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2012 IAL Conference. Jasim Uddin Rod Smith Nigel Hancock Joseph Foley National Centre for Engineering In Agriculture (NCEA) University of Southern Queensland, Toowoomba QLD 4350 Australia. A novel technique to measure the total evaporation and its components during sprinkler irrigation . - PowerPoint PPT Presentation
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2012 IAL Conference
A novel technique to measure the total evaporation and its components during
sprinkler irrigation
Jasim UddinRod Smith
Nigel HancockJoseph Foley
National Centre for Engineering In Agriculture (NCEA)University of Southern Queensland,
Toowoomba QLD 4350Australia
Presentation layout
Background Hypothesis Objectives Methodology Results Conclusions
BackgroundFigure 1: Components of evaporation losses during sprinkler
irrigation
Droplet evaporation
Canopy evaporationSoil evaporation
Background
Components Theoretical Experimental
Canopy evaporation
8% Unable to measure
Droplet evaporation
<1% 0-45%
Soil evaporation negligible Unable to measure
Limitations of the catch-can method
Laborious and time consuming Unable to measure ET over crop
(Source : Smith, Cotton CRC)
Catch-can
Limitations of the lysimeter method
Figure 3: Measured ET using lysimeter and predicted ET (source : Thompson et al. 1997)
Lysimeter could not measure ET during irrigation
Irrigation period
Background
Hypothesis:Eddy covariance – sap flow method can be used to measure total ET and its components during sprinkler irrigation
Objectives: To measure the total ET and transpiration
To estimate the components of ET
Methodology
Figure 4: Experimental set upEddy covariance system
Sap flow system
Methodology
Eddy covariance (ECV) system Sonic anemometer
Infrared Gas analyzer
Net radiometer
Sap flow system
Datalogger Hub
sensor Interface
MethodologyMeasurements
Latent heat flux (λE) and sensible heat flux (H)Eddy covariance technique
Net radiation (Rn) Four components net radiometer
Soil heat flux (G)Soil heat flux plates
Transpiration (T) measured bySap flow method
Air temperature (Ta) and Relative humidity (RH)
Temperature and RH probe
nE ET R H G
MethodologyData processing
Calculation of λE:
Bowen Ratio,
Calculations of ET in mm/hr :
Calculations of ETref : FAO Penman-Monteith
1nR G
E
/H E
(28.36 24)EET
Results Figure 3: Measurement of ET and tarnspiration
over mature cotton
Results Figure 4: Components of total ET measured by ECV-sap flow
method
ConclusionsMeasurement of total ET during sprinkler irrigation is possible which includes: canopy evaporation and droplet evaporation during
irrigation reduction of transpiration during irrigation canopy interception soil evaporation
Thanks for your attendance
Questions