A garden water-saving irrigation control system suitable for terrain layout

Abstract

This invention discloses a garden water-saving irrigation control system adapted to terrain layout, belonging to the field of garden water-saving irrigation technology. It includes a terrain division module to acquire three-dimensional terrain and divide upstream and downstream areas, determining surface runoff paths; a downstream monitoring module to monitor downstream soil matrix potential and generate a trigger signal when it falls below a suction threshold; an upstream execution module receiving the signal and irrigating at an intensity higher than the stable infiltration rate, forming surface runoff to replenish downstream areas; and a flow regulation module monitoring the downstream change rate, gradually reducing the valve opening when the change rate first exceeds the rising rate threshold, maintaining the opening when the change rate falls back, and continuing to reduce it when the change rate exceeds it again, until the downstream matrix potential recovers to the upper limit of the target range or the opening returns to zero, at which point the valve is closed. This invention achieves closed-loop control from terrain identification to runoff regulation to on-demand water replenishment, improving the accuracy of garden irrigation adaptation to natural terrain and the efficiency of water resource utilization.

Description

Technical Field

[0001] This invention belongs to the field of garden water-saving irrigation technology, and in particular relates to a garden water-saving irrigation control system adapted to the terrain layout. Background Technology

[0002] Garden irrigation systems typically employ timed and quantitative irrigation schemes or soil moisture-based trigger-based irrigation schemes. Timed and quantitative systems irrigate according to a preset schedule and water volume, failing to dynamically adjust based on actual soil moisture conditions and plant water requirements, easily leading to water waste or insufficient irrigation. While soil moisture-based trigger-based systems can initiate irrigation based on measured soil moisture content, in sloping garden settings, the redistribution of water due to terrain undulations often results in upstream irrigation water being lost via surface runoff, leaving the downstream soil still dry, creating a "waterlogged upstream, drought-stricken downstream" situation.

[0003] While existing technologies include schemes that divide sloping land into different irrigation zones and control them separately, these schemes lack consideration for hydrological connectivity between zones and still employ a localized irrigation logic of "irrigating where water is scarce," failing to utilize topographical differences to achieve cross-regional water resource allocation. Furthermore, existing irrigation systems are mostly based on fixed durations or fixed water volumes, unable to detect the actual timing of runoff arrival downstream, leading to insufficient or excessive downstream water replenishment and making precise control difficult.

[0004] Therefore, a garden water-saving irrigation control scheme is needed that can adapt to the terrain layout, utilize natural runoff paths, and adjust based on feedback from the actual downstream response. Summary of the Invention

[0005] This invention provides a garden water-saving irrigation control system adapted to the terrain layout, in order to solve the problems of existing garden irrigation systems ignoring terrain undulations and the waste of water resources or water shortage downstream caused by unified upstream and downstream control.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A garden water-saving irrigation control system adapted to terrain layout includes a terrain division module, a downstream monitoring module, an upstream execution module, and a flow regulation module.

[0007] The terrain division module is used to acquire the three-dimensional terrain of the target garden area, divide the area into an upstream water replenishment area and a downstream water demand area, and determine the surface runoff path between the two.

[0008] The downstream monitoring module is located in the downstream water demand area and is used to continuously monitor the downstream soil matrix potential. When the downstream soil matrix potential is lower than the preset downstream suction threshold, an irrigation trigger signal is generated.

[0009] The upstream execution module is located in the upstream water replenishment area and is used to open the upstream irrigation valve after receiving the irrigation trigger signal, so as to continuously irrigate at an irrigation intensity higher than the stable infiltration rate of the upstream soil.

[0010] The flow regulation module is used to monitor the rate of change of the downstream soil matrix potential during irrigation and calculate its absolute value. When the absolute value of the rate of change first exceeds a preset rate of increase threshold, the opening of the upstream irrigation valve is gradually reduced at a preset fixed step size. If the absolute value of the rate of change falls back below the rate of increase threshold during the reduction process, the current opening is maintained until the absolute value of the rate of change exceeds the rate of increase threshold again or the downstream soil matrix potential recovers to the upper limit of the preset target range. The flow regulation module is also used to close the irrigation valve when the downstream soil matrix potential recovers to the upper limit of the target range, or when the opening of the upstream irrigation valve has been reduced to zero. The step size and stabilization period are preset according to the valve response characteristics and soil water conductivity characteristics.

[0011] Preferably, the depth of the matrix potential sensor buried in the downstream monitoring module matches the depth of the active water absorption layer of the main plant roots in the downstream water-demanding area; the downstream suction threshold is set according to the matrix potential of the plant's permanent wilting point.

[0012] Preferably, the rate of increase threshold is obtained through pre-calibration: test irrigation is carried out in the upstream water replenishment area at the maximum irrigation intensity; the absolute value of the rate of change from the start of irrigation to the moment when the downstream soil matrix potential first shows a significant increase is recorded, wherein the significant increase refers to the absolute value of the rate of change of the downstream soil matrix potential exceeding the maximum absolute value of the natural rate of change of the downstream soil matrix potential during the pre-irrigation period; the absolute value of the rate of change is multiplied by a preset coefficient less than 1 as the rate of increase threshold.

[0013] Preferably, the target range is the interval formed by the lower limit and the upper limit of the downstream soil matrix potential; wherein the lower limit is the downstream suction threshold and the upper limit is the matrix potential corresponding to the field capacity.

[0014] Preferably, the terrain division module is further used to: when there are multiple water flow path branches between the upstream water replenishment area and the downstream water demand area, further divide the upstream water replenishment area into multiple sub-areas, each sub-area corresponding to a downstream water demand area; the downstream monitoring module and the flow regulation module are independently set in each downstream water demand area; the upstream execution module triggers irrigation based on the downstream water demand area with the lowest matrix potential (i.e., the most negative) among all downstream water demand areas, and independently adjusts the valve opening of the corresponding sub-area according to their respective rate of change, and the total upstream irrigation flow corresponding to the sum of the valve openings of each sub-area does not exceed the maximum water supply capacity of the upstream water supply system.

[0015] Preferably, the system further includes a rainfall response module: used to acquire the real-time rainfall intensity of the target garden area; when the real-time rainfall intensity is greater than a preset runoff generation threshold, to suppress the irrigation trigger signal and prohibit the upstream irrigation valve from opening; when the rainfall stops and the downstream soil matrix potential is still lower than the downstream suction threshold, to re-enable the irrigation trigger signal.

[0016] Preferably, the flow regulation module is further configured to: forcibly close the irrigation valve when the opening of the upstream irrigation valve has been reduced to a preset minimum maintenance opening, and the cumulative change rate of the downstream soil matrix potential has exceeded the rise rate threshold for a preset duration; generate an alarm signal to prompt for checking whether there is blockage or abnormal leakage in the surface runoff path.

[0017] Preferably, when the upstream execution module continuously irrigates at an irrigation intensity higher than the stable infiltration rate of the upstream soil, the irrigation intensity is determined based on the stable infiltration rate of the upstream soil obtained from a field double-ring infiltration test or by referring to a table of soil texture; its value is greater than the stable infiltration rate and does not exceed the maximum allowable irrigation intensity of the upstream soil; the maximum allowable irrigation intensity is determined based on a field double-ring infiltration test combined with the critical flow velocity for soil erosion resistance.

[0018] Preferably, the system further includes an upstream local water replenishment module: used to acquire the soil matrix potential of the upstream water replenishment area; when the soil matrix potential of the upstream water replenishment area is lower than a preset upstream water demand threshold, after responding to the irrigation trigger signal, the upstream water replenishment area is pre-irrigated at an irrigation intensity equal to or lower than the upstream stable soil infiltration rate, and the upstream soil matrix potential is continuously monitored; when the upstream soil matrix potential recovers to the upstream water demand threshold, the irrigation intensity is immediately increased to a level higher than the stable infiltration rate to form surface runoff and replenish the downstream water demand area; during the pre-irrigation period, the flow regulation module does not intervene temporarily, and whether the downstream soil matrix potential is lower than a preset emergency threshold is used as the only interruption condition; the emergency threshold is lower than the downstream suction threshold; if the downstream soil matrix potential is lower than the emergency threshold, the pre-irrigation is interrupted and the irrigation intensity is immediately switched to a level higher than the stable infiltration rate.

