ET Standardized Reference Task Committee

The EWRI Task Committee on Standardization of Reference Evapotranspiration has released a draft report entitled "The ASCE Standardized Reference Evapotranspiration Equation." The 172 page report presents a single, unified equation for calculating reference evapotranspiration for two standardized reference surfaces, which are clipped grass and full-cover alfalfa. The reference equation, based on the ASCE Penman-Monteith equation of ASCE Manual 70, is simplified into a standardized form and is presented with standardized forms of all necessary equations for calculating intermediate parameters.

The report appendices include techniques for assessing the integrity and quality of weather measurement data and example calculations for the standardized procedures. The draft report can be can be reviewed and downloaded from the web site.

For more information, contact Committee Chair Mr. Ivan Walter, walterivana1@qwest.net or (303) 798-5967, or Dr. Richard Allen, RALLEN@uidaho.edu or (208) 423-6601, chair of the EWRI Technical Committee on Evapotranspiration in Irrigation and Hydrology.