Water Flow in Soil Macropores Ii. A Combined Flow Model

Seven, K.; Germann, Peter

doi:10.1111/j.1365-2389.1981.tb01682.x

Cited by 232 publications

(153 citation statements)

References 10 publications

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“…In wetter areas, the limit was, for instance, 450 (Likens et al, 1977) and 420 (Hudson, 1988) mm yr -1 . Additionally, the rapid wetting of the deep horizons (Moreno et al, 1996) could indicate the existence of water loss by drainage, due to rapid circulation via macropores (Beven and German, 1981), although the soil would still be below field capacity, a fact that is not included in the model used.…”

Section: Net Losses or Gains Of Nutrientsmentioning

confidence: 99%

Water and bioelement fluxes in four Quercus pyrenaica forests along a pluviometric gradient

et al. 1996

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Section: Net Losses or Gains Of Nutrientsmentioning

confidence: 99%

Water and bioelement fluxes in four Quercus pyrenaica forests along a pluviometric gradient

et al. 1996

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“…Film flow of water along macropore or fracture surfaces could reconcile the paradoxical occurrence of fast flow in unsaturated channels [Beven and Germann, 1981;Germann, 1990]. Our alternative conceptual model of unsaturated flow in fractures allows water to exist in continuous films as well as in pendular regions associated with aperture minima.…”

mentioning

confidence: 99%

Water film flow along fracture surfaces of porous rock

Tokunaga¹,

Wan²

1997

Water Resources Research

256

186

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Abstract. This study shows that hydraulic properties of individual fracture surfaces can be meaningfully defined and measured, and that water film flow is a mechanism contributing to fast, unsaturated flow in fractures. The hydraulic conductivity of an unconfined block of Bishop Tuff was measured over a range of near-zero matric potentials, where differences between hydraulic conductivities obtained without and with wax sealing of its lateral sides allowed isolation of film flow effects. Tensiometer and flux measurements showed that surface film flow in this system was significant for matric potentials greater (more positive) than about -250 Pa. In this range the average film thickness was shown to be potential dependent and proportional to the observed enhanced hydraulic conductivity. Measured average surface film thicknesses ranged from 2 to 70 tzm, with average film velocities in the range of 2 to 40 rn d -* (about 10 3 times faster than that of the pore water under unit gradient saturated flow). Our experiments demonstrate that hydraulic properties of macroscopic surfaces of porous media are quantifiable, related to surface roughness, and potentially important in the flow of water in vadose environments. This study further shows that contrary to existing conceptual models, unsaturated flow in fractures cannot generally be predicted solely on the basis of aperture distribution information. The high velocities of these surface films suggest that film flow can be an important mechanism contributing to fast flow in unsaturated fractures and macropores, especially in media characterized by low-permeability matrix and along regions of convergent flow in partially saturated fractures.

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“…Equation (8a) expressess the flow relation of a kinematic wave (see, for instance, Beven & Germann, 1981;Germann, 1985Germann, , 1990) whose volume balance is:…”

Section: Momentum Of Flow Within the Soil Profilementioning

confidence: 99%

Dissipation of momentum during flow in soils

Germann

Niggli

1998

Hydrological Sciences Journal

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The basic principles are derived of steady momentum dissipation during laminar boundary-layer flow in macroporous soils. The principles lead to a flux law and to geometrical measures of the flow paths. The theory of kinematic waves evolves, and the shock fronts are routed with the method of characteristics. The approach is applied to TDR soil moisture readings at depths 0.15, 0.35 and 0.55 m in a soil under meadow during an infiltration experiment (rate and duration of sprinkling were 2.78 x 10" 5 m s" 1 and 4500 s, respectively). Momentum dissipation during flow within the soil profile is independent of momentum added to the soil surface by sprinkling. Specific momentum dissipation per unit depth in the soil profile was about 0.02 kg m 2 s' 1 , with a tendency to increase with depth.

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Water Flow in Soil Macropores Ii. A Combined Flow Model

Cited by 232 publications

References 10 publications

Water and bioelement fluxes in four Quercus pyrenaica forests along a pluviometric gradient

Water and bioelement fluxes in four Quercus pyrenaica forests along a pluviometric gradient

Water film flow along fracture surfaces of porous rock

Dissipation of momentum during flow in soils

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