[0019] Preferably, the flow regulation module is further used to monitor the response characteristics of the downstream soil matrix potential to determine the unobstructed status of the surface runoff path: when the upstream irrigation valve is opened for more than a preset first time period, the first time period is determined by multiplying the runoff arrival time obtained by the aforementioned calibration by a preset coefficient, and the downstream soil matrix potential still does not show the change rate exceeding the rise rate threshold, it is determined that there is blockage or serious leakage in the surface runoff path, and a path abnormality alarm is generated; when the upstream irrigation valve has been closed and the downstream soil matrix potential continues to decline and falls below the downstream suction threshold again within a preset second time period, it is determined that there is excessive leakage in the surface runoff path, resulting in the upstream water failing to effectively replenish the downstream, and a path repair prompt is generated.

[0020] This invention identifies and divides garden terrain by constructing a terrain segmentation module, a downstream monitoring module, an upstream execution module, and a flow regulation module. This identifies the upstream water replenishment area, the downstream water demand area, and the surface runoff path between them. Based on the actual state of the downstream soil matrix potential, upstream irrigation is triggered, generating controllable surface runoff at an intensity higher than the stable infiltration rate. This directs excess water from the upstream to the downstream under gravity. The valve opening is then dynamically adjusted using a rate of change feedback to sense the arrival of runoff and control the replenishment amount accordingly, preventing over-irrigation. Therefore, a closed-loop control system can be achieved from terrain identification to runoff regulation to on-demand water replenishment, improving the accuracy of garden irrigation's adaptation to natural terrain and water resource utilization efficiency, reducing system energy consumption, and enabling the irrigation system to adapt to various slope terrain layouts. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system framework structure of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0023] Example 1 like Figure 1 As shown, the terrain-adaptive garden water-saving irrigation control system of this embodiment is deployed in a garden green space with a natural slope. The garden green space includes an upstream water replenishment area located above the slope and a downstream water demand area located below the slope, which are connected by a natural surface runoff path. The system includes a terrain division module, a downstream monitoring module, an upstream execution module, and a flow regulation module.

[0024] The terrain division module is used to acquire the three-dimensional terrain of the target garden area, divide the area into an upstream water replenishment area and a downstream water demand area, and determine the surface runoff path between the two.

[0025] The terrain mapping module includes an industrial control computer equipped with digital elevation model processing software and a lidar scanner mounted on a drone.

[0026] During operation, the drone flies along a preset route over the target garden area. The lidar scanner collects point cloud data of the ground surface in the area. After being processed by the digital elevation model processing software in the industrial control computer, a three-dimensional terrain raster map with a resolution of 0.5 meters by 0.5 meters is generated.

[0027] The industrial control computer extracts surface slope information from a 3D terrain raster map, dividing the upper part of a continuous slope area with a slope greater than 2% into the upstream water replenishment area and the lower part of the same continuous slope area into the downstream water demand area; the boundary between the two areas is taken as the elevation contour line at the point of maximum slope change. Simultaneously, the industrial control computer performs hydrological flow direction analysis based on a digital elevation model (using the D8 algorithm) to determine the surface runoff path from the upstream water replenishment area to the downstream water demand area. The surface runoff path is the channel through which rainwater or excess irrigation water flows naturally along the surface under gravity, and its spatial location is determined by the raster line with the maximum cumulative runoff volume calculated by the D8 algorithm.

[0028] Traditional irrigation systems divide gardens into regular rectangular or circular units, ignoring the topographical undulations that lead to water loss on uphill slopes and continued drought on downhill slopes. This solution uses a digital elevation model to automatically identify natural runoff paths, designating areas with strong infiltration capacity above the slope as water source areas and areas with concentrated vegetation below as water receiving areas. Irrigation water flows naturally along the terrain under gravity, achieving cross-regional water allocation without the need for additional pumping stations or water pipelines.

[0029] The downstream monitoring module, located in the downstream water-demand area, continuously monitors the downstream soil matrix potential. When the downstream soil matrix potential falls below a preset downstream suction threshold, it generates an irrigation trigger signal. The downstream monitoring module includes a matrix potential sensor and a data acquisition unit buried in the soil of the downstream water-demand area. The depth of the matrix potential sensor buried in the downstream monitoring module matches the depth of the active water absorption layer of the main plant roots in the downstream water-demand area.

[0030] The matrix potential sensor selected is a gypsum block resistive soil water potential sensor, which is suitable for large-scale deployment in landscaping due to its high accuracy and moderate cost within the range of -10 to -100 kPa. Its burial depth is 30 cm, which matches the active water absorption layer depth of the tall fescue root system, the main planted plant in the downstream water-requiring area. Root profile sampling showed that over 80% of the root length of tall fescue under soil conditions is concentrated in the 25-35 cm depth range; therefore, 30 cm was chosen as the sensor burial depth. The downstream suction threshold is set based on the matrix potential of the plant's permanent wilting point. The data acquisition unit continuously reads the output signal of the matrix potential sensor at a sampling cycle of 10 minutes, converting it into a soil matrix potential value (unit: kPa, negative values ​​indicate soil suction). The 10-minute sampling cycle balances the response speed to soil moisture changes and sensor power consumption; too short a cycle results in data redundancy, while too long a cycle misses critical points in runoff arrival.

[0031] When the soil matrix potential falls below the downstream suction threshold, the data acquisition unit generates an irrigation trigger signal and sends it to the upstream execution module via a wireless communication module. The downstream suction threshold is set based on the permanent wilting point matrix potential of tall fescue: Under controlled environmental conditions (temperature 25 degrees Celsius, relative humidity 60%, light intensity 400 micromoles per square meter per second), a drought stress test is conducted on potted tall fescue, and leaf water potential and soil matrix potential are measured daily. When the leaf water potential drops to -1.5 MPa and does not recover for 48 consecutive hours, the corresponding soil matrix potential is the permanent wilting point. In this embodiment, the measured permanent wilting point matrix potential is -80 kPa. Considering the strong evaporation in actual garden environments, the downstream suction threshold is set to -70 kPa, slightly higher than the permanent wilting point to allow for a safety margin.

[0032] The sensor depth is matched with the root active layer, and the monitored values ​​directly reflect the actual water absorption status of the plant. Using the permanent wilting point as the trigger threshold, the irrigation starting point is correlated with the plant's physiological limit, avoiding the problem of the traditional volumetric water content threshold having a confusing meaning in different soils: a water content of 20% is close to saturation in sandy soil, but may be drought-prone in clay soil. Meanwhile, matrix potential, as a measure of soil water energy, has a unified plant physiological significance in soils of different textures.

[0033] The upstream execution module, located in the upstream water replenishment area, is used to open the upstream irrigation valve after receiving the irrigation trigger signal, and continuously irrigate at an irrigation intensity higher than the stable infiltration rate of the upstream soil.

[0034] The upstream execution module includes an electromagnetic irrigation valve and a valve controller installed on the water supply main pipe in the upstream water replenishment area. After receiving an irrigation trigger signal from the downstream monitoring module, the valve controller sends an opening command to the electromagnetic irrigation valve, which then fully opens to provide continuous irrigation at an intensity higher than the stable infiltration rate of the upstream soil.

[0035] When the upstream execution module continuously irrigates at an irrigation intensity higher than the stable infiltration rate of the upstream soil, the irrigation intensity is determined based on the stable infiltration rate of the upstream soil obtained from the on-site double-ring infiltration test or by referring to a table of soil texture; its value is greater than the stable infiltration rate but does not exceed the maximum allowable irrigation intensity of the upstream soil; the maximum allowable irrigation intensity is determined based on the on-site double-ring infiltration test combined with the critical flow velocity for soil erosion resistance.

[0036] The method for determining the multiple factor k of irrigation intensity relative to the stable infiltration rate is as follows.

[0037] The first step is to determine the stable infiltration rate fs. A representative point is selected in the upstream water replenishment area. A standard double-ring infiltrator with an inner ring diameter of 20 cm and an outer ring diameter of 40 cm is used. Water is simultaneously injected into both the inner and outer rings, maintaining a water head of 5 cm. The rate of water level decline in the inner ring is recorded over time. When the rate of water level decline does not exceed 5% over three consecutive 10-minute periods, infiltration is considered to have reached a stable state. The infiltration rate at this point is the stable infiltration rate fs of the upstream soil. In this example, fs was measured to be 12 mm / hour.

