A method and system for simulating dynamic hydrological processes in rice irrigation areas

Abstract

This invention discloses a method and system for simulating dynamic hydrological processes in rice irrigation areas. The method includes: constructing a spatial correlation information database between rice paddies and ditches; simulating cycles in daily increments, dynamically adjusting the effective field ridge height according to the rice growth stage, and calculating lateral recharge or discharge based on field type and water level potential energy difference; applying an exponential decay correction to the saturated hydraulic conductivity of the plow pan based on the number of consecutive flooded days, and calculating vertical infiltration; updating the field water depth by substituting overflow drainage, lateral discharge, and vertical infiltration into the water balance equation; constructing a confluence topology network based on the spatial location and elevation of the fields, and performing staggered superposition considering confluence time delay to obtain the total runoff at the sub-basin outlet. This method achieves refined simulation of the entire process of field ridge water storage, field-ditch lateral interaction, nonlinear infiltration of the plow pan, and distributed confluence, significantly improving the accuracy of hydrological process simulation in rice irrigation areas and providing a scientific basis for water resource management in irrigation areas.

Description

Technical Field

[0001] This invention belongs to the field of agricultural hydrological simulation technology, and in particular relates to a method and system for simulating dynamic hydrological processes in rice irrigation areas. Background Technology

[0002] As a vital global food crop, rice has stringent requirements for water conditions during its growth process, especially in irrigated agricultural areas. Efficient water resource management is crucial for ensuring food security and sustainable ecological development. The hydrological processes in rice-irrigated areas are complex, influenced not only by natural rainfall and evapotranspiration but also by significant human interventions such as irrigation, drainage, and field drying. These management activities result in significant dynamics and unique characteristics in the water depth, soil moisture, and water flow paths of rice paddies.

[0003] Currently, surface hydrological models such as SWAT (Soil and Water Assessment Tool) are widely used in hydrological simulations in non-rice-growing areas. However, traditional SWAT models face the following technical bottlenecks when dealing with the unique hydrological processes in paddy fields: First, the simulation of water storage and overflow on paddy field ridges is crude. Traditional SWAT models often simplify the treatment of water depth in the field, making it difficult to accurately simulate the rice growing season. In particular, the control role of paddy field ridges on water depth and overflow drainage is not fully reflected, resulting in a large deviation between field water level changes and actual conditions.

[0004] Second, the nonlinear infiltration process in the plow pan is missing. Prolonged flooding in paddy fields leads to soil aeration, forming a dense plow pan, which significantly reduces the soil's saturated hydraulic conductivity, causing the infiltration process to exhibit a nonlinear decay characteristic. Traditional models typically employ constant or simple linear infiltration models, which cannot accurately capture this crucial hydrophysical process, resulting in inaccurate infiltration calculations.

[0005] Third, the lateral interaction mechanism between paddy fields and irrigation ditches is neglected. Significant lateral hydraulic connections exist between paddy fields and adjacent irrigation ditches, including the replenishment (infiltration) from ditches to fields and the drainage (outfiltration) from fields to ditches. This lateral seepage is a crucial component of the irrigation district's water balance. Traditional SWAT models, when simulating lateral runoff at the regional scale, are typically based on topographic slope, making it difficult to accurately quantify the fine hydraulic exchange between fields and ditches.

[0006] Fourth, the spatial heterogeneity of the runoff process between fields is not considered. Traditional hydrological models usually use sub-basins as the basic unit, ignoring the time delay of runoff caused by topographic differences within and between fields, and thus failing to reflect the spatial migration process of water volume between fields.

[0007] Therefore, developing a method and system that can more accurately simulate the dynamic hydrological processes in rice irrigation areas is of great theoretical and practical significance for improving the level of water resource management in irrigation areas and optimizing irrigation systems. Summary of the Invention

[0008] This invention provides a method and system for simulating dynamic hydrological processes in rice irrigation areas, aiming to solve the technical problems in the prior art, such as inaccurate water storage control on field ridges, lack of nonlinearity infiltration of the plow pan, neglect of the field-ditch lateral interaction mechanism, and failure to consider spatial heterogeneity in the confluence process between fields.

[0009] In a first aspect, the present invention provides a method for simulating dynamic hydrological processes in rice irrigation areas, comprising: Obtain digital elevation models, land use maps, soil type maps, daily meteorological data, and spatial distribution data of irrigation canal systems for the study area; Based on the land use map, the digital elevation model, and the spatial distribution data of the irrigation canal system, a spatial association information database of paddy fields and ditches is constructed. The spatial association information database includes at least the spatial location information, ground elevation information, field type information of each paddy field, and the bottom elevation information and effective contact length information of the ditches adjacent to each paddy field. The simulation cycle is carried out with a daily time step. On each simulation day, the effective field ridge height is dynamically adjusted according to the key growth stage of the rice. Based on the current field type and field water depth, the bottom elevation information and effective contact length information of the adjacent ditches corresponding to the current rice field are called from the spatial association information database to calculate the lateral supply or lateral discharge and update the field water depth. Based on the current field water depth of the paddy field, the number of consecutive flooding days is recorded. The saturated hydraulic conductivity of the plow pan is nonlinearly attenuated and corrected based on the number of consecutive flooding days. The vertical infiltration is calculated and then deducted from the field water depth. Substitute the overflow discharge, lateral discharge, and vertical infiltration into the preset water balance equation to update the field water depth for the day; After completing the daily updates of all paddy fields, a confluence topology network is constructed based on the spatial location information and ground elevation information of each paddy field in the spatial association information database. The overflow and lateral discharge of each paddy field are then transferred step by step along the confluence direction to obtain the total runoff of the sub-basin outlet section, and the simulation results are output.

[0010] Secondly, the present invention provides a field dynamic hydrological process simulation system for rice irrigation areas, comprising: The acquisition module is configured to acquire digital elevation models, land use maps, soil type maps, daily meteorological data, and spatial distribution data of irrigation canal systems for the study area. The construction module is configured to construct a spatial association information database of paddy fields and ditches based on the land use map, the digital elevation model and the spatial distribution data of the irrigation canal system. The spatial association information database includes at least the spatial location information, ground elevation information, field type information of each paddy field, and the bottom elevation information and effective contact length information of the ditches adjacent to each paddy field. The calculation module is configured to perform a simulation cycle with a daily time step. On each simulation day, the effective field ridge height is dynamically adjusted according to the key growth stage of the rice. Based on the current field type and field water depth, the module calls the bottom elevation information and effective contact length information of the adjacent ditches corresponding to the current rice field from the spatial association information database to calculate the lateral supply or lateral discharge and update the field water depth. The correction module is configured to record the number of consecutive flooding days based on the current paddy field water depth, perform nonlinear attenuation correction on the saturated hydraulic conductivity of the plow pan based on the number of consecutive flooding days, calculate the vertical infiltration amount, and deduct the vertical infiltration amount from the field water depth. The update module is configured to substitute the overflow discharge volume, lateral discharge volume, and vertical infiltration volume into the preset water balance equation to update the field water depth for the day; The output module is configured to construct a confluence topology network based on the spatial location information and ground elevation information of each paddy field in the spatial association information database after completing the daily update of all paddy fields. The overflow and lateral discharge of each paddy field are then transmitted step by step along the confluence direction to obtain the total runoff of the sub-basin outlet section, and the simulation results are output.

