Real-time irrigation forecasting method and system for rice irrigation areas based on variable unit design

Abstract

The present invention proposes a real-time irrigation forecasting method and system for rice irrigation areas based on variable unit design, including: respectively designing variable water demand calculation units, hydrological calculation units and water supply calculation units; predicting the net irrigation water demand in each water demand calculation unit and the water supply in each hydrological calculation unit; taking the minimum water shortage in each water supply calculation unit as the objective function, performing water resource allocation and scheduling for the water supply calculation unit, and updating the total water storage in each hydrological calculation unit and the depth of the field water layer in each water demand calculation unit. The present invention is based on the irrigation area data base, modularization as a means, and online monitoring of water and rainfall conditions in the irrigation area, to achieve integrated simulation of water demand forecasting, water supply forecasting, and water resource allocation within the irrigation area, providing technical support for scientifically and rationally guiding irrigation area water management and compiling irrigation water use plans, and providing reliable guarantees for promoting accurate forecasting of drought conditions and forward-looking early warnings in irrigation areas.

Description

Technical Field

[0001] The invention relates to the technical field of irrigation forecasting, and in particular to a real-time irrigation forecasting method and system for rice irrigation areas based on variable unit design. Background Art

[0002] Real-time irrigation forecast for rice irrigation areas is aimed at irrigation areas where rice is the main crop. Based on the current conditions, the water source and field water layer water conservation conditions of the irrigation area are taken as the premise. According to the daily weather forecast for the next ten days, the water inflow of water conservancy projects such as reservoirs and ponds within the irrigation area is forecast, and the water demand of the main crop rice within the irrigation area is predicted. Various water sources within the irrigation area are configured and dispatched, and the irrigation water volume of the internal water source of the irrigation area, the change process of the field water layer depth, and the gross irrigation water volume of the required external water source are predicted. Using real-time irrigation forecasts to guide irrigation area water management and adjust irrigation water use plans, so that crops can be irrigated in a timely, appropriate, and appropriate manner, and improve irrigation efficiency, will be conducive to promoting efficient agricultural water use, and is an effective way to solve the problem of water resource shortage. It is of great significance to promote high-quality agricultural development and realize agricultural modernization.

[0003] The selection of calculation units in the real-time irrigation forecast model of irrigation areas is crucial. Selecting the field scale as the unit can well describe the spatial variability of soil, crops and other elements, but the field scale data collection, field monitoring and observation covering the entire irrigation area will inevitably consume a lot of resources and have certain difficulties; selecting the irrigation area scale as the unit may lead to ignoring the spatial variability of elements such as soil texture, crop type, and internal water sources, and it is impossible to predict the irrigation water demand well, and it is also impossible to guide the irrigation water use of water diversion gates on channels at all levels. Therefore, the variable unit calculation method is used in the real-time irrigation forecast model of irrigation areas. In the actual application of the model, the calculation units can be divided in combination with the coverage and granularity of the irrigation area monitoring station network, which is an urgent problem to be solved in the real-time irrigation forecast model of irrigation areas to achieve accurate simulation. Summary of the invention

[0004] The purpose of the present invention is to provide a real-time irrigation forecast method and system for rice irrigation areas based on variable unit design, which makes full use of the different coverage and granularity of the information infrastructure of modern irrigation areas in water situation monitoring, rainfall monitoring, crop monitoring, etc., and can quickly and accurately simulate the real-time irrigation forecast of the irrigation area, providing technical support and reliable guarantee for scientifically and rationally guiding the water management of the irrigation area and compiling irrigation water use plans.

[0005] To achieve the above object, the technical solution of the method of the present invention is:

[0006] The real-time irrigation forecasting method for rice irrigation areas based on variable unit design includes the following steps:

[0007] Step 1. Obtain the irrigation area meteorological unit division map, the irrigation area minimum management range map, the irrigation area soil type distribution map, and the irrigation area rice planting structure distribution map respectively and superimpose them. Superimpose and take intersections for different meteorological units, different soil types, different crop planting structures, and different management ranges to determine the minimum basic unit, and merge the determined minimum basic units to form water demand calculation units with different coverage areas;

[0008] Step 2. Obtain the distribution map of water storage projects within the irrigation area, the type map of water storage project catchment area, the area of ​​water storage project catchment area, the distribution map of water storage projects with complete data, and the distribution map of water level monitoring stations of water storage projects and superimpose them, select water storage projects with different sizes and types and different catchment area types as typical water storage projects, take each typical water storage project as a hydrological calculation unit, and form hydrological calculation units of different water storage types;

[0009] Step 3. Based on the water demand calculation unit, the hydrological calculation unit and the irrigation range, the water supply calculation units with different aggregation degrees are divided for different water sources;

[0010] Step 4. Generate a water demand calculation unit attribute table based on the water demand calculation units divided in step 1, calculate the predicted rainfall and actual crop evapotranspiration in each water demand calculation unit in combination with the meteorological forecast data, and predict the net irrigation water demand in each water demand calculation unit based on the field water dynamic balance model;

[0011] Step 5. Generate a hydrological calculation unit attribute table based on the hydrological calculation units divided in step 2, predict the water inflow process of each hydrological calculation unit in combination with meteorological forecast data, and predict the available water volume in each hydrological calculation unit based on the water balance model of the water storage project;

[0012] Step 6. Based on the water supply calculation units divided in step 3, configure and dispatch the irrigation water volume in each water supply calculation unit, calculate the irrigation water volume of the water source in each hydrological calculation unit and update the total water storage capacity of the corresponding water storage project, calculate the irrigation water volume in each water demand calculation unit and update the corresponding field water layer depth;

[0013] Step 7. Taking the minimum water shortage in each water supply calculation unit as the objective function, and taking the water balance, storage capacity of the water storage project, and water supply capacity as constraints, water resources are allocated for each water supply calculation unit.

[0014] Furthermore, the step 1 includes the following sub-steps:

[0015] Step 1.1. For irrigation areas of different levels, combine the irrigation area vector layer of the irrigation area and the distribution of meteorological stations within and near the irrigation area to form a meteorological unit division map to ensure that there is a meteorological station in each meteorological unit;

[0016] Step 1.2. Take the irrigation area managed by the management office or management section within the irrigation area as the irrigation unit, and form the minimum management area map of the irrigation area;

[0017] Step 1.3. Based on the gridded soil type data within the irrigation area, a soil type distribution map of the irrigation area is formed;

[0018] Step 1.4. Based on the rice planting structure within the rice irrigation area inverted by remote sensing, a distribution map of the rice planting structure in the irrigation area is formed;

[0019] Step 1.5. Overlay the meteorological unit division map, the minimum management range map of the irrigation area, the soil type distribution map of the irrigation area, and the rice planting structure distribution map of the irrigation area. Overlay and take intersections for different meteorological units, different soil types, different crop planting structures, and minimum management ranges of the irrigation area to determine the minimum basic unit. Merge the minimum basic units according to the preset channel level to form water demand calculation units with different coverage areas.

[0020] Furthermore, the step 2 includes the following sub-steps:

[0021] Step 2.1. Based on the longitude and latitude of the water storage projects within the irrigation area, a distribution map of the water storage projects within the irrigation area is formed;

[0022] Step 2.2. Based on the size types of water storage projects within the irrigation area, a size type map of water storage projects within the irrigation area is formed, and combined with the catchment area types of water storage projects within the irrigation area, a catchment area type map of water storage projects within the irrigation area is formed;

[0023] Step 2.3. Extract the catchment area of ​​the water storage project within the irrigation area and generate the catchment area of ​​the water storage project;

[0024] Step 2.4. Collect basic data of water storage projects within the irrigation area, including water level-volume curve, characteristic water level and characteristic storage capacity, eliminate water storage projects with incomplete basic data of water storage projects, and form a water storage project distribution map with complete data;

[0025] Step 2.5. Collect water level monitoring sites of water storage projects within the irrigation area to form a distribution map of water level monitoring sites of water storage projects within the irrigation area;

[0026] Step 2.6. Overlay the water storage project distribution map within the irrigation area, the water storage project size type map, the water storage project catchment area type map, the water storage project distribution map with complete data, and the water storage project water level monitoring station distribution map. Select water storage projects of different sizes and types and different catchment area types as typical water storage projects, and use each typical water storage project as a hydrological calculation unit, which are divided into reservoir-type hydrological calculation units and pond-type hydrological calculation units.

[0027] Furthermore, the water supply calculation unit in step 3 is an independent water supply calculation unit or an aggregated water supply calculation unit, wherein:

[0028] (1) Independent water supply calculation unit

[0029] For large and medium-sized reservoirs within the irrigation area, their irrigation areas are selected as independent water supply calculation units;

[0030] (2) Aggregate water supply calculation unit

[0031] For small reservoirs or ponds within the irrigation area, the aggregated water supply calculation units are divided according to the irrigation area management scope and business needs to ensure that there is at least one typical water storage project in each aggregated water supply calculation unit.

[0032] Furthermore, the step 4 includes the following sub-steps:

[0033] Step 4.1. Generate a water demand calculation unit attribute table based on the water demand calculation units divided in step 1, the water demand calculation unit attribute table includes the code and name of each water demand calculation unit, the irrigation area and main canal to which it belongs, the management section and management office to which it belongs, the meteorological unit corresponding to each water demand calculation unit, and the field leakage rate and crop planting structure of each water demand calculation unit;

[0034] Step 4.2. Combine the measured meteorological data in each meteorological unit to calculate the reference crop evapotranspiration in each meteorological unit during the historical period, and calculate the multi-year average maximum daily evapotranspiration mean value and its corresponding day number during the historical period of the reference crop;

[0035] Step 4.3. Obtain the meteorological forecast data in each meteorological unit, calculate the forecast rainfall in each meteorological unit, and calculate the reference crop evapotranspiration forecast value in each meteorological unit;

[0036] Step 4.4. Calculate the actual crop evapotranspiration prediction value in each water demand calculation unit in combination with the calculated reference crop evapotranspiration prediction value;

[0037] Step 4.5. Combine the field infiltration rate, the predicted rainfall in each meteorological unit, and the predicted value of actual crop evapotranspiration in each water demand calculation unit to obtain the initial field water layer depth, and use the field water balance model to calculate the field water layer depth at the end of the period in each water demand calculation unit without considering irrigation conditions;

[0038] Step 4.6. Calculate the net irrigation water requirement in each water demand calculation unit based on the field water layer depth at the end of the time period and the crop planting structure in each water demand calculation unit.

