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Estimating evapotranspiration from the Sonoita Creek Watershed near Patagonia, Arizona
Author(s) -
BenAsher J.
Publication year - 1981
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/wr017i004p00901
Subject(s) - evapotranspiration , watershed , environmental science , hydrology (agriculture) , water balance , dew , relative humidity , dew point , climatology , meteorology , geography , geology , ecology , geotechnical engineering , machine learning , computer science , biology , condensation
In a study that was proposed to evaluate the water balance of the Sonoita Creek watershed near Tucson, Arizona, monthly evapotranspiration was defined by Morton's conceptual approach for large areas. The objective of this study was to test the model. The available climatological data were solar radiation, dew point temperature, mean monthly temperature, and humidity. The model was evaluated by testing the relationship between potential and actual evapotranspiration in Africa. Data for Africa were found to be in agreement with the concept of a complementary relationship. When applied to a small watershed such as Sonoita Creek, the model performance was good on an annual basis and in the hot seasons. In the cold seasons, however, an alternative approach was used. Error analysis indicated that a major source of error lies in the fact that the model neglects the effect of surface moisture content on net radiation. It assumes a single value of net radiation for both the Priestley‐Taylor and Penman’s formulae. However, the assumption of a well‐watered surface, which is inherent in the first formula, must be associated with net radiation which is higher than that associated with Penman's formula. As a result, a maximum error as large as 52% of the annual evapotranspiration may occur.