[0038] The second step is to determine the maximum allowable irrigation intensity, fmax. This is determined based on the apparent velocity corresponding to the period of maximum water level drop in the double-ring infiltration test, combined with the critical velocity for soil erosion resistance. For loam, the critical velocity is typically taken as 0.3 m / s, or it can be determined through an undisturbed soil flume erosion test. When the apparent velocity exceeds the critical velocity, the infiltration rate corresponding to the critical velocity is taken as fmax. In this embodiment, fmax is 25 mm / h.

[0039] The third step is to determine the range of values ​​for the multiplier coefficient k. The multiplier coefficient k is defined as the ratio of the actual irrigation intensity f to the stable infiltration rate fs, i.e., k equals f divided by fs. k must satisfy the following conditions: k is greater than 1 (to ensure surface runoff formation) and k multiplied by fs does not exceed fmax (to ensure no soil erosion occurs). In this embodiment, the range of k is 1 less than k and less than or equal to 25 divided by 12, approximately equal to 2.08.

[0040] The fourth step is to select a specific value for k within the range of possible values. The selection of the k value needs to take into account the following factors.

[0041] First, there's the demand for runoff formation. The closer k is to 1, the smaller the surface runoff and the weaker the downstream replenishment capacity; the larger k is, the larger the runoff and the stronger the replenishment capacity. When the surface runoff path length between the upstream water replenishment area and the downstream water demand area exceeds 50 meters or the slope is less than 3%, a larger k value (such as 1.6 to 2.0) should be selected to compensate for path losses; when the path is short or the slope is steep, a smaller k value (such as 1.2 to 1.5) should be selected to avoid excessive downstream flow.

[0042] Second, soil texture is a factor. Sandy soils have higher infiltration rates and stronger erosion resistance, so k can be taken as 1.5 to 2.0; clay soils have lower infiltration rates but are prone to surface crusting, so k should be taken as 1.2 to 1.5 to prevent concentrated runoff erosion after crusting; for loam, k should be taken as 1.3 to 1.7. In this example, the soil is loam, the path length is about 30 meters, and the slope is about 4%. Taking all factors into account, k is selected as 1.5, so the actual irrigation intensity f is equal to 1.5 multiplied by 12, which equals 18 millimeters per hour.

[0043] Thirdly, seasonal adjustments are needed. In summer, plant transpiration is strong and the initial soil moisture content is low, so k can be taken as the upper limit; in winter, transpiration is weak, so k can be taken as the lower limit.

[0044] The method for determining the multiplier k described above allows technicians to independently select an appropriate irrigation intensity within the range of 1 to fmax divided by fs, based on site conditions, rather than relying solely on a fixed 1.5 times. For example, if a garden site has fs of 8 mm / h, fmax of 20 mm / h, a path length of 60 meters, and sandy loam soil, then k can be taken as 1.8, and the actual irrigation intensity is 14.4 mm / h.

[0045] Irrigation at an intensity higher than the stable infiltration rate upstream results in some water failing to infiltrate in time, forming surface runoff that flows downstream along the natural terrain. This is fundamentally different from the traditional approach of "irrigating where water is scarce": localized irrigation on slopes often leads to runoff uphill and drought downhill. This solution proactively utilizes the upstream area as a water source, achieving water redistribution through controllable runoff. Hydrological connectivity between upstream and downstream can be established solely through topographical differences and moderate irrigation intensity, eliminating the need for pumping stations and water pipeline networks.

[0046] The flow regulation module is used to monitor the rate of change of downstream soil matrix potential during irrigation. When the absolute value of the rate of change first exceeds the preset rate of increase threshold, the opening of the upstream irrigation valve is gradually reduced. If the absolute value of the rate of change falls back below the rate of increase threshold during the reduction process, the current opening is maintained until the absolute value of the rate of change exceeds the rate of increase threshold again or the downstream soil matrix potential recovers to the upper limit of the preset target range. The flow regulation module is also used to close the irrigation valve when the downstream soil matrix potential recovers to the upper limit of the target range or when the opening of the upstream irrigation valve has been reduced to zero.

[0047] The flow regulation module includes an electric actuator installed on the upstream irrigation valve, a data acquisition unit shared with the downstream monitoring module, and a state machine logic unit built into the valve controller.

[0048] The state machine logic unit pre-sets four mutually exclusive states and their transition conditions: State S0 (Standby): The electromagnetic irrigation valve is closed, and the data acquisition unit collects downstream soil matrix potential at 10-minute intervals. Transition condition: When the downstream soil matrix potential is lower than the downstream suction threshold, the system transitions to State S1.

[0049] State S1 (Full-speed irrigation): The electromagnetic irrigation valve is fully open, the irrigation intensity is 18 mm / hour, and the data acquisition unit simultaneously calculates the rate of change of downstream soil matrix potential. The calculation method for the rate of change is: subtract the previous sampling value from the current sampling value, then divide by the sampling interval (10 minutes, i.e., one-sixth of an hour), and take the absolute value of the difference, in kPa / h. The reason for taking the absolute value here is that the soil matrix potential is negative. When the soil dries, the negative value of the matrix potential increases (e.g., from -70 kPa to -75 kPa), and the difference quotient is negative; when the soil becomes wet, the negative value of the matrix potential decreases (e.g., from -75 kPa to -73 kPa), and the difference quotient is positive. Regardless of whether it becomes dry or wet, the absolute value of the difference quotient reflects the drastic change in soil moisture, while the rate of increase threshold is used to detect the rapid wetting of the soil caused by runoff reaching the downstream, so the absolute value is used as the comparison benchmark.

[0050] The transition conditions for state S1 are as follows: when the absolute value of the rate of change first exceeds the rate of increase threshold, the transition is to state S2; if the downstream soil matrix potential directly recovers to the upper limit of the target range (this occurs when the upstream soil moisture content is already high, the runoff arrives rapidly, and the downstream water demand is small), then the transition is to state S4.

[0051] State S2 (Decrease Adjustment State): The electric actuator gradually decreases the current opening of the electromagnetic irrigation valve in 10% increments. After each decrease, a 5-minute stabilization period is maintained. During this period, the data acquisition unit continues to collect downstream soil matrix potential data at 10-minute intervals and calculates the absolute value of the rate of change. The 5-minute stabilization period is set based on the following: the mechanical response time of the electric actuator is approximately 2 seconds, and it takes about 3 to 5 minutes for the water flow to stabilize again after the valve opening changes. The 5-minute stabilization period ensures that the collected rate of change reflects the steady-state response under the new opening, rather than the transient fluctuations during the opening switching process.

[0052] The first sampling data after the end of the stabilization period is used as the evaluation basis after this adjustment. That is, the state machine logic unit calculates the difference between the first downstream soil matrix potential sampling value collected by the data acquisition device after the end of the stabilization period and the previous sampling value and takes the absolute value as the current rate of change for priority determination. After the stabilization period ends, the state machine logic unit performs the following priority determinations (in descending order of priority): First priority: If the downstream soil matrix potential has recovered to the upper limit of the target range, proceed to state S4; Second priority: If the current valve opening has decreased to 0%, proceed to state S4; Third priority: If the current valve opening has been reduced to the minimum maintenance opening (5% in this embodiment), and the absolute value of the rate of change still exceeds the rising rate threshold, then the cumulative timer is started; when the cumulative duration exceeding the rising rate threshold reaches the preset duration (30 minutes in this embodiment), the system transitions to state S4 and generates an alarm signal, prompting the system to check whether there is blockage or abnormal leakage in the surface runoff path; if the cumulative duration does not reach the preset duration, the current minimum maintenance opening is maintained, and the rate of change is reassessed every 5 minutes until the exit condition is met; The cumulative timer is reset in the following situations: 1) the absolute value of the rate of change falls below the rising rate threshold, indicating that supply and demand have reached equilibrium at the current opening level, and there is no need to continue accumulating; 2) the system resets after entering state S4; 3) the system returns to standby state S0. If the entry condition of the third priority is met again after resetting, the accumulating starts again from zero. Fourth priority: If the absolute value of the rate of change still exceeds the rate of increase threshold, and the current valve opening is greater than the minimum maintenance opening, it indicates that the upstream water is still excessive at the current opening. Continue to execute a one-step reduction (step size 10%), maintain a 5-minute stabilization period, and then execute the priority determination again. Fifth priority: If the absolute value of the rate of change has fallen below the rate of increase threshold, it indicates that the supply and consumption at the current opening degree are approaching balance, and the state transitions to S3.

