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

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

doi:10.1029/95wr03645

Cited by 6 publications

(5 citation statements)

References 17 publications

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“…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: 97%

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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“…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: 97%

The Green–Ampt limit with reference to infiltration coefficients

Triadis

Broadbridge

2012

Water Resources Research

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“…Our results also indicate that the use of the nonuniform integral equations (Eqs. 9-12) effectively limit errors in the t p estimation that sometimes occur when utilizing the Green-Ampt model (Barry et al, 1996).…”

Section: Numerical Testingmentioning

confidence: 99%

Shallow water table effects on water, sediment and pesticide transport in vegetative filter strips: Part A. non-uniform infiltration and soil water redistribution

Muñoz‐Carpena¹,

Lauvernet²,

Carluer³

2017

Preprint

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Abstract. Vegetation buffers like vegetative filter strips (VFS) are often used to protect water bodies from surface runoff pollution from disturbed areas. Their typical placement in bottomland often results in the presence of a seasonal shallow water table (WT) that can decrease soil infiltration and increase surface pollutant transport during a rainfall/runoff event. Simple and robust components of hydrological models are needed to analyse the impacts of WT in the landscape. To simulate VFS infiltration under realistic rainfall conditions with WT, we propose a generic infiltration solution (Shallow Water table INfiltration algorithm: SWINGO) based on a combination of approaches by Salvucci and Entekhabi (1995) and Chu (1997) with new integral formulae to calculate singular times (time of ponding, shift time, and time to soil profile saturation). The algorithm was tested successfully on 5 distinct soils both against Richards’s numerical solution and experimental data in terms of infiltration and soil moisture redistribution predictions, and applied to study the combined effects of varying WT depth, soil type, and rainfall intensity and duration. The results show the robustness of the algorithm and its ability to handle various soil hydraulic functions, and initial non-ponding conditions under unsteady rainfall. The effect of a WT on infiltration under ponded conditions was found effectively decoupled from surface infiltration/excess runoff processes for depths larger than 1.2 to 2 m, shallower for fine soils and shorter events. For non-ponded initial conditions, the influence of WT depth also varies with rainfall intensity. Also, we observed that soils with a marked air entry (bubbling pressure) exhibit a distinct behaviour with WT near the surface. The features and good performance of SWINGO support its coupling with an existing VFS model in the companion paper, where the potential effects of seasonal or permanent WTs on VFS pollutant transport and control are studied.

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“…Some authors suggest that the reduction of infiltration and VFS efficiency can be problematic for seasonal WT depths above 2 m, typical of hydromorphic soils (Dosskey et al, 2006(Dosskey et al, , 2011Lacas et al, 2012). As cited by Salvucci and Entekhabi (1995), the importance of accounting for areas of WT effects in water balance and runoff studies has been recognized for a long time, and specialized analysis and simulation approaches have been proposed by numerous authors (for example, Vachaud et al, 1974;Srivastava and Yeh, 1991;Salvucci and Entekhabi, 1995;Chu, 1997;Basha, 2000).…”

Section: Introductionmentioning

confidence: 99%

Authors Response to Interactive comments from RC2- S. Reichenberger

Muñoz‐Carpena¹

2017

Preprint

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Vegetation buffers like vegetative filter strips (VFSs) are often used to protect water bodies from surface runoff pollution from disturbed areas. Their typical placement in floodplains often results in the presence of a seasonal shallow water table (WT) that can decrease soil infiltration and increase surface pollutant transport during a rainfallrunoff event. Simple and robust components of hydrological models are needed to analyze the impacts of WT in the landscape. To simulate VFS infiltration under realistic rainfall conditions with WT, we propose a generic infiltration solution (Shallow Water table INfiltration algorithm: SWINGO) based on a combination of approaches by Salvucci and Entekhabi (1995) and Chu (1997) with new integral formulae to calculate singular times (time of ponding, shift time, and time to soil profile saturation). The algorithm was tested successfully on five distinct soils, both against Richards's numerical solution and experimental data in terms of infiltration and soil moisture redistribution predictions, and applied to study the combined effects of varying WT depth, soil type, and rainfall intensity and duration. The results show the robustness of the algorithm and its ability to handle various soil hydraulic functions and initial nonponding conditions under unsteady rainfall. The effect of a WT on infiltration under ponded conditions was found to be effectively decoupled from surface infiltration and excess runoff processes for depths larger than 1.2 to 2 m, being shallower for fine soils and shorter events. For nonponded initial conditions, the influence of WT depth also varies with rainfall intensity. Also, we observed that soils with a marked air entry (bubbling pressure) exhibit a distinct behavior with WT near the surface. The good performance, robustness, and flexibility of SWINGO supports its broader use to study WT effects on surface runoff, infiltration, flooding, transport, ecological, and land use processes. SWINGO is coupled with an existing VFS model in the companion paper (Lauvernet and Muñoz-Carpena, 2018), where the potential effects of seasonal or permanent WTs on VFS sediment and pesticide trapping are studied.

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

Cited by 6 publications

References 17 publications

The Green–Ampt limit with reference to infiltration coefficients

The Green–Ampt limit with reference to infiltration coefficients

Shallow water table effects on water, sediment and pesticide transport in vegetative filter strips: Part A. non-uniform infiltration and soil water redistribution

Authors Response to Interactive comments from RC2- S. Reichenberger

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