Estimation of evapotranspiration, transpiration ratio and water-use efficiency from a sparse canopy using a compartment model

Kato, Tomomichi; Kimura, Reiji; Kamichika, Makio

doi:10.1016/j.agwat.2003.10.001

Cited by 117 publications

(60 citation statements)

References 33 publications

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“…At annual scale, T/ET of these three forests were higher than that of grasslands (Hu et al, 2009;Lauenroth and Bradford, 2006) and croplands (Kato et al, 2004), which resulted from the higher LAI (Huxman et al, 2005). The interannual variation and the spatial variation of T/ET were governed by mean annual G c (MG c ) (Fig.…”

Section: Factors Affecting the Variations Of T/etmentioning

confidence: 99%

“…Shuttleworth-Wallace model (S-W model) is the first model designed for ET partition, which is a physically-based combination model based on Penman-Monteith equation (Shuttleworth and Wallace, 1985). S-W model has also been regarded as an accurate model and the foundation of other ET partition models, which provides a validation for other models (Kool et al, 2014) and has been widely used (Hu et al, 2009;Iritz et al, 2001;Kato et al, 2004), while there have been no attempt in using S-W model to partition ET into its components at forests of China, which occupied an important portion in global forests (FAO, 2010). China has conducted eddy covariance measurements since 2003 at three forests along the north-south transect of Eastern China (NSTEC), which experiences apparent decreasing temperature and precipitation gradients with the increasing latitude .…”

Section: Introductionmentioning

confidence: 99%

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Spatiotemporal variations of T/ET (the ratio of transpiration to evapotranspiration) in three forests of Eastern China

Zhu

et al. 2015

Ecological Indicators

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The ratio of transpiration to evapotranspiration (T/ET) Forest a b s t r a c t Evapotranspiration (ET), which is comprised by evaporation from soil surface (E), transpiration (T) and evaporation from the intercepted water by canopy (EI), plays an important role in maintaining global energy balance and regulating climate. Quantifying the spatiotemporal variations of T/ET (the ratio of T to ET) can improve our understandings on the role of vegetation ecophysiological processes in climate regulation. Using eddy covariance measurements at three forest ecosystems (Changbaishan temperate broad-leaved Korean pine mixed forest (CBS), Qianyanzhou subtropical coniferous plantation (QYZ) and Dinghushan subtropical evergreen mixed forest (DHS)) in north-south transect of Eastern China (NSTEC), we run the revised Shuttleworth-Wallace model (S-W model), validated its performance with the water vapor fluxes measured at two layers, and quantified the spatiotemporal variations of T/ET. The S-W model performed well in simulating ET and T/ET. The mean value of annual T/ET at three forests during the observation period all exceeded 0.6. The diurnal variation of canopy stomal conductance (G c ) dominated that of T/ET. The seasonal dynamics of T/ET was mainly shaped by that of leaf area index (LAI), vapor pressure deficit (VPD) and air temperature (T a ) through altering G c and the portion that the energy absorbed by canopy (P EC ) at temperate forest (CBS), while the seasonal dynamics of T/ET at subtropical forests (QYZ and DHS) were mainly affected by T a , net radiation, VPD, and soil water content through altering G c and soil surface conductance (G s ). The variation of mean annual G c governed the interannual varaition and spatial variation of T/ET. Therefore, forests in Eastern China played an important role in regulating climate through T and G c primarily affected the spatial and temproal variations of the role of forest T in regulating climate.

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Section: Factors Affecting the Variations Of T/etmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spatiotemporal variations of T/ET (the ratio of transpiration to evapotranspiration) in three forests of Eastern China

Zhu

et al. 2015

Ecological Indicators

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“…The canopy resistance rsc was calculated following Eq. 1, while the aerodynamic resistances raa and ras as well as the soil surface resistance coefficients Cc and Cs were computed as reported by Shuttleworth and Gurney (1990) and Kato et al (2004). The SW model is expected to provide affordable results for bare to full covered soils under water stressed and well-watered conditions.…”

Section: Two-layers Shuttleworth (Sw) Modelmentioning

confidence: 99%

“…This is mainly due to the complexity of the crop coefficient, which actually integrates several physical and biological factors. On the contrary, many researchers assessed the validity of "direct" approaches (Kato et al, 2004;Farahani and Bausch, 1995;Lafleur and Rouse, 1990), concluding that their ability to simulate the processes is good, provided that the resistances involved are calculated appropriately (Brisson et al, 1998). In order to adopt these models for operational uses, however, the main problems limiting their practical application must be solved.…”