[0011] Thirdly, an electronic device is provided, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the steps of the rice irrigation area field dynamic hydrological process simulation method according to any embodiment of the present invention.

[0012] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the steps of the method for simulating dynamic hydrological processes in rice irrigation areas according to any embodiment of the present invention.

[0013] The method and system for simulating dynamic hydrological processes in rice irrigation areas presented in this application have the following specific benefits: By introducing a dynamic coupling mechanism between the key growth stages of rice and the effective field ridge height, agricultural management is directly mapped to time-varying parameters of the field ridge water storage capacity, thereby achieving precise simulation of the artificial regulation process of field water depth. A model for the exponential decay of saturated hydraulic conductivity of the plow pan based on the number of consecutive flooding days was constructed. This model accurately reflects the physical process of soil aeration and gradual decay of hydraulic conductivity caused by long-term flooding, and significantly improves the accuracy of vertical infiltration calculation. By establishing the spatial topological relationship between paddy fields and ditches, and introducing the Darcy-type seepage formula to calculate the lateral recharge and discharge based on the real-time water level potential energy difference, a refined simulation of the two-way hydraulic exchange between the paddy field and the ditch was realized for the first time, filling the gap in the traditional hydrological model on the lateral interaction mechanism of the irrigation area. By constructing a directed graph confluence topology using the spatial location and ground elevation of paddy fields, and combining the confluence path length and field surface roughness to calculate the time delay, the spatiotemporal peak superposition of water migration between fields was achieved, making the sub-basin outlet runoff process more consistent with actual physical laws. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A flowchart illustrating a method for simulating dynamic hydrological processes in a rice irrigation area, as provided in an embodiment of the present invention; Figure 2 This is a structural block diagram of a field dynamic hydrological process simulation system for rice irrigation areas provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see Figure 1 The diagram shows a flowchart of a method for simulating dynamic hydrological processes in rice irrigation areas according to this application.

[0018] like Figure 1 As shown, the simulation method for dynamic hydrological processes in rice irrigation areas specifically includes the following steps: Step S101: Obtain the digital elevation model, land use map, soil type map, daily meteorological data, and spatial distribution data of irrigation canal system for the study area.

[0019] In this step, the digital elevation model (DEM) is preferably generated using 1:50,000 or 1:10,000 scale data released by the surveying and mapping department, or obtained from public sources such as the Space Shuttle Radar Topographic Mapping Mission (SRTM, 30-meter resolution) and ALOS (12.5-meter resolution). If conditions permit, a high-resolution DEM of 1 to 5 meters is generated using UAV LiDAR.

[0020] Land use maps are obtained directly from the latest year's land use change survey results (1:10,000 or 1:50,000 vector data), or based on Sentinel-2 (10-meter resolution) and Landsat 8 / 9 (30-meter) remote sensing images. After radiometric calibration and atmospheric correction, supervised classification (support vector machine or random forest) methods are used for interpretation. Map features with land use codes of "paddy field" or "rice paddy" are extracted and exported as separate vector layers. Jagged edges and isolated areas at the boundaries are smoothed and corrected.

[0021] Soil type maps are based on soil survey results. After loading vector or raster data, the maps are cropped according to the study area. The attribute table must include soil type name, soil texture (sand, silt, and clay content), organic matter content, plow pan thickness, and initial saturated hydraulic conductivity.

[0022] Daily meteorological data were obtained from the meteorological bureau, including daily observations from 3 to 5 meteorological stations in and around the study area. These data included precipitation, daily maximum temperature, daily minimum temperature, average wind speed, relative humidity, and sunshine duration. After outlier removal and linear interpolation to fill gaps, the data were spatially interpolated to the center of each paddy field or sub-basin using inverse distance weighting or ordinary kriging methods.

[0023] The spatial distribution data of the irrigation canal system is collected from the irrigation district management agency in CAD or GIS format canal system map (including linear vectors of main, branch, tributary, and farm canals). The bottom elevation and cross-sectional dimensions of each canal section are extracted. If there is no bottom elevation, the minimum value is sampled from the DEM at 10-meter intervals along the canal line for estimation.

[0024] Step S102: Based on the land use map, the digital elevation model, and the spatial distribution data of the irrigation canal system, construct a spatial association information database of paddy fields and ditches. The spatial association information database includes at least the spatial location information, ground elevation information, field type information of each paddy field, and the bottom elevation information and effective contact length information of the ditches adjacent to each paddy field.

[0025] In this step, the spatial location and geometric boundaries of each paddy field are identified based on the land use map, the ground elevation of each paddy field is extracted based on the digital elevation model, and the spatial location and bottom elevation of each ditch are extracted based on the spatial distribution data of the irrigation canal system. Using the spatial overlay analysis method, the geometric boundaries of each paddy field and the geometric boundaries of each ditch are matched for proximity. Ditches that overlap with the geometric boundaries of each paddy field or have a distance less than a preset distance threshold are identified, and the topological association between each paddy field and its adjacent ditch is established. Calculate the length of the overlapping boundary between a certain paddy field and its adjacent ditch, and use it as the effective contact length between the certain paddy field and its adjacent ditch; Based on the difference between the ground elevation of a certain paddy field and the bottom elevation of the adjacent ditch of the certain paddy field, the certain paddy field is divided into ditch-replenished field and ditch-drained field, and the field type is recorded. The spatial coordinates, ground elevation, field type, bottom elevation of adjacent ditches, and effective contact length of each paddy field are associated and stored to form the spatial association information database.

[0026] In one specific embodiment, based on the land use map of the study area, all land use types "paddy fields" are identified by raster-to-vector conversion or direct extraction of vector map features. For each paddy field feature, its spatial coordinates (such as center point coordinates, coordinates of the vertices of the enclosing rectangle or polygon) and geometric boundaries (polygon vector boundaries) are extracted. Simultaneously, based on a digital elevation model, the average ground elevation within the range of each paddy field feature is extracted using spatial interpolation or regional statistical methods. For fields with complex boundaries, the elevation value of the geometric center point can be used as the representative elevation, or the average value of all covered pixels can be used to improve accuracy. The extraction results are recorded as a paddy field spatial information table, containing the fields: field ID, geometric boundary, center point coordinates, and ground elevation.

[0027] Based on the spatial distribution data of irrigation canal systems (usually a linear vector layer), the spatial coordinates (starting point, ending point coordinates, and inflection point coordinates), geometric shape (linear vector), and bottom elevation attributes of each canal are extracted. The bottom elevation of the canal can be obtained through field measurement data, extraction along the canal line using a digital elevation model (DEM), or interpolation. For canals lacking measured bottom elevation data, a DEM-based sampling method can be used, where DEM elevation values ​​are sampled at equal intervals along the canal line, and the average value is taken as the average bottom elevation of the canal. The extraction results are recorded in a canal spatial information table, containing the fields: Canal ID, Geometric Boundary (Line), and Bottom Elevation.

[0028] A spatial overlay analysis method is used to perform spatial proximity matching between the paddy field polygon layer and the ditch line layer. Specifically, for each paddy field polygon, the minimum Euclidean distance between its geometric boundary and the geometric boundaries of each ditch is calculated. If this minimum distance is less than a preset proximity threshold (e.g., 1 meter), or if the two boundaries have geometric overlap (distance is 0), then the ditch is determined to be adjacent to the paddy field. To improve matching accuracy, a buffer analysis method can be used: a buffer with a preset buffer distance (e.g., 1 meter) is generated outward for each paddy field polygon, and then intersection analysis is performed with the ditch line layer; intersecting ditches are considered adjacent ditches. For each paddy field, a list of ditch IDs of its adjacent ditches is recorded, forming a topological association between the paddy field and the ditches. If a paddy field is adjacent to multiple ditches, the association information of each ditch is recorded separately.