[0039] Furthermore, the step 5 includes the following sub-steps:

[0040] Step 5.1. Generate a hydrological calculation unit attribute table based on the hydrological calculation units divided in step 2, wherein the hydrological calculation unit attribute table includes the code and name of each hydrological calculation unit, the meteorological unit to which it belongs, the basin area, the size and type of the water storage project, the type of the catchment area, the characteristic water level, the characteristic storage capacity, and the water level-storage capacity curve;

[0041] Step 5.2. Combine the water level monitoring stations of the water storage projects corresponding to each hydrological calculation unit, obtain the initial water level of the water storage project corresponding to each hydrological calculation unit, and calculate the initial total water storage capacity of the water storage project corresponding to each hydrological calculation unit;

[0042] Step 5.3. Combine the measured rainfall data to calculate the surface rainfall of each meteorological unit in the historical period; Combine the measured meteorological data to calculate the potential evapotranspiration of each meteorological unit in the historical period; Combine the meteorological forecast data to calculate the forecast surface rainfall and potential evapotranspiration of each meteorological unit in the forecast period;

[0043] For each hydrological calculation unit, the inflow forecast value of the water storage project corresponding to each hydrological calculation unit is calculated based on the surface rainfall and potential evapotranspiration time series in the historical period of the corresponding meteorological unit and the forecast surface rainfall and potential evapotranspiration time series in the forecast period;

[0044] Step 5.4. Combine the initial total water storage and the forecast value of the inflow, and use the water balance calculation formula to calculate the total water storage at the end of the period of each hydrological calculation unit corresponding to the water storage project without considering the irrigation condition;

[0045] Step 5.5. Combined with the total water storage at the end of the period, according to the characteristic storage capacity of the water storage project, determine the effective water storage at the end of the period of each hydrological calculation unit corresponding to the water storage project;

[0046] Step 5.6. Determine the available water volume in each hydrological calculation unit based on the effective water storage volume at the end of the time period and the designed water supply flow of the water storage project.

[0047] Furthermore, the step 6 calculates the irrigation water volume of the target time period and the target water supply calculation unit based on the water supply calculation unit divided in step 3. First, a time period cycle calculation is performed within the forecast period, and then a traversal calculation is performed on each water supply calculation unit in the entire irrigation area. A certain time period in the time period cycle is used as the target time period, and a certain water supply calculation unit in the irrigation area is used as the target water supply calculation unit. The specific calculation process is as follows:

[0048] Step 6.1. Count the total net irrigation water demand of all water demand calculation units within the target time period and target water supply calculation unit :

[0049]

[0050] In the formula, PUIndicates the water supply calculation unit identifier; RU(i) For the i The water demand calculation unit identifier; ni The number of water demand calculation units within the target water supply calculation unit; For the i The net irrigation water demand in each water demand calculation unit, ∑ is the summation symbol;

[0051] Step 6.2. Calculate the total amount of water available in all hydrological calculation units within the target period and target water supply calculation unit , including the total amount of water available in the reservoir hydrological calculation unit Total water supply in the hydrological calculation unit of the pond and weir :

[0052]

[0053] Total water supply in reservoir hydrological calculation unit :

[0054]

[0055] Total water supply in pond and weir hydrological calculation units :

[0056]

[0057] In the formula, HU(jr) Indicates jr Reservoir hydrological calculation unit; nj res Indicates the number of reservoir-type hydrological calculation units within the target water supply calculation unit; It represents the sum of the beneficial storage capacity of the water storage projects corresponding to the reservoir hydrological calculation units within the target water supply calculation unit; For the jr Each reservoir hydrological calculation unit corresponds to the beneficial storage capacity of the water storage project; Indicates the target water supply calculation unit. jr The amount of water available within each reservoir hydrological calculation unit; HU(js) Indicates js A pond and weir hydrological calculation unit; nj sma Indicates the number of pond and weir hydrological calculation units within the target water supply calculation unit; It represents the sum of the volumes of the corresponding water storage projects of the pond and weir hydrological calculation units within the target water supply unit; For the js Each pond-and-weir hydrological calculation unit corresponds to the pond-and-weir volume of the water storage project; Indicates the target water supply calculation unit js The amount of water available within each pond and weir hydrological calculation unit;

[0058] Step 6.3. Configure multiple water sources within the irrigation area. The implementation process is as follows:

[0059] 1) Determine the target time period and the number of water sources in the target water supply calculation unit n , water source code, and define water supply priorities for ponds, small reservoirs, medium reservoirs and large reservoirs;

[0060] 2) For a water source with a water supply priority of 1, it indicates that water is taken from this water source first. If the water supply of this water source can meet the net irrigation water demand, the water distribution calculation program ends and is transferred to the next irrigation calculation program; if the water supply of this water source cannot fully meet the net irrigation water demand, the remaining net irrigation water demand after the water distribution of this water source is transferred to the next water source;

[0061] 3) The priority of water supply is k If the water supply of the water source can meet the remaining net irrigation water demand after the water distribution of the previous water source, the water distribution calculation program ends and is transferred to the next irrigation calculation program; if the water supply of the water source cannot meet the remaining net irrigation water demand, the remaining net irrigation water demand after the water distribution of the water source is transferred to the next water source;

[0062] 4) The priority of water supply is n If the water supply of the water source can meet the remaining net irrigation water demand after the water distribution of the previous water source, the water distribution calculation program ends and is transferred to the next irrigation calculation program; if the water supply of the water source cannot meet the remaining net irrigation water demand, the remaining net irrigation water demand after the water distribution of the water source is the net irrigation water demand of the required external water source irrigation;

[0063] The water supply priority order within the water supply calculation unit is: k The water source, the amount of irrigation water :

[0064]

[0065] In the order of priority for water supply k The remaining net irrigation water requirement after water distribution The calculation formula is as follows:

[0066]

[0067] In the formula, The priority order for water supply is k The amount of water available from the water source; is the net irrigation water requirement before water distribution from the source; In order to prioritize water supply k -1 remaining net irrigation water requirement after water distribution from the water source; Calculate the net irrigation water requirement within the unit for the target water supply; is the field irrigation water utilization coefficient; kk For water supply order, kk =1~ k ; is the canal water utilization coefficient; The water supply order in the water supply calculation unit is kk Irrigation water volume from water sources;

[0068] Step 6.4. Based on the target time period and target water supply, calculate the irrigation water volume of the water source in the unit and calculate the priority level. k The water source corresponds to j Irrigation water volume of water source in hydrological calculation unit , which is divided into the water source irrigation water volume of the reservoir type hydrological calculation unit or the water source irrigation water volume of the pond type hydrological calculation unit:

[0069]

[0070] In the formula, HU(j) For the j Hydrological calculation unit;

[0071] When water source k If it is a reservoir type, the irrigation water volume of the water source of the reservoir type hydrological calculation unit for:

[0072]

[0073] When water source k When it is a pond or weir type, the irrigation water volume of the water source of the pond or weir hydrological calculation unit for:

[0074]

[0075] Step 6.5. Calculate the irrigation water volume of the water source corresponding to the water storage project in the target period and target hydrological calculation unit. j The total water storage capacity at the end of the period corresponding to the water storage project for each hydrological calculation unit :

[0076]

[0077] In the formula, Without considering irrigation conditions j The total water storage at the end of the period corresponding to each hydrological calculation unit of the water storage project, noirr Irrigation conditions were not considered;

[0078] Step 6.6. Calculate the irrigation water volume of the target period and target water supply calculation unit. kType of water source for the target water supply calculation unit i Irrigation water volume per water demand calculation unit :

[0079]

[0080] In the formula, For the i The water supply sequence in each water demand calculation unit is: kk The amount of irrigation water from the water source, Indicates i Internal water source of water demand calculation unit k The net irrigation water requirement remaining after irrigation is completed;

[0081] Step 6.7. Calculate the irrigation water volume after irrigation with internal water source based on the field irrigation water volume within the target period and the target water demand calculation unit. i The depth of water layer in the field at the end of the period within the water demand calculation unit :

[0082]

[0083] In the formula, For the i The depth of water layer in the field at the end of the period within each water demand calculation unit; For the i The rice planting area per water demand calculation unit.

[0084] Furthermore, in step 7, the following objective function and constraint conditions are satisfied in the water resource configuration for the target water supply calculation unit:

[0085] Objective function: The water shortage in the target water supply calculation unit is minimized;

[0086] Water balance constraint: The remaining irrigation water demand in the target water supply calculation unit during the target period is equal to the net irrigation water demand in the unit during the target period minus the sum of the effective irrigation water from different water sources;

[0087] Reservoir capacity constraint: The water supply of the reservoir-type hydrological calculation unit corresponding to the water storage project in the target water supply calculation unit is subject to the reservoir capacity constraint, and the water supply of the pond-type hydrological calculation unit corresponding to the water storage project is subject to the volume constraint:

[0088] Water supply capacity constraint: The water supply capacity within the target water supply calculation unit is constrained by the water supply capacity of the corresponding water storage projects of all hydrological calculation units within the unit.

[0089] On the other hand, the present invention provides a real-time irrigation forecasting system for rice irrigation areas based on a variable unit design, comprising:

[0090] A water demand calculation unit division module is used to respectively obtain the irrigation area meteorological unit division map, the irrigation area minimum management range map, the irrigation area soil type distribution map, and the irrigation area rice planting structure distribution map and superimpose them, and superimpose and obtain intersections for different meteorological units, different soil types, different crop planting structures, and different management ranges to determine the minimum basic unit, and merge the determined minimum basic units to form water demand calculation units with different coverage areas; a hydrological calculation unit division module is used to respectively obtain the water storage project distribution map within the irrigation area, the water storage project catchment area type map, the water storage project catchment area, the water storage project distribution map with complete data, and the water storage project water level monitoring station distribution map and superimpose them, select water storage projects of different sizes and types and different catchment area types as typical water storage projects, use each typical water storage project as a hydrological calculation unit, and form hydrological calculation units of different water storage types;

[0091] A water supply calculation unit division module, which is used to divide water supply calculation units of different aggregation levels for different water sources based on water demand calculation units, hydrological calculation units and irrigation ranges;

[0092] The net irrigation water demand prediction module is used to generate a water demand calculation unit attribute table based on the divided water demand calculation units, calculate the predicted rainfall and actual crop evapotranspiration prediction values ​​in each water demand calculation unit in combination with the meteorological forecast data, and predict the net irrigation water demand in each water demand calculation unit based on the field water dynamic balance model;

[0093] The hydrological unit available water volume prediction module is used to generate a hydrological calculation unit attribute table based on the divided hydrological calculation units, predict the water inflow process of each hydrological calculation unit in combination with meteorological forecast data, and predict the available water volume in each hydrological calculation unit based on the water balance model of the water storage project;

[0094] The irrigation water volume calculation module of the water supply calculation unit is used to configure and dispatch the irrigation water volume in the target time period and target water supply calculation unit based on the divided water supply calculation unit, calculate the irrigation water volume of the water source in each hydrological calculation unit and update the total water storage capacity of the corresponding water storage project, calculate the irrigation water volume in each water demand calculation unit and update the corresponding field water layer depth;

[0095] The water resource allocation module is used to allocate water resources for each water supply calculation unit with the minimum water shortage in each water supply calculation unit as the objective function and the water balance, water storage project storage capacity and water supply capacity as the constraints;

[0096] The real-time irrigation forecasting system for rice irrigation areas based on variable unit design is used to execute the steps in the above-mentioned real-time irrigation forecasting method for rice irrigation areas based on variable unit design.

