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
ABSTRACT
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
for more information please contact Dr. Dale Devitt
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