Start to day - watering would make Zone at well over 110%

Question on the flex schedule regarding how the watering amount is working and how the lawn handles it.

Right now the zones are set to water when they go below 50%. However, the amount the system calculated to water as a norm is 100% of the inches which equals saturation. However, due to the evapotranspiration (or whatever it is called) by the end of the day it is within the 50-100% range generally.

My question is - if it starts watering in the early morning and the zone is at 30%, then the normal watering would initially make the zone at 130%. Then as the water evaporates and drains throughout the day, it theoretically goes down to some number, say 75% depending on the temp/wind/soil type for the day. So what happens immediately when it gets above saturation, does this water run off? Drain quickly through ground? Evaporate as soon as sun comes up? It would seem that the system would max the water put down in the early morning to 100%. But since the calculation is an entire day mass balance it doesn’t really show you what is going on that first part of the day when the soil is theoretically over-saturated.

I remember reading somewhere that the system only tracks to 110%. But why do you say that normal watering would take a zone to 130%? I would expect normal watering (+ expected precipitation for the day) to take soil to estimated 100%.

Yes it only tracks to 110%. But if you think about actual moisture as a function of time, the evapotranspiration (drainage and evaporation basically) happens over time throughout the 24 hours. So if you consider this zone of mine for today, it comes into the day (midnight) at .11 inches. For my lawn, 0.35 inches is 100% saturated. So the watering starts around 3:00AM, by that time, the day is only 1/8 over (and night/cold) so worst case is 1/8 of the days evapotranspiration of 0.24 which would be 0.03. So by 3:00 AM, the total moisture would be 0.08 inches. If the watering puts down 0.35 inches, that would make 0.43 inches at that time which is 123% saturation.

Theoretically you can’t oversaturate so this would mean it either runs off, drains deeply out of root reach, or sits on surface and immediately evaporates? Or I am not understanding the concept of saturation. I am just trying to understand if going above saturation in morning, even though it would go below saturation in late morning, what happens with the water during the over saturation period.

If this excess water is lost for some reason, then my lawn would actually be less saturated over time than the calculation. And perhaps I am overthinking it, but perhaps Rachio should calculate what is needed to hit 100% and only do that amount, rather than it’s default estimated average. Or perhaps by doing it the way they do, it supports deeper root growth because it actually goes dryer sooner. Not sure, but would be interesting to better understand.