How Do Sprinkler and Drip Schedules Vary?

ETwater's scheduling algorithms treat drip systems differently from sprinkler systems. The low volume of drip systems influences several irrigation variables, making it important to address the differences between sprinklers and drip systems. While sprinkler systems saturate entire areas of a landscape, drip irrigation applies water only to selected portions of a landscaped area, impacting runtimes and irrigation frequency.

In most instances, ETwater's approach to drip irrigation will result in lighter, but more frequent irrigation events. Lighter, more frequent waterings using point source irrigation (drip emitters) have been found in field research to produce healthier plants across varied plant and landscape types.

Drip and ET Threshold Rates

With drip systems, a specified ET threshold rate triggers additional watering instead of a pre-determined moisture depletion level. In order to apply water for a particular drip station, ETwater first calculates a daily adjusted ET rate using the reference ET rate, a plant factor and a shade factor for the drip-supported zone of the landscape. The ET threshold rate varies depending on the season. For the summer months, the threshold is typically set at .2 inches. Thus, if the daily adjusted ET is .24 inches on average during the summer, a light watering will occur on a daily basis.

In addition, when the user first configures the landscape station, the type of irrigation system at the station must be identified. With a sprinkler system, users are asked to enter a sprinkler precipitation rate, or they can use ETwater's pre-defined default rate.

If a drip system is selected, the user enters the average canopy size of the plants being served by the station, the number of emitters per plant and the flow rate per emitter. Using this information and the daily adjusted ET rate, ETwater calculates the duration of watering time. If the station serves a mix of plant types, the watering time will always be set to serve the most demanding plant in the grouping.

How ETwater Differs From Other Systems

Other weather–based controllers require the user to measure square footage of the drip station, conduct a flow test at the site's water meter to determine flow rate and then perform calculations to determine average run times for the station. At best, this process is tedious and does not address the density of plantings and the actual amount of water being applied per plant. ETwater's approach dramatically simplifies the process and improves accuracy at the same time.