 scenarios. The generated data is input into the Naive Bayes program to fit the yield and water function coefficients of 12 scenarios generated by four soils and three crops.

[0075] Output: a ic 、b ic and d ic These are the fitting parameters for soil type i and crop c, with a total of 12 groups.

[0076] S3: Calculate the functional relationship between total water demand and total yield according to the soil water retention threshold and soil fitting parameters obtained in step S2;

[0077] S31: Prepare the data required for the water demand and yield function, including: 12 sets of yield and water volume correlation coefficients output by step S2; canal system data for water supply and drainage in the irrigation area, including channel length, channel width, channel depth, design flow, and loss coefficient; sluice-related data, including sluice power consumption, flow through the sluice, and sluice parameters; soil and crop properties of the farmland in the irrigation area; and meteorological data related to rainfall, floods, droughts, and waterlogging.

[0078] S32: Irrigation area scale calculation: First, select the appropriate yield and water correlation coefficient based on the soil and crop properties of the farmland where the irrigation area is located, and calculate the maximum total yield of each crop:

[0079]

[0080] In the formula, A icis the area planted with crop c of soil type i, hm 2 .

[0081] S33: Construct water delivery objective function:

[0082] minWP=WT·CP (3)

[0083] WT=∑q ur t ur +∑IQ ic ·A ic (4)

[0084] Where WP is the total power loss of canal water distribution system, kWh; WT is the total water loss of canal water distribution system, m 3 CP is the electrical energy consumed by the canal system to transport a single cubic meter of water, m 3 / kWh; u is the number of channel sections; r is the water supply and distribution period; q ur is the water loss flow rate of channel section u during period r, m 3 / s;t ur is the water delivery and distribution time for channel section u during period r, s.

[0085]

[0086] In the formula, β u is the reduction coefficient of channel bed leakage after anti-seepage measures are taken in channel section u; u is the groundwater support correction factor for channel section u; X u is the soil permeability coefficient of the channel bed in channel section u; m u is the soil permeability index of the channel bed in channel section u; l u is the length of channel segment u.

[0087] minTI=(st j +t j ) (6)

[0088] Where j is the field index; TI is the total water distribution time of the canal system, s; st j is the time when water distribution starts in field j, s; t j is the duration of water distribution to field j, s.

[0089] S34: Water distribution constraints:

[0090] (1) Channel water delivery capacity constraints: The water delivery flow of channels at all levels shall not exceed the design flow.

[0091] WT≤DQ (7)

[0092] Where DQ is the design flow rate of the channel, m 3 / s.

[0093] (2) Irrigation time constraints: The start and end times of water distribution should be within the maximum allowable canal water supply and distribution cycle.

[0094] 0≤st j ≤st j +t j ≤3600T (8)

[0095] Where T is the maximum allowable canal water distribution cycle, h.

[0096] (3) Channel water balance constraints

[0097]

[0098] Where, X ur is a 0-1 variable, X ur =1 means water distribution starts; X ur =0 means no water supply.

[0099] S35: Construct drainage targets:

[0100] WD=(δ·R+H+G-Σp ur t ur -ΣIQ ic ·A ic )·Z (10)

[0101] Where WD is the total displacement, m 3 ; δ is the rainfall runoff coefficient; R is the total rainfall, m 3 ; H is the flood water volume, m 3 ; G is the total water supply, m 3 ; Z is a drainage 0-1 variable, Z = 1 means drainage starts; Z = 0 means no drainage; p ur is the drainage flow rate m 3 / s.

[0102] S36: Drainage constraints:

[0103] (1) When rainfall is greater than crop water demand, and flood damage and water allocation are greater than the sum of crop water demand and loss water consumption, the drainage system begins to drain water.

[0104]

[0105] (2) During irrigation, when the drainage is turned on, the water distribution system is automatically closed, and when the water distribution starts, the drainage is automatically closed; when not irrigating, both the water distribution and drainage are closed.

[0106]

[0107] S37: Output: irrigation water plan for each canal system and field, total amount of irrigation water required, optimal crop yield and water ratio.

