Available Water Increased w/o Rain

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Aaron Long

July 10, 2018 01:04

I've just installed my RM a month ago and it hasn't watered at all.  I assumed that was because there has been a lot of rain in June.  We haven't had any rain now for over 7 days...and started researching the reasons why.  First, in the watering history screen there isn't any special reason (i.e. surplus water).  I looked at the zones and click the graph next to field capacity.  I've had available water above the Optimal Level since July 1st and it has been slowing decreasing.  But today it increased by 0.15 inches even though there was no rain and ET of 0.23.  The program hasn't scheduled any watering until the 11th and now will water 100% for four days straight.  I can't make sense of how it is behaving or if I've set it up incorrectly.  Any insight appreciated.  Thanks!

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  RainMachine Nicholas July 10, 2018 07:35

  If no rain was forecasted the only reason Available Water can increase is a "Forecast Correction". This means that the EvapoTranspiration for a day was forecasted to be higher (when program started) than it actually was using the day latest weather information. So the algorithm must correct this and the only way to reduce future irrigation, because of extra previous irrigation, is to "put back" some available water in soil. This might seem counter intuitive but it's a more uniform algorithm.

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  Aaron Long July 12, 2018 00:05

  Thank you Nicholas.  The rotors water 1:45 minutes per zone...that seems like a lot (every 3 days).  If I were to back it off to 60 minutes with a custom setting rather than the suggested would it just water days to make up?  Or is the time of watering per station not connected to the available water calculation?

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  RainMachine Nicholas July 12, 2018 07:11

  1:45 minutes meaning 1 hour and 45 minutes ? Now it depends on the type of rotors/heads, some are very slow with a low precipitation rate, others (newer ones) have much better precipitation rate (double than our default setting). The precipitation rate can be changed by using a custom sprinkler head and increasing precipitation rate and efficiency.

  The available water is not connected to irrigation, we just replenish to reach the plant optimal level, the available water is above that. That means no matter how much you irrigate we don't add to available water. Doing that would lead to other potential issues.

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