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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING WATER PRODUCTIVITY AND NEW WATER MANAGEMENT TECHNOLOGIES TO SUSTAIN RURAL ECONOMIES

Location: Soil and Water Management Research

Title: Recent advances in the two source energy balance model to calculate E.T. and ET for row crops

Authors
item Colaizzi, Paul
item Agam, Nurit -
item Tolk, Judy
item Evett, Steven
item O`shaughnessy, Susan
item Gowda, Prasanna
item Howell, Terry
item Kustas, William
item Anderson, Martha

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 27, 2012
Publication Date: October 23, 2012
Citation: Colaizzi, P.D., Agam, N., Tolk, J.A., Evett, S.R., Oshaughnessy, S.A., Gowda, P., Howell, T.A., Kustas, W.P., Anderson, M.C. 2012. Recent advances in the two source energy balance model to calculate E.T. and ET for row crops [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. 2012 CDROM. Paper No 204-2.

Interpretive Summary: Crops use water in two different ways, evaporation and transpiration. Most evaporation is from the soil, and transpiration is from the plant. Only transpiration contributes directly to plant growth, but soil evaporation does not. Therefore, water can be conserved by reducing soil evaporation. Both evaporation and transiration are difficult to measure. Instead, they can be calculated using a mathematical model. We improved an existing model for this purpose. The model can be used to test different methods that might reduce soil evaporation of crops. This presentation reviews these improvements, and discusses improvements that are still needed.

Technical Abstract: Calculation of evaporation (E), transpiration (T), and evapotranspiration (ET) are fundamental to assess strategies and tactics that might improve crop water productivity in both irrigated and dryland production systems. One approach to calculate E, T, and ET is by a two-source energy balance model (TSEB), which calculates the energy budget of the soil and canopy separately. A remote sensing-based TSEB has been developed that only requires a single measurement of directional surface brightness temperature, commonly available meteorological variables, and measurements or estimates of crop phenology. Recent advances in the TSEB have addressed several aspects that relate to the non-random spatial distribution of row crop vegetation, the unique view geometries of ground-based remote sensing platforms, and the wide range of meteorological conditions that are typical of semiarid, advective climates. These advances were applied to the TSEB and tested against measurements of E, T, and ET using microlysimeters, sap flow gauges, and large weighing lysimeters, respectively. This presentation will review these advances and discuss needs for future research.

Last Modified: 8/2/2014
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