Wheat canopy temperature: A practical tool for evaluating water requirements

Abstract

Canopy temperatures were measured on durum wheat grown in six differentially irrigated plots. Soil water content was measured by using a neutron‐scattering technique at two locations within each plot. Water contents, in 20‐cm increments to 160 cm, were determined two to five times per week. Using a sliding cubic smoothing technique, we calculated daily water contents and thus water depletion rates for the entire growing season. Canopy temperatures were measured daily between 1330 and 1400 hours. Air temperatures measured at 150 cm above the soil surface were subtracted from the canopy temperatures to form the difference Tc – Ta. The summation of Tc – Ta over time yielded a factor termed the ‘stress degree day’ (SDD). The SDD concept shows promise as an indicator for determining the times and amounts of irrigations. An expression relating evapotranspiration (ET) to net radiation and Tc – Ta was simplified and tested by using ET measurements with a lysimeter. The expression was used to predict water use by wheat in the six plots. Predicted ET and measured water used agreed reasonably well. The expression may be useful in determining amounts of irrigation water to apply.

Validation of the land-surface temperature products retrieved from Terra Moderate Resolution Imaging Spectroradiometer data

“…The remotely sensed LST has been used in land cover and land-cover change analysis (Ehrlich & Lambin, 1996;Lambin & Ehrlich, 1997) and in the production of the Moderate Resolution Imaging Spectroradiometer (MODIS) land cover product, in estimation and parameterization of surface fluxes (Brutsaert, Hsu, & Schmuuge, 1993;French, Schmugge, & Kustas, 2000b), and in estimating the diurnal cycle (Jin & Dickinson, 1999). LST can be also used to monitor drought and estimate surface soil moisture (Feldhake, Glenn, & Peterson, 1996;McVicar & Jupp, 1998), to evaluate water requirements of wheat (Jackson, Reginato, & Idso, 1977) and to determine frosts in orange groves (Caselles & Sobrino, 1989).…”

Surface resistance calibration for a hydrological model using evapotranspiration retrieved from remote sensing data in Nahe catchment forest area

“…The simplified method was firstly proposed by Jackson et al (1977), in which the sensible heat flux is linearly related to the instantaneous temperature difference between surface and air at midday with a constant B, as well as the integrated daily soil heat flux is considered as negligible. Based on the surface energy equation, evapotranspiration is obtained as its energy consumption -the latent heat flux, by subtracting sensible heat flux from net radiation.…”

A remote sensing-based approach for water accounting in the East Rapti River Basin, Nepal

“…In this framework, land use and land cover classes and their benefits for agriculture, economy and environment are explicitly described (Karimi et al 2012). WA+, a remote sensing data based water accounting framework, can be applied when ground data are not available or not accessible.Accurate estimation of actual evapotranspiration (ET a ) is a key challenge for analyzing water availability and water consumption in a river basin (Perry 2007 Jackson et al (1977) performed pioneering work on thermal infrared applications for assessing ET fluxes, which was followed by development of several new ET algorithms using remotely sensed thermal measurements (see reviews by Kustas et al 2003, Courault et al 2005, Kalma et al 2008, Allen et al 2011). Many of these methods were developed and validated in a flat landscape.…”

“…Allen et al 2011, Bastiaanssen and Bandara 2001, Kustas et al 2003. For example, Jackson et al (1977) performed pioneering work on thermal infrared applications for assessing ET fluxes, which was followed by development of several new ET algorithms using remotely sensed thermal measurements (see reviews by Kustas et al 2003, Courault et al 2005, Kalma et al 2008, Allen et al 2011). Many of these methods were developed and validated in a flat landscape.…”