We compared evaporation measurements from a floating pan, land pan, chamber, and the Priestley-Taylor (PT) equation. Floating
pan, land pan, and meteorological data were collected from June 6 to July 21, 2005, at a small wetland in the Canadian River
alluvium in central Oklahoma, USA. Evaporation measured with the floating pan compared favorably to 12 h chamber measurements.
Differences between chamber and floating pan rates ranged from −0.2 to 0.3 mm, mean of 0.1 mm. The difference between chamber
and land pan rates ranged from 0.8 to 2.0 mm, mean of 1.5 mm. The mean chamber-to-floating pan ratio was 0.97 and the mean
chamber-to-land pan ratio was 0.73. The chamber-to-floating pan ratio of 0.97 indicates the use of a floating pan to measure
evaporation in small limited-fetch water bodies is an appropriate and accurate method for the site investigated. One-sided
Paired t-Tests indicate daily floating pan rates were significantly less than land pan and PT rates. A two-sided Paired t-Test
indicated there was no significant difference between land pan and PT values. The PT equation tends to overestimate evaporation
during times when the air is of low drying power and tends to underestimate as drying power increases.
Keywords Chamber - Class A pan - Evaporation - Floating pan - Land pan - Net radiation - Priestley-Taylor