Certified Landscape Irrigation Auditor

How can the number of soak events be calculated?

1. Counting total rainfall per month

2. Dividing total run time by time to runoff

3. Measuring evaporative losses

4. Averaging water needs of various plants

The correct answer is: Dividing total run time by time to runoff

The calculation of soak events is essential in understanding how efficiently water penetrates the soil when irrigating. The method of dividing total run time by time to runoff is accurate because it provides a practical means to determine how many soak events occur within a specific irrigation interval. When irrigation systems run, water is applied over a certain duration (total run time). However, the ability of the soil to absorb that water can vary based on its composition, saturation levels, and existing moisture content. The time to runoff refers to the point when the soil becomes saturated, and additional water begins to flow over the surface instead of being absorbed. By using the relationship between total run time and time to runoff, one can quantify how many effective soak events occur, ensuring that irrigation is applied efficiently without wasting water. Other methods, such as counting total rainfall or measuring evaporative losses, do not directly relate to the analysis of soak events. Averaging the water needs of various plants may offer insights into irrigation depths but does not provide a metric for calculating soak events based on water application timing and absorption rates. Thus, dividing total run time by time to runoff specifically addresses the process of how soil absorbs the applied water, making it the correct approach to calculate soak events.