[0029] For rice paddy and ditch pairs with established topological associations, the overlap length between the polygonal boundary of the rice paddy and the linear layer of the ditch is calculated. Specifically, the intersection of the rice paddy polygonal boundary and the ditch line (which may be one or more line segments) is extracted, and the total length of these segments is calculated as the effective contact length between the rice paddy and the ditch. If the rice paddy and ditch are only adjacent but their boundaries do not overlap (i.e., the distance is greater than 0 but less than the proximity threshold), the projected length of the ditch within the proximity threshold range can be taken as the approximate effective contact length. The effective contact length reflects the potential channel size for lateral hydraulic exchange between the rice paddy and the ditch and is a key parameter for subsequent calculations of lateral seepage. The calculated effective contact length is recorded in the association information table.

[0030] For each paddy field, obtain its ground elevation. The bottom elevation of the ditch and its adjacent ditches Calculate the difference between the two. Based on the preset hydraulic gradient threshold (For example, 0.2 meters, which can be adjusted according to regional terrain conditions), the paddy field plots are divided into different types: like If the elevation of the paddy field is significantly higher than the bottom elevation of the ditch, the paddy field is identified as a ditch-drainage type of paddy field. Under the influence of gravity, water in such fields easily drains into the ditches, forming lateral drainage.

[0031] like If the elevation of the paddy field is significantly lower than the bottom elevation of the ditch, the paddy field is identified as a ditch-recharged field. Under the influence of gravity, water from the ditch easily replenishes the field, forming lateral irrigation.

[0032] like If the elevation of paddy fields and ditches is similar, supplementary judgment can be made based on actual hydrological relationships or experience, or they can be temporarily classified as medium-type fields and treated as equilibrium fields.

[0033] Record the identified field types (such as "drainage type" or "replenishment type") in the associated information table.

[0034] All extracted and calculated information is integrated to form a structured spatial association information database.

[0035] In summary, classifying paddy field types based on the difference between the ground elevation of paddy fields and the bottom elevation of ditches can accurately determine the role (replenishment or drainage) of each field in lateral hydraulic interaction, avoiding the crude problem of applying a uniform treatment mode to all fields. The introduction of effective contact length enables the calculation of lateral seepage to reflect the differences in the length of the contact boundary between the field and the ditch, improving the ability to express the spatial heterogeneity of seepage estimation.

[0036] Step S103: Perform a simulation cycle with a daily time step. On each simulation day, dynamically adjust the effective field ridge height according to the key growth stage of the rice. Based on the current paddy field type and field water depth, call the bottom elevation information and effective contact length information of the adjacent ditches corresponding to the current paddy field in the spatial association information database to calculate the lateral supply or lateral discharge and update the field water depth.

[0037] In this step, the key growth stages of rice corresponding to the current simulated day are obtained. The key growth stages include the flooding period, the drying period, and the re-watering period. If the current period is the flood season, the effective field ridge height is the minimum value between the physical height of the field ridge and the upper limit of the target flood depth, expressed as: ,in For effective field ridge height, The physical height of the field ridge, The upper limit of the target irrigation depth; If the field is currently in the drying season, the effective field ridge height is taken as the target drainage depth, expressed as: , The target drainage depth; If the current period is the re-irrigation phase, the difference between the previous day's field water depth and the lower limit of the target irrigation depth is obtained. The effective field ridge height is then linearly adjusted based on this difference, expressed as: , In the formula, The water level in the fields was high the day before. The target is the lower limit of the irrigation depth. The preset rehydration rate coefficient is used to control the speed at which the height of the field ridges recovers.

[0038] Furthermore, the field type, bottom elevation of adjacent ditches, and effective contact length of the current paddy field are obtained from the spatial association information database; If the field type is a ditch-replenished field, then determine whether the current field water depth is lower than the preset replenishment start threshold; If the water level is below the preset replenishment threshold, the current field surface water level and the water level of adjacent ditches are obtained. The lateral replenishment amount is calculated based on the potential energy difference between the field surface water level and the ditches, the field ridge permeability coefficient, the effective contact length, and the preset effective path length, and then added to the field water depth. Otherwise, no lateral replenishment is performed. The formula for calculating the potential energy difference between the field surface water level and the ditches is: , In the formula, Due to potential energy difference, This represents the current water level in the paddy field. To obtain the current ground elevation of the paddy field from the spatial association information database, The water level of the ditches adjacent to the current paddy fields. The bottom elevation of the ditch adjacent to the current paddy field is obtained from the spatial association information database; If the field type is a ditch drainage field, then determine whether the current water depth in the field exceeds the effective field embankment height: If the water level exceeds the effective field ridge height, the current field surface water level and the water level of the adjacent ditch are obtained. The lateral discharge volume is calculated based on the potential energy difference between the field surface water level and the ditch water level, the field ridge permeability coefficient, the effective contact length, and the preset effective path length, and the lateral discharge volume is deducted from the field water depth; otherwise, no lateral discharge is performed.

[0039] In summary, by directly mapping the key growth stages of rice to the dynamic changes in the effective field ridge height, the model can realistically reflect the regulatory effect of agricultural activities such as artificial irrigation and drainage on field water volume. The linear regression adjustment function used during the rehydration period can simulate the gradual process of water layer recovery after field drying, avoiding the unreasonable phenomenon of water layer recovery being too rapid or too slow in traditional models. By introducing the potential energy difference between the field surface water level and the ditch water level, and combining the spatial information of the field ground elevation and the bottom elevation of the ditch, the lateral water flow direction (replenishment or discharge) and intensity at each moment can be accurately determined. Compared with the traditional model that uses a fixed direction or simple empirical coefficients, this invention can dynamically respond to changes in ditch water level and field water level, and more realistically reflect the two-way hydraulic exchange process between the field and the ditch. In the formula for calculating lateral seepage, the effective contact length and effective path length are both obtained from the spatial association information database, so that the lateral interaction capability of each field is matched with its geometric shape (length of contact boundary) and physical properties (width of field ridge), avoiding systematic errors caused by uniform parameters; By setting a replenishment start threshold and a discharge trigger condition (field water depth exceeding the effective field ridge height), calculations are only performed when lateral interaction is required, avoiding indiscriminate lateral flux calculations for all fields on each simulation day, thus improving computational efficiency while ensuring simulation accuracy. The magnitude of lateral replenishment reflects the actual water supply capacity of ditches to fields, while lateral discharge reflects the drainage capacity of fields to ditches. These quantified lateral fluxes can provide a quantitative basis for water resource allocation in irrigation districts and optimize the formulation of irrigation systems.

[0040] Step S104: Record the number of consecutive flooding days based on the current paddy field water depth, perform nonlinear attenuation correction on the saturated hydraulic conductivity of the plow pan based on the number of consecutive flooding days, calculate the vertical infiltration amount, and deduct the vertical infiltration amount from the field water depth.

