Review and comparison of models for describing non-equilibrium and preferential flow and transport in the vadose zone

Šimůnek, Jirka; Jarvis, Nick; Genuchten, Martinus Th. van; Gärdenäs, Annemieke I.

doi:10.1016/s0022-1694(02)00252-4

Cited by 829 publications

(624 citation statements)

References 51 publications

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“…where C w is the mass transfer between two domains, which is assumed to be proportional to the difference in effective saturations of the two regions Simunek et al, 2003):…”

Section: Theorymentioning

confidence: 99%

“…Compared to assuming a pressure head based driving force for the mass transfer, the dualporosity model based on (7) requires significantly less parameters since one does not need to know the retention function (and corresponding parameters) for the matrix region explicitly, but only its residual and saturated water contents (Simunek et al, 2003). The residual water content for the mobile domain of both the base and sub-base layers is assumed to be 0.0 (Simunek et al, 2003).…”

Section: Theorymentioning

confidence: 99%

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A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

Brunetti

Šimůnek

Piro

2016

Journal of Hydrology

115

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a b s t r a c tThe increasing frequency of flooding events in urban catchments related to an increase in impervious surfaces highlights the inadequacy of traditional urban drainage systems. Low Impact Development (LID) techniques have proven to be a viable and effective alternative by reducing stormwater runoff and increasing the infiltration and evapotranspiration capacity of urban areas. However, the lack of adequate modeling tools represents a barrier in designing and constructing such systems. This paper investigates the suitability of a mechanistic model, HYDRUS-1D, to correctly describe the hydraulic behavior of permeable pavement installed at the University of Calabria. Two different scenarios of describing the hydraulic behavior of the permeable pavement system were analyzed: the first one uses a singleporosity model for all layers of the permeable pavement; the second one uses a dual-porosity model for the base and sub-base layers. Measured and modeled month-long hydrographs were compared using the Nash-Sutcliffe efficiency (NSE) index. A Global Sensitivity Analysis (GSA) followed by a Monte Carlo filtering highlighted the influence of the wear layer on the hydraulic behavior of the pavement and identified the ranges of parameters generating behavioral solutions. Reduced ranges were then used in the calibration procedure conducted with the metaheuristic Particle swarm optimization (PSO) algorithm for the estimation of hydraulic parameters. The best fit value for the first scenario was NSE = 0.43; for the second scenario, it was NSE = 0.81, indicating that the dual-porosity approach is more appropriate for describing the variably-saturated flow in the base and sub-base layers. Estimated parameters were validated using an independent, month-long set of measurements, resulting in NSE values of 0.43 and 0.86 for the first and second scenarios, respectively. The improvement in correspondence between measured and modeled hydrographs confirmed the reliability of the combination of GSA and PSO in dealing with highly dimensional optimization problems. Obtained results have demonstrated that PSO, due to its easiness of implementation and effectiveness, can represent a new and viable alternative to traditional optimization algorithms for the inverse estimation of unsaturated hydraulic properties. Finally, the results confirmed the suitability and the accuracy of HYDRUS-1D in correctly describing the hydraulic behavior of permeable pavements.

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“…where C w is the mass transfer between two domains, which is assumed to be proportional to the difference in effective saturations of the two regions Simunek et al, 2003):…”

Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

Brunetti

Šimůnek

Piro

2016

Journal of Hydrology

115

View full text Add to dashboard Cite

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“…At present it is still difficult to use the more complex dual-permeability model (involving matrix and preferential flow, such as used by JARVIS (2007) and KOHLER et al (2001)), because the use of these models has been restricted to theoretical applications and laboratory studies carried out under well-defined and controlled conditions (JARVIS, 2007;SIMUNEK et al, 2003), which require much more input data than models assuming homogeneous flow conditions.…”

Section: Influence Of Soil Texturementioning

confidence: 99%

Impact of Seasonality on Artificial Drainage Discharge under Temperate Climate Conditions

Hirt¹,

Wetzig²,

Amatya³

et al. 2011

International Review of Hydrobiology

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Artificial drainage systems affect all components of the water and matter balance. For the proper simulation of water and solute fluxes, information is needed about artificial drainage discharge rates and their response times. However, there is relatively little information available about the response of artificial drainage systems to precipitation. To address this need, we analysed 11 datasets from artificial drainage study sites (daily or hourly resolution), one daily dataset from an open ditch system, and three datasets from rainfall simulations on tile-drained fields.When we considered all 11 artificial drainage study sites, we found that artificial drainage discharge responded to 70% of all rainfall events during the year, and that the response rate differed significantly between 56% summer and 84% in winter. A median of 23% of the yearly precipitation rate is discharged by artificial drainage systems, varying from 9% of the precipitation in summer to 54% of the precipitation in winter. The artificial drainage systems usually started to respond within the first hour under rain fed conditions, and the response time increased at lower rainfall intensities ( < 1 mm h -1 ). The peak outflow normally occurred within the first two days. The influence of soil texture and land use on artificial drainage discharge rates could not be reproduced properly, due to the spatial high variability caused by other site-specific properties.

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“…The dual-permeability model of Gerke and van Genuchten [1993b] as implemented into HYDRUS-1D [Simunek et al, 2003] uses two mixed-type Richards' equations to describe water flow in the fractures (14a) and the matrix (14b):…”

Section: Effect Of Matrix Block Size On Water Transfer Resultsmentioning

confidence: 99%

Numerical evaluation of a second‐order water transfer term for variably saturated dual‐permeability models

Köhne

Mohanty

Šimůnek

et al. 2004

Water Resources Research

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[1] Dual-permeability models contain a lumped mass transfer term that couples equations for water flow in the soil matrix and fracture systems. Linear first-order transfer terms cannot accurately calculate water transfer between the domains during early times of pressure head nonequilibrium. In this study, a second-order equation for water transfer into spherical rock matrix blocks [Zimmerman et al., 1993[Zimmerman et al., , 1996 was adapted and evaluated comprehensively for water transfer into and out of variably saturated soil matrix blocks of different hydraulic properties, geometries, and sizes, for different initial and boundary conditions. Numerical solutions of the second-order term were compared with respective results obtained with a first-order term and a one-dimensional horizontal flow equation. Accurate results were obtained after implementing two modifications in the second-order term. First, the hydraulic conductivity was calculated as a weighted arithmetic average of conductivities that used pressure heads in matrix and fracture. For a time-variable pressure head boundary condition, a fixed weighting factor of 17 could be applied irrespective of texture, initial condition, and matrix block size up to 10 cm. Second, if direction of water transfer changed (to or from matrix), the initial pressure head was reset to the equilibrium pressure head at the time of transfer reversal. The modified secondorder term was implemented into a dual-permeability model, which closely approximated reference results obtained with a two-dimensional flow model. For rectangular slab-type or comparable geometry of soil matrix, the modified second-order term considerably improves the accuracy of dual-permeability models to simulate variably saturated preferential flow in soil.

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Review and comparison of models for describing non-equilibrium and preferential flow and transport in the vadose zone

Cited by 829 publications

References 51 publications

A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

Impact of Seasonality on Artificial Drainage Discharge under Temperate Climate Conditions

Numerical evaluation of a second‐order water transfer term for variably saturated dual‐permeability models

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