[0097] Compared with the prior art, the present invention has the following beneficial effects:

[0098] The real-time irrigation forecasting method and system for rice irrigation areas based on variable unit design provided by the present invention adopt a variable water demand calculation unit design method to divide water demand calculation units of different coverage areas, adopt a variable hydrological calculation unit design method to divide hydrological calculation units of different water storage types, and adopt a variable water supply calculation unit design method to divide water supply calculation units of different aggregation degrees. Based on the division of calculation units, water demand forecasting, water supply forecasting of internal water sources in the irrigation area and water resource allocation are carried out within the forecast period, and the depth change process of field water layer within the forecast period, the irrigation water volume of internal water sources in the irrigation area and the gross irrigation water demand of external water sources are predicted, which provides technical support for scientifically and rationally guiding water management in irrigation areas and compiling irrigation water use plans, and provides reliable guarantee for promoting accurate forecasting and forward-looking early warning of drought conditions in irrigation areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] In order to more clearly illustrate the technical solutions in the present invention or 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 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.

[0100] Figure 1 It is a schematic diagram of the overall process of an embodiment of the present invention.

[0101] Figure 2 Schematic diagram of a design method for a variable water demand calculation unit according to an embodiment of the present invention.

[0102] Figure 3 Schematic diagram of a design method for a variable hydrological calculation unit according to an embodiment of the present invention.

[0103] Figure 4 The present invention is a schematic diagram of a water demand prediction process based on a water demand unit according to an embodiment of the present invention.

[0104] Figure 5 The figure is a schematic diagram of a water supply prediction process based on hydrological units according to an embodiment of the present invention.

[0105] Figure 6 It is a schematic diagram of the water resource allocation process based on the water supply unit according to an embodiment of the present invention.

[0106] Figure 7 This is a canal topological structure diagram of the Zhanghe irrigation area according to an embodiment of the present invention.

[0107] Figure 8 This is a schematic diagram of the distribution of small reservoirs and medium-sized reservoirs in the Zhanghe Irrigation District according to an embodiment of the present invention.

[0108] Fig. 9This is a schematic diagram of the distribution of ponds and weirs in the Zhanghe Irrigation Area according to an embodiment of the present invention.

[0109] Fig.10 This is a schematic diagram of the high-precision weather forecast data range and its relative position for the Zhanghe Irrigation District in an embodiment of the present invention.

[0110] Fig.11 This is a schematic diagram of the daily forecast rainfall process for each meteorological unit in the next ten days in the Zhanghe Irrigation District according to an embodiment of the present invention.

[0111] Fig.12 This is a schematic diagram of the daily temperature variation process of each meteorological unit in the next ten days according to an embodiment of the present invention.

[0112] Fig.13 This is a schematic diagram of the daily temperature variation process of each meteorological unit in the next ten days according to an embodiment of the present invention.

[0113] Fig.14 This is a schematic diagram of the change process of potential evapotranspiration of each meteorological unit on a daily basis in the next ten days according to an embodiment of the present invention.

[0114] Fig.15 This is a schematic diagram of the daily irrigation water demand change process in a water demand calculation unit in the next ten days according to an embodiment of the present invention.

[0115] Fig.16 It is a schematic diagram of the daily field water layer change process in the next ten days in the water demand calculation unit of an embodiment of the present invention.

[0116] Fig.17 Schematic diagram of the daily change process of the gross irrigation water demand in the next ten days in the water demand calculation unit of the embodiment of the present invention.

[0117] Fig.18 This is a schematic diagram of the change process of the daily gross irrigation water demand of the upper water diversion gate of the main canal in the next ten days in embodiment 3 of the present invention. DETAILED DESCRIPTION

[0118] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0119] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0120] Example 1

[0121] like Figure 1As shown, this embodiment provides a real-time irrigation forecasting method for rice irrigation areas based on variable unit design, comprising the following steps:

[0122] Step 1. Obtain the irrigation area meteorological unit division map, the irrigation area minimum management range map, the irrigation area soil type distribution map, and the irrigation area rice planting structure distribution map respectively and superimpose them. Superimpose and take intersections for different meteorological units, different soil types, different crop planting structures, and different management ranges to determine the minimum basic unit, and merge the determined minimum basic units to form water demand calculation units with different coverage areas;

[0123] Step 2. Obtain the distribution map of water storage projects within the irrigation area, the type map of water storage project catchment area, the area of ​​water storage project catchment area, the distribution map of water storage projects with complete data, and the distribution map of water level monitoring stations of water storage projects and superimpose them, select water storage projects with different sizes and types and different catchment area types as typical water storage projects, take each typical water storage project as a hydrological calculation unit, and form hydrological calculation units of different water storage types;

[0124] Step 3. Based on the water demand calculation unit, the hydrological calculation unit and the irrigation range, the water supply calculation units with different aggregation degrees are divided for different water sources;

[0125] Step 4. Generate a water demand calculation unit attribute table based on the water demand calculation units divided in step 1, calculate the predicted rainfall and actual crop evapotranspiration in each water demand calculation unit in combination with the meteorological forecast data, and predict the net irrigation water demand in each water demand calculation unit based on the field water dynamic balance model;

[0126] Step 5. Generate a hydrological calculation unit attribute table based on the hydrological calculation units divided in step 2, predict the water inflow process of each hydrological calculation unit in combination with meteorological forecast data, and predict the available water volume in each hydrological calculation unit based on the water balance model of the water storage project;

[0127] Step 6. Based on the water supply calculation units divided in step 3, configure and dispatch the irrigation water volume in each water supply calculation unit, calculate the irrigation water volume of the water source in each hydrological calculation unit and update the total water storage capacity of the corresponding water storage project, calculate the irrigation water volume in each water demand calculation unit and update the corresponding field water layer depth;

[0128] Step 7. Taking the minimum water shortage in each water supply calculation unit as the objective function, and taking the water balance, storage capacity of the water storage project, and water supply capacity as constraints, water resources are allocated for each water supply calculation unit.

[0129] In step 1, in the real-time irrigation forecast model for rice irrigation areas, the prediction of irrigation water demand involves information such as meteorological forecast data, initial field water layer depth, crop planting structure, field leakage rate (related to soil texture), groundwater recharge (related to topography), and irrigation water utilization coefficient (related to irrigation facilities). Considering the different soil textures, crop planting structures, topography, irrigation facilities, and the complexity of the canal system in different irrigation areas, the present invention divides water demand calculation units RU with different coverage ranges according to different situations, such as Figure 2 As shown, the specific steps include:

[0130] (1) For irrigation areas of different levels, large, medium and small, ArcGIS is used to form a meteorological unit division map based on the irrigation area vector layer and the distribution of meteorological stations within and near the irrigation area to ensure that there is one meteorological station data in one meteorological unit;

[0131] (2) Since the canal water utilization coefficient is related to the construction, maintenance, and management of irrigation facilities within the irrigation area, for irrigation areas of different sizes, ArcGIS is used to form a minimum management area map of the irrigation area, taking the irrigation area managed by the management office or management section as a unit, to ensure that the conditions of irrigation facilities within a management area are basically consistent;

[0132] (3) Based on the gridded soil type data within the irrigation area, ArcGIS was used to generate a soil type distribution map of the irrigation area;

[0133] (4) Based on the rice planting structure in the rice irrigation area inverted by remote sensing, ArcGIS was used to generate a rice planting structure distribution map in the irrigation area;

[0134] (5) Superimpose the meteorological unit division map, the minimum management range map of the irrigation area, the soil type distribution map of the irrigation area, and the rice planting structure distribution map of the irrigation area. Superimpose and take the intersection of different meteorological units, different soil types, different crop planting structures, and the minimum management range of the irrigation area to determine the minimum basic unit. Merge the minimum basic units according to the preset channel level to form water demand calculation units (RU) with different coverage areas.

[0135] In the variable hydrological calculation unit division method in step 2, the specific method is as follows:

[0136] In the real-time irrigation forecast model for rice irrigation areas, the internal water supply forecast is based on water storage projects such as reservoirs and ponds within the irrigation area. Taking into account the different levels of completeness and detail of water conservancy project data in different irrigation areas, the present invention proposes a variable hydrological calculation unit design method, which combines the type of water storage project, basic information (catchment area, longitude and latitude), characteristic curves (such as water level-volume curves), real-time water level monitoring stations, etc. to divide the hydrological calculation units HU of different water storage types. Specific steps (see the schematic diagram) Figure 3)include:

[0137] (1) Based on the longitude and latitude of the water storage projects within the irrigation area, ArcGIS was used to generate a distribution map of the water storage projects within the irrigation area;

[0138] (2) Combined with the size types of water storage projects within the irrigation area (large, medium, and small), ArcGIS was used to generate a map of the size types of water storage projects within the irrigation area; combined with the types of water conservancy project catchment areas (such as reservoirs in hilly areas and reservoirs in plain areas), ArcGIS was used to generate a map of the water storage project catchment area types within the irrigation area;

[0139] (3) Use Arc Hydro Tools in ArcGIS to extract the catchment area of ​​water storage projects such as reservoirs and ponds to generate the catchment area of ​​the water storage project;

[0140] (4) Collect the water level-volume curves, characteristic water levels, and characteristic storage capacities of water storage projects within the irrigation area, eliminate water storage projects with incomplete basic data, and use ArcGIS to generate a water storage project distribution map with complete data;

[0141] (5) Collect the water level monitoring stations of the water storage projects within the irrigation area and use ArcGIS to generate a distribution map of the water level monitoring stations of the water storage projects within the irrigation area;

[0142] (6) Superimpose the distribution map of water storage projects within the irrigation area, the map of water storage project size and type, the map of water storage project catchment area type, the distribution map of water storage projects with complete data, and the distribution map of water storage project water level monitoring stations. Select water storage projects of different sizes and types and different catchment area types as typical water storage projects, and use each typical water storage project as a hydrological calculation unit (HU), which is divided into reservoir hydrological calculation units and pond and weir hydrological calculation units. Ensure that there is a complete data base and water level monitoring station for the water storage project in each hydrological calculation unit.

