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Water Level Fluctuation in Evapotranspirometers
Author(s) -
Van Hylckama T. E. A.
Publication year - 1968
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/wr004i004p00761
Subject(s) - atmospheric pressure , environmental science , transpiration , atmospheric sciences , water level , hydrology (agriculture) , meteorology , geology , geotechnical engineering , chemistry , physics , biochemistry , photosynthesis , cartography , geography
Eleven plastic lined evapotranspirometer tanks were constructed near Buckeye, Arizona. The levels of the artificially maintained ground water in these instruments show distinct diurnal fluctuations. On bare tanks or on vegetated tanks that are not transpiring, this fluctuation is highly correlated with diurnal and semidiurnal atmospheric fluctuations. Two possible reasons for such response are discussed: There might be air bubbles in the saturated zone, or it might be caused by the flexible plastic lining of the tank. The barometric efficiency is about 40%. On vegetated tanks that are transpiring the water level and barometric curves are out of phase, but if the water levels are corrected for atmospheric pressure fluctuations a curve appears that represents the hourly rate of water use. The results may be important in the interpretation of transpiration well data.