Evaluation method for performance of irrigation and drainage integrated system in field

Abstract

This invention discloses a method for evaluating the drought and flood control performance of an integrated field irrigation and drainage system, relating to the fields of farmland water conservancy engineering, intelligent agricultural equipment, and agricultural information technology. The invention includes determining the original stress direction of a target drought or flood event based on the deviation of the initial field moisture state from the suitable moisture range of the crop root zone and the field waterlogging state; controlling the integrated field irrigation and drainage system to execute irrigation or drainage operations; acquiring field moisture state data and irrigation / drainage action data during irrigation and drainage operations; and forming an actual moisture state trajectory. This invention constructs a drought and flood physiological equivalent damage mapping, uniformly converting drought damage and waterlogging damage under different stress intensities, durations, and crop growth stages into physiological equivalent damage values. Combined with a non-controlled reference moisture state trajectory and normalized evaluation, it achieves a unified evaluation of irrigation and drainage control performance under different drought and flood events, plot conditions, and operation batches.

Description

Technical Field

[0001] This invention belongs to the fields of farmland water conservancy engineering, agricultural intelligent equipment and agricultural information technology, and in particular relates to a method for evaluating the drought and flood control performance of an integrated field irrigation and drainage system. Background Technology

[0002] Current farmland drought and flood control technologies primarily utilize soil moisture sensors, field water level gauges, meteorological monitoring equipment, and UAV multispectral and thermal infrared payloads to collect farmland moisture information. Monitoring data typically includes soil moisture content, water depth, waterlogging duration, canopy temperature, and vegetation index. Control systems set irrigation and drainage thresholds based on the planted crop, growth stage, and soil type. Once the monitored values ​​reach the corresponding thresholds, pumps, valves, or irrigation / drainage pipelines execute irrigation or drainage operations. Some evaluation methods also record irrigation / drainage flow rates, operation time, soil moisture changes, waterlogging receding time, crop physiological state, and yield changes, using this data to evaluate the water control effectiveness and operational status of the irrigation and drainage equipment.

[0003] The core flaw in existing technologies lies in the fact that the stress intensity, duration, and stage of different drought and flood events are not consistent. Existing evaluation methods do not uniformly quantify the drought and flood events themselves, nor do they normalize the evaluation data. The evaluation results are mixed with the influence of disaster intensity, site conditions, and crop growth stage, making it difficult to reflect the actual regulatory performance of the integrated irrigation and drainage system independently. Furthermore, results obtained from different sites, different drought and flood processes, and different operational batches lack a unified basis for comparison. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for evaluating the drought and flood control performance of integrated field irrigation and drainage systems. The technical problem this invention aims to solve is: how to address the lack of a unified comparative basis for irrigation and drainage control performance under different drought and flood events and plot conditions by using drought and flood physiological equivalent damage mapping, control-free reference trajectories, and normalized damage evaluation.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for evaluating the drought and flood control performance of an integrated field irrigation and drainage system, comprising: S1. Obtain the crop growth stage, suitable water range in the crop root zone, initial field water status and external water boundary data of the target drought and flood event for the field to be evaluated. The field water status includes root zone soil water status and field surface water status. S2. Based on drought and waterlogging calibration samples corresponding to different crop growth stages, drought and waterlogging damage anchor points are determined with the same yield loss rate. Normal physiological state is set as the damage benchmark, and drought physiological damage and waterlogging physiological damage are set in the opposite direction of the damage benchmark. A mapping relationship is established between the degree of water deviation, the duration of continuous deviation, the crop growth stage and the physiological equivalent damage value. S3. Based on the degree of deviation of the initial field moisture state from the suitable moisture range of the crop root zone and the water status of the field, determine the original stress direction of the target drought and flood event, control the field irrigation and drainage integrated system to perform irrigation or drainage operation, obtain field moisture state data and irrigation and drainage action data during irrigation and drainage operations, and form the actual moisture state trajectory. S4. Based on the field water balance relationship, obtain the predicted value of field water state according to the initial field water state, external water boundary data, and irrigation and drainage action data; form a water residual sequence according to the deviation between the measured value and the predicted value of field water state, remove the residual component related to the irrigation and drainage action, and obtain the common mode water residual; take the initial field water state as a common initial condition, keep the external water boundary data unchanged, set the irrigation and drainage action to zero, use the common mode water residual to correct the reference water state, and generate an uncontrolled reference water state trajectory paired with the actual water state trajectory. S5. Based on the mapping relationship, the actual water state trajectory and the uncontrolled reference water state trajectory are converted into the actual physiological equivalent damage trajectory and the reference physiological equivalent damage trajectory, respectively. Within the same evaluation time window, the reference cumulative damage amount of the reference physiological equivalent damage trajectory in the original stress direction, the actual residual damage amount of the actual physiological equivalent damage trajectory in the original stress direction, and the reverse control damage amount formed after the actual physiological equivalent damage trajectory crosses the damage benchmark are determined. The actual residual damage amount and the reverse control damage amount are subtracted from the reference cumulative damage amount to obtain the net damage reduction amount. The ratio of the net damage reduction amount to the reference cumulative damage amount is determined as the drought and flood control performance evaluation value of the field irrigation and drainage integrated system.

