Open AccessComparing Evapotranspiration Rates Estimated from Atmospheric Flux and TDR Soil Moisture Measurements
Author(s) -
Schelde Kirsten,
Ringgaard Rasmus,
Herbst Mathias,
Thomsen Anton,
Friborg Thomas,
Søgaard Henrik
Publication year - 2011
Publication title -
vadose zone journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.036
H-Index - 81
ISSN - 1539-1663
DOI - 10.2136/vzj2010.0060
Subject(s) - evapotranspiration , eddy covariance , environmental science , water content , moisture , dew , flux (metallurgy) , evaporation , potential evaporation , atmospheric sciences , reflectometry , soil water , dns root zone , soil science , hydrology (agriculture) , chemistry , ecosystem , meteorology , geology , geography , time domain , computer science , condensation , computer vision , biology , ecology , geotechnical engineering , organic chemistry
Measurements of water vapor fluxes using eddy covariance (EC) and measurements of root zone soil moisture depletion using time domain reflectometry (TDR) represent two independent approaches to estimating evapotranspiration. This study investigated the possibility of using TDR to provide a lower limit estimate (disregarding dew evaporation) of evapotranspiration on dry days. During a period of 7 wk, the two independent measuring techniques were applied in a barley ( Hordeum vulgare L.) field, and six dry periods were identified. Measurements of daily root zone soil moisture depletion were compared with daily estimates of water vapor loss. During the first dry periods, agreement between the two approaches was good, with average daily deviation between estimates below 1.0 mm d −1 Toward the end of the measurement period, the estimates of the two techniques tended to deviate due to different source areas contributing to the flux estimates. With certain limitations, TDR‐based evapotranspiration estimates are a promising approach for confining EC‐based evapotranspiration.