Free‐form estimation of the unsaturated soil hydraulic properties by inverse modeling using global optimization

Iden, Sascha C.; Durner, Wolfgang

doi:10.1029/2006wr005845

Cited by 55 publications

(69 citation statements)

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“…For soils with more complex pore size distributions, such as structured soils, more flexible functions of q(h) are needed. These can be either bi-or multimodal functions obtained from simple linear superposition of the unimodal expressions [Ross and Smettem, 1993;Durner, 1994], or as the most flexible way, free-form spline functions [Bitterlich et al, 2004;Iden and Durner, 2007].…”

Section: Introductionmentioning

confidence: 99%

A simple model for describing hydraulic conductivity in unsaturated porous media accounting for film and capillary flow

Peters

Durner

2008

Water Resources Research

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[1] The commonly used models for characterizing hydraulic conductivity of porous media rely on pore bundle concepts that account for capillary flow only and neglect film flow. Experimental evidence suggests that water flow at medium to low water contents in unsaturated porous media can be significantly underestimated by these capillary bundle models. We present a new model that combines a simple film flow function with the capillary flow model of Mualem. This new model can easily be coupled to any water retention function. Moreover, due to its mathematical simplicity, it can easily and efficiently be implemented in existing codes for the numerical solution of unsaturated flow problems. We investigated a set of soil water retention and conductivity data from the literature that all reached dry conditions and were poorly described by existing capillary bundle models. These data were well described with the new model if the model was coupled with an appropriate retention function. Investigation of conductivity data from the UNsaturated SOil hydraulic DAtabase (UNSODA) database showed that, in 75% of all data sets, the new model achieved the best performance using a modified version of Akaike's information criterion. The numeric simulation of an evaporation scenario using Richards's equation showed that by neglecting film flow, the evaporation rate may be underestimated by more than an order of magnitude.Citation: Peters, A., and W. Durner (2008), A simple model for describing hydraulic conductivity in unsaturated porous media accounting for film and capillary flow, Water Resour. Res., 44, W11417,

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Section: Introductionmentioning

confidence: 99%

A simple model for describing hydraulic conductivity in unsaturated porous media accounting for film and capillary flow

Peters

Durner

2008

Water Resources Research

Self Cite

117

150

View full text Add to dashboard Cite

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“…The pore space of a sandy soil consists, for instance, mainly of coarse pores with n values around 12-14, and the pore space of loamy soil contains on the contrary fine, middle and coarse pores, with corresponding n values between 2 and 4. These van Genuchten -Mualem parameters are usually determined based on multi-step outflow experiments with undisturbed soil cores (see, for instance, Iden & Durner 2008).…”

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confidence: 99%

The principle of ‘maximum energy dissipation’: a novel thermodynamic perspective on rapid water flow in connected soil structures

Zehe

Blume

Blöschl

2010

Phil. Trans. R. Soc. B

101

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Preferential flow in biological soil structures is of key importance for infiltration and soil water flow at a range of scales. In the present study, we treat soil water flow as a dissipative process in an open non-equilibrium thermodynamic system, to better understand this key process. We define the chemical potential and Helmholtz free energy based on soil physical quantities, parametrize a physically based hydrological model based on field data and simulate the evolution of Helmholtz free energy in a cohesive soil with different populations of worm burrows for a range of rainfall scenarios. The simulations suggest that flow in connected worm burrows allows a more efficient redistribution of water within the soil, which implies a more efficient dissipation of free energy/higher production of entropy. There is additional evidence that the spatial pattern of worm burrow density at the hillslope scale is a major control of energy dissipation. The pattern typically found in the study is more efficient in dissipating energy/producing entropy than other patterns. This is because upslope run-off accumulates and infiltrates via the worm burrows into the dry soil in the lower part of the hillslope, which results in an overall more efficient dissipation of free energy.

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“…The SCE-UA algorithm combines complex procedures with competition evolution theory, concepts of controlled random search, the complex shuffling method, and downhill simplex procedures to obtain a global optimal estimation. It has been used in many hydrological inverse models for determining unknown hydrological parameters [18,19,[40][41][42][43][44][45]. Previous studies have indicated that the SCE-UA algorithm is able to accurately identify the appropriate values for model parameters.…”

Section: Sce-ua Algorithmmentioning

confidence: 99%

Identification of Groundwater Pollution Sources by a SCE-UA Algorithm-Based Simulation/Optimization Model

Huang

Wang

Zhang

et al. 2018

Water

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Prevention and remediation strategies for groundwater pollution can be successfully carried out if the location, concentration, and release history of contaminants can be accurately identified. This, however, presents a challenge due to complex groundwater systems. To address this issue, a simulation-optimization (S/O) model by integrating MODFLOW and MT3DMS into a shuffled complex evolution (SCE-UA) optimization algorithm was proposed; this coupled model can identify the unknown groundwater pollution source characteristics. Moreover, the Grids Traversal algorithm was used for automatically searching all possible combinations of pollution source location. The performance of the proposed S/O model was tested by three hypothetical scenarios with various combinations of mixed situations (i.e., single and multiple pollution source locations, known and unknown pollution source locations, steady-state flow and transient flow). The field measurement errors was additionally considered and analyzed. Our results showed that this proposed S/O model performed reasonably well. The identified locations and concentrations of contaminants fairly matched with the imposed inputs with average normalized deviations less than 1% after sufficient generations. We further assessed the impact of generation number on the performance of the S/O model. The performance could be significantly improved by increasing generation number, which yet resulted in a heavy computational burden. Furthermore, the proposed S/O model performed more efficiently and robustly than the traditionally used artificial neural network (ANN)-based model. This is due to the internal linkage of numerical simulation in the S/O model that promotes the data exchange from external files to programming variables. This new model allows for solving the source-identification problems considering complex conditions, and thus for providing a platform for groundwater pollution prevention and management.

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Free‐form estimation of the unsaturated soil hydraulic properties by inverse modeling using global optimization

Cited by 55 publications

References 50 publications

A simple model for describing hydraulic conductivity in unsaturated porous media accounting for film and capillary flow

A simple model for describing hydraulic conductivity in unsaturated porous media accounting for film and capillary flow

The principle of ‘maximum energy dissipation’: a novel thermodynamic perspective on rapid water flow in connected soil structures

Identification of Groundwater Pollution Sources by a SCE-UA Algorithm-Based Simulation/Optimization Model

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