Validation of a root water uptake model to estimate transpiration constraints

Casaroli, Derblai; Lier, Quirijn de Jong van; Neto, Durval Dourado

doi:10.1016/j.agwat.2010.04.004

Cited by 34 publications

(18 citation statements)

References 30 publications

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“…The approach gave somewhat better predictions than the empirical Feddes et al (1978) model which does not consider compensatory uptake. More recently, Faria et al (2010) and Casaroli et al (2010) tested the model in experiments with split-compartment lysimeters and pots planted with sorghum and beans. Their results generally validated the overall model concept, but it was shown that ρ i in Eq.…”

Section: Theory and Conceptsmentioning

confidence: 99%

Simple physics-based models of compensatory plant water uptake: concepts and eco-hydrological consequences

Jarvis¹

2011

Hydrol. Earth Syst. Sci.

102

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Abstract. Many land surface schemes and simulation models of plant growth designed for practical use employ simple empirical sub-models of root water uptake that cannot adequately reflect the critical role water uptake from sparsely rooted deep subsoil plays in meeting atmospheric transpiration demand in water-limited environments, especially in the presence of shallow groundwater. A failure to account for this so-called "compensatory" water uptake may have serious consequences for both local and global modeling of water and energy fluxes, carbon balances and climate. Some purely empirical compensatory root water uptake models have been proposed, but they are of limited use in global modeling exercises since their parameters cannot be related to measurable soil and vegetation properties. A parsimonious physicsbased model of uptake compensation has been developed that requires no more parameters than empirical approaches. This model is described and some aspects of its behavior are illustrated with the help of example simulations. These analyses demonstrate that hydraulic lift can be considered as an extreme form of compensation and that the degree of compensation is principally a function of soil capillarity and the ratio of total effective root length to potential transpiration. Thus, uptake compensation increases as root to leaf area ratios increase, since potential transpiration depends on leaf area. Results of "scenario" simulations for two case studies, one at the local scale (riparian vegetation growing above shallow water tables in seasonally dry or arid climates) and one at a global scale (water balances across an aridity gradient in the continental USA), are presented to illustrate biasesCorrespondence to: N. J. Jarvis (nicholas.jarvis@slu.se) in model predictions that arise when water uptake compensation is neglected. In the first case, it is shown that only a compensated model can match the strong relationships between water table depth and leaf area and transpiration observed in riparian forest ecosystems, where sparse roots in the capillary fringe contribute a significant proportion of the water uptake during extended dry periods. The results of the second case study suggest that uncompensated models may give biased estimates of long-term evapotranspiration at the continental scale. In the example presented here, the uncompensated model underestimated total evapotranspiration by 5-7 % in climates of intermediate aridity, while the ratio of transpiration to evaporation was also smaller than for the compensated model, especially in arid climates. It is concluded that the parsimonious physics-based model concepts described here may be useful in the context of eco-hydrological modeling at local, regional and global scales.

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Section: Theory and Conceptsmentioning

confidence: 99%

Simple physics-based models of compensatory plant water uptake: concepts and eco-hydrological consequences

Jarvis¹

2011

Hydrol. Earth Syst. Sci.

102

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“…The transpiration reduction factor (λ), which represents the relationship between actual and potential transpiration (van Lier et al, 2008), has been widely used to assess OD and WD. The reduction function proposed by Feddes et al (1978) has often been used for estimating λ in hydrological models, such as HYDRUS-1D (Šimůnek and van Genuchten, 2008), and has also been compared with new approaches of calculating λ using matric flux potential (van Lier et al, 2008;Casaroli et al, 2010). Although estimation of λ using the matric flux potential seems more accurate (van Lier et al, 2008;Casaroli et al, 2010), calculation of λ with the Feddes function remains much simpler.…”

Section: Introductionmentioning

confidence: 99%

“…The reduction function proposed by Feddes et al (1978) has often been used for estimating λ in hydrological models, such as HYDRUS-1D (Šimůnek and van Genuchten, 2008), and has also been compared with new approaches of calculating λ using matric flux potential (van Lier et al, 2008;Casaroli et al, 2010). Although estimation of λ using the matric flux potential seems more accurate (van Lier et al, 2008;Casaroli et al, 2010), calculation of λ with the Feddes function remains much simpler. Thus, the Feddes function is a simple and useful proposition for relative evaluation of the effect of soil management on λ dynamics.…”

Section: Introductionmentioning

confidence: 99%

Transpiration Reduction Factor and Soybean Yield in Low Land Soil with Ridge and Chiseling

Gubiani

Müller

Somavilla

et al. 2018

Rev. Bras. Ciênc. Solo

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“…A linear relation between α and matric flux potential, a composite soil hydraulic function defined in Eq. (5), is physically more plausible and was experimentally corroborated by Casaroli et al (2010). Matric flux potential is defined as…”

Section: Theorymentioning

confidence: 99%

Benchmarking test of empirical root water uptake models

Santos

Lier

Dam

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. Detailed physical models describing root water uptake (RWU) are an important tool for the prediction of RWU and crop transpiration, but the hydraulic parameters involved are hardly ever available, making them less attractive for many studies. Empirical models are more readily used because of their simplicity and the associated lower data requirements. The purpose of this study is to evaluate the capability of some empirical models to mimic the RWU distribution under varying environmental conditions predicted from numerical simulations with a detailed physical model. A review of some empirical models used as sub-models in ecohydrological models is presented, and alternative empirical RWU models are proposed. All these empirical models are analogous to the standard Feddes model, but differ in how RWU is partitioned over depth or how the transpiration reduction function is defined. The parameters of the empirical models are determined by inverse modelling of simulated depth-dependent RWU. The performance of the empirical models and their optimized empirical parameters depends on the scenario. The standard empirical Feddes model only performs well in scenarios with low root length density R, i.e. for scenarios with low RWU "compensation". For medium and high R, the Feddes RWU model cannot mimic properly the root uptake dynamics as predicted by the physical model. The Jarvis RWU model in combination with the Feddes reduction function (JMf) only provides good predictions for low and medium R scenarios. For high R, it cannot mimic the uptake patterns predicted by the physical model. Incorporating a newly proposed reduction function into the Jarvis model improved RWU predictions. Regarding the ability of the models to predict plant transpiration, all models accounting for compensation show good performance. The Akaike information criterion (AIC) indicates that the Jarvis (2010) model (JMII), with no empirical parameters to be estimated, is the "best model". The proposed models are better in predicting RWU patterns similar to the physical model. The statistical indices point to them as the best alternatives for mimicking RWU predictions of the physical model.

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Validation of a root water uptake model to estimate transpiration constraints

Cited by 34 publications

References 30 publications

Simple physics-based models of compensatory plant water uptake: concepts and eco-hydrological consequences

Simple physics-based models of compensatory plant water uptake: concepts and eco-hydrological consequences

Transpiration Reduction Factor and Soybean Yield in Low Land Soil with Ridge and Chiseling

Benchmarking test of empirical root water uptake models

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