Estimating Evapotranspiration with Water-Production Functions or the Blaney-Criddle Method
T.W. Sammis, E.J. Gregory, C.E. Kallsen
Abstract:
Paper 1982 Transactions of ASAE Vo. 25 (6) 1656-1661
Seasonal evapotranspiration (Et) for cotton (Gossypium hirsutum L.), corn (Zea mays L.), alfalfa (Medicago sativa L.), and barley (Hordeum vulgare L.) can be estimated with either the Blaney-Criddle method or county yield data with a water-production function. As used here, a water-production function is an empirical relationship between yield and evapotranspiration. Blaney-Criddle crop coefficients vary depending upon crop season Et and yield. The original Blaney-Criddle coefficients (K) resulted in Et estimates that were very close, except for corn, to the Et determined from maximum county yields and linear water-production functions. The modified Blaney-Criddle method described by Doorenbos and Pruitt (1977), overestimated seasonal Et compared to Et computed using maximum county yields and linear water-production functions. Blaney-Criddle crop coefficients determined from plot studies in NM, AZ, and CA are larger than the original coefficients and result in estimates of yearly Et that are greater than those determined using county yields and the linear water-production functions.
Blaney and Hanson used the Blaney-Criddle method to compute consumptive use and consumptive use minus
effective precipitation (Consumptive irrigation requirements, CIR) for selected
location in New Mexico. Henderson and Sorenson* expanded the CIR calculations
for many more locations in New Mexico.
* Henderson, D. C. and E. F. Sorensen 1968. Consumptive Irrigation Requirements of
Selected Irrigated Areas in New Mexico. .Agr. Exp. Station. Bulletin 531