Climatic Assessment of the Arid Southwestern United States for Use in Predicting Evaporation of Turfgrass

D. A. Devitt
D. Kopec
M. J. Robey
R. L. Morris
P. Brown
V. A. Gileault
D. C. Bowman


Climatic conditions were assessed at three locations in the arid southwestern United States over a two year period. The three locations were Las Vegas, NV, Tucson, AZ and Palm Desert, CA. Automated weather stations monitored maximum and minimum temperature, relative humidity, solar radiation, wind run and rainfall. Data were input into the empirical based Penman combination equation to predict potential evapotranspiration (ETo). Surveys were conducted at all three location to evaluate the soil conditions, water availability, turfgrass management and crop coefficients used. Only slight differences existed between average monthly minimum temperatures, maximum temperature and solar radiation at the three sites. However, differences in average monthly wind run and relative humidity at the three sites led to greater separation in the ETo estimates during summer months. These differences resulted in a 7% and 13% error in estimating monthly ETo at the Palm Desert and Tucson sites respectively, based on using the Las Vegas monthly ETo data. However, when Palm Desert monthly ETo data was used to predict ETo at the Tucson site, a slightly larger error of 18% was observed. Greater variability existed in the daily ETo estimates during most months at the Tucson site, compared to the other two sites. This ETo variability combined with higher rainfall and a larger number of days on which temperatures dropped below freezing would indicated that potential differences in the response of turfgrass such as bermudagrass (Cynodon dactylon) would be greatest if comparisons were made with the Tucson site. However, the error is still low enough to suggest that under similar cultural management at any one of the three locations could be transferred and used at the other two locations, if consideration was given to the error in estimate and the time of year.

Article published in the Journal of Turfgrass Management, Vol. 1(2) 1995
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