[0041] In this step, the current water depth in the paddy field is obtained. If the water depth is greater than zero, the number of consecutive flooded days is increased by 1; if the water depth is equal to zero, the number of consecutive flooded days is reset to zero. The exponential decay model is used to perform nonlinear decay correction on the saturated hydraulic conductivity of the plow pan, and the expression is as follows: , In the formula, The corrected saturated hydraulic conductivity of the plow pan. The initial saturated hydraulic conductivity of the plow pan. The attenuation coefficient, pre-calibrated based on the clay and organic matter content of the plow pan soil, is used to characterize the rate at which the soil's water-conducting capacity decreases due to the soil's air-tightening effect caused by long-term flooding. This refers to the number of consecutive days of flooding. Calculate vertical infiltration based on the corrected saturated hydraulic conductivity of the plow pan; The calculated vertical infiltration amount is deducted from the current field water depth of the paddy field and added to the lower soil water or groundwater storage.

[0042] In one specific embodiment, the field water depth of the rice paddy on the current simulated day is obtained. (Unit: mm). This water depth value is an intermediate value obtained after completing the lateral hydraulic interaction update in step S103.

[0043] Determine the numerical status of water depth in the field: like If the water level indicates that the paddy field is flooded on that day, then the continuous flooding days counter will be activated. Increase by 1.

[0044] like If the water level is zero, it indicates that the paddy field is not flooded on that day (such as during the drying period or when it dries naturally), and the counter for consecutive flooded days will be reset to zero.

[0045] Number of consecutive days of flooding This is an accumulated variable that records the number of consecutive days the paddy field has been flooded. This variable reads the previous day's result at the start of each simulation day, updates it in this step, and stores it for use in subsequent simulation days. For the initial simulation day, if the initial field water depth is greater than 0, then... Initialize to 1; otherwise initialize to 0.

[0046] The plow pan is a dense soil layer formed under long-term cultivation and flooding conditions in paddy fields. Located below the cultivated layer, it is typically 10–20 cm thick. Under prolonged flooding, soil pores become filled with water, leading to soil aeration. Microbial activity in the soil consumes oxygen, creating a reducing environment. Simultaneously, soil particles expand and rearrange, altering the soil pore structure and gradually reducing its water conductivity. An exponential decay model is used to describe this physical process.

[0047] The physical meaning of this exponential decay model is: when the number of consecutive flood days... hour, The plow pan retains its initial water-conducting capacity; as the number of flooded days increases, the water-conducting capacity decreases exponentially; when the number of flooded days is sufficiently large, the water-conducting capacity approaches 0, indicating that the plow pan has become completely airtight due to prolonged flooding, making it difficult for water to pass through. The attenuation coefficient c controls the attenuation rate; the larger c is, the faster the water-conducting capacity decreases.

[0048] Based on the corrected saturated hydraulic conductivity of the plow pan, Darcy's Law is used to calculate the vertical infiltration through the plow pan. Darcy's Law describes the relationship between the flow rate of fluid in a porous medium and the head gradient. In this invention, the field water depth is considered as the driving head, and the plow pan is considered as a low-permeability medium. The greater the water depth in the field and the drier the underlying soil (the greater the substrate suction), the greater the infiltration rate; the thicker the plow pan or the lower the water conductivity, the smaller the infiltration rate.

[0049] The calculated vertical infiltration volume The current paddy field water depth is deducted, and the updated paddy field water depth is: , In the formula, For the updated field water depth, The water depth in the field has not been updated.

[0050] If the updated field water depth is negative, it is set to 0, and the excess (absolute value of the negative value) is attributed to the rapid infiltration of water caused by excessive suction of the lower soil. However, in actual physical processes, the field water depth will not be negative, so boundary constraint treatment is performed.

[0051] Simultaneously, the deducted vertical infiltration will be replenished to the underlying soil water or groundwater storage. The specific replenishment method depends on the underlying structure of the model. If the underlying soil layer is unsaturated, then It is added to the moisture content of the soil layer below the plow pan to renew the soil moisture balance; If the underlying soil layer is in the saturated zone (i.e., above the groundwater level), then It is considered as groundwater recharge and added to the groundwater storage.

[0052] Updated consecutive flood days Store the data in the paddy field state variable for use on the next simulation day. If the field water depth is set to 0 in this step, the number of consecutive flooded days will automatically reset to zero at the start of the next simulation day.

[0053] Step S105: Substitute the overflow discharge volume, lateral discharge volume, and vertical infiltration volume into the preset water balance equation to update the field water depth for the day.

[0054] In this step, the daily rainfall, daily irrigation amount, daily actual evapotranspiration, and the previous day's field water depth are obtained; The overflow drainage volume is determined based on the effective field ridge height: if the field water depth is greater than the effective field ridge height, the overflow drainage volume is the field water depth minus the effective field ridge height, and the field water depth is reset to the effective field ridge height; otherwise, the overflow drainage volume is zero. Substituting the overflow discharge, lateral discharge, vertical infiltration, rainfall, irrigation, and evapotranspiration into the water balance equation, the field water depth for the day is calculated. The water balance equation is as follows: , In the formula, The water depth in the field on day t. The water depth in the field on day t-1. Let be the rainfall on day t. Let be the irrigation amount on day t. Let t be the lateral supply amount. This represents the actual evaporation on day t. Let t be the overflow discharge volume on day t. Let be the vertical infiltration amount on day t. This represents the lateral discharge volume on day t. The calculated field water depth for the current day will be used as the initial field water depth for the next simulation day.

[0055] In one specific embodiment, the following data is obtained: Extract the rainfall (mm) for day t from daily meteorological data. The daily manual irrigation amount (mm) is obtained according to the agricultural management settings. If there is no irrigation plan for the day, the value is 0. The actual daily evapotranspiration (mm) can be calculated from the evaporation module of the SWAT model or the Penman-Monteith formula. This value reflects the sum of evaporation from the field water surface and crop transpiration. Read the field water depth (mm) at the end of the previous simulation day from the paddy field state variables; Obtain the daily lateral supply amount (mm) from step S103; if no lateral supply occurs, the value is 0. Obtain the daily lateral discharge volume (mm) from step S103. If no lateral discharge occurs, the value is 0. Obtain the daily vertical infiltration amount (mm) from step S104.

[0056] Overflow drainage refers to the process where excess water overflows from the top of the field embankment when the water depth in the field exceeds the embankment's water storage capacity. The effective embankment height is calculated based on step S103. and current field water depth (That is, the median value of the previous day's water depth after lateral interaction and vertical infiltration updates), determine the overflow discharge volume: like If the water depth in the field exceeds the water storage capacity of the field embankments, overflow drainage will occur. Overflow drainage volume. For the portion exceeding the limit: , At the same time, the water depth in the field will be reset to the effective height of the field ridges: , like If the water depth in the field does not exceed the water storage capacity of the field ridges, then no overflow or drainage will occur. , , It should be noted that the current water depth in the field is... This is the median field water depth obtained after completing step S103 (lateral interaction) and step S104 (vertical infiltration), i.e.: , In the formula, The water depth in the field on day t-1; Substitute all the above hydrological components into the preset water balance equation to calculate the final field water depth for the day.

[0057] Step S106: After completing the daily update of all paddy fields, construct a confluence topology network based on the spatial location information and ground elevation information of each paddy field in the spatial association information database, and transfer the overflow drainage and lateral discharge of each paddy field step by step along the confluence direction to obtain the total runoff of the sub-basin outlet section, and output the simulation results.