[0006] The present invention is further configured such that the suitable moisture range of the crop root zone is determined based on the soil field holding capacity, soil wilting moisture content, soil saturated moisture content and crop growth stage of the field to be evaluated, wherein the lower limit of the suitable moisture range of the crop root zone is higher than the soil wilting moisture content and the upper limit of the suitable moisture range of the crop root zone is lower than the soil saturated moisture content.

[0007] The present invention is further configured such that the drought calibration sample includes the degree of water deviation, the duration of continuous deviation, the rate of decline in leaf water potential, the rate of decline in photosynthetic rate, and the yield loss rate; the waterlogging calibration sample includes the degree of water deviation, the field water depth, the duration of continuous deviation, the rate of decline in root vitality, the increase in root malondialdehyde content, the increase in root ethanol content, and the yield loss rate; each physiological indicator is dimensionless relative to the normal physiological state, and the normalized result of the absolute value of the Pearson correlation coefficient between each dimensionless indicator and the yield loss rate is used as the weight to determine the comprehensive physiological damage value of drought and the comprehensive physiological damage value of waterlogging.

[0008] The present invention is further configured such that the drought-related damage anchor points and the waterlogging-related damage anchor points are set in pairs according to at least three successively increasing yield loss rate levels. The drought-related samples and waterlogging-related samples with the same yield loss rate are assigned physiologically equivalent damage values ​​with the same absolute value but opposite directions. Piecewise interpolation is performed between adjacent equal-damage anchor points according to the drought-related comprehensive physiological damage value and the waterlogging-related comprehensive physiological damage value, respectively. The degree of water deviation, the duration of continuous deviation, and the crop growth stage corresponding to each calibrated sample are used as mapping inputs, and the interpolated physiologically equivalent damage value is used as the mapping output. Piecewise drought-related and waterlogging-related segmentwise mappings are established respectively, under the same crop growth stage, where the absolute value of the physiologically equivalent damage value increases monotonically with the increase of the degree of water deviation and the duration of continuous deviation.

[0009] The present invention is further configured such that the integrated field irrigation and drainage system includes a mobile sprinkler irrigation device, a drainage pump, an irrigation waterway, a drainage waterway, an intelligent switching valve group, and a control unit; the irrigation and drainage action data includes irrigation inflow and drainage outflow; the control unit controls the intelligent switching valve group to connect to the irrigation waterway when the original stress direction is drought direction, and controls the intelligent switching valve group to connect to the drainage waterway when the original stress direction is waterlogging direction.

[0010] The present invention is further configured such that the common mode water residual includes the root zone common mode water residual and the field surface common mode water residual; based on the root zone response time difference between the change in irrigation and drainage action and the change in root zone soil moisture state, and the field surface response time difference between the change in irrigation and drainage action and the change in field surface water state, the irrigation and drainage action data are time-shifted respectively; using the time-shifted irrigation and drainage action data as independent variables and the corresponding water residual sequence as dependent variables, regression fitting is performed, and the regression fitting component is subtracted from the water residual sequence to obtain the root zone common mode water residual and the field surface common mode water residual.