[0108] S4: Construct a dynamic control framework for the water conservation and drainage system of soil-farmland-irrigation area-watershed, including the following steps:

[0109] S41: Prepare the data required for the dynamic control framework of the water conservation and drainage system of soil-farmland-irrigation area-watershed, including: the total amount of irrigation water required according to the output of step S3; meteorological data related to rainfall, floods, droughts and waterlogging; the total agricultural runoff supplied to the irrigation area; and the amount of surface water and groundwater.

[0110] S42: Basin scale calculation: The input surface water and groundwater are used as the available water volume of the basin, and the overall division is made according to the total amount of irrigation water required output by S3 and the water distribution plan of each irrigation area:

[0111] When the available water volume in the basin is greater than the total water demand in the irrigation area, the operation mode of the constructed dynamic control framework platform for water conservation and drainage systems is S1→S2→S3→S4;

[0112] When the available water supply in the basin is less than the total water demand in the irrigation area, the operation mode of the constructed dynamic control framework platform for water conservation and drainage systems is S4→S3→S2→S1.

[0113] When the amount of water from floods, droughts and waterlogging is greater than the threshold set by the dynamic control framework of the water conservation and drainage system of soil-farmland-irrigation area-watershed, the dynamic control framework will adjust the available water volume in the basin according to the feedback of flood, drought and waterlogging information, and then return to the S3 module.

[0114] The above embodiments are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for dynamically controlling a farmland-irrigation area-watershed drainage system in a black soil region, characterized in that: The following steps are included: S1: Basic data collection, including meteorological and hydrological data, irrigation data, environmental data and soil monitoring data. The soil monitoring data is based on the main soil types of the black soil in the study area, which are divided into four types: meadow soil, white pulp soil, black soil and dark brown soil. Each type of black soil is monitored at a fixed point, and the soil moisture content and porosity-related soil properties of the four soil types are monitored over a long period of time. S2: Naive Bayes method was used to analyze the water retention threshold and soil fitting parameters of four soils; S3: Calculate the functional relationship between water demand and yield according to the soil water retention threshold and soil fitting parameters obtained in step S2; input the soil water retention threshold into the management file of the DSSAT model as input, and use the DSSAT model to simulate the growth of four types of soils under the condition of planting multiple crops at the farmland scale; set different irrigation scenarios for the DSSAT model; obtain the yield of multiple different crops planted in four types of soils under different irrigation scenarios; use the naive Bayes method to fit the functional relationship between water volume and yield, and the calculation formula for the yield per unit area of ​​each crop is as follows: Where i is the soil type index, i = 1...4; c is the crop type, c = 1...3; YA ic is the yield per unit area of ​​crop c of soil type i, kg / hm 2 ; IQ ic is the irrigation water quantity for crop c of soil type i, i.e., the decision variable, m 3 / hm 2 ; a ic 、b ic and d ic is the fitting parameter of soil type i and crop c; S4: Construct a dynamic control framework for the water conservation and drainage system of soil-farmland-irrigation area-watershed. The dynamic control framework synergistically considers the water delivery time, water delivery and distribution energy consumption, and water delivery loss process, establishes a drainage feedback system that considers soil water conservation thresholds, farmland water demand feedback, and watershed water supply information, and constructs a drainage dynamic control system that automatically adjusts according to the drainage feedback system.