[0058] In this step, the spatial coordinates and ground elevation of each paddy field are obtained from the spatial association information database; Taking each paddy field as the center, determine the adjacent paddy fields within a preset range based on its spatial coordinates, calculate the ground elevation difference between the paddy field and each adjacent paddy field, select the adjacent paddy field with the largest elevation difference as the confluence direction, and if there are multiple adjacent paddy fields with the same maximum elevation difference, select the one closest to it. A directed graph-structured confluence topology network is established with each paddy field as a confluence node and the paddy field to which the confluence direction points as a downstream node; paddy fields whose confluence direction points to the sub-basin boundary or river channel are marked as sub-basin outlet nodes. The overflow and lateral discharge of each paddy field are used as the initial outflow. The outflow is accumulated from upstream to downstream according to the aforementioned confluence topology network. The outflow of each paddy field is equal to its own outflow plus the sum of the flows transferred to it from all upstream paddy fields. During the flow transmission process, the flow time delay is calculated based on the flow path length and the field surface roughness. The calculation formula is as follows: , In the formula, Due to the confluence time delay, The length of the confluence path from the upstream paddy field to the downstream paddy field. As the base bus speed, The roughness coefficient is the factor that influences roughness. The roughness coefficient is Manning's coefficient. Based on the confluence time delay, the outflows from different paddy fields are staggered and superimposed on the time axis, that is, the outflow calculated on the current simulation day is allocated to subsequent simulation days according to the delay time. The total runoff at the outlet sections of all sub-basins is obtained by summing the flows at all outlet nodes, and the simulation results are output in time series form.

[0059] In one specific embodiment, spatial coordinates and ground elevation data of all paddy fields are read in batches from the spatial association information database constructed in step S102. Spatial coordinates can be the planar coordinates of the geometric center of the paddy field (such as X and Y coordinates in a projected coordinate system), and ground elevation is the average elevation value of the paddy field (unit: mm or m). To ensure the accuracy of the runoff calculation, the elevation data of all paddy fields must be unified to the same reference surface.

[0060] Taking each paddy field as the analysis object, the natural direction of water flow on the field surface is determined based on its spatial location and ground elevation. The specific method is as follows: Determine the search area: Using the geometric center of the current paddy field as the center point, determine the adjacent paddy fields within the preset search radius (e.g., 100m to 500m, which can be adjusted according to the average size of the paddy field and the degree of terrain undulation). The selection of the search radius should ensure that it can cover the possible water flow directions on the terrain, while avoiding the introduction of non-adjacent paddy fields due to an excessively large search area.

[0061] Filtering candidate downstream fields: For each adjacent paddy field within the search range, calculate the ground elevation difference between the current paddy field and that adjacent paddy field. , in, The current ground elevation of paddy field i is... This represents the ground elevation of the adjacent paddy field j. Only the elevation of the adjacent paddy field j is retained. The adjacent fields are considered as candidate downstream fields, meaning only fields with lower elevations and potential water flow directions are considered. If the set of candidate downstream fields is empty, it indicates that the current paddy field is a local depression or a watershed boundary field.

[0062] Select the confluence direction: Among the candidate downstream fields, select the elevation difference. The field with the largest elevation difference is selected as the confluence direction. If multiple fields have the same maximum elevation difference, the Euclidean distance between the current paddy field and these candidate fields is further calculated, and the field with the closest distance is selected as the confluence direction. This strategy (the steepest slope method) simulates the natural law of surface runoff flowing along the direction of maximum slope under the influence of gravity.

[0063] Special circumstances handling: If the candidate downstream field set is empty (i.e., there are no adjacent fields with lower elevations), the current paddy field is marked as a depression or outlet node within the sub-basin, with its confluence direction pointing towards the sub-basin boundary or river channel. Further determination of whether it belongs to the sub-basin outlet needs to be based on actual terrain conditions.

[0064] If no adjacent paddy fields are found within the search range, the current paddy field is marked as an isolated field, and its overflow drainage and lateral discharge are directly included in the sub-basin outlet runoff and do not participate in the inter-field confluence.

[0065] A directed graph topology network is established, with each paddy field as a sink node and the paddy field to which the flow direction points as a downstream node. This network satisfies the following characteristics: Node: Each paddy field corresponds to a node in the graph.

[0066] Directed edge: If the flow direction of paddy field i points to paddy field j, then there exists a directed edge from node i to node j, indicating that the water flows from field i to field j.

[0067] Acyclicity: Since the flow direction is strictly based on the elevation difference (from high to low), this directed graph does not contain loops and is a directed acyclic graph (DAG), which guarantees the convergence of the flow calculation.

[0068] Outlet node: Paddy fields whose confluence direction points to the sub-basin boundary or river channel are marked as sub-basin outlet nodes. Outlet nodes can be: Fields whose confluence direction points to areas outside the sub-basin (without downstream fields); Fields adjacent to or located on the boundary of a river; The field corresponding to the predefined sub-basin outlet location based on actual terrain data.

[0069] The construction of a confluence topology network can be done using an adjacency list or adjacency matrix, which records the downstream node ID of each node and the list of upstream nodes for each node (for subsequent traffic accumulation).

[0070] The overflow and drainage volume generated by each paddy field on that day and lateral discharge volume As the initial outflow, the flow rate is accumulated step by step from upstream to downstream according to the confluence topology. Since the confluence network is a directed acyclic graph, a topology sorting algorithm can be used to determine the computation order, ensuring that the upstream nodes of each node are processed before the node itself.

[0071] Traffic accumulation rules: , In the formula, The total outflow (mm or m) from paddy field i to downstream. 3 ), The initial outflow of paddy field i itself, i.e. , This refers to the collection of all upstream paddy fields that directly flow into paddy field i. The outflow rate transmitted from the upstream paddy field k to its downstream area; The accumulation process begins at the upstream boundary node (fields without upstream nodes) and proceeds downstream level by level until all exit nodes have been accumulated. Accumulation result. This represents the total runoff contributed by paddy field i and all its upstream fields, which will eventually continue to be transmitted downstream along the confluence direction until the outlet node.

[0072] The water flow takes a certain amount of time to travel between fields, which depends on the length of the confluence path and the surface roughness. During the flow transfer process, the system calculates the confluence time delay between each field and its downstream fields. The calculation formula is as follows:

[0073] In the formula, The confluence time delay represents the time required for water to flow from an upstream field to a downstream field. This represents the confluence path length from the upstream paddy field to the downstream paddy field. This length can be the Euclidean distance between the geometric centers of the two fields, or the broken line distance of the actual water flow along the field boundary. For adjacent fields with overlapping boundaries, the distance between their centroids can be used. For fields with boundaries that are close but not overlapping, the shortest path length along the field boundary can be used. The baseline runoff velocity represents the flow velocity of water under ideal conditions (without the influence of roughness). The baseline runoff velocity can be set based on regional topographic features and empirical runoff values, typically ranging from 500 to 2000 m / d. This is the roughness influence coefficient, used to adjust the degree of influence of roughness on the confluence velocity, typically ranging from 5 to 20. The larger this coefficient, the more significant the amplification effect of roughness on time delay. Manning's roughness coefficient characterizes the effect of surface roughness on water flow obstruction. Paddy fields have lower surface roughness during flooding and higher roughness during drying due to soil exposure and crop residue. The value typically ranges from 0.03 to 0.10. The physical meaning of this formula is: reference convergence time. Multiply by roughness correction factor This yields the actual confluence time delay. The rougher the field surface (…), the more… The larger the volume, the longer the confluence time.

