J-Y. Parlange

Exact nonlinear solution for constant flux infiltration

Recently∗ an analytical nonlinear solution to the problem of two phase oil and water infiltration under a constant flux boundary condition was derived. We show that this solution also applies to the problem of constant infiltration of water by introducing a very simple change in the independent variables of space and time.

Application of a simple soil-water hysteresis model.

Abstract A simple hysteresis model is reformulated on the basis of the Brooks and Corey equation for the relationship between soil-water content and matric potential. In principle, the method requires the knowledge of a drying curve (boundary or primary) to predict the wetting boundary and all scanning curves. Experimental observations used recently to assess a variety of soil-water hysteresis models show that the present model is simple, accurate and general.

Competitive sorption of metals in water repellent soils: Implications for irrigation recycled water

Australia is a water-stressed nation and demand on potable water supply is increasing. Consequently water conservation and reuse are increasingly becoming important. Irrigation of recycled wastewater on water repellent soils is a technology that is being trialled as a means of improving crop production and conserving potable supply. However, recycled water contains potentially harmful heavy metals. This paper reports the competitive sorption and desorption of several common heavy metals found in soils collected from a farm located in the south-east of South Australia. The soil from this location is severely water repellent, but some sites were amended with kaolinite clay (Si4Al4O10(OH)8) about 7 and 15 years ago. The metals studied were Cu, Pb, Cd, Cr, Ni, and Zn. Competitive sorption of the metals was distinctly observed. For all heavy metals, the quantity of metal sorbed was higher in amended soil, and there was a strong correlation between the specific sorption to total sorption ratio and the amount of clay in the soil. The sorption intensities varied with metal, Cr, Pb, and Cu having a high sorption tendencies and Zn, Cd, and Ni having comparatively low sorption tendencies. The total sorption capacity for all metals increased in clay-treated soils compared with non-treated soils. On average, clay-amended water repellent soils had a 20–40% increased capacity to adsorb total metals; however, this increase was largely caused by the increased capacities to adsorb Zn, Cd, and Ni. The effect of clay treatment largely enhanced the sorption capacity of relatively weakly adsorbing heavy metals. The implications for using recycled wastewater on the long-term sustainable agro-environmental management of these soils are discussed.

Preferential flow influences on drainage of shallow sloping soils

The dramatic effect of flow through macropores and hardpan fissures on artificial drainage in shallow sloping soils is demonstrated. Implications of these preferential flow mechanisms on drainage design and water management are discussed. In designing drainage systems on these types of soils, more emphasis should be given to the characteristics of the hardpan.

ADDENDUM TO “FIRST INTEGRALS OF THE INFILTRATION EQUATION”

A simple and accurate procedure is given for solving the infiltration equation for nonlinear diffusivity and conductivity. It overcomes some of the numerical difficulties associated with an earlier procedure given by Hogarth et al. (1989), but confirms the accuracy of their results.

Comment on "Modeling transient stream/aquifer interaction with the non-linear Boussinesq equation and its analytical solution" by Serrano, S. E., Workman, S. R., 1998. Journal of Hydrology 206, 245-255.

Keywords: FLOW EQUATION ; DECOMPOSITION Reference ECOL-ARTICLE-2000-001doi:10.1016/S0022-1694(00)00246-8 URL: http://www.elsevier.com/wps/find/journaldescription.cws_home/503343/description#description Record created on 2005-12-09, modified on 2016-11-26

SIMULTANEOUS NONLINEAR IRREVERSIBLE REACTION AND MOVEMENT OF SOLUTES IN SOILS

This paper presents an approximate analytical solution for a nonlinear irreversible reaction involving the movement of solute when two substrates are involved. The presence of the second substrate determines when the reaction will proceed. The implicit solution obtained enables the continuum of irreversible reactions to be explored through the Michaelis-Menten form. The effect of the second substrate being present or not at the start of the reaction is investigated. Validation of the approximate analytical solution is achieved by systematic comparison with a numerical solution. The effect of boundary conditions on the solution for a finite column is examined. With a change from aerobic to anaerobic conditions initially, the effect on the breakthrough curves and concentration profiles of having a flux-concentration inlet boundary condition with a zero-flux outlet condition for a finite column is compared with a fixed-concentration inlet condition for a semi-infinite column. The approximate solution is also applied to an experimental breakthrough curve to estimate nonlinear denitrification parameters.

Comment on “Series solution for Richards Equation under concentration boundary conditions and uniform initial conditions” by Guido Daniel Salvucci

Reference ECOL-ARTICLE-1998-002doi:10.1029/98WR01834 URL: http://www.agu.org/journals/wr/ Record created on 2005-12-09, modified on 2016-08-08