2. The method for dynamically controlling the drainage system of farmland-irrigation area-watershed in black soil region according to claim 1, characterized in that: Step S3: Calculate the functional relationship between total water demand and total yield based on the soil water retention threshold and soil fitting parameters obtained in step S2. The specific steps are as follows: S31: Prepare the data required for the water demand and yield function, including: 12 sets of yield and water volume correlation coefficients output in step S2; canal system data for water delivery and drainage in the irrigation area, including canal length, canal width, canal depth, design flow, and loss coefficient; sluice-related data, including sluice power consumption, flow through the sluice, and gate parameters; soil and crop properties of the farmland in the irrigation area; and meteorological data related to rainfall, floods, droughts, and waterlogging. S32: Irrigation area scale calculation, first select the appropriate yield and water correlation coefficient according to the soil and crop properties of the farmland where the irrigation area is located, and calculate the maximum total yield of various crops: In the formula, A ic is the area planted with crop c of soil type i, hm 2 ; S33: Construct water delivery objective function: minWP=WT·CP (3) WT=∑q ur t ur +∑IQ ic ·A ic (4) Where WP is the total power loss of canal water distribution system, kWh; WT is the total water loss of canal water distribution system, m 3 CP is the electrical energy consumed by the canal system to transport a single cubic meter of water, m 3 / kWh; u is the number of channel sections; r is the water supply and distribution period; q ur is the water loss flow rate of channel section u during period r, m 3 / s;t ur is the water delivery and distribution time for channel section u and period r, s; In the formula, β u is the reduction coefficient of the channel bed leakage after anti-seepage measures are taken in channel section u; u is the groundwater support correction factor for channel section u; X u is the soil permeability coefficient of the channel bed in channel section u; m u is the soil permeability index of the channel bed in channel section u; l u is the length of channel segment u; minTI=(st j +t j ) (6) Where j is the field index; TI is the total water distribution time of the canal system, s; st j is the time when water distribution starts in field j, s; t j is the duration of water distribution to field j, s; S34: Water transmission and distribution constraints, including: Constraints on channel water delivery capacity: The water delivery flow of channels at all levels shall not exceed the design flow; WT≤DQ (7) Where DQ is the design flow rate of the channel, m 3 / s; Irrigation time constraints: water distribution start time and water distribution end time should be within the maximum allowable canal water distribution cycle; 0≤st j ≤st j +t j ≤3600T (8) Where T is the maximum allowable canal water distribution cycle, h; Channel water balance constraints: Where, X ur is a 0-1 variable, X ur =1 means water distribution starts; X ur =0 means no water distribution; S35: Construct drainage targets: WD=(δ·R+H+G-∑p ur t ur -∑IQ ic ·A ic )·Z (10) Where WD is the total displacement, m 3 ; δ is the rainfall runoff coefficient; R is the total rainfall, m 3 ; H is the flood water volume, m 3 ; G is the total water supply, m 3 ; Z is a drainage 0-1 variable, Z = 1 means drainage starts; Z = 0 means no drainage; p ur is the drainage flow rate m 3 / s; S36: Drainage constraints, including: When rainfall is greater than crop water demand, and flood damage and water allocation are greater than the sum of crop water demand and loss water consumption, the drainage system begins to drain water; During irrigation, when the drainage is turned on, the water distribution system is automatically closed, and when the water distribution starts, the drainage is automatically closed; when not irrigating, both the water distribution and drainage are closed; S37: Output: irrigation water plan for each canal system and field, total amount of irrigation water required, optimal crop yield and water ratio.

3. The method for dynamically controlling the drainage system of farmland-irrigation area-watershed in black soil region according to claim 2, characterized in that: Step S4 includes the following steps: S41: Prepare the data required for the dynamic control framework of the water conservation and drainage system of soil-farmland-irrigation area-watershed, including: the total amount of irrigation water required according to the output of step S3; meteorological data related to rainfall, floods, droughts, and waterlogging; the total agricultural runoff supplied to the irrigation area; and the amount of surface water and groundwater; S42: Basin scale calculation: The input surface water and groundwater are used as the available water volume of the basin, and the overall division is made according to the total amount of irrigation water required output by S3 and the water distribution plan of each irrigation area: When the available water volume in the basin is greater than the total water demand in the irrigation area, the operation mode of the constructed dynamic control framework platform for water conservation and drainage systems is S1→S2→S3→S4; When the available water volume in the basin is less than the total water demand in the irrigation area, the operation mode of the constructed dynamic control framework platform for water conservation and drainage system is S4→S3→S2→S1; When the amount of water from floods, droughts and waterlogging is greater than the threshold set by the dynamic control framework of the water conservation and drainage system of soil-farmland-irrigation area-watershed, the dynamic control framework will adjust the available water volume in the basin according to the feedback of flood, drought and waterlogging information, and then return to the S3 module.

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