[0011] The present invention is further configured such that the normal damage interval used in the evaluation time window is determined according to the range of physiologically equivalent damage values ​​of normal calibration samples under the corresponding crop growth stage; the evaluation time window starts at the start time of irrigation and drainage operation and ends at the moment when the actual physiologically equivalent damage trajectory enters the normal damage interval and is continuously maintained for at least two sampling periods; if the normal damage interval is not entered within the longest evaluation time, the end time is the moment when the longest evaluation time expires, and the longest evaluation time is determined according to the maximum recovery time of the calibration samples under the corresponding crop growth stage; the reference cumulative damage amount and the actual residual damage amount are accumulated according to the product of the absolute value of the physiologically equivalent damage value of the corresponding trajectory in the original stress direction and the sampling time; when the actual physiologically equivalent damage trajectory crosses the damage benchmark and is continuously maintained for at least two sampling periods in the opposite direction, the reverse regulation damage amount starts to accumulate from the moment it crosses the damage benchmark.

[0012] The present invention is further configured such that, after the field irrigation and drainage integrated system stops operating under either irrigation or drainage conditions, it continues to acquire the root zone soil moisture status until the absolute value of the rate of change of the root zone soil moisture status does not exceed a stable threshold for at least two consecutive sampling periods. The stable threshold is determined based on the maximum value of the absolute value of the rate of change of the root zone soil moisture status within at least three consecutive sampling periods before the start of irrigation and drainage operations. When the reverse regulation damage is greater than zero, under irrigation conditions, the difference between the stable value of the root zone soil moisture status after irrigation stops and the corresponding value at the stop time is determined as the residual irrigation effect, and the irrigation stop threshold for the next regulation cycle is lowered to determine the residual irrigation effect. Under drainage conditions, the difference between the corresponding value at the drainage stop time and the stable value of the root zone soil moisture status is determined as the residual drainage effect, and the drainage stop threshold for the next regulation cycle is raised to determine the residual drainage effect.

[0013] The beneficial effects of this invention are as follows: By constructing a physiologically equivalent damage mapping for drought and waterlogging, this invention uniformly converts drought damage and waterlogging damage under different stress intensities, durations, and crop growth stages into physiologically equivalent damage values. Combined with the uncontrolled reference water state trajectory and normalized evaluation, it achieves a unified evaluation of irrigation and drainage regulation performance under different drought and waterlogging events, plot conditions, and operation batches.

[0014] This invention uses common-mode water quantity residual correction to refer to water state, and comprehensively refers to cumulative damage, actual residual damage and reverse regulation damage to determine the degree of net damage reduction. This reduces the interference of external water boundary and excessive irrigation and drainage on the evaluation results, and improves the accuracy and comparability of the regulation performance evaluation results. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0016] Fig. 1 This is the main flowchart of the overall evaluation method of the present invention.

[0017] Fig. 2 This is a schematic diagram of the moisture trajectory conversion and damage evaluation logic of the present invention.

[0018] Fig. 3 This is a flowchart illustrating the system structure and control feedback of the present invention. Detailed Implementation

[0019] The technical solutions of the present invention will be described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Example 1 Please see Figs. 1-3 This invention provides a method for evaluating the drought and flood control performance of an integrated field irrigation and drainage system, comprising: S1. Obtain data on the crop growth stage, suitable water range for the crop root zone, initial field water status, and external water boundary for the target drought / flood event in the field to be evaluated. Field water status includes root zone soil moisture status and surface water status. The suitable water range for the crop root zone is determined based on the soil field holding capacity, soil wilting water content, soil saturated water content, and crop growth stage of the field to be evaluated. The lower limit of the suitable water range for the crop root zone is higher than the soil wilting water content, and the upper limit of the suitable water range for the crop root zone is lower than the soil saturated water content.

