A Lagrangian model for soil water dynamics during rainfall-driven conditions

Zehe, Erwin; Jackisch, Conrad

doi:10.5194/hess-20-3511-2016

Cited by 24 publications

(73 citation statements)

References 53 publications

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“…The third challenge refers to exchange/mixing of rapid event water particles with the pre-event water to establish local thermodynamic equilibrium (LTE) -the well-organised distribution of water particles in the respective smallest fractions of the available pore space as we further explained earlier (Zehe and Jackisch, 2016).…”

Section: Limitations Of the 1d Representationmentioning

confidence: 99%

“…2). With this it obtains its reference to the water retention curve as explained in Zehe and Jackisch (2016). Then u and D in equation 1 are dependent on the particle's bin.…”

mentioning

confidence: 99%

“…We have shown in a previous study (Zehe and Jackisch, 2016) that the space domain random walk (1D) allows for a physically consistent representation of capillarity-driven, unsaturated soil water flow in accordance with the Richards equation.…”

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confidence: 99%

“…In Zehe and Jackisch (2016) we described this 1D model with water particles of constant mass traveling according to the Itô form of the Fokker Planck equation. The model concept builds on established soil physics by estimating the drift velocity and the diffusion term based on the soil water retention characteristics.…”

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confidence: 99%

“…3.2 Diffusion in the soil matrix based on a 2D random walk 10 Diffusive soil water flow is simulated as non-linear, space domain random walk as presented in our previous study (Zehe and Jackisch, 2016). We describe the trajectory of a singe particle of water in a time step ∆t as Itô form of the Fokker Planck equation based on the formal equivalence of the Richards equation and the advection dispersion equation consisting of a trivial drift term u(θ z,x,t ) = k(θz,x,t) θz,x,t characterising downward water fluxes driven by gravity and a diffusive term representing water movements driven by the matric head gradient and controlled by the diffusivity D(θ z,x,t ) of soil water or particles respectively.…”

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confidence: 99%

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Ecohydrological particle model based on representative domains

Jackisch¹,

Zehe²

2017

Preprint

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Abstract. Non-uniform infiltration and subsurface flow in structured soils is observed in most natural settings. It arises from imperfect lateral mixing of fast advective flow in structures and diffusive flow in the soil matrix and remains one of the most challenging topics with respect to match observation and modelling of water and solutes at the plot scale.This study extends the fundamental introduction of a space-domain random walk of water particles as alternative approach to the Richards equation for diffusive flow (Zehe and Jackisch, 2016) to a stochastic-physical model framework simulating 5 soil water flow in a representative, structured soil domain. The central objective of the proposed model is the simulation of non-uniform flow fingerprints in different ecohydrological settings and antecedent states by making maximum use of field observables for parameterisation. Avoiding non-observable parameters for macropore-matrix exchange, an energy-balance approach to govern film flow in representative flow paths is employed. We present the echoRD model (ecohydrological particle model based on representative domains) and a series of application test cases. 10The model proves as a powerful alternative to existing dual-domain models, driven on experimental data and with selfcontrolled, dynamic macropore-matrix exchange from the topologically semi-explicitly defined structures.

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Section: Limitations Of the 1d Representationmentioning

confidence: 99%

“…2). With this it obtains its reference to the water retention curve as explained in Zehe and Jackisch (2016). Then u and D in equation 1 are dependent on the particle's bin.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Ecohydrological particle model based on representative domains

Jackisch¹,

Zehe²

2017

Preprint

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Multimodal water age distributions and the challenge of complex hydrological landscapes

Rodriguez

Benettin

Klaus

2020

Hydrological Processes

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Travel time distributions (TTDs) are concise descriptions of transport processes in catchments based on water ages, and they are particularly efficient as lumped hydrological models to simulate tracers in outflows. Past studies have approximated catchment TTDs with unimodal probability distribution functions (pdf) and have successfully simulated tracers in outflows with those. However, intricate flow paths and contrasting water velocities observed in complex hydrological systems may generate multimodal age distributions. This study explores the occurrence of multimodal age distributions in hydrological systems and investigates the consequences of multimodality for tracer transport.Lumped models based on TTDs of varying complexity (unimodal and multimodal) are used to simulate tracers in the discharge of hydrological systems under well-known conditions. Specifically, we simulate tracer data from a controlled lysimeter irrigation experiment showing a multimodal response and we provide results from a virtual catchment-scale experiment testing the ability of a unimodal age distribution to simulate a known and more complex multimodal age system. Models are based on composite StorAge Selection functions, defined as weighted sums of pdfs, which allow a straightforward implementation of uni-or multi-modal age distributions while accounting for unsteady conditions. These two experiments show that simple unimodal models provide satisfactory simulations of a given tracer, but they fail in reproducing processes occurring at different temporal scales. Multimodal distributions, instead, can better capture the detailed dynamics embedded in the observations. We conclude that experimental knowledge of flow paths and the systematic use of data from multiple, independent tracers can be used to validate the assumption of water age unimodality. Multimodal age distributions are more likely to emerge in landscapes where the distributions of flow path lengths and/or water velocities are themselves multimodal. In general, age multimodality may not be particularly pronounced and detectable, unless comparable amounts of water with contrasting ages reach a given outflow. K E Y W O R D Shydrological tracer, lumped model, multimodal distribution, StorAge Selection function, travel time, water age distribution, water chemistry, water velocity

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3D stochastic modeling of flow and solute transport in karst vadose zone

Zeqiraj¹

2022

Case Studies in Chemical and Environmental Engineering

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A Lagrangian model for soil water dynamics during rainfall-driven conditions

Cited by 24 publications

References 53 publications

Ecohydrological particle model based on representative domains

Ecohydrological particle model based on representative domains

Multimodal water age distributions and the challenge of complex hydrological landscapes

3D stochastic modeling of flow and solute transport in karst vadose zone

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