Computer models to simulate pesticide transport in the unsaturated zone will be an important management tool in coming years. However, not many efforts were directed to validate the usefulness of such models. In this study, the simulation models GLEAMS, PRZM, and LEACHM were validated. The three models use different mathematical concepts to compute one-dimensional flow and transport in a homoge...

Cellular automata (CA) are discrete dynamic systems that have been used for modeling many physical systems. CA are often used as an alternative to model and solve large-scale systems where the use of partial differential equations involve complex and computationally expensive simulations. The purpose of this work is to investigate the use of CA based techniques for modeling and parallel simulat...

As compared with mineral soils, there are few in situ measurements of the unsaturated hydraulic properties of peat soils available. We used parameter estimation (inverse) methods to estimate the water retention and hydraulic conductivity functions of drained peat soils from both laboratory and field data. The laboratory data were obtained on small cores using the traditional evaporation method,...

This paper presents a 1D numerical model developed to simulate the EDTA chelation process of metal (lead) applied to a soil flushing remediation action. The model considers the non–stationary conditions, typical of unsaturated soil. Flow and transport equations are solved simultaneously. Metal mobilization is evaluated considering both the chemical aspects of chelating agents and the characteri...

Experimentally determined values of unsaturated soil hydraulic conductivity are presented for an Alfisol of the county of Piracicaba, S.P., Brazil. Simultaneous measurements of soil water content and pressure head are made along a 125 m transect within an irrigated field during the internal drainage process. Calculations of the soil hydraulic conductivity were made using the instantaneous profi...

The soil-water characteristic curve can be used to estimate various parameters used to describe unsaturated soil behaviour. A general equation for the soil-water characteristic curve is proposed. A nonlinear, least-squares computer program is used to determine the best-fit parameters for experimental data presented in the literature. The equation is based on the assumption that the shape of the...

Recently, we presented a steady-state analytical hillslope stability model to study rain-induced shallow landslides. This model is based on kinematic wave dynamics of saturated subsurface storage and the infinite slope stability assumption. Here we apply the model to investigate the effect of neglecting the unsaturated storage on the assessment of slope stability in the steady-state hydrology. ...

The unsaturated soil hydraulic properties (the soil water characteristic and relative permeability curves) are key hydrodynamic parameters in the fields of soil science and civil engineering. Because of the strong dependency of these properties on water content, their determination is subject to considerable experimental and numerical problems. Difficulties increase when the soil approaches ove...

abstract to estimate spatial variability of soil hydraulic functions, scaling methods were developed and have been widely used. among these functions, physically based methods have been found more desirable because of possibility of estimating soil hydraulic functions from soil physical properties. in this paper, a new and physically based method has been described for scaling soil hydraulic co...

Guidelines for seismic spectral amplification are provided in current building codes based on soil strength/stiffness by means of seismic site class. However, current codes do not make a difference between fully saturated and unsaturated soil deposits and do not account for effects of soil heterogeneity on seismic amplification. This study investigates the effect of natural small scale soil het...