[0053] State S3 (Maintenance State): Maintaining the current valve opening, the data acquisition unit continues to monitor the downstream soil matrix potential at 10-minute intervals and calculates the absolute value of the rate of change. Transfer conditions are as follows: If the absolute value of the rate of change exceeds the rate of increase threshold again, it indicates that the downstream soil moisture consumption is accelerating or the upstream water inflow is increasing, and the state S2 continues to reduce the opening. If the downstream soil matrix potential recovers to the upper limit of the target range, the process transitions to state S4. If the duration of the current maintenance state reaches the preset maximum maintenance duration (set to 2 hours in this embodiment, which is estimated based on one-tenth of the typical time it takes for the downstream soil to naturally deplete from the field water holding capacity to the suction threshold after water replenishment is stopped), and the current valve opening is greater than the minimum maintenance opening, then the process will switch to state S2 to perform a step reduction to prevent the maintenance state from being too long due to sensor drift. If the current maintenance state lasts for the maximum duration and the current valve opening is equal to the minimum maintenance opening, then the system will directly switch to state S4 and generate an alarm signal to prompt the system to check for blockages or abnormal leaks in the surface runoff path.

[0054] State S4 (Closed State): The electric actuator drives the electromagnetic irrigation valve to close, and the system returns to State S0. This state is triggered by three mutually exclusive scenarios: First, the downstream soil matrix potential recovers to the upper limit of the target range, indicating that the water replenishment target has been achieved; second, the valve opening has decreased to 0% but the downstream has not yet recovered, indicating that the upstream water supply cannot effectively replenish the downstream or the downstream water demand is extremely high, and the valve is closed to avoid ineffective irrigation; third, in State S1, the downstream soil matrix potential directly recovers to the upper limit.

[0055] Using the absolute value of the rate of change as the basis for feedback adjustment, rather than a fixed duration or fixed water volume, the system can sense when runoff arrives downstream and adjust dynamically accordingly. When the absolute value of the rate of change first exceeds a threshold, it indicates that upstream water has reached the downstream area, at which point the opening degree is reduced to prevent over-flow; when the absolute value falls back, it indicates that replenishment and consumption are approaching balance at the current opening degree, and it can be maintained; when the absolute value exceeds it again, the opening degree continues to decrease. This closed-loop control of sensing-response-re-sensing transforms irrigation regulation from open-loop timing to closed-loop servo-processing.

[0056] Using the rate of change as the basis for feedback adjustment, rather than a fixed duration or fixed water volume, the system can sense the "timing" of runoff reaching the downstream and adjust dynamically accordingly. When the rate of change first exceeds a threshold, it indicates that upstream water has reached the downstream, at which point the opening degree is reduced to prevent over-flow; when the rate of change falls back, it means that supply and consumption are approaching balance at the current opening degree, and it can be maintained; when the rate of change exceeds it again, it continues to decrease. This closed-loop control of "sensing-response-re-sensing" transforms irrigation regulation from open-loop timing to closed-loop responsiveness, adapting to combinations of different rainfall histories, initial soil moisture content, and plant transpiration intensities, without needing to preset different irrigation programs for each situation.

[0057] The target range is the interval formed by the lower limit and the upper limit of the downstream soil matrix potential; where the lower limit is the downstream suction threshold and the upper limit is the matrix potential corresponding to the field capacity.

[0058] The target range is defined by the lower and upper limits of the downstream soil matrix potential. The lower limit is the aforementioned downstream suction threshold (-70 kPa), and the upper limit is the matrix potential corresponding to field capacity. Field capacity is determined through field measurements: a representative point is selected in the downstream water-demanding area, fully irrigated, and covered with a plastic film to prevent evaporation. After the gravity water has completely infiltrated (approximately 48 hours), the soil matrix potential at a depth of 30 cm is measured, which is the matrix potential corresponding to field capacity. In this embodiment, the upper limit was measured to be -10 kPa. Therefore, the target range is from -70 kPa to -10 kPa. When the downstream soil matrix potential recovers from below -70 kPa to -10 kPa, it indicates that the downstream soil moisture has been replenished to a suitable level, and the flow regulation module closes the irrigation valve.

[0059] The upper limit is set at the matrix potential corresponding to field capacity, rather than simply filling the soil completely. This is because field capacity is the amount of water that can be stably maintained after the soil has been drained by gravity. At this point, the water is sufficient and the aeration is good, which is most conducive to root absorption. If the water is continued to be saturated, the pores will be filled with water and the roots will suffer from hypoxia, which is detrimental. Therefore, the upper limit is set at field capacity and the lower limit is set at the wilting point. This allows for precise water replenishment that is sufficient but not excessive, avoiding the nutrient leaching and root hypoxia problems caused by over-irrigation, which are common in traditional irrigation methods.

[0060] In summary, the core of this case lies in the fact that it's not simply about "timed and quantitative" irrigation upstream, nor is it a simple "turn on when there's a water shortage" response downstream. Instead, it uses the upstream as the water source initiation zone, the downstream as the signal feedback zone, and the topographic runoff path as the natural water conveyance channel, forming a closed loop through the physical quantity of "rate of change." The upstream irrigation intensity is specifically designed to be "higher than the infiltration rate" to generate runoff; the downstream sensors are specifically designed to capture the "rate of change" to sense the arrival of runoff; and the flow regulation is specifically designed to "immediately adjust back after sensing arrival" to prevent over-irrigation. All three are indispensable: without topographic recognition, the runoff path is unclear; without exceeding the infiltration rate, runoff cannot be formed; and without rate of change feedback, the degree of downstream water replenishment cannot be accurately controlled.

[0061] In another embodiment, the rate of increase threshold is obtained through pre-calibration. The specific calibration process is as follows: test irrigation is carried out in the upstream water replenishment area with the maximum irrigation intensity; the rate of change from the start of irrigation to the moment when the downstream soil matrix potential first shows a significant increase is recorded; where a significant increase means that the absolute value of the rate of change of the downstream soil matrix potential exceeds the maximum absolute value of the natural rate of change of the downstream soil matrix potential during the pre-irrigation period; the absolute value of the rate of change is multiplied by a preset coefficient α less than 1 as the rate of increase threshold.

[0062] The calibration process is as follows. Test irrigation was carried out in the upstream water replenishment area at the maximum allowable irrigation intensity (25 mm per hour), while the downstream monitoring module recorded the downstream soil matrix potential at a high density with a sampling cycle of 5 minutes.

[0063] Before the irrigation test began, the natural changes in the downstream soil matrix potential were continuously monitored and recorded for 24 hours during the pre-irrigation period, and the natural rate of change sequence was calculated. The calculation method for the natural rate of change was the same as that in state S1 in Example 1: the absolute value of the difference quotient between adjacent sampling points was taken. The maximum value among all the absolute values ​​of the natural rate of change was recorded as the maximum absolute value of the natural rate of change, denoted as Rnatural. In this example, Rnatural is 0.3 kPa per hour, corresponding to the maximum natural rate of change of soil moisture under conditions without artificial irrigation.

[0064] After the irrigation test began, the differential rate of change was calculated and its absolute value was taken at 5-minute intervals, starting from the first sampling point. When the absolute value of the rate of change first exceeded Rnatural, it indicated that the irrigation water had reached the downstream area via the surface runoff path and caused a significant change in soil moisture. The absolute value of the rate of change at this moment was recorded as the calibration rate of change Rcalib. In this embodiment, Rcalib was 2.5 kPa per hour.

[0065] The calibrated rate of change is then multiplied by a coefficient α to obtain the rate of increase threshold θ, i.e., θ equals α multiplied by Rcalib, where 0.3 is less than or equal to α and less than 1. The value of α is determined as follows.

[0066] The lower limit for α is 0.3. If α is too small (e.g., less than 0.3), the rate of increase threshold is too low, which may cause normal diurnal temperature variations in the soil or evaporation fluctuations caused by light winds to be misinterpreted as runoff arrival, resulting in frequent false triggers. According to statistics from multiple site tests, when α is below 0.3, the false trigger rate exceeds 15%, indicating insufficient system stability.

[0067] The upper limit of α is less than 1. α must be less than 1 to ensure that θ is less than Rcalib, so that the flow regulation has a certain delay in response after the runoff arrives, avoiding the immediate and significant valve closure as soon as the runoff front reaches the downstream, which would lead to subsequent runoff interruption and insufficient downstream water replenishment.