[0021] S2. Based on drought-calibrated and waterlogging-calibrated samples corresponding to different crop growth stages, drought- and waterlogging-equivalent damage anchor points are determined with the same yield loss rate. Normal physiological state is set as the damage benchmark, and drought- and waterlogging-related physiological damage are set in opposite directions to the benchmark. A mapping relationship is established between the degree of water deviation, duration of continuous deviation, crop growth stage, and physiologically equivalent damage value. The drought-calibrated samples include the degree of water deviation, duration of continuous deviation, leaf water potential decline rate, photosynthetic rate decline rate, and yield loss rate. The waterlogging-calibrated samples include the degree of water deviation, field water depth, duration of continuous deviation, root activity decline rate, increase in root malondialdehyde content, increase in root ethanol content, and yield loss rate. Each physiological indicator is dimensionless relative to the normal physiological state, and the normalized result of the absolute value of the Pearson correlation coefficient between each dimensionless indicator and the yield loss rate is used as the weight to determine the comprehensive physiological damage value for drought and waterlogging, respectively. Drought-induced damage anchor points and waterlogging-induced damage anchor points are paired according to at least three progressively increasing yield loss rate levels. Samples corresponding to drought and waterlogging with the same yield loss rate are assigned physiologically equivalent damage values ​​with the same absolute value but opposite directions. Segmented interpolation is performed between adjacent damage anchor points based on the comprehensive physiological damage values ​​for drought and waterlogging, respectively. Using the degree of water deviation, duration of continuous deviation, and crop growth stage corresponding to each calibrated sample as mapping inputs, and the interpolated physiologically equivalent damage value as the mapping output, segmented mappings are established for drought and waterlogging directions, respectively, where the absolute value of the physiologically equivalent damage value monotonically increases with the degree of water deviation and duration of continuous deviation at the same crop growth stage.

[0022] S3. Based on the deviation of the initial field moisture state from the suitable moisture range in the crop root zone and the waterlogging status in the field, determine the original stress direction of the target drought / flood event, control the integrated field irrigation and drainage system to execute irrigation or drainage operations, acquire field moisture state data and irrigation / drainage action data during irrigation and drainage operations, and form the actual moisture state trajectory. The integrated field irrigation and drainage system includes mobile sprinkler irrigation equipment, drainage pumps, irrigation water lines, drainage water lines, intelligent switching valve groups, and control units. Irrigation / drainage action data includes irrigation inflow and drainage outflow. When the original stress direction is drought, the control unit controls the intelligent switching valve group to connect to the irrigation water line; when the original stress direction is waterlogging, it controls the intelligent switching valve group to connect to the drainage water line.

[0023] S4. Based on the field water balance relationship, predicted values ​​of field water state are obtained according to the initial field water state, external water boundary data, and irrigation and drainage action data. A water residual sequence is formed based on the deviation between the measured and predicted values ​​of field water state. The residual components related to irrigation and drainage action are removed to obtain the common-mode water residual. Using the initial field water state as a common initial condition, keeping the external water boundary data unchanged, and setting the irrigation and drainage action to zero, the reference water state is corrected using the common-mode water residual, generating an uncontrolled reference water state trajectory paired with the actual water state trajectory. The common-mode water residual includes the root zone common-mode water residual and the field surface common-mode water residual. Based on the root zone response time difference between changes in irrigation and drainage action and changes in root zone soil water state, and the field surface response time difference between changes in irrigation and drainage action and changes in field surface water state, the irrigation and drainage action data are time-shifted respectively. Using the time-shifted irrigation and drainage action data as independent variables and the corresponding water volume residual sequence as dependent variables, regression fitting was performed. The regression fitting components were subtracted from the water volume residual sequence to obtain the root zone common mode water volume residual and the field surface common mode water volume residual.

