Rensburg, Leon D. van

Tesfuhuney, Weldemichael A.

Walker, Sue

English

Wageningen UR (University & Research Centre): Publication System

Comparison of energy available for evapotranspiration under in-field 
rainwater harvesting with wide and narrow runoff strips 
Weldemichael A. Tesfuhuney1, Sue Walker1 and Leon D. van Rensburg1 
1Department of Soil, Crop and Climate Sciences, University of Free State, PO Box 339 Bloemfontein 9300 RSA 
Email: weldit78@yahoo.com 
 
ABSTRACT 
When a maize crop is grown in an arrangement with basin and runoff areas, as in the case of in-field rainwater 
harvesting (IRWH), heat and water vapour transfer within the canopy influences the energy and water balances. The 
aim of the study was to quantify the energy balance components and to estimate evapotranspiration (ET) from the 
maize crop under IRWH with wide and narrow runoff strips. Based on micrometeorological measurements, energy 
balance components were compared for selected days under dry and wet conditions. The diurnal changes and daily 
peaks of evaporation fluxes around midday were analysed. The average fraction of available energy was used to 
evaluate the efficiency of converting available energy to latent heat flux (LE). The results indicated that the LE was 
dominant and higher in wide compared to narrow runoff strips (RSL) during both dry and wet conditions. However, 
sensible heat (Hs) showed lower values on wide runoff strips during wet conditions due to the advective effect of the 
runoff area. Therefore, the wide runoff strip with a higher leaf area index (LAI) of 2.43 had more ET and used more 
energy on evaporating water compared to narrow runoff with a lower LAI of 1.42. Wide runoff strips converted the 
higher available energy more efficiently into a higher biomass production. During wet days, the wide RSL used 
more than 70% of the available energy, while the narrow RSL response to the available energy (63%) was stronger 
during dry compared to wet days. 
 
Keywords: Water harvesting, Energy balance, Micrometeorology, Latent heat flux 
 


Comparison of energy available for evapotranspiration under in-field rainwater harvesting with wide and narrow runoff strips

https://library.wur.nl/ojs/index.php/AE2012/article/download/12431/11934

Comparison of energy available for evapotranspiration under in-field rainwater harvesting with wide and narrow runoff strips

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