[0143] In the variable water supply calculation unit design method in step 3, the specific method is as follows:

[0144] In the real-time irrigation forecast model for rice irrigation areas, the water resource allocation model is based on the water supply calculation unit. Based on the prediction results of irrigation water demand and internal water source available water, the water supply of the internal water source in the irrigation area is allocated and dispatched, and the irrigation water demand of the required external water source is predicted. Taking into account the differences in the completeness of the basic data of water storage projects within the irrigation area, the area of ​​irrigation range, etc., the present invention proposes a variable water supply calculation unit design method, which divides the water supply calculation units PU of different degrees of aggregation for different water sources. The specific steps (see the schematic diagram) Figure 3 )as follows:

[0145] (1) Independent water supply calculation unit

[0146] For large and medium-sized reservoirs within the irrigation area, their irrigation range is relatively large, and there is cross-regional irrigation. Therefore, for this type of water storage project, its irrigation range is selected as an independent water supply calculation unit to ensure that there is an important water storage project in each independent water supply calculation unit, and the basic information is complete and the measured data is perfect.

[0147] (2) Aggregate water supply calculation unit

[0148] For small reservoirs and ponds within the irrigation area, there are generally large numbers, high distribution density and small irrigation range. Therefore, for this type of water storage projects, on the basis of superimposing water demand calculation units and hydrological calculation units, the aggregated water supply calculation units are divided in combination with the irrigation area management scope and business needs to ensure that there are multiple typical water storage projects in each aggregated water supply calculation unit.

[0149] In step 4, the irrigation water demand prediction module based on the water demand unit is designed. The specific method (schematic diagram is shown in Figure 4 )as follows:

[0150] (1) Division of water demand calculation units

[0151] The variable water demand unit design method in step 1 is used to divide the irrigation area into water demand calculation units, and a water demand calculation unit attribute table is generated, providing the code and name of each water demand calculation unit, the irrigation area and main canal to which it belongs, the management section and management office to which it belongs, and clarifying the attribute information such as the meteorological unit METU, soil type, field leakage rate, crop planting structure, etc. corresponding to each water demand calculation unit.

[0152] (2) Meteorological preprocessing based on meteorological unit

[0153] For each meteorological unit, combined with the measured meteorological data in each meteorological unit, the reference crop evapotranspiration in each meteorological unit in the historical period is calculated, and the Penman formula is used to calculate the multi-year average maximum daily evapotranspiration mean of the reference crop in the historical period and its corresponding day sequence number;

[0154] (3) Reference crop evapotranspiration forecast

[0155] For each meteorological unit, the arithmetic mean method is used to calculate the forecast rainfall in each meteorological unit. , using the daily mean correction method to predict the reference crop evapotranspiration forecast value in each meteorological unit , the specific calculation formula is as follows:

[0156]

[0157] Where, METU is the meteorological unit identifier; i t Forecast period t The ordinal number of the day in the year; It is the average of the maximum daily evapotranspiration over many years in the historical period of the reference crop; I m for The corresponding day number; A 0 are the empirical parameters of the study area; The correction coefficient corresponding to the weather type during the forecast period;

[0158] (4) Prediction of actual crop evapotranspiration

[0159] For the i A water demand calculation unit is calculated based on the meteorological unit corresponding to the water demand calculation unit. i Prediction of actual crop evapotranspiration in a water demand calculation unit :

[0160]

[0161] In the formula, RU(i) For the i The water demand calculation unit identifier; For the i The soil moisture stress coefficient of each water demand calculation unit; for rice fields, the parameter value is 1; For the i The crop coefficient for each water demand calculation unit can be determined based on the crop type (rice) and its growth stage;

[0162] (5) Calculation of dynamic balance of field water

[0163] The field water balance model was used to calculate the water content of the first i The depth of water layer in the field at the end of the period within the water demand calculation unit :

[0164]

[0165] In the formula, For the i The amount of leakage or groundwater recharge within each water demand calculation unit; For the i The initial field water layer depth within each water demand calculation unit; t is the time step of the target period, noirr Irrigation conditions were not considered;

[0166] (6) Net irrigation water demand forecast

[0167] No. i Net irrigation water requirement per water demand calculation unit The calculation formula is as follows:

[0168]

[0169] In the formula, D up and D low They are the upper and lower limits of suitable water depth for rice at the corresponding growth stage; For the i The rice planting area per water demand calculation unit.

[0170] The design of the internal water source water supply prediction module based on the hydrological unit in step 5 is as follows (see the schematic diagram for details). Figure 5 )as follows:

[0171] (1) Division of hydrological calculation units

[0172] The variable hydrological calculation unit design method in step 2 is used to divide the hydrological calculation unit, and a hydrological calculation unit attribute table is generated, providing the code and name of each hydrological calculation unit, the meteorological unit to which it belongs, the basin area, the size and type of the water storage project, the type of the catchment area, the characteristic water level, the characteristic storage capacity, the characteristic curve, etc.;

[0173] (2) Calculation of initial total water storage capacity

[0174] For the j Hydrological calculation unit, get the j The hydrological calculation unit corresponds to the real-time water level of the water storage project , determine the j The initial total water storage capacity of the water storage project corresponding to each hydrological calculation unit :

[0175]

[0176] In the formula, HU(j) For the j The hydrological calculation unit identifier; f(Z,V) For the j The hydrological calculation unit corresponds to the water level-volume curve of the water storage project; Z represents the water level; V represents the water storage capacity; g() represents the total water storage capacity function corresponding to the measured water level calculated in combination with the water level-volume curve;

[0177] (3) Water inflow process forecast

[0178] Combined with the measured rainfall data, the Thiessen polygon method is used to calculate the surface rainfall of each meteorological unit in the historical period; combined with the measured meteorological data, the potential evapotranspiration of each meteorological unit in the historical period is calculated; combined with the meteorological forecast data, the predicted surface rainfall and potential evapotranspiration of each meteorological unit in the forecast period are calculated.

[0179] For each hydrological calculation unit, the Xin'anjiang model or runoff coefficient method is used to calculate the inflow forecast value of the water storage project corresponding to each hydrological calculation unit based on the historical and forecast surface rainfall and potential evapotranspiration time series of its corresponding meteorological unit;

[0180] (4) Calculation of water balance of water storage projects

[0181] For the j Hydrological calculation unit, based on the water balance calculation formula to calculate the j The total water storage capacity at the end of the period corresponding to the water storage project for each hydrological calculation unit :

[0182]

[0183] In the formula, For the j Each hydrological calculation unit corresponds to the total initial water storage capacity of the water storage project period; For the j The inflow forecast value of the water storage project corresponding to each hydrological calculation unit; For the j Each hydrological calculation unit corresponds to the leakage rate of the water storage project (including evaporation and leakage losses).

[0184] (5) Calculation of effective water storage capacity

[0185] Combined with the total water storage at the end of the period calculated in the previous step , determine the j The effective water storage capacity at the end of the period corresponding to the water storage project for each hydrological calculation unit , the hydrological calculation units of reservoir type and pond type are calculated separately:

[0186]

[0187] In the formula, Indicates jr The effective water storage capacity at the end of the period of each reservoir hydrological calculation unit corresponding to the water storage project; Indicates js The effective water storage capacity at the end of the period of each pond and weir hydrological calculation unit corresponding to the water storage project; For the jr The dead storage capacity of the water storage project corresponding to each reservoir hydrological calculation unit; For the jr Each reservoir hydrological calculation unit corresponds to the beneficial storage capacity of the water storage project; For the js Each pond-and-weir hydrological calculation unit corresponds to the pond-and-weir volume of the water storage project;

[0188] (6) Forecast of available water supply

[0189] Combined with the effective water storage at the end of the period calculated in the previous step, determine the j The water supply of the water storage project corresponding to each hydrological calculation unit , divided into reservoir type and pond type hydrological calculation unit:

[0190]

[0191]

[0192]

[0193] In the formula, Indicates jr Each reservoir hydrological calculation unit corresponds to the water supply of the water storage project; Indicates js The water supply of each pond and weir hydrological calculation unit corresponding to the water storage project; For the j Each reservoir hydrological calculation unit corresponds to the design water supply flow of the water storage project; For the js Each pond and weir type hydrological calculation unit corresponds to the design water supply flow of the water storage project.