[0068] Soil texture adjustment: Sandy soil (sand content greater than 70%) has fast water conductivity and a steep runoff front, so α should be 0.7 to 0.85 to ensure a rapid system response and prevent downstream over-wetting; clay soil (clay content greater than 30%) has slow water conductivity and a gentle runoff front, so α should be 0.35 to 0.5 to provide a longer response delay; loam soil uses a mid-range value of 0.5 to 0.7. In this example, the soil is loam, so α is taken as 0.6, therefore θ is 0.6 multiplied by 2.5, which equals 1.5 kPa per hour.

[0069] Seasonal adjustment: In summer, evaporation is strong and the natural variation rate of soil fluctuates greatly, so α should be taken at the upper limit to enhance the ability to resist interference; in winter, the fluctuation is small, so α can be taken at the lower limit to improve the response sensitivity.

[0070] During the calibration test, the time interval from the opening of the irrigation valve to the first occurrence of a rate of change exceeding the maximum natural rate of change downstream was recorded synchronously and denoted as the runoff arrival time. In this embodiment, the runoff arrival time is 15 minutes. This value is the measured time required for runoff to flow from the upstream water replenishment area through the surface runoff path to the downstream water demand area, and is used for reference in subsequent embodiments.

[0071] Using the maximum natural rate of change during the pre-irrigation period as the criterion for "significant increase," rather than setting a fixed value artificially, allows the standard to adapt to background fluctuations under different climate zones, seasons, and soil conditions. The natural soil drying rate during the high-temperature summer months may reach 1 kPa / h, while in winter it may only be 0.1 kPa / h. If a fixed threshold of 0.5 kPa / h is used, the system may never trigger in winter and will frequently trigger falsely in summer. The relative determination method based on locally measured natural rate of change ensures the objectivity and reproducibility of the term "significant," eliminating the need to reset empirical thresholds when deploying the same system in different regions.

[0072] In another embodiment, when there are multiple water catchment path branches between the upstream water replenishment area and the downstream water demand area, the upstream water replenishment area is further divided into multiple sub-areas, each sub-area corresponding to a downstream water demand area; the downstream monitoring module and the flow regulation module are independently set in each downstream water demand area; the upstream execution module triggers irrigation based on the downstream water demand area with the lowest matrix potential (i.e., the most negative) among all downstream water demand areas, and independently adjusts the valve opening of the corresponding sub-area according to their respective rate of change, and the total upstream irrigation flow corresponding to the sum of the valve openings of each sub-area does not exceed the maximum water supply capacity of the upstream water supply system.

[0073] Taking two water flow path branches as an example, the terrain division module further divides the upstream water replenishment area into two sub-areas. The runoff from the first sub-area flows into the first downstream water demand area via the first path, and the runoff from the second sub-area flows into the second downstream water demand area via the second path.

[0074] The downstream monitoring module is independently located in two downstream water demand areas, each equipped with a matrix potential sensor to measure the soil matrix potential value. The upstream execution module includes electromagnetic irrigation valves installed on the water supply branch pipes of the two sub-areas, as well as valve controllers. The flow regulation module includes electric actuators that are matched with each valve.

[0075] Irrigation triggering logic: The valve controller reads the soil matrix potential values ​​of all downstream water demand zones and takes the minimum value (i.e., the most negative value) as the trigger source. For example, when the first downstream water demand zone measures -75 kPa and the second downstream water demand zone measures -60 kPa, since -75 kPa is less than -60 kPa, irrigation is triggered based on the monitoring result of the first downstream water demand zone. The valve controller simultaneously sends an opening command to both valves, and irrigation begins simultaneously in both sub-zones.

[0076] During the flow regulation phase, the valve opening of each sub-zone is adjusted independently: the first electric actuator adjusts the opening of the first valve according to the rate of change of the first downstream water demand zone, and the second electric actuator adjusts the opening of the second valve according to the rate of change of the second downstream water demand zone. The two do not affect each other and each operates according to the logic of Example 1.

[0077] The valve controller calculates the sum of irrigation flow rates Qtotal corresponding to the current opening degree of each valve in real time and compares it with the maximum water supply capacity Qmax of the upstream water supply system.

[0078] When Qtotal does not exceed Qmax, the valves in each sub-zone operate according to the independent decision-making of their respective flow regulation modules, without the need for reduction.

[0079] When Qtotal is greater than Qmax, the proportional reduction algorithm under the flow constraint is started, and the steps are as follows.

[0080] The first step is to calculate the water shortage level Di for each downstream water-demanding area. For the i-th downstream water-demanding area, Di is equal to the absolute value of the difference between ψi and ψupper, where ψi is the current soil matrix potential of the area and ψupper is the upper limit of the target range. The larger Di is, the more water-scarce the area is. If ψi of a certain area has recovered to above ψupper (i.e., Di is less than or equal to 0), then that area does not participate in the allocation, and its valve is directly closed.

[0081] The second step is to calculate the total water shortage level Dtotal, which is the sum of Di for all sub-regions where Di is greater than 0.

[0082] The third step is to calculate the allocation coefficient γi for each sub-region, where γi is equal to Di divided by Dtotal.

[0083] The fourth step is to calculate the target flow rate qi for each sub-region after reduction, where qi is equal to γi multiplied by Qmax.

[0084] The fifth step is to convert qi into the corresponding valve opening command. The conversion method is as follows: based on the pre-calibrated flow-opening characteristic curve of each valve (this curve is obtained through on-site measurement, specifically: under five operating conditions of valve opening of 0%, 25%, 50%, 75%, and 100%, the corresponding actual flow is measured, five sets of (θ, q) data are recorded, and the least squares method is used to fit q as a multiplied by θ squared plus b multiplied by θ, where θ is the opening percentage, and a and b are fitting coefficients), the opening θi corresponding to qi is solved in reverse.

[0085] For example, consider two downstream water demand zones: Zone 1 has ψ1 of -75 kPa, Zone 2 has ψ2 of -60 kPa, and ψupper has -10 kPa. Then D1 equals -75 minus the absolute value of -10, which is 65; D2 equals -60 minus the absolute value of -10, which is 50; and Dtotal equals 115. γ1 equals 65 divided by 115, approximately 0.565; γ2 equals 50 divided by 115, approximately 0.435. If Qmax is 10 cubic meters per hour, then q1 equals 5.65 cubic meters per hour, and q2 equals 4.35 cubic meters per hour. Assuming the first valve characteristic is q equal to 0.0008 multiplied by θ squared plus 0.08 multiplied by θ (θ is a percentage, q is in cubic meters per hour), the inverse solution gives θ1 approximately 56.5%; the second valve characteristic is similar, with θ2 approximately 43.5%.

[0086] The core principle of this proportional reduction algorithm is to allocate water resources based on the degree of water shortage, rather than simply reducing them proportionally. Proportional reduction (such as reducing all valves to 83.3% of their original opening) would result in severely water-scarce areas not receiving sufficient replenishment, while mildly water-scarce areas would receive excessive flow. Weighting based on the degree of water shortage ensures that limited water supply capacity is prioritized for areas that need it most, which aligns with the management principle of prioritizing emergency response in garden irrigation.

[0087] Using a "most negative priority" approach as the triggering principle for multiple zones, this ensures that limited water resources are first allocated to areas most in need of replenishment. Each sub-zone adjusts independently rather than uniformly, allowing sub-zones with shorter runoff paths to enter maintenance or shutdown mode earlier, while sub-zones with longer paths can continue full-speed irrigation, avoiding a "one-size-fits-all" approach that could lead to over-irrigation in some areas and under-irrigation in others. A proportional reduction algorithm under total flow constraints achieves a fair distribution of water scarcity levels within the limitations of physical water supply capacity, rather than proportionally reducing water levels to the point that all areas receive insufficient replenishment.

[0088] In another embodiment, the system further includes a rainfall response module: used to acquire the real-time rainfall intensity of the target garden area; when the real-time rainfall intensity is greater than a preset runoff generation threshold, to suppress the irrigation trigger signal and prohibit the upstream irrigation valve from opening; when the rainfall stops and the downstream soil matrix potential is still lower than the downstream suction threshold, to re-enable the irrigation trigger signal.