[0024] S5. Based on the mapping relationship, the actual water state trajectory and the uncontrolled reference water state trajectory are converted into the actual physiological equivalent damage trajectory and the reference physiological equivalent damage trajectory, respectively. Within the same evaluation window, the reference cumulative damage amount of the reference physiological equivalent damage trajectory in the original stress direction, the actual residual damage amount of the actual physiological equivalent damage trajectory in the original stress direction, and the reverse regulation damage amount formed after the actual physiological equivalent damage trajectory crosses the damage benchmark are determined. The actual residual damage amount and the reverse regulation damage amount are subtracted from the reference cumulative damage amount to obtain the net damage reduction amount. The ratio of the net damage reduction amount to the reference cumulative damage amount is determined as the drought and flood regulation performance evaluation value of the field irrigation and drainage integrated system. The normal damage interval used in the evaluation window is determined according to the range of physiological equivalent damage values ​​of the normal calibration samples under the corresponding crop growth stage. The evaluation window starts at the start time of irrigation and drainage operation and ends at the time when the actual physiological equivalent damage trajectory enters the normal damage interval and remains there for at least two sampling periods. If the normal damage range is not reached within the longest evaluation period, the end of the longest evaluation period is taken as the endpoint. The longest evaluation period is determined based on the maximum recovery time of the calibrated samples at the corresponding crop growth stage. The cumulative damage and actual residual damage are accumulated by multiplying the absolute value of the physiologically equivalent damage value of the corresponding trajectory in the original stress direction by the sampling duration. When the actual physiologically equivalent damage trajectory crosses the damage benchmark and remains continuously in the opposite direction for at least two sampling periods, the reverse regulation damage begins to accumulate from the moment it crosses the damage benchmark. The field irrigation and drainage integrated system continues to acquire root zone soil moisture status after irrigation or drainage operations cease until the absolute value of the rate of change of root zone soil moisture status does not exceed a stability threshold for at least two consecutive sampling periods. The stability threshold is determined based on the maximum absolute value of the rate of change of root zone soil moisture status within at least three consecutive sampling periods before the start of irrigation and drainage operations. When the reverse regulation damage is greater than zero, under irrigation conditions, the difference between the stable value of root zone soil moisture status after irrigation cessation and the corresponding value at the cessation time is determined as the irrigation residual effect, and the irrigation cessation threshold for the next regulation cycle is lowered to reduce the irrigation residual effect. Under drainage conditions, the difference between the value corresponding to the drainage cessation time and the stable value of soil moisture state in the root zone is determined as the drainage residual effect, and the drainage cessation threshold for the next regulation cycle is adjusted upwards to increase the drainage residual effect.

[0025] By adopting damage scales such as drought and flood corresponding to yield loss rates, and combining the pairing comparison of actual trajectories with uncontrolled reference trajectories, the contribution of irrigation and drainage operations and the influence of external water boundaries can be separated, so that the evaluation results under different stress intensities, durations and crop growth stages have a unified benchmark.

[0026] Including both actual residual damage and reverse regulation damage in the net damage reduction can take into account the degree of stress relief, the recovery process, and the risk of excessive irrigation and drainage. By adopting normalized evaluation and adjusting the stopping threshold according to the residual effect of irrigation and drainage, the comparability of evaluation results can be improved, and a basis can be provided for subsequent adjustment of regulation parameters.

[0027] Example 2 Please see Fig. 2 Based on Example 1, this example is used to verify the feasibility of using the evaluation method to uniformly quantify irrigation regulation performance under drought events.

[0028] 1. Field Data Acquisition A 0.8-hectare summer maize field was selected, with the crop at the jointing stage. Soil field capacity, wilting water content, and saturated water content were 30.0%, 12.0%, and 43.0%, respectively. The effective root zone depth was 0.30 meters, and the suitable root zone moisture range was 21.0% to 28.0%. Sampling was performed every 15 minutes. At the start of irrigation, the root zone moisture content was 16.5%, with no standing water on the field surface, and had remained below the suitable range for 30 hours. No rain fell during the evaluation period, with a cumulative evapotranspiration of 5.6 mm.

[0029] 2. Establishment of physiological equivalent damage mapping Calibrated samples of the same variety and growth stage were used, including 6 groups of normal samples and 27 groups each of drought and waterlogging samples. The weights for the decline rate of leaf water potential and the decline rate of photosynthetic rate were 0.483 and 0.517, respectively, while the weights for the decline rate of root activity, the increase in root malondialdehyde content, and the increase in root ethanol content were 0.345, 0.322, and 0.333, respectively. When the yield loss rate was 5%, 10%, and 20%, the anchor points for drought-related damage were -0.25, -0.50, and -1.00, respectively, and the anchor points for waterlogging-related damage were 0.25, 0.50, and 1.00, respectively. The normal damage range was -0.05 to 0.05.

[0030] Based on the calibrated samples, bilinear piecewise interpolation is performed between adjacent nodes formed by the degree of moisture deviation and the duration of continuous deviation.

[0031] The degree of water deviation in the drought direction was determined as the ratio of the difference between the lower limit of the suitable water range and the root zone water content to the difference between the lower limit of the suitable water range and the wilting water content. The water deviation at startup was 0.50, and after 30 consecutive hours of deviation, the initial damage value was -0.63.