[0194] Further, in step 6: based on the design of the water resource allocation module of the water supply unit, the specific method (schematic diagram is shown in Figure 6 )as follows:

[0195] Based on the water supply calculation units divided in step 3, the irrigation water volume of the target time period and the target water supply calculation unit is calculated. First, the cycle calculation is performed in each time period in the forecast period, and then the water supply calculation units in the entire irrigation area are traversed and calculated. A certain time period in the cycle of each time period, i.e., the target time period, and a certain water supply calculation unit in the irrigation area are used as the target water supply calculation unit. The specific calculation process is as follows:

[0196] (1) Statistics of irrigation water demand

[0197] Count the total net irrigation water demand of all water demand calculation units within the target water supply calculation unit during the target period , the specific calculation formula is as follows:

[0198]

[0199] In the formula, PU Indicates the water supply calculation unit identifier; ni The number of water demand calculation units within the target water supply calculation unit;

[0200] (2) Statistics of available water supply

[0201] Calculate the total water supply of all hydrological calculation units corresponding to the water storage project in the target period and target water supply calculation unit , including the total amount of water available in the reservoir hydrological calculation unit Total water supply in the hydrological calculation unit of the pond and weir :

[0202]

[0203] Total water supply in reservoir hydrological calculation unit :

[0204]

[0205] Total water supply in pond and weir hydrological calculation units :

[0206]

[0207] In the formula, nj res Indicates the number of reservoir-type hydrological calculation units within the target water supply calculation unit; It represents the sum of the beneficial storage capacity of the water storage projects corresponding to the reservoir hydrological calculation units within the target water supply calculation unit; For the jr Each reservoir hydrological calculation unit corresponds to the beneficial storage capacity of the water storage project; nj sma Indicates the number of pond and weir hydrological calculation units within the target water supply calculation unit; It represents the sum of the volumes of the corresponding water storage projects of the pond and weir hydrological calculation units within the target water supply unit; For the js Each pond-and-weir hydrological calculation unit corresponds to the pond-and-weir volume of the water storage project;

[0208] (3) Multiple water sources are configured within the irrigation area. The implementation process is as follows:

[0209] 1) For the target time period and the current water supply calculation unit, determine the number of water sources nk and the water source code in the time period and the water supply calculation unit, and define the water supply priority of different water sources such as ponds, reservoirs, etc.;

[0210] 2) For a water source with a water supply priority of 1, it indicates that water is taken from this water source first. If the water supply of this water source can meet the net irrigation water demand, the water distribution calculation program ends and is transferred to the next irrigation calculation program; if the water supply of this water source cannot fully meet the net irrigation water demand, the remaining net irrigation water demand after the water distribution of this water source is transferred to the next water source;

[0211] 3) The priority of water supply is kIf the water supply of the water source can meet the remaining net irrigation water demand after the water distribution of the previous water source, the water distribution calculation program ends and is transferred to the next irrigation calculation program; if the water supply of the water source cannot meet the remaining net irrigation water demand, the remaining net irrigation water demand after the water distribution of the water source is transferred to the next water source;

[0212] 4) The priority of water supply is n If the water supply of the water source can meet the remaining net irrigation water demand after the water distribution of the previous water source, the water distribution calculation program ends and is transferred to the next irrigation calculation program; if the water supply of the water source cannot meet the remaining net irrigation water demand, the remaining net irrigation water demand after the water distribution of the water source is the net irrigation water demand of the required external water source irrigation;

[0213] The priority order for water supply is k The water source is a reservoir type res or a pond type sma, and the irrigation water volume of this water source The calculation formula is as follows:

[0214]

[0215] In the order of priority for water supply k The remaining net irrigation water requirement after water distribution The calculation formula is as follows:

[0216]

[0217] In the formula, The priority order for water supply is k The amount of water available from the water source; is the net irrigation water requirement before water distribution from the source; In order to prioritize water supply k -1 remaining net irrigation water requirement after water distribution from the water source; Calculate the net irrigation water requirement within the unit for the target water supply; is the field irrigation water utilization coefficient; is the canal water utilization coefficient; kk For water supply order, kk =1~ k ; The water supply order in the water supply calculation unit is kk Irrigation water volume from water sources;

[0218] (4) Water intake module design

[0219] Based on the target time period and target water supply, the irrigation water volume of the water source in the calculation unit is calculated, and the calculation priority level is k The water source corresponds to j Irrigation water volume of water source in hydrological calculation unit , divided into reservoir type hydrological calculation unit water source irrigation water volume Irrigation water volume of water sources in hydrological calculation units such as ponds and weirs :

[0220]

[0221] When water source k If it is a reservoir type, the irrigation water volume of the water source of the reservoir type hydrological calculation unit for:

[0222]

[0223] When water source k When it is a pond or weir type, the irrigation water volume of the water source of the pond or weir hydrological calculation unit for:

[0224]

[0225] (5) Update of total water storage at the end of the period

[0226] Based on the irrigation water volume of the water source corresponding to the water storage project in the target hydrological calculation unit during the target period, calculate the total water storage volume at the end of the period corresponding to the water storage project of the jth hydrological calculation unit :

[0227]

[0228] (6) Irrigation module design

[0229] Calculate the irrigation water volume of the target period and target water supply calculation unit. k Irrigation water volume of the i-th water demand calculation unit in the target water supply calculation unit by the water source of this type :

[0230]

[0231] In the formula, For the i The water supply sequence in each water demand calculation unit is: kk The amount of irrigation water from the water source, Indicates i Internal water source of water demand calculation unit k The net irrigation water requirement remaining after irrigation is completed;

[0232] (7) Update of field water depth at the end of the period

[0233] Based on the target time period and field irrigation water volume in the target water demand calculation unit, calculate the field water layer depth at the end of the time period in the i-th water demand calculation unit after irrigation from the internal water source of the irrigation area. :

[0234]

[0235] Furthermore, in step 7: water resource allocation rule design, the specific method is as follows:

[0236] (1) Objective function

[0237] The water resource allocation of the internal water source of the irrigation area takes the minimum water shortage in each water supply calculation unit as the objective function:

[0238]

[0239] (2) Constraints

[0240] The following constraints are met in the water resource allocation for the target water supply calculation unit:

[0241] Water balance constraints

[0242] The remaining irrigation water demand in the target period and target water supply calculation unit is equal to the net irrigation water demand in the period and the unit minus the sum of the effective irrigation water from different water sources. The specific calculation formula is as follows:

[0243]

[0244] Storage capacity constraints

[0245] The water supply of the reservoir hydrological calculation unit corresponding to the water storage project in the target water supply calculation unit is subject to the storage capacity constraint:

[0246]

[0247] The water supply capacity of the water storage project corresponding to the pond and weir hydrological calculation unit within the target water supply calculation unit is subject to volume constraints:

[0248]

[0249] Water supply capacity constraints

[0250] The water supply capacity within the target water supply calculation unit is constrained by the water supply capacity of the corresponding water storage projects of all hydrological calculation units within the unit:

[0251]

[0252] In the formula, It is the water supply capacity within the target water supply unit.

[0253] This embodiment takes the Zhanghe Irrigation District as an example. The Zhanghe Irrigation District has a designed irrigation area of ​​2.6052 million mu (large irrigation district). It has formed an irrigation system that combines large, medium, small and micro irrigation with the Zhanghe Reservoir as the backbone, medium and small reservoirs and ponds as the basis, and electric irrigation stations as supplements. The Zhanghe Irrigation District is located between 122°~123° east longitude and 30°~31° north latitude in the central part of Hubei Province. The irrigation district is bordered by the Han River in the east, the Ju River in the west, the Changhu Lake in the south, and Yicheng in the north. It spans 7 counties and districts, including Dongbao District, Zhanghe New District, Shayang County, Duodao District, Zhongxiang City, Jingzhou District and Dangyang City in the three cities of Jingmen, Jingzhou and Yichang.

[0254] The water source reservoir of the Zhanghe Irrigation Area is the Zhanghe Reservoir, which has a designed irrigation area of ​​2.6052 million mu and an effective irrigation area of ​​2.3350 million mu, and is responsible for the production and living water supply task of Jingmen City. The Zhanghe Reservoir controls a basin area of ​​2,212 square kilometers and a water surface area of ​​105 square kilometers. The total storage capacity is 2.113 billion cubic meters, of which 924 million cubic meters are beneficial storage capacity and 862 million cubic meters are dead storage capacity.

[0255] The canals in the Zhanghe Irrigation District are divided into nine levels, namely the main trunk, trunk, branch trunk, sub-trunk, branch, branch, dou, agricultural, and Mao canals. There are a total of 13,990 canals in the irrigation district, with a total length of 7,167.56 km. The main trunk, west trunk, and first trunk are respectively diverted from the Zhanghe Reservoir by Yandun Gate, Linjiagang Gate, and Xujiaxiwan Gate. The second trunk draws water from the head section of the main trunk, and the third and fourth trunks divert water from the tail of the main trunk. There are 6 backbone channels in the Zhanghe Irrigation District, including the main trunk, west trunk, first trunk, second trunk, third trunk, and fourth trunk; there are 122 branch trunks, sub trunks, branch canals, and reservoir pump station canals, with a total length of 1,330.176 km. The topological structure diagram of the canal system in the Zhanghe Irrigation District is shown in Figure 7 .

[0256] In addition to the Zhanghe Reservoir, there are 314 small and medium-sized reservoirs (including 19 medium-sized reservoirs and 295 small reservoirs) in the Zhanghe Irrigation Area, with a total storage capacity of 845 million cubic meters and a beneficial storage capacity of 489 million cubic meters; there are 81,595 ponds and weirs with a water storage capacity of 190 million cubic meters. Figure 8 The figure shows the distribution of small and medium-sized reservoirs in the Zhanghe Irrigation Area. Fig. 9 Shown is the distribution of ponds and weirs in the Zhanghe Irrigation Area.

[0257] (1) Meteorological unit

[0258] Combined with the six main canals of the Zhanghe Irrigation Area to be simulated (main canal, first canal, second canal, third canal, fourth canal, and west canal), the entire Zhanghe Irrigation Area is divided into six meteorological forecast units, namely the main canal area, first canal area, second canal area, third canal area, fourth canal area, and west canal area. Combined with high-precision meteorological forecast grid data, the forecast meteorological data of each meteorological unit is extracted. The position of each meteorological unit in the meteorological forecast grid data is shown in Fig.10 .

[0259] (2) Water demand calculation unit

[0260] The crops that need to be irrigated in the Zhanghe Irrigation District are mainly rice (mid-season rice), and most of the area within the irrigation area is plain. The irrigation facilities within the irrigation area are managed and maintained by different management offices (based on the main canal). Therefore, in this example, it is assumed that the operation status of the irrigation facilities in each main canal area is basically the same. According to the survey, the soil types in the three main canal areas are slightly different, and the field water leakage rate is greater than that in the other areas. Therefore, the field leakage rate of each water demand calculation unit is determined based on the main canal area.

[0261] Combined with the actual situation of Zhanghe Irrigation District: ① Zhanghe Engineering Management Bureau mainly manages the water diversion gates on the six main canals in the irrigation district, namely the main canal, the first main canal, the second main canal, the third main canal, the fourth main canal, and the west main canal; ② The high-efficiency water-saving demonstration field area in the irrigation district is located within the irrigation range of the third main canal, the third main canal, and the Hongmiao branch canal. In this example, the irrigation range corresponding to each water diversion gate on the six main canals in Zhanghe Irrigation District and the irrigation range of each water diversion gate on the third main canal, the third main canal, and the Hongmiao branch canal are divided into water demand calculation units. Therefore, the main canal area is divided into 24 water demand calculation units, the west main canal area is divided into 82 water demand calculation units, the first main canal area is divided into 124 water demand calculation units, the second main canal area is divided into 238 water demand calculation units, the third main canal area is divided into 103 water demand calculation units, the fourth main canal area is divided into 20 water demand calculation units, and the third main canal, the third main canal, and the Hongmiao branch canal area is divided into 93 water demand calculation units. As shown in Table 1, the water demand calculation units corresponding to each water diversion outlet on the third main canal of Zhanghe Irrigation District are shown. As shown in Table 2, the water demand calculation units corresponding to the water diversion outlet gates on the Hongmiao branch canal of the third main canal and the third branch canal of Zhanghe Irrigation District are shown.

