Regional estimates of evapotranspiration from irrigated alfalfa

• Main Author: Konrad, Sara L.
• Other Authors: Gay, Lloyd W.
• Language: en
• Published: The University of Arizona. 1997
• Online Access: http://hdl.handle.net/10150/192099

This study applied a simple empirical evaporation model (SWET) proposed by Osmolski (1985) to estimate evapotranspiration over alfalfa using only solar radiation and wind data. SVVET was used to inventory evapotranspiration from irrigated alfalfa in lowland deserts in the southern half of Arizona. Meteorological data were obtained from the Arizona Meteorological Network (AZMET) for 21 sites in key agricultural regions. The number of years at each site ranged from 10 to 3 making possible for the first time the expression of long term means and standard deviations of alfalfa evapotranspiration. Results from SWET are compared to values of Penman reference evapotranspiration produced by AZMET and to estimates derived from the Blaney-Criddle and Thornthwaite methods. Temporal variability of daily estimates is examined as the scale lengthens from days to years. The spatial variability of predicted evapotranspiration is small across the width of southern Arizona, as illustrated by contour plots of evapotranspiration.