[0032] 3. Formation of actual moisture state trajectory The sprinkler irrigation system operated for 2 hours, with an irrigation volume of 24 mm. The root zone water content after 0, 2, 4, 6, 8, 10, and 12 hours was 16.5%, 18.8%, 21.5%, 22.8%, 23.0%, 22.7%, and 22.3%, respectively.

[0033] 4. Generation of uncontrolled reference trajectories Field water balance was determined using a root depth of 0.30 meters and an irrigation efficiency coefficient of 0.85. Cross-correlation analysis was performed on a 15-minute time series with a response time difference of 1 hour.

[0034] A linear regression with intercept was performed using the time-shifted irrigation amount as the independent variable and the water residual as the dependent variable. After deducting the regression fitting components, the common-mode water residual ranged from 0 to 0.10 percentage points. Keeping the outer boundary unchanged and setting the irrigation amount to zero, the reference water contents were 16.5%, 16.2%, 15.9%, 15.6%, 15.3%, 15.0%, and 14.7%, respectively.

[0035] 5. Evaluation of regulation performance The actual damage values ​​were -0.63, -0.50, -0.29, -0.12, -0.04, -0.02 and -0.01, respectively, and the reference damage values ​​were -0.63, -0.67, -0.72, -0.77, -0.82, -0.87 and -0.92, respectively.

[0036] The actual damage value entered the normal damage range at the 8th hour and remained there for two consecutive sampling periods. The evaluation time window was set at 12 hours. Accumulated using the trapezoidal method, the reference accumulated damage was 9.25 equivalent damage hours, the actual residual damage was 2.58 equivalent damage hours, the reverse-adjusted damage was 0, and the performance evaluation value was 0.721.

[0037] In summary, the irrigation regulation performance evaluation value is 0.721. The actual residual damage is lower than the reference cumulative damage under no regulation conditions, and no reverse regulation damage is generated. This indicates that irrigation operations reduce drought stress damage, and the evaluation results can reflect the actual regulation contribution of the integrated irrigation and drainage system.

[0038] Example 3 Please see Fig. 3 Based on Examples 1 and 2, this example is used to verify the ability of the evaluation method to identify the reverse regulation damage and residual effect of drainage caused by excessive drainage.

[0039] 1. Field Data Acquisition The summer maize varieties, jointing period mapping, soil parameters, suitable root zone moisture range and sampling rules were used in Example 2.

[0040] A 1.0-hectare field was selected. When drainage was started, the root zone moisture content was 34.0%, the water depth in the field was 70 mm, the water accumulation lasted for 18 hours, and 6 mm of rainfall occurred in the second to third hours after the start of drainage.

[0041] 2. Mapping Invocation Invoke the segmented mapping of waterlogging direction during the jointing stage.

[0042] 3. Formation of the actual trajectory The drainage pump ran for 8 hours, draining a total of 106 millimeters of water.

[0043] 4. Reference trajectory generation The root zone response time difference is 1.5 hours, and the field surface response time difference is 0.5 hours. By keeping the external boundary unchanged and setting the drainage volume to zero, an uncontrolled reference trajectory is obtained.

[0044] 5. Performance Evaluation and Threshold Correction The actual damage values ​​at 0, 2, 4, 6, 8, 10, 12 and 14 hours were 0.77, 0.63, 0.41, 0.15, 0.02, -0.08, -0.18 and -0.32 respectively, and the reference damage values ​​were 0.77, 0.81, 0.85, 0.88, 0.91, 0.90, 0.89 and 0.87 respectively.

[0045] The damage trajectory crossed the damage benchmark at 8.4 hours. The actual damage value did not remain within the normal damage range for two consecutive sampling periods. Based on the maximum recovery time of the sample calibrated during the jointing stage, the 14th hour was determined as the evaluation endpoint.

[0046] With a cumulative damage amount of 12.12 equivalent damage hours, an actual residual damage amount of 3.17 equivalent damage hours, and a reverse-controlled damage amount of 0.82 equivalent damage hours, the performance evaluation value is 0.670.

[0047] The root zone moisture content was 24.00% when drainage stopped. Using the maximum absolute value of the root zone moisture content change rate of 0.05 percentage points per hour during the three sampling periods before drainage started as the stabilization threshold, the stable root zone moisture content was 18.66% when the root zone moisture content change rate did not exceed the stabilization threshold for two consecutive sampling periods after drainage stopped.