[0089] The rainfall response module includes a tipping bucket rain gauge installed above the target garden area and a controller that communicates with the downstream monitoring module and the upstream execution module. The rain gauge outputs real-time rainfall intensity (in millimeters per hour) at 1-minute intervals. The controller has a preset runoff generation threshold, which is typically set to 5 millimeters per hour for loam soil. This value is based on the following considerations: when the rainfall intensity is less than the stable soil infiltration rate, all the rainfall infiltrates and no surface runoff is generated. In this case, upstream irrigation water and rainfall runoff will not overlap, causing downstream waterlogging. When the rainfall intensity is greater than the stable infiltration rate, the rainfall itself has already generated surface runoff. If irrigation water is added on top, it may lead to excessively wet downstream soil or even runoff overflow. In this embodiment, the stable infiltration rate is 12 millimeters per hour, and 5 millimeters per hour is taken as a conservative threshold.

[0090] The rainfall response module maintains a rainfall status flag, which can be either 0 or 1. The initial value of 0 indicates that there is no rainfall suppression.

[0091] In actual operation, when the real-time rainfall intensity exceeds the runoff generation threshold, the rainfall status flag is set to 1, and the controller sends a suppression signal to the downstream monitoring module. While the rainfall status flag is set to 1, the downstream monitoring module does not generate an irrigation trigger signal even if the downstream soil matrix potential is below the downstream suction threshold, and the upstream execution module remains closed.

[0092] When the real-time rainfall intensity drops below the runoff generation threshold, a rainfall stop timer is started. If the real-time rainfall intensity does not exceed the runoff generation threshold for 30 consecutive minutes, rainfall is considered to have stopped, the rainfall status flag is set to 0, and the suppression is lifted. If the real-time rainfall intensity exceeds the runoff generation threshold again during this period, the timer is reset to zero and restarts.

[0093] When the rainfall status flag changes from 1 to 0, the downstream monitoring module checks the current downstream soil matrix potential: if it is lower than the downstream suction threshold, an irrigation trigger signal is immediately generated and the upstream execution module responds normally; if it has recovered to above the downstream suction threshold, it remains in standby mode.

[0094] The key to rainfall suppression lies in distinguishing between natural rainfall and artificial irrigation. When rainfall intensity exceeds the runoff generation threshold, natural rainfall itself has already formed downstream surface runoff. If upstream irrigation is initiated at this time, the superposition of artificial and natural runoff can easily lead to downstream soil oversaturation, nutrient leaching, and even surface waterlogging. Traditional timed irrigation systems often lack rainfall sensing capabilities, irrigating as usual on rainy days, resulting in water waste and oxygen deficiency in plant roots. This solution achieves an "interlock" between natural rainfall and artificial irrigation through real-time rainfall monitoring and trigger signal suppression, ensuring that the two do not occur simultaneously and avoiding ineffective irrigation. The delay determination after rainfall stops (30 minutes of continuous no rain) avoids frequent start-stop cycles during intermittent showers, ensuring system stability.

[0095] Preferably, the flow regulation module is also used to: forcibly close the irrigation valve when the opening of the upstream irrigation valve has been reduced to the preset minimum maintenance opening and the cumulative change rate of the downstream soil matrix potential has exceeded the rise rate threshold for a preset duration; generate an alarm signal to prompt the inspection of whether there is blockage or abnormal leakage in the surface runoff path.

[0096] The minimum adjustable opening degree of the electric actuator is 5% of the fully open position. This value is determined by the flow characteristic curve of the electromagnetic irrigation valve. When the opening degree is less than 5%, the valve flow rate and opening degree no longer maintain a linear relationship, and the adjustment accuracy is lost. Therefore, 5% is set as the minimum maintaining opening degree.

[0097] If, during the process of gradually reducing the opening of the flow regulation module, the valve opening has been reduced to the minimum maintenance opening, and the cumulative rate of change of the downstream soil matrix potential continues to exceed the rising rate threshold for a preset duration, the flow regulation module will forcibly close the electromagnetic irrigation valve and generate an alarm signal to be sent to the mobile terminal of the garden management personnel.

[0098] The preset duration is estimated based on the length of the surface runoff path and the average flow velocity: the preset duration equals twice the path length divided by the average flow velocity. In this embodiment, the path length is 50 meters, and the average flow velocity is 0.05 meters per second (average surface runoff velocity under loam and gentle slope conditions), so the preset duration is 2000 seconds, approximately equal to 33 minutes, rounded to 30 minutes. This alarm prompts a check for blockages (such as leaf litter accumulation or local depressions caused by soil erosion leading to water diversion) or abnormal leakage (such as cracks along the path causing runoff to dissipate midway).

[0099] The combination of minimum maintained opening degree and duration of continuous exceedance of the threshold constitutes the automatic identification of the "regulation failure" state. Under normal circumstances, as the valve opening gradually decreases, the downstream change rate should also decrease. If the opening has dropped to the minimum adjustable value but the change rate continues to exceed the threshold, it indicates that the supply and demand relationship between upstream water and downstream soil has become unbalanced. Either the path is blocked, causing water to accumulate downstream (the change rate remains high), or the path is leaking, causing upstream water to continuously flow away (continuous water replenishment is needed to maintain the downstream water level). At this point, further fine-tuning is meaningless, and a forced shutdown and alarm are triggered, freeing the system from ineffective regulation and prompting manual intervention to investigate path anomalies. Compared with the simple logic of traditional irrigation systems that "either irrigate continuously or shut off at a set time," this adds the ability to diagnose the system's own operating status, avoiding continuous ineffective irrigation and water waste caused by path anomalies.

[0100] In another embodiment, the system further includes an upstream local water replenishment module for acquiring the soil matrix potential of the upstream water replenishment area. When the soil matrix potential of the upstream water replenishment area is lower than a preset upstream water demand threshold, after responding to the irrigation trigger signal, the upstream water replenishment area is pre-irrigated at an irrigation intensity equal to or lower than the upstream stable soil infiltration rate, and the upstream soil matrix potential is continuously monitored. When the upstream soil matrix potential recovers to the upstream water demand threshold, the irrigation intensity is immediately increased to a level higher than the stable infiltration rate to form surface runoff and replenish the downstream water demand area. During the pre-irrigation period, the flow regulation module does not intervene temporarily, and whether the downstream soil matrix potential is lower than a preset emergency threshold is used as the only interruption condition. The emergency threshold is lower than the downstream suction threshold. If the downstream soil matrix potential is lower than the emergency threshold, the pre-irrigation is interrupted and the irrigation intensity is immediately switched to a level higher than the stable infiltration rate.

[0101] The pre-irrigation intensity fpre is determined by ensuring that fpre does not exceed fs, where fs is the stable infiltration rate of the upstream soil. Specifically, there are two implementation methods.

[0102] Implementation method A uses a stable infiltration rate, where fpre equals fs. This method is suitable for situations where the upstream soil is moderately dry (matrix potential is between the permanent wilting point and the suitable lower limit of growth), with all irrigation water infiltrating locally, resulting in no surface runoff and a uniform increase in upstream soil moisture content. In this embodiment, fs is 12 mm / h, therefore fpre equals 12 mm / h.

[0103] Implementation method B uses a pre-irrigation coefficient lower than the steady-state infiltration rate, where fpre equals β multiplied by fs, and β is the pre-irrigation coefficient, with 0.5 less than or equal to β and β less than 1. This method is suitable for situations where the upstream soil is extremely dry (matrix potential close to or below the permanent wilting point) or the soil texture is heavy clay (prone to compaction). The reason for choosing β less than 1 is that an extremely dry soil surface layer easily forms a water-repellent layer. If irrigation is carried out at an intensity equal to fs, the water flow may rapidly infiltrate through local preferential channels, leading to uneven wetting fronts. Reducing the intensity prolongs the contact time between water and soil, promoting capillary water absorption and forming a more uniform wetting body. For heavy clay soils, reducing the intensity can prevent surface water accumulation and soil structure damage.

[0104] For example, if the soil at a certain site is clay, fs is 5 mm / h, and the upstream soil matric potential is -150 kPa (close to the permanent wilting point), and β is taken as 0.8, then fpre is 0.8 multiplied by 5, which equals 4 mm / h. Pre-irrigation continuously monitors the upstream matric potential. When it recovers to the upstream water demand threshold (e.g., -30 kPa), it switches to high-intensity irrigation with f equal to 1.5 multiplied by fs equal to 7.5 mm / h, generating surface runoff to replenish the downstream area.