[0262] Table 1 Water demand calculation units corresponding to each water diversion gate on the three main canals of Zhanghe Irrigation Area

[0263]

[0264] Table 2 Water demand calculation units corresponding to the upper diversion gates of the third main canal, third main canal and Hongmiao branch canal in Zhanghe Irrigation Area

[0265]

[0266] (3) Hydrological calculation unit

[0267] The variable hydrological calculation unit design method is used to divide the hydrological calculation units of different water sources. Considering the large number of ponds and weirs in the irrigation area, several typical ponds and weirs are selected, and the catchment areas of each typical pond and weir are used as hydrological calculation units; considering the large number of small reservoirs in the irrigation area, several typical small reservoirs are selected, and the catchment areas of typical small reservoirs are used as hydrological calculation units; the number of medium-sized reservoirs in the irrigation area is limited (19 medium-sized reservoirs), and the catchment areas of 19 medium-sized reservoirs are used as hydrological calculation units.

[0268] (4) Water supply calculation unit

[0269] The variable water supply calculation unit design method is used to divide the water supply calculation units of different water sources in the irrigation area. For medium-sized reservoirs, the irrigation range of medium-sized reservoirs is used as an independent water supply calculation unit, and the irrigation effect of medium-sized reservoirs in the irrigation area is considered; for small reservoirs and ponds, the main canal area is used as an aggregated water supply calculation unit, and the irrigation effect of small reservoirs and ponds in the irrigation area is considered.

[0270] Step 3: Simulation calculation

[0271] Based on the model construction shown in step 2, in this example, the time step is selected as one day, the forecast period is ten days, and May 22, 2024 is taken as the starting time. The simulation calculation is performed on a daily basis for the next ten days (ten days). The simulation results include meteorological preprocessing results (as shown in step 4), water demand forecast results (as shown in step 5), water supply forecast results (as shown in step 6), water resource allocation results (as shown in step 7), and statistical analysis results of the irrigation water demand of each water outlet (see step 8).

[0272] The parameters, initial conditions and boundary conditions required for the simulation calculation are as follows:

[0273] (1) Calculation unit parameters

[0274] The water demand, hydrology and water supply calculation parameters are given in the main canal area, including field water demand calculation parameters (field leakage rate, crop water demand parameters, etc.), hydrology calculation parameters (reservoir water loss rate of ponds, small reservoirs and medium-sized reservoirs), and water supply calculation parameters (irrigation water utilization coefficient of ponds, small reservoirs and medium-sized reservoirs, and irrigation water utilization coefficient of channels and fields). Table 3 shows the calculation parameters of each main canal area in the Zhanghe Irrigation District.

[0275] Considering that the main crop that needs to be irrigated in the Zhanghe irrigation area is rice, and that medium-season rice has been the main crop planted in recent years, the crop in each water demand calculation unit is determined to be medium-season rice.

[0276] The water supply priority of internal water sources in the irrigation area within each water supply calculation unit is determined as ponds, small reservoirs and medium-sized reservoirs.

[0277] Table 3 Calculation parameters for each main canal area

[0278]

[0279] (2) Initial water depth of field water layer

[0280] The typical field monitoring station built based on the digital twin Zhanghe River can obtain the field water layer depth of the typical field at any time in real time. The model is set to automatically read the real-time water depth of the typical field at the reporting time and use it as the initial water depth of the field water layer. In this example, the initial water depth is uniformly defined as 3.75mm.

[0281] (3) Initial water level of irrigation area water source

[0282] The reservoir and pond water monitoring stations built based on the digital twin Zhanghe River can obtain the water level of the online reservoir at any time in real time. The model is set to automatically read the real-time water level of typical reservoirs and typical ponds at the reporting time, and use it as the initial water level of the irrigation area water source.

[0283] (4) Meteorological forecast boundary conditions

[0284] Based on the high-precision weather forecast service purchased by Digital Twin Zhanghe, the daily weather forecast data for the next ten days for each meteorological unit is obtained after preprocessing.

[0285] Step 4: Weather forecast preprocessing results

[0286] By reading high-precision weather forecast grid data, the rainfall, maximum temperature, minimum temperature, average temperature and of each meteorological unit are calculated to determine the corresponding weather type. Fig.11 The following table shows the daily change process of the predicted rainfall in each meteorological unit in the next ten days. Fig.12 Shown is the daily changes in the predicted maximum temperature, minimum temperature and average temperature in each meteorological unit in the next ten days.

[0287] Step 5: Water demand forecast results

[0288] (1) Actual crop evapotranspiration

[0289] According to the daily weather type in each meteorological unit in the next ten days in step 2 (1), the reference crop evapotranspiration ET is predicted using the daily mean correction method in step S4. 0 Actual crop evapotranspiration ET of the main crop (rice) in the Hezhang River irrigation area C , which is used for field water balance calculation. Since the weather types in the entire irrigation area are basically the same in the next ten days, the ET predicted by the daily mean correction method is used. 0and E.T. C Basically the same, such as Fig.13 Shown is the daily ET forecast for each meteorological unit in the next ten days 0 and E.T. C Change process.

[0290] (2) Potential evapotranspiration

[0291] According to the daily maximum temperature, minimum temperature and average temperature change process of the meteorological unit in the next ten days in step 2 (1), the daily potential evapotranspiration PET of each meteorological unit in the next ten days is predicted, which is used as the input condition of the subsequent Xinanjiang model. Fig.14 The figure shows the daily PET change process predicted for each meteorological unit in the next ten days.

[0292] (3) Net irrigation water requirement

[0293] Taking the water demand calculation unit as the object, combined with the field seepage given in step 3, the meteorological unit rainfall determined in step 4 (the meteorological unit where the water demand calculation unit is located), the actual crop transpiration calculated in step (1), and the initial field water level (the first period uses the initial field water layer conditions determined in step 3, and the subsequent periods use the calculated water layer depth of the previous period), the net irrigation water demand of each water demand calculation unit is calculated according to the field water dynamic balance formula. Fig.15 The figure shows the changes in the net irrigation water storage and field irrigation water demand in the rice fields of Liuji Village within the irrigation range of the No. 1 culvert of the Hongmiao branch canal of the third main canal in the next ten days.

[0294] Step 6: Water supply forecast results

[0295] (1) Initial water supply of small reservoirs and ponds

[0296] According to the measured water levels of typical small reservoirs and typical ponds at the initial moment, the initial water supply of small reservoirs and ponds in each water supply calculation unit is calculated by the method of step 5: design of water supply prediction module based on hydrological unit, as shown in Table 4. At the same time, manual correction can be made according to the real-time calculated water supply. In this example, due to the failure to read the real-time water level of the typical pond at the start time, the calculated value of the pond water supply is 0, and the initial water supply of the pond in each water supply calculation unit is confirmed to be 0. Therefore, in the irrigation area water resources allocation simulation in step 7, the pond water source in the irrigation area will not be used for irrigation.

[0297] Table 4 Initial water supply capacity of small reservoirs and ponds in each water supply calculation unit

[0298]

[0299] (2) Water supply of medium-sized reservoirs

[0300] According to the measured water level of each medium-sized reservoir at the initial moment, the initial water supply of the medium-sized reservoir in the corresponding hydrological calculation unit is calculated by the method of step S5: design of water supply prediction module based on hydrological unit, as shown in Table 6. At the same time, manual correction can be made according to the real-time calculated water supply. In this example, the water supply of the medium-sized reservoir is manually modified to 0. Therefore, in step 7, the water resources allocation simulation of the irrigation area will not use the water source of the medium-sized reservoir in the irrigation area for irrigation.

[0301] Table 5 Water supply capacity of medium-sized reservoirs corresponding to water supply calculation units

[0302]

[0303] (3) Water inflow process of hydrological calculation unit

[0304] Taking each hydrological calculation unit as the object, based on the meteorological forecast preprocessing results, the Xin'anjiang model is used to predict the water inflow process of the reservoir in each unit, and the runoff coefficient method is used to predict the water inflow process of the pond weir in each unit. Table 6 shows the daily forecast of the inflow process of the hydrological calculation unit of Cheqiao Reservoir in the next ten days. To ensure accuracy, manual correction can be made based on the water supply calculated according to the real-time water level.

[0305] Table 6 Daily forecast of reservoir inflow in the next ten days within the hydrological calculation unit

[0306]

[0307] Step 7: Results of water resource allocation within the irrigation area

[0308] According to the water supply calculation unit and its information determined in step 2, step 6: design of water resource allocation module based on water supply unit and step 7: design of water resource allocation rules are adopted to configure and dispatch the water source inside the irrigation area, and the water resource allocation results of each water demand calculation unit can be obtained.

[0309] Taking the rice fields in Liuji Village, which is within the irrigation range of the 1# culvert of the Hongmiao branch of the Sangan Canal, as an example, Table 7 shows the daily water distribution process of the internal water source in the water demand calculation unit in the next ten days. Fig.16 The figure shows the change process of the field water layer depth in the water demand calculation unit. Fig.17 The figure shows the daily changes in the net irrigation water demand in the next ten days within the water demand calculation unit, the remaining net irrigation water demand after internal water source irrigation, and the gross irrigation water demand of the Zhanghe Reservoir.

[0310] Table 7 Daily water distribution process in the next ten days within the water demand calculation unit

[0311]

[0312] Note: The irrigation water volume of the pond is the irrigation water volume of the pond water source, and the net irrigation water volume of the crop = the irrigation water volume of the pond Effective utilization coefficient of pond water Effective utilization coefficient of field water; the same applies to small and medium-sized reservoirs; the remaining net irrigation water demand is the net irrigation water storage after deducting the internal water source irrigation from the net irrigation water demand; the gross irrigation water demand of Zhanghe Reservoir is the required irrigation water demand of Zhanghe Reservoir, which is = remaining net irrigation water demand / effective utilization coefficient of channel water.

