Moving Multi-Front (MMF): A generalized Green-Ampt approach for vertical unsaturated flows

Alastal, Khalil; Ababou, Rachid

doi:10.1016/j.jhydrol.2019.124184

Cited by 12 publications

(9 citation statements)

References 46 publications

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“…The thus predicted infiltration by GA was close to Hydrus‐1D predictions for a soil column with a single initial water content. Alastal and Ababou (2019) also succeeded using the inflection point of the van Genuchten (1980) water retention curve for h f to predict infiltration in two homogeneous soils with a modified GA model. Despite these results, both methods would fail in several cases of the 75 scenarios evaluated in our study.…”

Section: Resultsmentioning

confidence: 99%

“…Using the inflection point of the van Genuchten (1980) water retention curve as an estimate of h f , as suggested by Alastal and Ababou (2019), yields

h_{f} = \frac{1}{normalα} {((), 1 - \frac{1}{n})}^{1 / n}

where n is the respective van Genuchten (1980) parameter. According to this equation, h f would be 45 cm in the clay loam soil and ranged between 11 and 16 cm for the other soils.…”

Section: Resultsmentioning

confidence: 99%

“…The model is expected to succeed in infiltration rate prediction when provided with specific boundary conditions. The upper boundary condition refers to the continuous ponding on the soil surface, whereas the bottom boundary condition establishes an abrupt change from θ i to θ s at the saturation front, thus characterizing a piston‐type flow (Chen et al., 2015; Alastal & Ababou, 2019; Ma, Feng, Su, Gao, & Huo, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…(1996) equation, which estimates the capillary pressure at the wetting front as a function of van Genuchten (1980) retention parameters. Bouwer (1969) suggested to set h f as the air‐entry value suction divided by two, whereas Alastal and Ababou (2019) used the inflection point of the Van Genuchten (1980) water retention curve to define h f . According to these approaches, values of h f would change among soils, but h f would not be sensitive to the initial soil water content, whereas it is physically plausible to expect the initial water content to affect h f .…”

Section: Introductionmentioning

confidence: 99%

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Calibration of Green‐Ampt wetting front suction for ponding and non‐ponding infiltration scenarios

Pereira

Gubiani

Lier

2020

Soil Science Soc of Amer J

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Mathematical formulations for layered soil profiles and corresponding parameterization to improve performance of the Green‐Ampt model (GA) have not always shown accurate. We evaluated GA maintaining its assumption of saturated flow but calibrating the effective matric suction at the wetting front (hf) by damping the initial matric suction (hi). The proposition was evaluated comparing cumulative infiltration simulated by GA to that simulated by Hydrus‐1D for five soils from three texture classes, three initial matric suctions, and five 24‐h water supply regimes. For each case, GA was run with a decreasing series of 20 values of hf from the initial matric suction (10, 100, or 1000 cm) to values near 1 cm. To minimize the relative error (RE) between cumulative infiltration simulated by GA and Hydrus‐1D for the 24‐h period we found the required damping of hf to be dependent on soil type, water supply regime and initial matric suction, the latter being the most important factor. The calibration of hf was efficient to approach GA predictions to numerical Hydrus‐1D simulations, even for cases with alternating ponding and non‐ponding conditions. Results suggest a large reduction of wetting front matric suction hf may be necessary to approach cumulative infiltration predicted by GA to corresponding Hydrus‐1D predictions, especially during rainfall events that do not imply in continuous ponding. Taking hf somewhere between 1 and 3 cm, values of RE of cumulative infiltration during the first 24 h were below 10% for all cases, independent of soil type, rainfall characteristics or initial water content.

