Heat and water transport in soils and across the soil‐atmosphere interface: 1. Theory and different model concepts

Vanderborght, Jan; Fetzer, Thomas; Mosthaf, Klaus; Smits, Kathleen M.; Helmig, Rainer

doi:10.1002/2016wr019982

Cited by 81 publications

(104 citation statements)

References 112 publications

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“…This perspective informs the approach to the physics of catchment ET developed by M. I. Budyko during the previous century and summarized in his iconic book, Climate and Life [10]. Budyko's approach is "Darwinian," as opposed to "Newtonian" [11,12], because it foregoes reductionist explanations based on constitutive equations [13] in favor of establishing universal relationships based solely on the mass and energy balance laws to which any physical system must conform.…”

Section: The Budyko Hypothesismentioning

confidence: 87%

Understanding the Budyko Equation

Sposito

2017

Water

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Abstract:The Budyko equation has achieved iconic status in hydrology for its concise and accurate representation of the relationship between annual evapotranspiration and long-term-average water and energy balance at catchment scales. Accelerating anthropogenic land-use and climate change have sparked a renewed interest in predictive applications of the Budyko equation to analyze future scenarios important to water resource management. These applications, in turn, have inspired a number of attempts to derive mathematical models of the Budyko equation from a variety of specific assumptions about the original Budyko hypothesis. Here, we show that the Budyko equation and all extant models of it can be derived rigorously from a single mathematical assumption concerning the Budyko hypothesis. The implications of this fact for parametric models of the Budyko equation also are explored.

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Section: The Budyko Hypothesismentioning

confidence: 87%

Understanding the Budyko Equation

Sposito

2017

Water

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“…But when multiphases are involved, two‐domain approach is physical and accurate. This two‐domain approach has been successfully used in multiphase coupling free‐flow and porous‐media flow problems (Baber et al, ; Davarzani et al, ; Han et al, ; Mosthaf et al, ; Tezduyar et al, ; Vanderborght et al, ).…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study of Evaporation From Wavy Surfaces by Coupling Free Flow and Porous Media Flow

Gao

Davarzani

Helmig

et al. 2018

Water Resources Research

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The macroscale roughness of the soil surface has significant influences on the mass/energy interactions between the subsurface and the atmosphere during evaporation. However, most previous works only consider evaporation behavior from flat surfaces. Based on experimental and numerical approaches, the goal of this work is to provide a framework for the understanding of the mechanisms of evaporation from irregular soil surfaces at representative elementary volume scale. A coupling free flow‐porous media flow model was developed to describe evaporation under nonisothermal conditions. For simplicity, sinusoidal‐type wavy surfaces were considered. To validate this modeling approach, an experiment using an open‐ended wind tunnel and soil tank was conducted. The experimental system was instrumented with various environmental sensors to continuously collect atmospheric and subsurface data. Results demonstrate that the surface roughness directly affects both atmospheric and diffusion‐dominated stages I and II evaporation behavior, respectively. The atmospheric conditions directly affect the boundary layer during stage I. The evaporation rate is determined by the diffusion in the boundary layer, but not that in the porous media. The soil properties exert intrinsic influence on the capillary flow and determine the evaporation amount. The complex interaction between capillarity and the boundary layer leads to a heterogeneous distribution of evaporative flux with undulation (i.e., location along the soil surface) and time. Additionally, more and steeper waves indicate more influence from capillary flow, enhancing evaporation compared to a single wave system with the same wave amplitude, while steeper waves also result in a thicker boundary layer and weaken evaporation.

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“…In our manuscript, the multiphase functional equations D(θ,t) and K(θ, t) containing two independent variables θ and t were proposed to describe the effect of the SAP on water transport in soil. This is different from the previous soil hydraulic functions, which usually had only one independent variable θ (Pachepsky, Timlin, & Rawls, 2003;Sun, Meerschaert, Zhang, Zhu, & Chen, 2013;Vanderborght, Fetzer, Mosthaf, Smits, & Helmig, 2017;Zuo et al, 2004). However, it does not mean the multiphase functional equations no longer satisfied the basic equations of soil hydraulics such as the Richards and van Genuchten equations.…”

Section: Independent Variable Selectionmentioning

confidence: 80%

Establishing and validating a root water uptake model under the effects of superabsorbent polymers

Liao

Yang

et al. 2018

Land Degrad Dev

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In‐depth understanding of the patterns of root water uptake (RWU) is the key to improving the water‐use efficiency of plants. Superabsorbent polymers (SAPs) can repeatedly absorb and then release water to plants when needed, which substantially increases the water‐use efficiency of plants in arid and semiarid farming. However, it also creates a challenge in modeling RWU due to unstable soil hydraulic parameters and the unclear response of root growth to SAP application. A controlled soil column experiment was conducted to investigate the response of two important root indexes, that is, root length density (RLD) and root nitrogen mass density (RND), to SAP application, as well as their relationships with RWU. The results showed that the use of the SAP caused a steady increase in RND, and it also substantially increased the RLD in the early stage, but the rate of increase gradually slowed over time. The effect of unstable soil hydraulic parameters on RWU was analyzed in a numerical experiment, which indicated that the time‐dependent effect of SAP on soil hydraulic parameters should be considered to avoid errors in calculating RWU. A specific method for calculating the RWU source/sink term in the Richards equation was proposed and ultimately used as the theoretical value of RWU to verify the RWU models based on RLD and RND to ensure the best one was selected. The results showed that RND was better able to be used for development of the RWU model to simulate the patterns of RWU under SAP application.

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Heat and water transport in soils and across the soil‐atmosphere interface: 1. Theory and different model concepts

Cited by 81 publications

References 112 publications

Understanding the Budyko Equation

Understanding the Budyko Equation

Experimental and Numerical Study of Evaporation From Wavy Surfaces by Coupling Free Flow and Porous Media Flow

Establishing and validating a root water uptake model under the effects of superabsorbent polymers

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