[0313] Combined with the water demand forecast, water supply forecast and water resource allocation results of each water demand calculation unit, the gross irrigation water demand of each main canal in the Zhanghe Irrigation Area is counted, providing a data basis for the Hubei Provincial Zhanghe Project Management Bureau to guide irrigation area water management and prepare irrigation water use plans. Fig.18 The figure shows the daily changes in gross irrigation water demand in the next ten days based on statistics from eight water diversion gates, including two branch canals, two branch canals, seven branch canals, three branch canals, one branch canal, one branch canal, 97# culvert canal and 10# culvert canal on the third main canal.

[0314] Example 2

[0315] This embodiment provides a real-time irrigation forecasting system for rice irrigation areas based on a variable unit design, including:

[0316] The water demand calculation unit division module is used to obtain the irrigation area meteorological unit division map, irrigation area management scope map, irrigation area soil type distribution map, irrigation area rice planting structure distribution map and superimpose them, perform cross processing for different meteorological units, different soil types, different crop types, and different management scopes, preliminarily divide the water demand calculation units and merge the preliminary calculation units to form water demand calculation units with different coverage areas;

[0317] The hydrological calculation unit division module is used to obtain the distribution map of water storage projects within the irrigation area, the type map of water storage project catchment area, the area of ​​water storage project catchment area, the data distribution map of water storage projects, and the distribution map of water level monitoring stations of water storage projects and superimpose them, select water storage projects of different sizes and types and different catchment area types as typical water storage projects, and use each typical water storage project as a hydrological calculation unit;

[0318] A water supply calculation unit division module, which is used to divide water supply calculation units of different aggregation levels for different water sources based on water demand calculation units, hydrological calculation units and irrigation ranges;

[0319] The net irrigation water demand prediction module is used to generate a water demand calculation unit attribute table based on the divided water demand calculation units, calculate the actual crop evapotranspiration in the water demand calculation unit in combination with the meteorological data in the meteorological unit, and predict the net irrigation water demand in the water demand calculation unit based on the field water dynamic balance calculation;

[0320] A hydrological unit available water volume prediction module, which is used to generate a hydrological calculation unit attribute table based on the divided hydrological calculation units, and to predict the water inflow process of the hydrological calculation unit in combination with the meteorological data in the meteorological unit, and to predict the available water volume in the hydrological calculation unit based on the water balance calculation of the water storage project;

[0321] A water supply calculation unit irrigation water volume calculation module, which is used to calculate the irrigation water volume of the target water supply calculation unit within the target time period based on the divided water supply calculation units;

[0322] The water resource allocation module is used to allocate water resources for the water supply calculation unit with the minimum water shortage in each water supply unit as the objective function and the water balance, storage capacity of the water storage project and water supply capacity as the constraints.

[0323] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0324] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0325] Other parts not described in detail are all prior art.

Claims

1. A real-time irrigation forecasting method for rice irrigation areas based on variable unit design, characterized in that: The steps include: Step 1. Obtain the irrigation area meteorological unit division map, the irrigation area minimum management range map, the irrigation area soil type distribution map, and the irrigation area rice planting structure distribution map respectively and superimpose them. Superimpose and take intersections for different meteorological units, different soil types, different crop planting structures, and different management ranges to determine the minimum basic unit, and merge the determined minimum basic units to form water demand calculation units with different coverage areas; Step 2. Obtain the distribution map of water storage projects within the irrigation area, the type map of water storage project catchment area, the area of ​​water storage project catchment area, the distribution map of water storage projects with complete data, and the distribution map of water level monitoring stations of water storage projects and superimpose them, select water storage projects with different sizes and types and different catchment area types as typical water storage projects, take each typical water storage project as a hydrological calculation unit, and form hydrological calculation units of different water storage types; Step 3. Based on the water demand calculation unit, the hydrological calculation unit and the irrigation range, the water supply calculation units with different aggregation degrees are divided for different water sources; Step 4. Generate a water demand calculation unit attribute table based on the water demand calculation units divided in step 1, calculate the predicted rainfall and actual crop evapotranspiration in each water demand calculation unit in combination with the meteorological forecast data, and predict the net irrigation water demand in each water demand calculation unit based on the field water dynamic balance model; Step 5. Generate a hydrological calculation unit attribute table based on the hydrological calculation units divided in step 2, predict the water inflow process of each hydrological calculation unit in combination with meteorological forecast data, and predict the available water volume in each hydrological calculation unit based on the water balance model of the water storage project; Step 6. Based on the water supply calculation units divided in step 3, configure and dispatch the irrigation water volume in each water supply calculation unit, calculate the irrigation water volume of the water source in each hydrological calculation unit and update the total water storage capacity of the corresponding water storage project, calculate the irrigation water volume in each water demand calculation unit and update the corresponding field water layer depth; Step 7. Taking the minimum water shortage in each water supply calculation unit as the objective function, and taking the water balance, storage capacity of the water storage project, and water supply capacity as constraints, water resources are allocated for each water supply calculation unit.

2. The real-time irrigation forecasting method for rice irrigation areas based on variable unit design according to claim 1 is characterized by: The step 1 includes the following sub-steps: Step 1.

1. For irrigation areas of different levels, combine the irrigation area vector layer of the irrigation area and the distribution of meteorological stations within and near the irrigation area to form a meteorological unit division map to ensure that there is a meteorological station in each meteorological unit; Step 1.

2. Take the irrigation area managed by the management office or management section within the irrigation area as the irrigation unit, and form the minimum management area map of the irrigation area; Step 1.

3. Based on the gridded soil type data within the irrigation area, a soil type distribution map of the irrigation area is formed; Step 1.

4. Based on the rice planting structure within the rice irrigation area inverted by remote sensing, a distribution map of the rice planting structure in the irrigation area is formed; Step 1.

5. Overlay the meteorological unit division map, the minimum management range map of the irrigation area, the soil type distribution map of the irrigation area, and the rice planting structure distribution map of the irrigation area. Overlay and take intersections for different meteorological units, different soil types, different crop planting structures, and minimum management ranges of the irrigation area to determine the minimum basic unit. Merge the minimum basic units according to the preset channel level to form water demand calculation units with different coverage areas.

3. The real-time irrigation forecasting method for rice irrigation areas based on variable unit design according to claim 1 is characterized by: The step 2 includes the following sub-steps: Step 2.

1. Based on the longitude and latitude of the water storage projects within the irrigation area, a distribution map of the water storage projects within the irrigation area is formed; Step 2.

2. Based on the size types of water storage projects within the irrigation area, a size type map of water storage projects within the irrigation area is formed, and combined with the catchment area types of water storage projects within the irrigation area, a catchment area type map of water storage projects within the irrigation area is formed; Step 2.

3. Extract the catchment area of ​​the water storage project within the irrigation area to generate the catchment area of ​​the water storage project; Step 2.

4. Collect basic data of water storage projects within the irrigation area, including water level-volume curve, characteristic water level and characteristic storage capacity, eliminate water storage projects with incomplete basic data of water storage projects, and form a water storage project distribution map with complete data; Step 2.

5. Collect water level monitoring sites of water storage projects within the irrigation area to form a distribution map of water level monitoring sites of water storage projects within the irrigation area; Step 2.

6. Overlay the water storage project distribution map within the irrigation area, the water storage project size type map, the water storage project catchment area type map, the water storage project distribution map with complete data, and the water storage project water level monitoring station distribution map. Select water storage projects of different sizes and types and different catchment area types as typical water storage projects, and use each typical water storage project as a hydrological calculation unit, which are divided into reservoir-type hydrological calculation units and pond-type hydrological calculation units.

4. The real-time irrigation forecasting method for rice irrigation areas based on variable unit design according to claim 1 is characterized in that: The water supply calculation unit in step 3 is an independent water supply calculation unit or an aggregated water supply calculation unit, wherein: (1) Independent water supply calculation unit For large and medium-sized reservoirs within the irrigation area, their irrigation areas are selected as independent water supply calculation units; (2) Aggregate water supply calculation unit For small reservoirs or ponds within the irrigation area, the aggregated water supply calculation units are divided according to the irrigation area management scope and business needs to ensure that there is at least one typical water storage project in each aggregated water supply calculation unit.

5. The real-time irrigation forecasting method for rice irrigation areas based on variable unit design according to claim 1 is characterized in that: The step 4 includes the following sub-steps: Step 4.

1. Generate a water demand calculation unit attribute table based on the water demand calculation units divided in step 1, the water demand calculation unit attribute table includes the code and name of each water demand calculation unit, the irrigation area and main canal to which it belongs, the management section and management office to which it belongs, the meteorological unit corresponding to each water demand calculation unit, and the field leakage rate and crop planting structure of each water demand calculation unit; Step 4.

2. Combine the measured meteorological data in each meteorological unit to calculate the reference crop evapotranspiration in each meteorological unit during the historical period, and calculate the multi-year average maximum daily evapotranspiration mean value and its corresponding day number during the historical period of the reference crop; Step 4.

3. Obtain the meteorological forecast data in each meteorological unit, calculate the forecast rainfall in each meteorological unit, and calculate the reference crop evapotranspiration forecast value in each meteorological unit; Step 4.

4. Calculate the actual crop evapotranspiration prediction value in each water demand calculation unit in combination with the calculated reference crop evapotranspiration prediction value; Step 4.

5. Combine the field infiltration rate, the predicted rainfall in each meteorological unit, and the predicted value of actual crop evapotranspiration in each water demand calculation unit to obtain the initial field water layer depth, and use the field water balance model to calculate the field water layer depth at the end of the period in each water demand calculation unit without considering irrigation conditions; Step 4.

6. Calculate the net irrigation water requirement in each water demand calculation unit based on the field water layer depth at the end of the time period and the crop planting structure in each water demand calculation unit.

6. The real-time irrigation forecasting method for rice irrigation areas based on variable unit design according to claim 5 is characterized by: The step 5 includes the following sub-steps: Step 5.

1. Generate a hydrological calculation unit attribute table based on the hydrological calculation units divided in step 2, wherein the hydrological calculation unit attribute table includes the code and name of each hydrological calculation unit, the meteorological unit to which it belongs, the basin area, the size and type of the water storage project, the type of the catchment area, the characteristic water level, the characteristic storage capacity, and the water level-storage capacity curve; Step 5.

2. Combine the water level monitoring stations of the water storage projects corresponding to each hydrological calculation unit, obtain the initial water level of the water storage project corresponding to each hydrological calculation unit, and calculate the initial total water storage capacity of the water storage project corresponding to each hydrological calculation unit; Step 5.

