480 D use diff erent strategies to survive and fl ourish with erratically available water (Hamerlynck et al., 2002; Lombardini, 2006). Th e persistence of soil water within a particular depth range and its characteristic time scales of fl uctuation (Katul et al., 2007) help determine the resulting plant community. Th e depth to which infi ltration percolates and the degree to which water is ret...

Numerical simulation of flow through multidimensional heterogeneous soils under unsaturated conditions is a computationally intensive task. The governing unsaturated flow equation is nonlinear. The degree of nonlinearity depends on the unsaturated hydraulic properties of the soil and the degree of heterogeneity. In this paper, we present a highly efficient method to simulate unsaturated steady ...

The unsaturated zone has a crucial role in subsurface processes that, turn, impact soil moisture, groundwater quality and quantity, ecosystem function [...]

In this study, a stochastic model for transient saturated–unsaturated flow is developed based on the Karhunen-Loeve expansion of the input random soil properties combined with a perturbation method. The log-transformed saturated hydraulic conductivity f ðxÞ and the soil pore size distribution parameter aðxÞ are assumed to be normal random functions with known covariances. We decompose f ðxÞ and...

A semianalytical solution is presented for transient streaming potentials associated with flow to a pumping well in an unconfined aquifer, taking into account the effect of flow in the unsaturated zone above the water table. Flow in the unsaturated zone is modeled with a linearized form of Richards’ equation using an exponential model for soil moisture retention and unsaturated hydraulic conduc...

SPARG/AIRFIX is developed by Mohtar and Rahbeh in 2001 as a practical unsaturated flow and multiphase transport model that can be used for the design and operation of sparging and soil vapor extraction systems [5]. The model uses first order kinetics to represent the mass transfer among the aqueous, gaseous, solid, and NAPL phases. The theoretical basis of the model is build on the fact that so...

Laboratory column experiments were conducted by employing various porous media to delineate the characteristics of gaseous ozone transport in the unsaturated zone under various conditions. Water content, soil organic matter (SOM), and metal oxides (MOs) were found to be the factors most influential in the fate and transport of gaseous ozone in unsaturated porous media. The migration velocity of...

Background: It is essential for residents to understand ground disaster and improve disaster prevention awareness, because natural disasters have occurred frequently in recent years. In this study, nondestructive unsaturated seepage behavior was continuously visualized by using MRI (magnetic resonance imaging) with test equipment constructed of non-metal parts. Additionally, the water content o...

Modeling flow and solute transport in the unsaturated zone on the basis of the Richards equation requires specifying values for unsaturated hydraulic conductivity and water potential as a function of saturation. The objectives of the paper are to evaluate the design of a transient, radial, multi-step outflow experiment, and to determine unsaturated hydraulic parameters using inverse modeling. W...