[0074] Based on the confluence time delay, the outflows from different paddy fields are staggered and superimposed on the time axis to simulate the temporal distribution of the runoff process. The specific method is as follows: For each simulated day t, the paddy field i generates an initial outflow. (Including overflow drainage and lateral discharge). This flow is transmitted step by step along the confluence path, with a time delay added for each field it passes through. Finally, the time when the flow contribution from paddy field i reaches the exit node is: , in, Let i be the set of all fields along the confluence path from paddy field i to the exit node. This represents the cumulative time delay along this path.

[0075] The contribution of all paddy fields is allocated to the runoff process line at the outlet section according to the arrival time: For each simulated day t, iterate through all rice paddies and calculate their cumulative time delay; The initial outflow of paddy field i Accumulated at the outlet section in time In the runoff; Since the time delay may not be an integer number of days, linear interpolation can be used to distribute the traffic to adjacent simulated days, or a finer time step (such as hours) can be used for distribution.

[0076] By summing the flow contributions of all sub-basin outlet nodes at different times, the runoff sequence of the sub-basin outlet section over time is obtained: , in, The total runoff (m³) at the outlet section of the sub-basin at time T 3 / s or mm / d), The set of all sub-basin outlet nodes. The runoff from paddy field i to the outlet section at time T.

[0077] The simulation results are output in time series format, including: The daily (or hourly) total runoff at the outlet section of the sub-basin; Daily field water depth, overflow drainage volume, lateral discharge volume, and vertical infiltration volume for each paddy field; Runoff process curves at the outlet of the sub-basin, cumulative runoff statistics, etc.

[0078] Output formats can include text files, CSV tables, databases, or GIS layers, facilitating subsequent analysis, visualization, and integration with other models.

[0079] In summary, the method of this application acquires digital elevation models, land use maps, soil type maps, meteorological data, and irrigation canal system data to construct a spatial correlation information database between paddy fields and ditches. It simulates cycles on a daily basis, dynamically adjusting the effective field ridge height according to the rice growth stage, and calculates lateral recharge or discharge based on field type and water level potential energy difference. It performs exponential decay correction on the saturated hydraulic conductivity of the plow pan based on the number of consecutive flooded days to calculate vertical infiltration. It substitutes overflow drainage, lateral discharge, and vertical infiltration into the water balance equation to update the field water depth. Based on the spatial location and elevation of the fields, it constructs a confluence topology network, considers confluence time delays for peak stacking, and obtains the total runoff at the sub-basin outlet. This achieves a refined simulation of the entire process of field ridge water storage, field-canal lateral interaction, nonlinear infiltration of the plow pan, and distributed confluence, significantly improving the accuracy of hydrological process simulation in rice irrigation areas and providing a scientific basis for water resource management in irrigation areas.

[0080] Please see Figure 2 The diagram shows a structural block diagram of a field dynamic hydrological process simulation system for rice irrigation areas according to this application.

[0081] like Figure 2 As shown, the field dynamic hydrological process simulation system 200 for rice irrigation areas includes an acquisition module 210, a construction module 220, a calculation module 230, a correction module 240, an update module 250, and an output module 260.

[0082] The acquisition module 210 is configured to acquire digital elevation models, land use maps, soil type maps, daily meteorological data, and spatial distribution data of irrigation canals for the study area. The construction module 220 is configured to construct a spatial association information database of paddy fields and ditches based on the land use map, the digital elevation model, and the spatial distribution data of the irrigation canals. This database includes at least the spatial location information, ground elevation information, field type information, and bottom elevation information and effective contact length information of ditches adjacent to each paddy field. The calculation module 230 is configured to perform a simulation cycle with a daily time step. On each simulation day, it dynamically adjusts the effective field ridge height according to the key growth stage of the rice, and calls the adjacent ditches corresponding to the current paddy field from the spatial association information database based on the current field type and water depth. The system uses the bottom elevation information and effective contact length information of the ditch to calculate the lateral recharge or lateral discharge and update the field water depth. A correction module 240 is configured to record the number of consecutive flooded days based on the current field water depth of the paddy field, perform nonlinear attenuation correction on the saturated hydraulic conductivity of the plow pan based on the number of consecutive flooded days, calculate the vertical infiltration, and deduct the vertical infiltration from the field water depth. An update module 250 is configured to substitute the overflow discharge, lateral discharge, and vertical infiltration into a preset water balance equation to update the field water depth for the day. An output module 260 is configured to, after completing the daily update of all paddy fields, construct a confluence topology network based on the spatial location information and ground elevation information of each paddy field in the spatial association information database, and progressively transfer the overflow discharge and lateral discharge of each paddy field along the confluence direction to obtain the total runoff at the sub-basin outlet section, and output the simulation results.

[0083] It should be understood that Figure 2 The modules and references described in the document Figure 1 The steps described in the text correspond to those in the method described above. Therefore, the operations, features, and corresponding technical effects described above also apply to the method described in the text. Figure 2 The various modules in the document will not be described in detail here.

[0084] In other embodiments, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the method for simulating dynamic hydrological processes in rice irrigation areas in any of the above method embodiments. In one embodiment, the computer-readable storage medium of the present invention stores computer-executable instructions, which are configured as follows: Obtain digital elevation models, land use maps, soil type maps, daily meteorological data, and spatial distribution data of irrigation canal systems for the study area; Based on the land use map, the digital elevation model, and the spatial distribution data of the irrigation canal system, a spatial association information database of paddy fields and ditches is constructed. The spatial association information database includes at least the spatial location information, ground elevation information, field type information of each paddy field, and the bottom elevation information and effective contact length information of the ditches adjacent to each paddy field. The simulation cycle is carried out with a daily time step. On each simulation day, the effective field ridge height is dynamically adjusted according to the key growth stage of the rice. Based on the current field type and field water depth, the bottom elevation information and effective contact length information of the adjacent ditches corresponding to the current rice field are called from the spatial association information database to calculate the lateral supply or lateral discharge and update the field water depth. Based on the current field water depth of the paddy field, the number of consecutive flooding days is recorded. The saturated hydraulic conductivity of the plow pan is nonlinearly attenuated and corrected based on the number of consecutive flooding days. The vertical infiltration is calculated and then deducted from the field water depth. Substitute the overflow discharge, lateral discharge, and vertical infiltration into the preset water balance equation to update the field water depth for the day; After completing the daily updates of all paddy fields, a confluence topology network is constructed based on the spatial location information and ground elevation information of each paddy field in the spatial association information database. The overflow and lateral discharge of each paddy field are then transferred step by step along the confluence direction to obtain the total runoff of the sub-basin outlet section, and the simulation results are output.

