Rainfall prediction and compensation in irrigation control

1. A method of controlling irrigation, the method comprising:

obtaining a barometric pressure (BP) profile corresponding to changes in BP over a period of time and corresponding to a location where irrigation is to be controlled;

determining a dew point factor (DPF) profile as a function of changes in temperature and relative humidity over the period of time and corresponding to the location where irrigation is to be controlled;

making a determination that a rain event is likely to occur as a function of both the BP profile and the DPF profile; and

generating, based on the determination that the rain event is likely to occur, a control signal configured to cause one or both of current and scheduled irrigation to be limited;

wherein the step of making the determination that the rain event is likely comprises:

identifying a slope of the BP profile over the period of time;

identifying a slope of the DPF profile over the period of time; and

determination that the rain event is likely to occur as a function of the slope of the BP profile and the slope of the DPF profile; and

generating a correction factor in response to determining the rain event is likely, wherein the correction factor is proportional to at least one of the slope of the BP profile or the slope of the DPF profile and the correction factor is configured to be applied in adjusting irrigation runtimes.

2. The method of claim 1 , further comprising:

limiting, in response to the control signal, one or both of current and scheduled irrigation based on the determination that the rain event is likely to occur.

3. The method of claim 1 , wherein the step of generating the control signal comprises:

generating the correction factor in response to the step of making the determination the rain event is likely.

4. The method of claim 3 , further comprising:

communicating the correction factor along with multiple previous correction factors calculated for previous days to an irrigation controller, wherein the correction factor and the multiple previous correction factors are configured to be cooperatively used by the irrigation controller in determining adjustments to the irrigation runtimes.

5. The method of claim 3 , further comprising:

averaging the correction factor with one or more previous correction factors calculated for previous days and generating an averaged correction factor configured to be used in adjusting the irrigation runtimes.

6. The method of claim 3 , wherein the correction factor comprises a percentage adjustment configured to cause the irrigation runtimes to be adjusted proportionally to the percentage adjustment.

7. The method of claim 1 , wherein the step of making the determination that the rain event is likely comprises:

predicting an approximate time when the rain event is expected to occur as a function of the identified slope of the at least one of the BP profile or the DPF profile.

8. The method of claim 1 , wherein the step of making the determination that the rain event is likely comprises:

determining whether a current BP has a predetermined relationship with a BP reference threshold;

determining whether a current DPF has a predetermined relationship with a DPF reference threshold; and

determination that the rain event is likely to occur as a function of whether one or both the current BP has the predetermined relationship with the BP reference threshold and the current DPF has the predetermined relationship with the DPF reference threshold.

9. The method of claim 1 , further comprising:

determining whether a predicted rain event occurred;

calculating a compensation factor in response to determining that the rain event did not occur; and

applying the compensation factor in calculating one or more subsequent correction factors.

10. The method of claim 1 , further comprising:

determining whether an amount of rain detected during a rain event compensates for water not applied as a result of limiting one or both of the current and the scheduled irrigation; and

calculating a compensation factor in response to determining that the amount of rain does not compensate for water not applied.

11. The method of claim 1 , wherein the step of making the determination the rain event is likely comprises:

detecting that the BP profile has a predetermined relationship with a threshold rate of change of the BP; and

detecting that the DPF profile has a predetermined relationship with a threshold rate of change of the DPF.

12. The method of claim 1 , wherein the step of generating the control signal comprises generating the control signal configured to suspend at least one of the current or scheduled irrigation.

13. The method of claim 1 , wherein the DPF profile comprises a dew point differential (DPD) profile, wherein the DPD profile is proportional to a change over the period of time of a difference between temperate and a dew point temperature.

14. The method of claim 1 , wherein the generating the control signal comprises generating a control signal control signal configured to cause an interrupt of one or both of the current and the scheduled irrigation based on the determination that the rain event is likely to occur.

15. A method of controlling irrigation, the method comprising:

obtaining a barometric pressure (BP) profile corresponding to changes in BP over a period of time and corresponding to a location where irrigation is to be controlled;

determining a dew point factor (DPF) profile as a function of changes in temperature and relative humidity over the period of time and corresponding to the location where irrigation is to be controlled;

making a determination that a rain event is likely to occur as a function of both the BP profile and the DPF profile; and

generating, based on the determination that the rain event is likely to occur, a control signal to adjust one or both of current and scheduled irrigation to be limited;

wherein the step of making the determination that the rain event is likely comprises:

identifying a slope of the BP profile over the period of time;

identifying a slope of the DPF profile over the period of time; and

determination that the rain event is likely to occur as a function of the slope of the BP profile and the slope of the DPF profile; and

wherein the step of making the determination that the rain event is likely to occur comprises:

identifying that at least one of the slope of the BP profile or the slope of the DPF profile is decreasing at a rate that has a predetermined relationship with a first threshold, and the other of the slope of the BP profile and the slope of the DPF profile is not increasing at a rate that has a predetermined relationship with a second threshold.