[0048] In summary, the drainage regulation performance evaluation value is 0.670, and the reverse regulation damage amount is 0.82 equivalent damage hours. This indicates that although the drainage operation reduced waterlogging damage, there was excessive drainage. After adjusting the stop threshold based on the residual drainage effect, it is expected that the stable water content can be maintained within the appropriate water content range in the root zone.

[0049] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating the drought and flood control performance of an integrated field irrigation and drainage system, characterized in that, include: S1. Obtain the crop growth stage, suitable water range in the crop root zone, initial field water status and external water boundary data of the target drought and flood event for the field to be evaluated. The field water status includes root zone soil water status and field surface water status. S2. Based on drought and waterlogging calibration samples corresponding to different crop growth stages, drought and waterlogging damage anchor points are determined with the same yield loss rate. Normal physiological state is set as the damage benchmark, and drought physiological damage and waterlogging physiological damage are set in the opposite direction of the damage benchmark. A mapping relationship is established between the degree of water deviation, the duration of continuous deviation, the crop growth stage and the physiological equivalent damage value. S3. Based on the degree of deviation of the initial field moisture state from the suitable moisture range of the crop root zone and the water status of the field, determine the original stress direction of the target drought and flood event, control the field irrigation and drainage integrated system to perform irrigation or drainage operation, obtain field moisture state data and irrigation and drainage action data during irrigation and drainage operations, and form the actual moisture state trajectory. S4. Based on the field water balance relationship, obtain the predicted value of field water state according to the initial field water state, external water boundary data, and irrigation and drainage action data; form a water residual sequence according to the deviation between the measured value and the predicted value of field water state, remove the residual component related to the irrigation and drainage action, and obtain the common mode water residual; take the initial field water state as a common initial condition, keep the external water boundary data unchanged, set the irrigation and drainage action to zero, use the common mode water residual to correct the reference water state, and generate an uncontrolled reference water state trajectory paired with the actual water state trajectory. S5. Based on the mapping relationship, the actual water state trajectory and the uncontrolled reference water state trajectory are converted into the actual physiological equivalent damage trajectory and the reference physiological equivalent damage trajectory, respectively. Within the same evaluation time window, the reference cumulative damage amount of the reference physiological equivalent damage trajectory in the original stress direction, the actual residual damage amount of the actual physiological equivalent damage trajectory in the original stress direction, and the reverse control damage amount formed after the actual physiological equivalent damage trajectory crosses the damage benchmark are determined. The actual residual damage amount and the reverse control damage amount are subtracted from the reference cumulative damage amount to obtain the net damage reduction amount. The ratio of the net damage reduction amount to the reference cumulative damage amount is determined as the drought and flood control performance evaluation value of the field irrigation and drainage integrated system.

2. The method for evaluating the drought and flood control performance of the integrated field irrigation and drainage system according to claim 1, characterized in that: The suitable moisture range for the crop root zone is determined based on the soil field holding capacity, soil wilting moisture content, soil saturated moisture content, and crop growth stage of the field to be evaluated. The lower limit of the suitable moisture range for the crop root zone is higher than the soil wilting moisture content, and the upper limit of the suitable moisture range for the crop root zone is lower than the soil saturated moisture content.

3. The method for evaluating the drought and flood control performance of the integrated field irrigation and drainage system according to claim 1, characterized in that: The drought calibration samples include the degree of water deviation, duration of continuous deviation, leaf water potential decline rate, photosynthetic rate decline rate, and yield loss rate. The waterlogging calibration samples include the degree of water deviation, field water depth, duration of continuous deviation, root activity decline rate, increase in root malondialdehyde content, increase in root ethanol content, and yield loss rate. Each physiological indicator is dimensionless relative to the normal physiological state, and the normalized result of the absolute value of the Pearson correlation coefficient between each dimensionless indicator and the yield loss rate is used as the weight to determine the comprehensive physiological damage value of drought and the comprehensive physiological damage value of waterlogging.

