Irrigation Audit Calculator

Calculate Distribution Uniformity (DU) and Christiansen's CU from catch can test data to evaluate irrigation system performance.

Number of catch cans

Mean catch volume (mL)

Low-quarter average (mL)

Minimum reading (mL)

Maximum reading (mL)

Can diameter (in)

Test duration (min)

System flow rate (GPM)

Field size (acres)

Tab to move between fields

Distribution Uniformity (%)

Christiansen CU (%)

83.6

Coefficient of Variation (%)20.6

Application rate (in/hr)1.08

Scheduling coefficient1.25

Rating (1=Excellent, 4=Poor)2

Over-irrigation factor (%)25

Savings if improved to 90% DU (%)11.1

Water wasted (gal/hr)12,000

Mean catch depth (in)0.54

Max/Min ratio2.56

How to Use This Calculator

Enter Number of catch cans, Mean catch volume (mL), and Low-quarter average (mL).
Set Minimum reading (mL), Maximum reading (mL), and Can diameter (in).
Adjust Test duration (min), System flow rate (GPM) as needed.
Review Distribution Uniformity (%) and Christiansen CU (%).
Use Coefficient of Variation (%) and Application rate (in/hr) to inform your decision.

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