Glossary of Irrigation Terms

A region that's considered subhumid is not the opposite of subarid! As a general rule, a region is subhumid when it experiences moderate rainfall - more than 20-inches but less than 40-inches annually - and a moderate to high evaporation potential.

As its name suggests, a region that's considered semiarid is neither completely humid nor arid. As a general rule, a region is considered semiarid if it normally experiences an annual average of between 10 and 20-inches rainfall.

A characteristic of a region with a humid climate is high rainfall and a low evaporation potential. As a general rule, a region is considered humid if it normally experiences an annual average rainfall of more than 40-inches.

A characteristic of a region with an arid climate is low rainfall and a high evaporation potential. As a general rule, a region is considered arid if it normally experiences an annual average rainfall of less than 10-inches.

Sometimes called a uniformity coefficient, this is a measure of how evenly irrigation water is applied across a specific area of landscaping. To calculate, take the average depth to which irrigation water infiltrates the soil, subtract the average deviation from this depth, and then divide the result by the average depth to produce a percentage measurement.

A centrifugal pump consists of a pump with an impeller (rotating vanes) and either an electric motor or engine. The rotational energy the motor creates is converted to the hydrodynamic energy of the water as it flows.