4. The method for evaluating the drought and flood control performance of the integrated field irrigation and drainage system according to claim 3, characterized in that: The drought and waterlogging damage anchor points are set in pairs according to at least three progressively increasing yield loss rate levels. The drought-corresponding samples and waterlogging-corresponding samples with the same yield loss rate are assigned physiologically equivalent damage values ​​with the same absolute value but opposite directions. Piecewise interpolation is performed between adjacent equal-damage anchor points according to the comprehensive physiological damage values ​​of drought and waterlogging, respectively. The degree of water deviation, duration of continuous deviation, and crop growth stage corresponding to each calibration sample are used as mapping inputs, and the physiological equivalent damage value obtained by interpolation is used as mapping output. Piecewise mapping in the drought direction and piecewise mapping in the waterlogging direction are established respectively, with the absolute value of the physiological equivalent damage value increasing monotonically with the increase of the degree of water deviation and duration of continuous deviation under the same crop growth stage.

5. The method for evaluating the drought and flood control performance of the integrated field irrigation and drainage system according to claim 1, characterized in that: The integrated field irrigation and drainage system includes a mobile sprinkler irrigation device, a drainage pump, an irrigation waterway, a drainage waterway, an intelligent switching valve group, and a control unit. The irrigation and drainage action data includes irrigation inflow and drainage outflow. When the original stress direction is drought, the control unit controls the intelligent switching valve group to connect to the irrigation waterway, and when the original stress direction is waterlogging, the control unit controls the intelligent switching valve group to connect to the drainage waterway.

6. The method for evaluating the drought and flood control performance of the integrated field irrigation and drainage system according to claim 1, characterized in that: The common-mode water residual includes the root zone common-mode water residual and the field surface common-mode water residual. Based on the root zone response time difference between the changes in irrigation and drainage effects and the changes in soil moisture state in the root zone, and the field surface response time difference between the changes in irrigation and drainage effects and the changes in field surface water state, the irrigation and drainage effect data are time-shifted respectively. Using the time-shifted irrigation and drainage effect data as independent variables and the corresponding water residual sequence as dependent variables, regression fitting is performed. The regression fitting component is subtracted from the water residual sequence to obtain the root zone common-mode water residual and the field surface common-mode water residual.

7. The method for evaluating the drought and flood control performance of the integrated field irrigation and drainage system according to claim 1, characterized in that: The normal damage interval used in the evaluation time window is determined based on the range of physiologically equivalent damage values ​​of normal calibrated samples under the corresponding crop growth stage; the evaluation time window starts at the start time of irrigation and drainage operations and ends at the moment when the actual physiologically equivalent damage trajectory enters the normal damage interval and remains there for at least two sampling periods. If the normal damage range is not entered within the longest evaluation period, the end of the longest evaluation period shall be taken as the endpoint. The longest evaluation period shall be determined based on the maximum recovery time of the calibrated sample at the corresponding crop growth stage. The reference cumulative damage and the actual residual damage shall be accumulated according to the product of the absolute value of the physiological equivalent damage value of the corresponding trajectory in the original stress direction and the sampling time. When the actual physiological equivalent damage trajectory crosses the damage benchmark and is continuously maintained in the opposite direction for at least two sampling periods, the reverse regulation damage shall start to accumulate from the moment it crosses the damage benchmark.

8. The method for evaluating the drought and flood control performance of the integrated field irrigation and drainage system according to claim 1, characterized in that: The integrated field irrigation and drainage system continues to acquire root zone soil moisture status after irrigation or drainage operations cease, until the absolute value of the rate of change of the root zone soil moisture status does not exceed a stable threshold for at least two consecutive sampling periods. The stable threshold is determined based on the maximum value of the absolute value of the rate of change of the root zone soil moisture status within at least three consecutive sampling periods before the start of irrigation and drainage operations. When the reverse regulation damage is greater than zero, under irrigation conditions, the difference between the stable value of the root zone soil moisture status after irrigation stops and the corresponding value at the time of cessation is determined as the residual irrigation effect, and the irrigation cessation threshold for the next regulation cycle is lowered for the residual irrigation effect. Under drainage conditions, the difference between the corresponding value at the time of drainage cessation and the stable value of the root zone soil moisture status is determined as the residual drainage effect, and the drainage cessation threshold for the next regulation cycle is raised for the residual drainage effect.

Images