Comment on “Falling Head Ponded Infiltration” by J. R. Philip

Barry, David Andrew; Parlange, Jean‐Yves; Haverkamp, R.

doi:10.1029/94wr02565

Cited by 10 publications

(11 citation statements)

References 7 publications

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“…From the analytically solvable model, infiltration coefficients were constructed unambiguously from a complicated but explicit recurrence relation. Our recent results support the ideas of Parlange [1972, 1975] and Barry et al [1995], since along the curves in the two‐parameter space that have a limiting delta‐function diffusivity, the second infiltration coefficient is not uniquely determined, but it has a limiting value that depends on the form of

K (θ)

. Or more directly, it depends on the form of the function that maps the Buckingham soil‐water potential

Ψ

to K .…”

Section: Introductionsupporting

confidence: 78%

“…Unfortunately, this model predicts S 1 to be

2 K_{s} / 3

, which is approximately double that calculated numerically from models with strongly increasing but more realistic continuous functions for

D (θ)

and

K (θ)

[ Philip , 1990; Barry et al , 1995; Ross et al , 1996] or inferred from infiltration data [ Talsma , 1969; Youngs , 1995]. In the aftermath of the papers by Philip [1992a, 1992b, 1993] three comments debating delta‐function soils were published with replies from John Philip [ Barry et al , 1994, 1995, 1996; Philip , 1994, 1995, 1996]. From Philip [1995]: “The topic of ‘delta‐function’ soils and their relation to the Green–Ampt model seems to remain in confusion.” More recently, Barry et al [2010] have pointed out that setting a soil's “effective conductivity” to be half the saturated hydraulic conductivity within a Green–Ampt infiltration analysis [ Mailapalli et al , 2009; Rawls et al , 1993] has the effect of halving the value of S 1 .…”

Section: Introductionmentioning

confidence: 83%

“… Barry et al [1995] argued that different soil models, each with a limiting delta‐function diffusivity and each predicting step function water content profiles, but with different conductivity functions, could have different values for the infiltration coefficients S j beyond j = 0. At first this sounds paradoxical, since in the limit of step function water profiles, the cumulative infiltration function i ( t ) should be determined uniquely by the Green–Ampt parameters that include no information about

K (θ)

except its values at the endpoints

θ = θ_{s}

and

θ_{n}

.…”

Section: Introductionmentioning

confidence: 99%

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The Green–Ampt limit with reference to infiltration coefficients

Triadis

Broadbridge

2012

Water Resources Research

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[1] Recent progress with an analytic nonlinear model has provided the exact infiltration coefficients for realistic soil behaviors with nonsingular hydraulic functions, as well as their exact delta-function diffusivity limits. After some correction and reinterpretation of the approximate analytical method, the exactly solvable model validates some previously obtained approximate infiltration functions. The Green-Ampt infiltration function follows from a delta-function diffusivity limit with a hydraulic conductivity that may be, among other possibilities, a linear function of water content. Just as a linear conductivity function is an overestimate for a realistic soil, the second Philip infiltration coefficient S 1 in the Green-Ampt infiltration function is too large due to conductivity being overestimated. Better agreement with experiment (halving the value of S 1 ) is obtained from the analytic nonlinear model, with a limiting delta-function diffusivity and a matching Gardner exponential hydraulic conductivity function. In general, infiltration behavior is determined by the limiting forms of the diffusivity and conductivity relative to one another at the saturated water content, or alternatively, the relationship between the conductivity and soil moisture potential. A new infiltration model demonstrates the possible range of S 1 for physically valid limiting conductivity functions. We show that in the delta-function diffusivity limit, the solution behaves as if the potential at the wet front were time dependent, decreasing in magnitude from an initial value at the traditional Green-Ampt level.Citation: Triadis, D., and P. Broadbridge (2012), The Green-Ampt limit with reference to infiltration coefficients, Water Resour. Res., 48, W07515,

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K (θ)

. Or more directly, it depends on the form of the function that maps the Buckingham soil‐water potential

Ψ

to K .…”

Section: Introductionsupporting

confidence: 78%

“…Unfortunately, this model predicts S 1 to be

2 K_{s} / 3

, which is approximately double that calculated numerically from models with strongly increasing but more realistic continuous functions for

D (θ)

and

K (θ)

Section: Introductionmentioning

confidence: 83%

K (θ)

except its values at the endpoints

θ = θ_{s}

and

θ_{n}

.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Green–Ampt limit with reference to infiltration coefficients

Triadis

Broadbridge

2012

Water Resources Research

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“…Material in the paper follows directly from previous work by the same author [Philip, 1992a, b]. We have commented on these papers [Barry et al, 1994[Barry et al, , 1995, and some of the same remarks are relevant to the theory presented by Philip [1993, p. …”

Section: Introductionmentioning

confidence: 94%

Comment on “Variable‐Head Ponded Infiltration Under Constant or Variable Rainfall” by J. R. Philip

Barry¹,

Parlange²,

Haverkamp³

1996

Water Resources Research

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“…Parlange et al (1982) provided a three-parameter infiltration equation that reduces to the Green-Ampt and Talsma-Parlange models as limiting cases. It has been shown that infiltration into soil is usually closer to the Talsma-Parlange model than the Green-Ampt model (e.g., Fuentes et al, 1992;Barry et al, 1995c;Ross et al, 1996;Clausnitzer et al, 1998).…”

mentioning

confidence: 99%