[0085] Computer-readable storage media may include a stored program area and a stored data area, wherein the stored program area may store an operating system and an application program required for at least one function; the stored data area may store data created based on the use of the rice irrigation area field dynamic hydrological process simulation system, etc. Furthermore, the computer-readable storage medium may include high-speed random access memory, and may also include memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, the computer-readable storage medium may optionally include memory remotely configured relative to a processor, which can be connected to the rice irrigation area field dynamic hydrological process simulation system via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0086] Figure 3 This is a schematic diagram of the structure of the electronic device provided in the embodiment of the present invention, such as... Figure 3As shown, the device includes a processor 310 and a memory 320. The electronic device may also include an input device 330 and an output device 340. The processor 310, memory 320, input device 330, and output device 340 can be connected via a bus or other means. Figure 3 Taking a bus connection as an example, the memory 320 is the computer-readable storage medium described above. The processor 310 executes various server functions and data processing by running non-volatile software programs, instructions, and modules stored in the memory 320, thereby implementing the rice irrigation area field dynamic hydrological process simulation method described in the above embodiment. The input device 330 can receive input digital or character information and generate key signal inputs related to user settings and function control of the rice irrigation area field dynamic hydrological process simulation system. The output device 340 may include a display screen or other display device.

[0087] The aforementioned electronic device can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in the embodiments of the present invention.

[0088] In one implementation, the above-mentioned electronic device is applied to a field dynamic hydrological process simulation system for rice irrigation areas, serving as a client, and includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to: Obtain digital elevation models, land use maps, soil type maps, daily meteorological data, and spatial distribution data of irrigation canal systems for the study area; Based on the land use map, the digital elevation model, and the spatial distribution data of the irrigation canal system, a spatial association information database of paddy fields and ditches is constructed. The spatial association information database includes at least the spatial location information, ground elevation information, field type information of each paddy field, and the bottom elevation information and effective contact length information of the ditches adjacent to each paddy field. The simulation cycle is carried out with a daily time step. On each simulation day, the effective field ridge height is dynamically adjusted according to the key growth stage of the rice. Based on the current field type and field water depth, the bottom elevation information and effective contact length information of the adjacent ditches corresponding to the current rice field are called from the spatial association information database to calculate the lateral supply or lateral discharge and update the field water depth. Based on the current field water depth of the paddy field, the number of consecutive flooding days is recorded. The saturated hydraulic conductivity of the plow pan is nonlinearly attenuated and corrected based on the number of consecutive flooding days. The vertical infiltration is calculated and then deducted from the field water depth. Substitute the overflow discharge, lateral discharge, and vertical infiltration into the preset water balance equation to update the field water depth for the day; After completing the daily updates of all paddy fields, a confluence topology network is constructed based on the spatial location information and ground elevation information of each paddy field in the spatial association information database. The overflow and lateral discharge of each paddy field are then transferred step by step along the confluence direction to obtain the total runoff of the sub-basin outlet section, and the simulation results are output.

[0089] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or some parts of embodiments.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for simulating a dynamic hydrological process in a field of a rice irrigation district, characterized by, include: Obtain digital elevation models, land use maps, soil type maps, daily meteorological data, and spatial distribution data of irrigation canal systems for the study area; Based on the land use map, the digital elevation model, and the spatial distribution data of the irrigation canal system, a spatial association information database of paddy fields and ditches is constructed. The spatial association information database includes at least the spatial location information, ground elevation information, field type information of each paddy field, and the bottom elevation information and effective contact length information of the ditches adjacent to each paddy field. The simulation cycle is carried out with a daily time step. On each simulation day, the effective field ridge height is dynamically adjusted according to the key growth stage of the rice. Based on the current field type and field water depth, the bottom elevation information and effective contact length information of the adjacent ditches corresponding to the current rice field are called from the spatial association information database to calculate the lateral supply or lateral discharge and update the field water depth. Based on the current field water depth of the paddy field, the number of consecutive flooding days is recorded. The saturated hydraulic conductivity of the plow pan is nonlinearly attenuated and corrected based on the number of consecutive flooding days. The vertical infiltration is calculated and then subtracted from the current field water depth of the paddy field after lateral interaction to obtain the intermediate water depth after deducting the vertical infiltration. The overflow discharge volume is determined based on the effective field ridge height and the intermediate water depth after deducting vertical infiltration. The overflow discharge volume, lateral discharge volume and vertical infiltration volume are substituted into the preset water balance equation to calculate the field water depth on that day. After completing the daily calculations for all paddy fields, a confluence topology network is constructed based on the spatial location information and ground elevation information of each paddy field in the spatial association information database. The overflow and lateral discharge of each paddy field are then transferred step by step along the confluence direction to obtain the total runoff at the outlet section of the sub-basin, and the simulation results are output.

2. The method according to claim 1, wherein, The construction of a spatial association information database between paddy fields and ditches based on the land use map, the digital elevation model, and the spatial distribution data of the irrigation canal system includes: Based on the land use map, the spatial location and geometric boundaries of each paddy field are identified; based on the digital elevation model, the ground elevation of each paddy field is extracted; and based on the spatial distribution data of the irrigation canal system, the spatial location and bottom elevation of each ditch are extracted. Using the spatial overlay analysis method, the geometric boundaries of each paddy field and the geometric boundaries of each ditch are matched for proximity. Ditches that overlap with the geometric boundaries of each paddy field or have a distance less than a preset distance threshold are identified, and the topological association between each paddy field and its adjacent ditch is established. Calculate the length of the overlapping boundary between a certain paddy field and its adjacent ditch, and use it as the effective contact length between the certain paddy field and its adjacent ditch; Based on the difference between the ground elevation of a certain paddy field and the bottom elevation of the adjacent ditch of the certain paddy field, the certain paddy field is divided into ditch-replenished field and ditch-drained field, and the field type is recorded. The spatial coordinates, ground elevation, field type, bottom elevation of adjacent ditches, and effective contact length of each paddy field are associated and stored to form the spatial association information database.

3. The method according to claim 1, wherein, The simulation cycle, which uses days as the time step, dynamically adjusts the effective field ridge height according to the key growth stage of the rice on each simulation day, including: Obtain the key growth stages of rice corresponding to the current simulated day, including the flooding period, the drying period, and the re-watering period; If the current is in the flooding period, the effective ridge height is the minimum value of the physical height of the ridge and the upper limit of the target flooding depth, expressed as: wherein is the effective ridge height, is the physical height of the ridge, is the upper limit of the target flooding depth; If the field is currently in the drying season, the effective field ridge height is taken as the target drainage depth, expressed as: , The target drainage depth; If the current period is the re-irrigation phase, the difference between the previous day's field water depth and the lower limit of the target irrigation depth is obtained. The effective field ridge height is then linearly adjusted based on this difference, expressed as: ， In the formula, The water level in the fields was high the day before. The target is the lower limit of the irrigation depth. The preset rehydration rate coefficient is used to control the speed at which the height of the field ridges recovers.

