Consumptive use program (CUP) model
Date
2002-07
Authors
Orang, Morteza N., author
Snyder, Richard L., author
Matyac, J. Scott, author
U.S. Committee on Irrigation and Drainage, publisher
Journal Title
Journal ISSN
Volume Title
Abstract
For many years, published crop efficient (Kc) values have been used to estimate crop evapotranspiration (ETc) from reference evapotranspiration (ETo). The Consumptive Use Program (CUP) was developed to improve estimates of Kc and ETc values to aid in California water planning. CUP computes ETo from mean monthly values for solar radiation, maximum, minimum, and dew point temperature, and wind speed. From this, the program uses a curve-fitting technique to produce daily ETo and rainfall data for a year. Bare soil evaporation is used to estimate Kc values for the off-season and as a baseline for early season Kc calculations. One improvement is to account for the influence of rainfall and/or irrigation frequency on Kc and ETc during initial growth. For tree crops, it is important to account for cover crops, which has not been done in the past. Another improvement is to compute and apply all ETo and Kc values on a daily basis to determine crop water requirements. Using new information on midseason Kc values and bare soil evaporation, a user-friendly Excel program, CUP, was developed to improve long-term estimates that account for rainfall, cover crop, and immaturity effects. This paper presents the advantages of CUP.
Description
Presented at the 2002 USCID/EWRI conference, Energy, climate, environment and water - issues and opportunities for irrigation and drainage on July 9-12 in San Luis Obispo, California.