[0105] The implementation method where the flow regulation module does not intervene during pre-irrigation is as follows: The state machine logic unit shields the transition condition judgment of states S1 to S4 during pre-irrigation, that is, it does not calculate the downstream change rate, does not perform opening adjustment, and only maintains the pre-irrigation intensity unchanged. However, the downstream monitoring module still collects the downstream soil matrix potential at a 10-minute cycle and compares it with the emergency threshold. This shielding is achieved through the mode flag bit in the valve controller: when the mode flag bit is 0, normal closed-loop regulation is performed (states S0 to S4); when the mode flag bit is 1, pre-irrigation mode is performed (only maintaining the fpre intensity, only judging the emergency threshold interruption). When the downstream soil matrix potential is lower than the emergency threshold, the mode flag bit is forcibly set to 0, and it immediately switches to the high-intensity state of normal closed-loop regulation.

[0106] The upstream local water replenishment module includes a matrix potential sensor buried at a depth of 30 cm in the soil of the upstream water replenishment area and a comparator that communicates with the valve controller.

[0107] In actual operation, when the valve controller responds to the irrigation trigger signal and prepares to open the electromagnetic irrigation valve, the comparator first reads the upstream soil matrix potential and compares it with the preset upstream water demand threshold. The upstream water demand threshold is determined based on the lower limit of the suitable growth matrix potential range for upstream plants. In this embodiment, the suitable range for tall fescue is -30 kPa to -10 kPa, so the upstream water demand threshold is set to -30 kPa. If the upstream soil matrix potential is lower than the upstream water demand threshold (i.e., the upstream soil is also relatively dry), the valve controller first pre-irrigates the upstream water replenishment area with an irrigation intensity equal to the stable infiltration rate (12 mm / h). This intensity is equal to the stable infiltration rate, and all irrigation water infiltrates in situ, without forming surface runoff.

[0108] During pre-irrigation, the flow regulation module does not intervene, meaning it does not execute the rate of change monitoring and opening regulation logic of Example 1. However, the downstream monitoring module still collects the downstream soil matrix potential at 10-minute intervals and compares it with a preset emergency threshold. The emergency threshold is lower than the downstream suction threshold. In this example, the emergency threshold is -90 kPa (the downstream suction threshold is -70 kPa), which is the dangerous lower limit of the downstream soil matrix potential. Below this value, the water absorption function of plant roots will be severely impaired.

[0109] The only interruption condition during pre-irrigation is as follows: if the downstream soil matrix potential falls below the emergency threshold at any sampling time, the valve controller immediately interrupts pre-irrigation, switching the irrigation intensity from 12 mm / h to 18 mm / h (higher than the stable infiltration rate). Simultaneously, the flow regulation module is activated, entering the full-speed irrigation state of Example 1. This emergency interruption mechanism ensures that the survival needs of downstream plants are prioritized under the most unfavorable circumstances.

[0110] If the downstream soil matrix potential remains above the emergency threshold during pre-irrigation, the comparator continuously monitors the upstream soil matrix potential. When the upstream soil matrix potential recovers to the upstream water demand threshold (-30 kPa), the valve controller increases the irrigation intensity from 12 mm / h to 18 mm / h within the next control cycle (10 seconds), and the flow regulation module is activated simultaneously, initiating surface runoff to replenish the downstream water demand area.

[0111] The upstream local water replenishment module addresses a crucial but often overlooked issue: if the upstream soil is also dry, direct irrigation at an intensity exceeding the stable infiltration rate results in significant water loss to the upstream surface (absorbed by the dry soil before forming surface runoff), leading to a much lower actual water volume reaching the downstream, or even none at all. Pre-irrigation, using an intensity equal to the stable infiltration rate to "moisten" the upstream soil and bring its moisture content to a level sufficient to support runoff formation, before switching to high intensity to generate runoff, is analogous to a "base coat before coloring" process. The flow regulation module's freezing during pre-irrigation prevents erroneous adjustments before the downstream rate of change responds; while the emergency threshold interruption mechanism skips pre-irrigation and directly replenishes water at full capacity when the downstream is already in a dangerous state, reflecting a hierarchical control strategy prioritizing "life safety" and preventing downstream plants from being damaged by water shortage during upstream water replenishment.

[0112] In another embodiment, the flow regulation module is also used to monitor the response characteristics of the downstream soil matrix potential to determine the unobstructed status of the surface runoff path: when the upstream irrigation valve is opened for more than a preset first time period, the first time period is determined by multiplying the runoff arrival time obtained by the aforementioned calibration by a preset coefficient, and the downstream soil matrix potential still does not show a change rate exceeding the rise rate threshold, it is determined that there is a blockage or serious leakage in the surface runoff path, and a path abnormality alarm is generated; when the upstream irrigation valve has been closed and the downstream soil matrix potential continues to decline and falls below the downstream suction threshold again within a preset second time period, it is determined that there is excessive leakage in the surface runoff path, resulting in the upstream water failing to effectively replenish the downstream, and a path repair prompt is generated.

[0113] First-duration alarm (path blockage or severe leakage determination): The flow regulation module presets a first duration, which is determined by multiplying the runoff arrival time obtained from the calibration in the aforementioned embodiment by a preset coefficient. The runoff arrival time is the time interval from the opening of the upstream valve to the first occurrence of a change rate absolute value greater than the maximum natural change rate in the downstream during the aforementioned calibration test; in this embodiment, it is 15 minutes. The preset coefficient is set to 1.5 to account for flow velocity fluctuations caused by differences in soil moisture content during actual operation; therefore, the first duration is 22.5 minutes, rounded up to 25 minutes.

[0114] If, after the electromagnetic irrigation valve has been open for more than the first time period (25 minutes), the downstream soil matrix potential has not shown a rate of change exceeding the rise rate threshold, the flow regulation module determines that there is a blockage or serious leakage in the surface runoff path and generates a path anomaly alarm. This alarm prompts managers to check whether there are physical obstacles (such as construction barriers, accumulated garden waste) or terrain changes (such as local subsidence causing runoff diversion) on the path.

[0115] Second duration alarm (excessive leakage judgment): The flow regulation module has a preset second duration T2, which is determined as follows.

[0116] The first step is to establish a baseline for the water-holding time of the normal flow path. During the initial system operation or after path maintenance, when the surface runoff path is confirmed to be in good condition (no blockages, no leakage), at least three complete irrigation shut-off and re-trigger cycles are executed. The time interval from valve closure to the downstream soil matrix potential returning to the downstream suction threshold is recorded as t1, t2, and t3. The average water-holding time tavg is calculated, which is equal to the sum of t1, t2, and t3 divided by 3. In this embodiment, based on historical data, tavg is approximately 48 hours.

[0117] The second step is to determine the warning threshold. T2 is set to equal tavg divided by 2, which equals 24 hours. The reason for using half rather than a lower percentage is that soil moisture changes in gardens are affected by natural factors such as rainfall and transpiration, and the water-holding time itself has a normal fluctuation of plus or minus 30%. If T2 is set too strictly (e.g., tavg divided by 3), it may cause frequent false alarms due to normal weather fluctuations; if it is set too leniently (e.g., tavg divided by 1.5), it may miss real seepage problems. Field verification shows that tavg divided by 2 achieves a good balance between false alarm rate and missed alarm rate.

[0118] The third step is dynamic updating. Each time the system completes a full irrigation cycle (from triggering to closing and then to the next trigger), it automatically updates tavg (using a moving average of the last three times) and updates T2 accordingly. This allows the second duration to adapt to seasonal changes (strong transpiration in summer, shorter tavg; weak transpiration in winter, longer tavg) and changes in plant growth stages (strong water absorption after root development, shorter tavg).

[0119] Judgment Logic: When the electromagnetic irrigation valve is closed, the system is in standby state S0, and the downstream soil matrix potential continues to decline (showing a downward trend for three consecutive sampling cycles, i.e., within 30 minutes), if the downstream soil matrix potential falls below the downstream suction threshold again within T2 (24 hours), the flow regulation module determines that there is excessive leakage in the surface runoff path, meaning that a large amount of water from upstream is lost in the path and fails to effectively replenish the downstream soil, causing the downstream to quickly become water-deficient again. At this time, a path repair prompt is generated, suggesting that the path be treated to prevent seepage (such as laying a permeable brick guide layer or repairing cracks).