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Section: Resultsmentioning

confidence: 99%

“…Using the inflection point of the van Genuchten (1980) water retention curve as an estimate of h f , as suggested by Alastal and Ababou (2019), yields

h_{f} = \frac{1}{normalα} {((), 1 - \frac{1}{n})}^{1 / n}

where n is the respective van Genuchten (1980) parameter. According to this equation, h f would be 45 cm in the clay loam soil and ranged between 11 and 16 cm for the other soils.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Calibration of Green‐Ampt wetting front suction for ponding and non‐ponding infiltration scenarios

Pereira

Gubiani

Lier

2020

Soil Science Soc of Amer J

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show abstract

“…Such research can consider one-dimensional vertical, or horizontal, geometries. In the first group, for instance, List and Radu (2016) proposed a new linearization scheme with better convergence properties; Alastal and Ababou (2019) Multi-Front method for solving the Richards equation for unsaturated flow in vertical homogeneous porous columns, and Shanmugam et al (2020) presented a weighting scheme for the computation of hydraulic conductivities that can produce more accurate results. A small snapshot of the different software currently available for solving Richards equation is reported in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Open-source high-performance software packages for direct and inverse solving of horizontal capillary flow

Gerlero

Kler

2023

Capillarity

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This work introduces Fronts, a set of open-source numerical software packages for nonlinear horizontal capillary-driven flow problems in unsaturated porous media governed by the Richards equation. The software uses the Boltzmann transformation to solve such problems in semi-infinite domains. The scheme adopted by Fronts allows it to be faster and easier to use than other tools, and provide continuous functions for all involved fields. The software is capable of solving problems that appear in hydrology, but also in other particular domains of interest such as paper-based microfluidics. As the first known open-source implementation to adopt this approach, Fronts has been validated against analytical solutions as well as existing software achieving remarkable results in terms of computational costs and numerical precision, and is meant to aid the study and modeling of capillary flow. Fronts can be freely downloaded and installed, and offers a friendly environment for new users with its complete documentation and tutorial cases.

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A simple, accurate, and explicit form of the Green–Ampt model to estimate infiltration, sorptivity, and hydraulic conductivity

Sadeghi,

Loescher,

Jacoby

et al. 2024

Vadose Zone Journal

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Finding an explicit solution to the widely used Green–Ampt (G–A) one‐dimensional infiltration model has been subject of efforts for more than half a century. We derived an explicit semiempirical approach that combines accuracy with simplicity, a concept that has been generally neglected in previous studies. The equation is , with F (L), Ks (L/T), S (L/T0.5) and t (T) being cumulative infiltration, saturated hydraulic conductivity, sorptivity, and time, respectively. Relative errors (ɛ) by the application of this equation generally do not exceed ±0.3% in most applied infiltration problems faced by water resources engineering today. We show both numerically and mathematically that │ɛ│> 0.3% could only occur if Kst/F > 0.904, a criterion that could apply to sand and loamy sand soils (i.e., coarse texture) and if they experience infiltration rates for over 6 h and 19 h, respectively. Hence, we also derived a simple linear adjustment in the model as Fadj ≅ 0.9796 F + 0.335 S2/Ks to address these longer infiltration rates, and to assure that ɛ remains within the expected ±0.3% range of uncertainty. A linearized regression technique was also developed to accurately estimate S and Ks when the G–A model is used. We numerically demonstrated that our fitting method could be used even when the G–A approach is less valid (diffusive soils), provided that the actual value of the capillary length (λ) is initially known. An added benefit of our approach is that by setting λ equal to 1/3 and 2/3, it can significantly limit the range of initializing, unknown, a priori values of S and Ks, as these two parameters are estimated through the inverse solution of implicit infiltration models. Due to the model's simplicity and accuracy, our solution should find application among hydrologists, natural resource scientists, and engineers who wish to easily derive accurate estimations from the G–A infiltration approach and/or estimate sorptivity and hydraulic conductivity without encountering divergence problems.

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Moving Multi-Front (MMF): A generalized Green-Ampt approach for vertical unsaturated flows

Cited by 12 publications

References 46 publications

Calibration of Green‐Ampt wetting front suction for ponding and non‐ponding infiltration scenarios

Calibration of Green‐Ampt wetting front suction for ponding and non‐ponding infiltration scenarios

Open-source high-performance software packages for direct and inverse solving of horizontal capillary flow

A simple, accurate, and explicit form of the Green–Ampt model to estimate infiltration, sorptivity, and hydraulic conductivity

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