3. Combine the measured rainfall data to calculate the surface rainfall of each meteorological unit in the historical period; Combine the measured meteorological data to calculate the potential evapotranspiration of each meteorological unit in the historical period; Combine the meteorological forecast data to calculate the forecast surface rainfall and potential evapotranspiration of each meteorological unit in the forecast period; For each hydrological calculation unit, the inflow forecast value of the water storage project corresponding to each hydrological calculation unit is calculated based on the surface rainfall and potential evapotranspiration time series in the historical period of the corresponding meteorological unit and the forecast surface rainfall and potential evapotranspiration time series in the forecast period; Step 5.

4. Combine the initial total water storage and the forecast value of the inflow, and use the water balance calculation formula to calculate the total water storage at the end of the period of each hydrological calculation unit corresponding to the water storage project without considering the irrigation condition; Step 5.

5. Combined with the total water storage at the end of the period, according to the characteristic storage capacity of the water storage project, determine the effective water storage at the end of the period of each hydrological calculation unit corresponding to the water storage project; Step 5.

6. Determine the available water volume in each hydrological calculation unit based on the effective water storage volume at the end of the time period and the designed water supply flow of the water storage project.

7. The real-time irrigation forecasting method for rice irrigation areas based on variable unit design according to claim 6 is characterized by: The step 6 calculates the irrigation water volume of the target time period and the target water supply calculation unit based on the water supply calculation unit divided in step 3. First, a cycle calculation is performed in each time period in the forecast period, and then a traversal calculation is performed for each water supply calculation unit in the entire irrigation area. A certain time period in the cycle is used as the target time period, and a certain water supply calculation unit in the irrigation area is used as the target water supply calculation unit. The specific calculation process is as follows: Step 6.

1. Count the total net irrigation water demand of all water demand calculation units within the target time period and target water supply calculation unit : In the formula, PU Indicates the water supply calculation unit identifier; RU(i) For the i The water demand calculation unit identifier; ni The number of water demand calculation units within the target water supply calculation unit; For the i The net irrigation water demand in each water demand calculation unit, ∑ is the summation symbol; Step 6.

2. Calculate the total amount of water available in all hydrological calculation units within the target period and target water supply calculation unit , including the total amount of water available in the reservoir hydrological calculation unit Total water supply in the hydrological calculation unit of the pond and weir : Total water supply in reservoir hydrological calculation unit : Total water supply in pond and weir hydrological calculation units : In the formula, HU(jr) Indicates jr Reservoir hydrological calculation unit; nj res Indicates the number of reservoir-type hydrological calculation units within the target water supply calculation unit; It represents the sum of the beneficial storage capacity of the water storage projects corresponding to the reservoir hydrological calculation units within the target water supply calculation unit; For the jr Each reservoir hydrological calculation unit corresponds to the beneficial storage capacity of the water storage project; Indicates the target water supply calculation unit jr The amount of water available within each reservoir hydrological calculation unit; HU(js) Indicates js A pond and weir hydrological calculation unit; nj sma Indicates the number of pond and weir hydrological calculation units within the target water supply calculation unit; It represents the sum of the volumes of the corresponding water storage projects of the pond and weir hydrological calculation units within the target water supply unit; For the js Each pond-and-weir hydrological calculation unit corresponds to the pond-and-weir volume of the water storage project; Indicates the target water supply calculation unit js The amount of water available within each pond and weir hydrological calculation unit; Step 6.

3. Configure multiple water sources within the irrigation area. The implementation process is as follows: 1) Determine the target time period and the number of water sources in the target water supply calculation unit n , water source code, and define water supply priorities for ponds, small reservoirs, medium reservoirs and large reservoirs; 2) For a water source with a water supply priority of 1, it indicates that water is taken from this water source first. If the water supply of this water source can meet the net irrigation water demand, the water distribution calculation program ends and is transferred to the next irrigation calculation program; if the water supply of this water source cannot fully meet the net irrigation water demand, the remaining net irrigation water demand after the water distribution of this water source is transferred to the next water source; 3) The priority of water supply is k If the water supply of the water source can meet the remaining net irrigation water demand after the water distribution of the previous water source, the water distribution calculation program ends and is transferred to the next irrigation calculation program; if the water supply of the water source cannot meet the remaining net irrigation water demand, the remaining net irrigation water demand after the water distribution of the water source is transferred to the next water source; 4) The priority of water supply is n If the water supply of the water source can meet the remaining net irrigation water demand after the water distribution of the previous water source, the water distribution calculation program ends and is transferred to the next irrigation calculation program; if the water supply of the water source cannot meet the remaining net irrigation water demand, the remaining net irrigation water demand after the water distribution of the water source is the net irrigation water demand of the required external water source irrigation; The water supply priority order within the water supply calculation unit is: k The water source, the amount of irrigation water : In the order of priority for water supply k The remaining net irrigation water requirement after water distribution The calculation formula is as follows: In the formula, The priority order for water supply is k The amount of water available from the water source; is the net irrigation water requirement before water distribution from the source; In order to prioritize water supply k -1 remaining net irrigation water requirement after water distribution from the water source; Calculate the net irrigation water requirement within the unit for the target water supply; is the field irrigation water utilization coefficient; kk For water supply order, kk =1~ k ; is the canal water utilization coefficient; The water supply order in the water supply calculation unit is kk Irrigation water volume from water sources; Step 6.

4. Based on the target time period and target water supply, calculate the irrigation water volume of the water source in the unit and calculate the priority level. k The water source corresponds to j Irrigation water volume of water source in hydrological calculation unit , which is divided into the water source irrigation water volume of the reservoir type hydrological calculation unit or the water source irrigation water volume of the pond type hydrological calculation unit: In the formula, HU(j) For the j Hydrological calculation unit; When water source k If it is a reservoir type, the irrigation water volume of the water source of the reservoir type hydrological calculation unit for: When water source k When it is a pond or weir type, the irrigation water volume of the water source of the pond or weir hydrological calculation unit for: Step 6.

5. Calculate the irrigation water volume of the water source corresponding to the water storage project in the target period and target hydrological calculation unit. j The total water storage capacity at the end of the period corresponding to the water storage project for each hydrological calculation unit : In the formula, Without considering irrigation conditions j The total water storage at the end of the period corresponding to each hydrological calculation unit of the water storage project, noirr Irrigation conditions were not considered; Step 6.

6. Calculate the irrigation water volume of the target period and target water supply calculation unit. k Type of water source for the target water supply calculation unit i Irrigation water volume per water demand calculation unit : In the formula, For the i The water supply sequence in each water demand calculation unit is: kk The amount of irrigation water from the water source, Indicates i Internal water source of water demand calculation unit k The net irrigation water requirement remaining after irrigation is completed; Step 6.

7. Calculate the irrigation water volume after irrigation with internal water source based on the field irrigation water volume within the target period and the target water demand calculation unit. i The depth of water layer in the field at the end of the period within the water demand calculation unit : In the formula, For the i The depth of water layer in the field at the end of the period within each water demand calculation unit; For the i The rice planting area per water demand calculation unit.

8. The real-time irrigation forecasting method for rice irrigation areas based on variable unit design according to claim 7 is characterized in that: In step 7, the following objective function and constraints are satisfied in the water resource allocation for the target water supply calculation unit: Objective function: The water shortage in the target water supply calculation unit is minimized; Water balance constraint: The remaining irrigation water demand in the target water supply calculation unit during the target period is equal to the net irrigation water demand in the unit during the target period minus the sum of the effective irrigation water from different water sources; Reservoir capacity constraint: The water supply of the reservoir-type hydrological calculation unit corresponding to the water storage project in the target water supply calculation unit is subject to the reservoir capacity constraint, and the water supply of the pond-type hydrological calculation unit corresponding to the water storage project is subject to the volume constraint: Water supply capacity constraint: The water supply capacity within the target water supply calculation unit is constrained by the water supply capacity of the corresponding water storage projects of all hydrological calculation units within the unit.

9. A real-time irrigation forecasting system for rice irrigation areas based on variable unit design, characterized in that: include: A water demand calculation unit division module is used to respectively obtain the irrigation area meteorological unit division map, the irrigation area minimum management range map, the irrigation area soil type distribution map, and the irrigation area rice planting structure distribution map and superimpose them, and superimpose and obtain intersections for different meteorological units, different soil types, different crop planting structures, and different management ranges to determine the minimum basic unit, and merge the determined minimum basic units to form water demand calculation units with different coverage areas; a hydrological calculation unit division module is used to respectively obtain the water storage project distribution map within the irrigation area, the water storage project catchment area type map, the water storage project catchment area, the water storage project distribution map with complete data, and the water storage project water level monitoring station distribution map and superimpose them, select water storage projects of different sizes and types and different catchment area types as typical water storage projects, use each typical water storage project as a hydrological calculation unit, and form hydrological calculation units of different water storage types; A water supply calculation unit division module, which is used to divide water supply calculation units of different aggregation levels for different water sources based on water demand calculation units, hydrological calculation units and irrigation ranges; The net irrigation water demand prediction module is used to generate a water demand calculation unit attribute table based on the divided water demand calculation units, calculate the predicted rainfall and actual crop evapotranspiration prediction values ​​in each water demand calculation unit in combination with the meteorological forecast data, and predict the net irrigation water demand in each water demand calculation unit based on the field water dynamic balance model; The hydrological unit available water volume prediction module is used to generate a hydrological calculation unit attribute table based on the divided hydrological calculation units, predict the water inflow process of each hydrological calculation unit in combination with meteorological forecast data, and predict the available water volume in each hydrological calculation unit based on the water balance model of the water storage project; The irrigation water volume calculation module of the water supply calculation unit is used to configure and dispatch the irrigation water volume in the target time period and target water supply calculation unit based on the divided water supply calculation unit, calculate the irrigation water volume of the water source in each hydrological calculation unit and update the total water storage capacity of the corresponding water storage project, calculate the irrigation water volume in each water demand calculation unit and update the corresponding field water layer depth; The water resource allocation module is used to allocate water resources for each water supply calculation unit with the minimum water shortage in each water supply calculation unit as the objective function and the water balance, water storage project storage capacity and water supply capacity as the constraints; The real-time irrigation forecasting system for rice irrigation areas based on variable unit design is used to execute the steps in the real-time irrigation forecasting method for rice irrigation areas based on variable unit design according to any one of claims 1-8.

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