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Test of an equation for evaporation from bare soil
Author(s) -
Novak M. D.,
Black T. A.
Publication year - 1982
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr018i006p01735
Subject(s) - potential evaporation , evaporation , advection , soil water , thermodynamics , hydrology (agriculture) , mathematics , chemistry , environmental science , soil science , geotechnical engineering , geology , physics
An empirical equation developed by Idso et al. (1979) at Phoenix, Arizona, to calculate daily average evaporation rates during all three drying stages of a bare soil was tested using measurements made at Agassiz, British Columbia, and is discussed on the basis of available evaporation theory. The results show that their expression for potential evaporation rate did not apply at Agassiz due to differences in the advection regimes at the two locations. The Agassiz potential evaporation rate data was well represented by the Priestley‐Taylor equation with a PT (‘alpha’) = 1.27 ± 0.1. It was concluded that the Idso et al. equation for potential evaporation rate has no greater generality than the Priestley‐Taylor or other such semiempirical approaches. The concept of expressing the stage III rate as proportional to the expression for potential evaporation rate worked marginally well at a culti‐packed site and quite well at a disc‐harrowed site. It was concluded that for soils with stage III rates much greater than 50% of potential evaporation rate, more complete procedures are necessary for calculating evaporation rates during extended drying periods.