16. The method of claim 1 , further comprising:

generating a correction factor in response to predicting the rain event, wherein the correction factor is configured to be applied in adjusting one or more irrigation runtimes implemented by an irrigation controller at the site to result in one or more corresponding adjusted irrigation runtimes that are less than the corresponding one or more irrigation runtimes;

determining whether a sensed amount of rain is received sufficient to compensate for an estimated amount of water that was not distributed because of an implementation of the one or more adjusted irrigation runtimes;

calculating a compensation factor in response to determining the received amount of rain is insufficient to compensate for the estimated amount of water that was not distributed in the implementation of the one or more adjusted irrigation runtimes; and

causing the compensation factor to be applied in subsequently adjusting the one or more irrigation runtimes.

17. The method of claim 16 , wherein the causing the compensation factor to be applied comprises distributing the compensation factor over multiple irrigation days such that a portion of the compensation factor is applied on each of the multiple irrigation days.

18. The method of claim 17 , further comprising:

identifying a watering restriction;

identifying that applying the compensation factor to a single irrigation day would result in exceeding the watering restriction; and

implementing distributing the compensation factor over multiple irrigation days in response to identifying the watering restriction would be exceeded.

19. The method of claim 16 , wherein the causing the compensation factor to be applied comprises causing the compensation factor to be applied independent of one or more other irrigation controller implemented runtime adjustments.

20. The method of claim 1 further comprising:

evaluating, as a function of two or more different predicted rain events, at least one of a BP reference threshold or a DPF reference threshold;

identifying an inconsistency between a detection of an actual rain event and the at least one of the BP reference threshold or the DPF reference threshold; and

adjusting the at least one of the BP reference threshold or the DPF reference threshold in response to identifying the inconsistency.

21. The method of claim 20 , further comprising:

evaluating the at least one of the slope the BP profile or the slope of the DPF profile relative to when it crosses the BP reference threshold and the DPF reference threshold, respectively.

22. The method of claim 21 wherein the determining that the rain event is likely to occur comprises:

determining that the rain event is likely to occur as a function of at least the evaluated slope of the BP profile relative to when it crosses the BP reference threshold, the evaluated slope of the DPF profile relative to when it crosses the DPF reference threshold, the BP profile relative to the BP reference threshold, or the DPF profile relative to the DPF reference threshold.

23. The method of claim 20 , further comprising:

identifying, for each of the two or more predicted rain events, an accuracy of the prediction and an accuracy of a predicted time of the rain event;

wherein the adjusting the at least one of the BP reference threshold or the DPF reference threshold comprises adjusting the at least one of the BP reference threshold or the DPF reference threshold as a function of the accuracy of the prediction and the accuracy of the predicted time of the rain event.

24. A system of controlling irrigation, comprising:

a processor;

a memory coupled with the processor and storing program code that when implemented by the processor causes the processor to:

obtain a barometric pressure (BP) profile corresponding to a change in BP over a period of time and corresponding to a location where irrigation is to be controlled;

determine a dew point factor (DPF) profile proportional to changes in temperature and relative humidity over the period of time and corresponding to the location where irrigation is to be controlled;

determine that a rain event is likely to occur as a function of both the current BP profile and the current DPF profile comprising identifying a slope of the BP profile over the period of time, identifying a slope of the DPF profile over the period of time, and determining that the rain event is likely to occur as a function of the slope of the BP profile and the slope of the DPF profile;

generate a correction factor in response to determining the rain event is likely, wherein the correction factor is proportional to at least one of the slope of the BP profile or the slope of the DPF profile and the correction factor is configured to be applied in adjusting irrigation runtimes; and

generate a control signal configured to cause one or both of current and scheduled irrigation to be limited based on the determination that the rain event is likely to occur.

25. The system of claim 24 , wherein the processor, in generating the control signal, is configured to generate the correction factor in response to determining the rain event is likely, wherein the correction factor is configured to be applied in adjusting irrigation runtimes in response to the determination that the rain event is likely.

26. The system of claim 25 , further comprising:

a transmitter coupled with the processor, wherein the transmitter is configured to transmit the correction factor to an irrigation controller.

27. The system of claim 24 , wherein the processor is further configured to receive communications from one or more sensors, and to determine at least one of the BP profile or the DPF profile as a function of the communications received from the one or more sensors.

28. The system of claim 24 , further comprising:

one or more sensors coupled with the processor, wherein the one or more sensors are configured to sense parameters used by the processor in determining at least one of the BP profile or the DPF profile.