ET Measurements over Riparian Saltcedar on the Colorado River

Abstract

Evapotranspiration (ET) from an extensive stand of saltcedar on the Colorado River floodplain was defined throughout the growing season by a series of Bowen ratio energy budget measurements in 1980 and 1981. The water table depth at the site near Blythe, California, was about 3 m during the two summers of measurement. Daily ET totals ranged from 2.9 mm/day in early April up to 11.0 mm/day in late June, and dropped down to 1.8 mm/day in late October. These values are means from two separate measurement systems, averaged over measurement periods of two to four days in length. The highest single day total measured by an individual system was 12.7 mm on June 28, 1981. The mid -summer ET rates from the saltcedar at this experimental site are substantial, and rank among the highest rates that have been reported elsewhere for irrigated cropland. The seasonal saltcedar water use of 1727 mm (including 90 mm of annual precipitation) is somewhat lower, however, than earlier, more speculative estimates for saltcedar that ranged up as high as 2100 mm per year.