Hydrodynamic Dispersion During Constant Rate Absorption of Water by Soil

Smiles, DE; Perroux, K. M.; Zegelin, S. J.; Raats, P. A. C.

doi:10.2136/sssaj1981.03615995004500030001x

Cited by 54 publications

(20 citation statements)

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“…This indicates that a piston-like displacement of soil solution occurred in these plots. This behaviour has also been recorded by Smiles et al (1978Smiles et al ( ,1981, Dahiya, Singh, Richter & Singh (1984) and many others in laboratory columns, Dahiya et al (1981Dahiya et al ( , 1982 in 2 x 2 m cropped plots, and by Leffelaar & Sharma (1977), Khosla et al (1979) and Dahiya et al (1983) in small infiltrometers.…”

Section: Nature Of Displacement Of Saline Constituentssupporting

confidence: 65%

Desodification of a salt-affected soil in plots of various sizes under two modes of water application

Dahiya¹,

Grewal

Dahiya

1987

J. Agric. Sci.

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Desodification of a highly saline-sodic, permeable, sandy loam soil was accomplished in 2x2 m (S,), 4x4 m (S s ) and 6x6 m (S 3 ) plots under continuous and intermittent ponding. The soil contained large amounts of soluble salts and exchangeable sodium throughout the profile to the water table. The chief salts were chlorides and sulphates of sodium, calcium, and magnesium. The leaching curves with respect to desodification did not differ significantly between the S,, S 2 and S 3 plots under continuous ponding but did under intermittent ponding. With intermittent ponding, the efficiency of leaching exchangeable sodium in the S, plots was very significantly higher than that in the S 2 and S 3 plots, i.e. the leaching efficiency decreased sharply with increased plot size. The leaching efficiency in the S, plots was significantly greater with intermittent than with continuous ponding, but the reverse was true in the S 2 and S 3 plots. The results further indicated that there is no need to apply an amendment such as gypsum, mainly because calcium and magnesium present in such soils are adequate to replace the initially high exchangeable sodium during leaching. The displacement of exchangeable sodium in the S x plots under intermittent ponding was nearly piston-like. With increased plot size, it tended to deviate from this behaviour. It is concluded that under practical situations in which reclamation is accomplished in large plots, the practice of leaching the saline constituents with intermittent ponding would be less effective. Thus, leaching of salts down into the soil with a single heavy irrigation would be more desirable.

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Section: Nature Of Displacement Of Saline Constituentssupporting

confidence: 65%

Desodification of a salt-affected soil in plots of various sizes under two modes of water application

Dahiya¹,

Grewal

Dahiya

1987

J. Agric. Sci.

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“…Hence, infiltration is conceived to be occurring in a medium of two homogeneous layers with the same porosity but different hydraulic conductivities. The study on the appropriateness of the Green-Ampt model for predicting water movement in homogeneous unsaturated soil by Smiles et al (1981), Dagan and Bresler (1983) and Govindaraju et al (1992) shows that soil water storage is predicted accurately by the Green-Ampt model under flux-dependent conditions at the soil surface. The Green-Ampt model for homogeneous unsaturated soil can be used as an alternative to the Richards equation (Govindaraju et al 1996).…”

Section: Green-ampt Model For Homogeneous Soilsmentioning

confidence: 99%

Green-Ampt Infiltration Models for Varied Field Conditions: A Revisit

Kale

Sahoo

2011

Water Resour Manage

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The Green-Ampt (GA) infiltration model is a simplified version of the physically based full hydrodynamic model, known as the Richards equation. The simplicity and accuracy of this model facilitates for its use in many field problems, such as, infiltration computation in rainfall-runoff modelling, effluent transport in groundwater modelling studies, irrigation management studies including drainage systems etc. The numerous infiltration models based on the Green-Ampt approach have been widely investigated for their applicability in various scenarios of homogeneous soils. However, recent advances in physically based distributed rainfall-runoff modeling demands for the use of improved infiltration models for layered soils with non-uniform initial moisture conditions under varying rainfall patterns to capture the actual infiltration process that exists in nature. The difficulty that modelers are facing now-a-days includes the estimation of time of ponding and the application of the infiltration model to unsteady rainfall events occurring in heterogeneous soil conditions. The investigation in this direction exhibits that only few infiltration models can handle these situations. Hence, it is of vital importance to analyze the usefulness of different variants of the Green-Ampt infiltration models in terms of their degree of accuracy, complexity and applicability limits. This paper provides a brief review of these infiltration models to bring out their usefulness in the rainfall-runoff and irrigation modeling studies as well as the drawbacks associated with these models.

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“…The piston-front of water is the interface between the displaced and displaced water if complete displacement of the initial resident soil-water occurred. [14] The position of the piston-front in the column experiments was about 25 cm from the column inlet, and coincided very closely with the final position of the wetting front. This is because the initial soilwater content was <0.01 m 3 /m 3 and, consequently, very little soil-water (equivalent depth ¼ 0.25 cm) would be pushed ahead of the advancing KCl pulse.…”

Section: Water Movementmentioning

confidence: 55%

Measurement and Prediction of Potassium Chloride Movement in an Unsaturated Sand

Phillips

2004

Communications in Soil Science and Plant Analysis

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In south-east Queensland, Australia, extensive areas of sandy soils (Podosols) with shallow (<1 m) watertables are used for exotic pine tree production. Leaching of surface-applied fertilizers (di-ammonium phosphate and potassium chloride) in these soils has been suggested as a contributing factor in a decline in local groundwater quality. This study investigated the movement of potassium chloride (KCl) in horizontal columns of sand under unsaturated flow conditions. A pulse of KCl (equivalent on a surface area basis of 300 kg K/ha) was applied to one end of the sand column, and immediately followed by deionized water at a constant flux of 0.398 cm/h for 12 h. The position of the maximum chloride (Cl) concentration lagged behind the ''piston-front'' of water, and potassium (K) moved at about half the rate of Cl. Despite having ORDER REPRINTS a very low effective cation exchange capacity (ECEC 2 cmol/kg), the sand retained about 71% of the applied K in the 0-10 cm interval through predominantly K-magnesium (Mg) and K-sodium (Na) exchange. The nonspecific mechanisms responsible for K retention suggests that this chemical could be readily displaced from the ECEC sites through subsequent cation exchange reactions, and eventually move into the groundwater. Resident ions were pushed ahead of the advancing wetting front, and this contribution should be taken into account when evaluating factors responsible for groundwater contamination. The models CHEMFLO and SWIMv2 were used to predict KCl leaching, and although both models predicted the distributions of water content and water-soluble Cl very closely, both over-estimated soluble K concentrations.

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Hydrodynamic Dispersion During Constant Rate Absorption of Water by Soil

Cited by 54 publications

References 0 publications

Desodification of a salt-affected soil in plots of various sizes under two modes of water application

Desodification of a salt-affected soil in plots of various sizes under two modes of water application

Green-Ampt Infiltration Models for Varied Field Conditions: A Revisit

Measurement and Prediction of Potassium Chloride Movement in an Unsaturated Sand

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