Hourly Reference Evapotranspiration by Bowen Ratio and Penman Methods

by Samuel O. Ortega-Farias,
R. H. Cuenca,
M. English,

Document Type: Proceeding Paper

Part of: Management of Irrigation and Drainage Systems: Integrated Perspectives


Hourly and daily reference evapotranspiration (ETo) computed from Bowen ratio energy balance (BREB) measurements were compared with ETo estimated from the hourly Penman equation (ETP). A very good agreement between the two methods was observed on an hourly and daily basis. On an hourly basis, the coefficient of determination and slope of the regression line analysis through the origin were 0.93 and 1.05, respectively. On a daily basis, the coefficient of determination was 0.92 and the slope of the regression line was 0.98. These result suggest that the Penman equation could be used with hourly weather data in the Willamette Valley to predict daily ETo for irrigation purposes.

Subject Headings: Evapotranspiration | Energy methods | Regression analysis | Irrigation | Slopes | Data analysis | Meteorology | Computing in civil engineering

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