4. The method for simulating dynamic hydrological processes in rice irrigation areas according to claim 1, characterized in that, The step of calculating lateral recharge or lateral discharge and updating the field water depth based on the current paddy field type and water depth status, by calling the bottom elevation information and effective contact length information of the adjacent ditches corresponding to the current paddy field from the spatial association information database, includes: Obtain the current paddy field type, bottom elevation of adjacent ditches, and effective contact length from the spatial association information database; If the field type is a ditch-replenished field, then determine whether the water depth in the field on the previous day was lower than the preset replenishment start threshold. If the water level is below the preset replenishment threshold, the previous day's field water depth and adjacent ditch water level are obtained. The lateral replenishment amount is calculated based on the potential energy difference between the field surface water level and the ditch water level, the field ridge permeability coefficient, the effective contact length, and the preset effective path length, and then added to the previous day's field water depth. Otherwise, no lateral replenishment is performed. The formula for calculating the potential energy difference between the field surface water level and the ditch water level is: ， In the formula, Due to potential energy difference, This represents the current water level in the paddy field. To obtain the current ground elevation of the paddy field from the spatial association information database, The water level of the ditches adjacent to the current paddy fields, The bottom elevation of the ditch adjacent to the current paddy field is obtained from the spatial association information database; If the field type is a ditch drainage field, then determine whether the water depth in the field exceeded the effective field embankment height the previous day: If the water level exceeds the effective field ridge height, the previous day's field water depth and adjacent ditch water level are obtained. The lateral discharge volume is calculated based on the potential energy difference between the previous day's field water depth and ditch water level, the field ridge permeability coefficient, the effective contact length, and the preset effective path length. The lateral discharge volume is then deducted from the previous day's field water depth. Otherwise, no lateral discharge is performed.

5. The method for simulating dynamic hydrological processes in rice irrigation areas according to claim 1, characterized in that, The nonlinear attenuation correction of the saturated hydraulic conductivity of the plow pan based on the number of consecutive flooded days, and the calculation of vertical infiltration, are then performed. This vertical infiltration is subtracted from the current paddy field water depth after lateral interaction to obtain the intermediate water depth after deducting vertical infiltration, which includes: Get the current field water depth of the paddy field after lateral interaction. If the current field water depth of the paddy field is greater than zero, the number of consecutive flood days will be increased by 1; if the current field water depth of the paddy field is equal to zero, the number of consecutive flood days will be reset to zero. The exponential decay model is used to perform nonlinear decay correction on the saturated hydraulic conductivity of the plow pan, and the expression is as follows: ， In the formula, The corrected saturated hydraulic conductivity of the plow pan. The initial saturated hydraulic conductivity of the plow pan. The attenuation coefficient, pre-calibrated based on the clay and organic matter content of the plow pan soil, is used to characterize the rate at which the soil's water-conducting capacity decreases due to the soil's air-tightening effect caused by long-term flooding. This refers to the number of consecutive days of flooding. Calculate vertical infiltration based on the corrected saturated hydraulic conductivity of the plow pan; The calculated vertical infiltration amount is deducted from the current paddy field water depth after lateral interaction and added to the lower soil water or groundwater storage.

6. The method for simulating dynamic hydrological processes in rice irrigation areas according to claim 1, characterized in that, The step of substituting the overflow discharge, lateral discharge, and vertical infiltration into a preset water balance equation to calculate the field water depth for the day includes: Obtain the daily rainfall, daily irrigation amount, daily actual evapotranspiration, and the previous day's field water depth; The overflow drainage volume is determined based on the effective field ridge height: if the intermediate water depth after deducting vertical infiltration is greater than the effective field ridge height, then the overflow drainage volume is the intermediate water depth after deducting vertical infiltration minus the effective field ridge height; otherwise, the overflow drainage volume is zero. Substituting the overflow discharge, lateral discharge, and vertical infiltration into the water balance equation, the field water depth for the day is calculated. The water balance equation is as follows: ， In the formula, The water depth in the field on day t. The water depth in the field on day t-1. Let be the rainfall on day t. Let be the irrigation amount on day t. Let t be the lateral supply amount. This represents the actual evaporation on day t. Let t be the overflow discharge volume on day t. Let be the vertical infiltration amount on day t. This represents the lateral discharge volume on day t. The calculated field water depth for the current day will be used as the initial field water depth for the next simulation day.

7. The method for simulating dynamic hydrological processes in rice irrigation areas according to claim 1, characterized in that, The process involves constructing a runoff topology network based on the spatial location and ground elevation information of each paddy field in the spatial association information database. The overflow and lateral discharge volumes of each paddy field are then progressively transferred along the runoff direction to obtain the total runoff at the sub-basin outlet section. The simulation results output include: The spatial coordinates and ground elevation of each paddy field are obtained from the spatial association information database; Taking each paddy field as the center, determine the adjacent paddy fields within a preset range based on its spatial coordinates, calculate the ground elevation difference between the paddy field and each adjacent paddy field, select the adjacent paddy field with the largest elevation difference as the confluence direction, and if there are multiple adjacent paddy fields with the same maximum elevation difference, select the one closest to it. A directed graph-structured confluence topology network is established with each paddy field as a confluence node and the paddy field to which the confluence direction points as a downstream node; paddy fields whose confluence direction points to the sub-basin boundary or river channel are marked as sub-basin outlet nodes. The overflow and lateral discharge of each paddy field are used as the initial outflow. The outflow is accumulated from upstream to downstream according to the aforementioned confluence topology network. The outflow of each paddy field is equal to its own outflow plus the sum of the flows transferred to it from all upstream paddy fields. During the flow transmission process, the flow time delay is calculated based on the flow path length and the field surface roughness. The calculation formula is as follows: ， In the formula, Due to the confluence time delay, The length of the confluence path from the upstream paddy field to the downstream paddy field. As the base bus speed, The roughness coefficient is the factor that influences roughness. This is the Manning roughness coefficient; Based on the confluence time delay, the outflows from different paddy fields are staggered and superimposed on the time axis, that is, the outflow calculated on the current simulation day is allocated to subsequent simulation days according to the delay time. The total runoff at the outlet sections of all sub-basins is obtained by summing the flows at all outlet nodes, and the simulation results are output in time series form.

8. A field dynamic hydrological process simulation system for rice irrigation areas, characterized in that, include: The acquisition module is configured to acquire digital elevation models, land use maps, soil type maps, daily meteorological data, and spatial distribution data of irrigation canal systems for the study area. The construction module is configured to construct a spatial association information database of paddy fields and ditches based on the land use map, the digital elevation model and the spatial distribution data of the irrigation canal system. The spatial association information database includes at least the spatial location information, ground elevation information, field type information of each paddy field, and the bottom elevation information and effective contact length information of the ditches adjacent to each paddy field. The calculation module is configured to perform a simulation cycle with a daily time step. On each simulation day, the effective field ridge height is dynamically adjusted according to the key growth stage of the rice. Based on the current field type and field water depth, the module calls the bottom elevation information and effective contact length information of the adjacent ditches corresponding to the current rice field from the spatial association information database to calculate the lateral supply or lateral discharge and update the field water depth. The correction module is configured to record the number of consecutive flooding days based on the current paddy field water depth, perform nonlinear attenuation correction on the saturated hydraulic conductivity of the plow pan based on the number of consecutive flooding days, calculate the vertical infiltration amount, and deduct the vertical infiltration amount from the current paddy field water depth after lateral interaction to obtain the intermediate water depth after deducting the vertical infiltration. The update module is configured to determine the overflow drainage volume based on the effective field ridge height and the intermediate water depth after deducting vertical infiltration. The overflow drainage volume, lateral discharge volume and vertical infiltration volume are substituted into the preset water balance equation to calculate the field water depth for the day. The output module is configured to construct a confluence topology network based on the spatial location information and ground elevation information of each paddy field in the spatial association information database after completing the daily calculation of all paddy fields. The overflow and lateral discharge of each paddy field are then passed down step by step along the confluence direction to obtain the total runoff of the sub-basin outlet section and output the simulation results.

9. An electronic device, characterized in that, include: At least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method according to any one of claims 1 to 7.

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