Flex daily advanced settings questions

Hello and appreciate any help here,

I have a Rachio flow meter installed and use Flex Daily schedules. I am working on tweaking the advanced settings to further optimize water usage and ultimately water each zone as accurately as possible. I am looking at modifying Available water and Nozzle inches per hour for each zone and have some questions:

  1. Available water - when using the Web Soil Survey (https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx) and looking for Available water capacity for cool season turf should I be setting the bottom depth to 6 inches to get the most accurate result?

  2. Nozzle inches per hour - I have the Rachio wireless flow meter installed and am looking to modify the Nozzle inches per hour. Based on what I have found the rate is based on GPM / Area * 96.25. I know the GPM but am trying to figure out the easiest/best way to find the area. Is the area in square feet based on where the water from the heads sprays to? The shape of the zone in question is irregular. I have looked at the mapping capabilities in the Rachio app, Google maps, and Google earth but there are too many trees and I cannot get an accurate look.

Thanks very much in advance,