[0120] The continuously decreasing determination increases timing stability and avoids false alarms caused by noise from a single sampling. If an alarm is triggered by only a single sampling fluctuation, the false alarm rate will be too high; requiring a decrease for three consecutive sampling cycles (30 minutes) can effectively filter out sensor noise and short-term evaporation fluctuations.

[0121] The difference between the two alarm types: the first alarm duration is for runoff obstruction during irrigation (water cannot reach the downstream at all), and the second alarm duration is for insufficient water retention after irrigation (water arrives but cannot be retained). Managers can take targeted maintenance measures according to different alarm types.

[0122] A key design feature of this solution is embedding path patency diagnostics into the normal irrigation control process, rather than requiring dedicated detection equipment. The first time-based alarm utilizes the anomaly of "should have responded but didn't." Under normal circumstances, runoff should reach downstream in about 15 minutes. If no increase in the rate of change is detected after 25 minutes, it indicates a path blockage. The second time-based alarm utilizes the anomaly of "shouldn't have decreased but did." After normal irrigation, downstream water levels should remain relatively high for a longer period. If the water level drops below the threshold within 24 hours, it indicates poor water retention capacity. Both diagnostic methods are based on existing sensor data and control logic within the system, requiring no additional hardware costs and achieving functional reuse. This is particularly important in cost-sensitive applications like garden irrigation, reducing system maintenance costs and deployment barriers.

[0123] This invention identifies and divides garden terrain by constructing a terrain segmentation module, a downstream monitoring module, an upstream execution module, and a flow regulation module. This identifies the upstream water replenishment area, the downstream water demand area, and the surface runoff path between them. Based on the actual state of the downstream soil matrix potential, upstream irrigation is triggered, generating controllable surface runoff at an intensity higher than the stable infiltration rate. This directs excess water from the upstream to the downstream under gravity. The valve opening is then dynamically adjusted using a rate of change feedback to sense the arrival of runoff and control the replenishment amount accordingly, preventing over-irrigation. Therefore, a closed-loop control system can be achieved from terrain identification to runoff regulation to on-demand water replenishment, improving the accuracy of garden irrigation's adaptation to natural terrain and water resource utilization efficiency, reducing system energy consumption, and enabling the irrigation system to adapt to various slope terrain layouts.

[0124] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A garden water-saving irrigation control system adapted to a topographic layout, characterized in that, include: The terrain division module is used to acquire the three-dimensional terrain of the target garden area, divide the area into an upstream water replenishment area and a downstream water demand area, and determine the surface runoff path between the two. The downstream monitoring module is located in the downstream water demand area and is used to continuously monitor the downstream soil matrix potential. When the downstream soil matrix potential is lower than the preset downstream suction threshold, an irrigation trigger signal is generated. An upstream execution module, located in the upstream water replenishment area, is used to receive the irrigation trigger signal and then open the upstream irrigation valve to continuously irrigate at an intensity higher than the stable infiltration rate of the upstream soil. The flow regulation module is used to monitor the rate of change of the downstream soil matrix potential during irrigation and calculate its absolute value. When the absolute value of the rate of change first exceeds the preset rate of increase threshold, the opening of the upstream irrigation valve is gradually reduced at a preset fixed step size. If the absolute value of the rate of change falls below the rate of increase threshold during the reduction process, the current opening is maintained until the absolute value of the rate of change exceeds the rate of increase threshold again or the downstream soil matrix potential recovers to the upper limit of the preset target range; the flow regulation module is also used to: close the irrigation valve when the downstream soil matrix potential recovers to the upper limit of the target range, or when the opening of the upstream irrigation valve has been reduced to zero.

2. The system according to claim 1, characterized in that, The depth of the matrix potential sensor buried in the downstream monitoring module is matched with the depth of the active water absorption layer of the main plant roots in the downstream water demand area. The downstream suction threshold is set based on the matrix potential of the plant's permanent wilting point.

3. The system of claim 1, wherein, The rate of rise threshold is obtained through pre-calibration: Test irrigation was conducted at maximum irrigation intensity in the upstream water replenishment area. Record the absolute value of the rate of change from the start of irrigation to the moment when the downstream soil matrix potential first shows a significant increase; wherein the significant increase refers to the absolute value of the rate of change of the downstream soil matrix potential exceeding the maximum absolute value of the natural rate of change of the downstream soil matrix potential during the pre-irrigation period; multiply the absolute value of the rate of change by a preset coefficient less than 1 as the rate of increase threshold.

4. The system according to claim 1, characterized in that, The target range is the interval formed by the lower and upper limits of the downstream soil matrix potential; The lower limit is the downstream suction threshold, and the upper limit is the matrix potential corresponding to the field water holding capacity.

5. The system according to claim 1, characterized in that, The terrain division module is also used to: when there are multiple water catchment path branches between the upstream water replenishment area and the downstream water demand area, further divide the upstream water replenishment area into multiple sub-areas, each sub-area corresponding to a downstream water demand area; The downstream monitoring module and the flow regulation module are each independently installed in each downstream water demand area; The upstream execution module triggers irrigation based on the downstream water demand zone with the lowest or most negative matrix potential among all downstream water demand zones, and independently adjusts the valve opening of the corresponding sub-zone according to their respective rate of change. The total upstream irrigation flow corresponding to the sum of the valve openings of each sub-zone does not exceed the maximum water supply capacity of the upstream water supply system.

6. The system according to claim 1, characterized in that, It also includes a rainfall response module: Used to obtain the real-time rainfall intensity of the target garden area; When the real-time rainfall intensity exceeds the preset runoff generation threshold, the irrigation trigger signal is suppressed, and the upstream irrigation valve is prohibited from opening. When rainfall stops and the downstream soil matrix potential is still below the downstream suction threshold, the irrigation trigger signal is reactivated.

7. The system according to claim 1, characterized in that, The flow regulation module is also used for: When the opening of the upstream irrigation valve has been reduced to the preset minimum maintenance opening, and the cumulative change rate of the downstream soil matrix potential continues to exceed the rise rate threshold for a preset duration, the irrigation valve is forcibly closed. An alarm signal is generated to prompt an inspection of the surface runoff path for any blockages or abnormal leaks.

8. The system according to claim 1, characterized in that, When the upstream execution module continuously irrigates at an irrigation intensity higher than the upstream soil stable infiltration rate, the irrigation intensity is determined based on the upstream soil stable infiltration rate obtained from the on-site double-ring infiltration test or by referring to a table of soil texture. Its value is greater than the stable infiltration rate and does not exceed the maximum allowable irrigation intensity of the upstream soil; the maximum allowable irrigation intensity is determined based on the field double-ring infiltration test combined with the critical flow velocity of soil erosion resistance.

9. The system according to claim 1, characterized in that, It also includes an upstream local water replenishment module: Used to obtain the soil matrix potential of the upstream water replenishment area; when the soil matrix potential of the upstream water replenishment area is lower than the preset upstream water demand threshold, after responding to the irrigation trigger signal, the upstream water replenishment area is pre-irrigated with an irrigation intensity equal to or lower than the upstream soil stable infiltration rate, and the upstream soil matrix potential is continuously monitored. When the upstream soil matrix potential recovers to the upstream water demand threshold, the irrigation intensity is immediately increased to a level higher than the stable infiltration rate to generate surface runoff and replenish the downstream water demand area; During pre-irrigation, the flow regulation module does not intervene temporarily, and the only interruption condition is whether the downstream soil matrix potential is lower than the preset emergency threshold; the emergency threshold is lower than the downstream suction threshold; if the downstream soil matrix potential is lower than the emergency threshold, pre-irrigation is interrupted and the irrigation intensity is immediately switched to a higher than the stable infiltration rate.

10. The system according to claim 1, characterized in that, The flow regulation module is also used to monitor the response characteristics of downstream soil matrix potential to determine the unobstructed state of the surface runoff path: If the upstream irrigation valve is opened for more than a preset first time, the first time is determined by multiplying the runoff arrival time obtained according to claim 3 by a preset coefficient, and the downstream soil matrix potential still does not show the change rate exceeding the rise rate threshold, it is determined that there is a blockage or serious leakage in the surface runoff path, and an abnormal path alarm is generated. When the upstream irrigation valve is closed and the downstream soil matrix potential continues to decline, and falls below the downstream suction threshold again within a preset second time period, it is determined that there is excessive leakage in the surface runoff path, resulting in the upstream water failing to effectively replenish the downstream, and a path repair prompt is generated.

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