Section: Introductionmentioning

confidence: 99%

Evapotranspiration models for a maize agro-ecosystem in irrigated and rainfed conditions

Facchi¹,

Gharsallah²,

Gandolfi³

2013

J Agricult Engineer

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A high level of accuracy in the estimation of crop evapotranspiration (ET) may lead to significant savings of economic and water resources in irrigated agriculture. Although ET is a fundamental process in many applications, it cannot be directly measured but it has to be estimated by monitoring the exchange of energy/water above the vegetated surface (micrometeorological methods), or as a residual term of the hydrological balance (lysimeters, soil water budget). The techniques to be adopted are often complex, costly and require specific equipment. Thus, since the '50s, many researchers have devoted their activity to the development of models for its estimation. The available approaches can be classified in "direct" methods, based on the original Penman-Monteith (PM) equation, in which the canopy resistance rc is modelled, and "indirect" methods, based on the preliminary calculation of ET for a well-watered reference grass (ET0) with a constant rc, which is then multiplied by a crop coefficient Kc and, in case, by a stress coefficient Ks to obtain ET. Even if the latter approaches are more widely adopted for their practical simplicity, many authors show that the former often provide better ET estimates in absence of calibration of crop parameters. In this study the performances of different direct and indirect methods were evaluated in the case of a surface irrigated and of a rainfed maize grown in the Padana Plain (Northern Italy). The following models were considered: the "one-layer" original PM equation with three different models for rc (Monteith, Jarvis, Katerji-Perrier), the "two-layers" PM model proposed by Shuttleworth and Wallace, the "single" and "double" crop coefficient models illustrated in the Paper FAO-56. Latent heat fluxes measured in 2006 and 2011 in an experimental maize field by eddy-covariance were used to evaluate the models accuracy. Crop, soil and meteo data monitored contextually were used for the implementation of the different models. Results confirm that direct methods are more performing for both irrigated (2006) and rainfed (2011) conditions, with the SW model providing the best results and the FAO-56 models with generalized crop coefficients overestimating ET, especially during the middle growth stage.

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“…Thereby, R n is one of the major input variables in soil evaporation models (Black et al, 1970), evapotranspiration models (Monteith and Unsworth, 1990) and hybrid models that estimate evaporation and transpiration separately (Kato et al, 2004). Furthermore, R n is also used in models that produce estimates of the period of leaf wetness (Sentelhas and Gillespie, 2008).…”

Section: Introductionmentioning

confidence: 99%

Observed and modelled solar radiation components in sugarcane crop grown under tropical conditions

Santos¹,

Souza²,

Lyra³

et al. 2017

International Agrophysics

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A b s t r a c t. The net radiation over vegetated surfaces is one of the major input variables in many models of soil evaporation, evapotranspiration as well as leaf wetness duration. In the literature there are relatively few studies on net radiation over sugarcane crop in tropical climates. The main objective of the present study was to assess the solar radiation components measured and modelled for two crop stages of a sugarcane crop in the region of Rio Largo, Alagoas, North-eastern Brazil. The measurements of the radiation components were made with a net radiometer during the dry and rainy seasons and two models were used to estimate net radiation: the Ortega-Farias model and the Monteith and Unsworth model. The highest values of net radiation were observed at the crop development stage, due mainly to the high indices of incoming solar radiation. The daily average albedos of sugarcane at the crop development and mid-season stages were 0.16 and 0.20, respectively. Both models showed a better fit for the crop development stage than for the mid-season stage. When they were inter-compared, Monteith and Unsworth model was more efficient than Ortega-Farias model, despite the dispersion of their simulated radiation components which was similar.

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Estimation of evapotranspiration, transpiration ratio and water-use efficiency from a sparse canopy using a compartment model

Cited by 117 publications

References 33 publications

Spatiotemporal variations of T/ET (the ratio of transpiration to evapotranspiration) in three forests of Eastern China

Spatiotemporal variations of T/ET (the ratio of transpiration to evapotranspiration) in three forests of Eastern China

Evapotranspiration models for a maize agro-ecosystem in irrigated and rainfed conditions

Observed and modelled solar radiation components in sugarcane crop grown under tropical conditions

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