Measurement of evapotranspiration during sprinkler irrigation using a precision energy budget (Bowen ratio, eddy covariance) methodology

Uddin, J. and Hancock, N. H. and Smith, R. J. and Foley, J. P. (2013) Measurement of evapotranspiration during sprinkler irrigation using a precision energy budget (Bowen ratio, eddy covariance) methodology. Agricultural Water Management, 116. pp. 89-100. ISSN 0378-3774


Eddy covariance (ECV) is a micrometeorological mass transfer method for measuring evapotranspiration (ET) which has been used successfully for the last decade to measure evapotranspiration from natural and agricultural plant communities. However, no such usage has been reported in relation to evaporation losses occurring during sprinkler irrigation. Instead, sprinkler irrigation research has focused on using traditional methods acknowledged to have many limitations. In this field study, the feasibility of precision energy budget measurement, utilising ECV, to measure the total ET during sprinkler irrigation over different surfaces has been established.
The trials were carried out at small scale using a low-pressure impact type sprinkler irrigation system over bare soil, grass and cotton during the Australian summer of 2010–11. All radiation components plus soil heat flux were measured. The sensible and latent heat fluxes measured using ECV were used to deduce instantaneous Bowen ratio values and hence partition the energy available for sensible plus latent heat (ET) transport. From the measurements of energy fluxes, the effect of advection on irrigation was inferred. Non-dimensionalisation of measured ET permitted comparison of the rate of change of ET in different phases of measurement, i.e. pre-, during and post-irrigation.
Results indicated that the technique was clearly able to measure the different rates of total evaporation over the short crops before, during and after sprinkler irrigation and a relative ET discrimination of order 0.06 mm h−1 was achieved, equivalent to a discrimination in the difference between irrigation and nonirrigation evaporation rates of ±11%. In addition, the results showed that nondimensional ET ranged from 1.4 to 1.6 times the reference (non-irrigating) ET value for mature cotton of height approaching 1 m.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to published version due to publisher copyright policy.
Faculty/School / Institute/Centre: Current - USQ Other
Faculty/School / Institute/Centre: Current - USQ Other
Date Deposited: 05 Dec 2012 05:23
Last Modified: 10 Jul 2014 06:24
Uncontrolled Keywords: eddy covariance; Bowen ratio; evapotranspiration; sprinkler irrigation; nondimensionalisation
Fields of Research (2008): 07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070199 Agriculture, Land and Farm Management not elsewhere classified
07 Agricultural and Veterinary Sciences > 0799 Other Agricultural and Veterinary Sciences > 079901 Agricultural Hydrology (Drainage, Flooding, Irrigation, Quality, etc.)
09 Engineering > 0999 Other Engineering > 099901 Agricultural Engineering
Socio-Economic Objectives (2008): B Economic Development > 82 Plant Production and Plant Primary Products > 8298 Environmentally Sustainable Plant Production > 829805 Management of Water Consumption by Plant Production
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