Estimation of soil hydraulic and solute transport parameters is important to provide input parameters for numerical models simulating transient water ̄ow and solute transport in the vadose zone. The Levenberg±Marquardt optimization algorithm in combination with the HYDRUS-1D numerical code was used to inversely estimate unsaturated soil-hydraulic and solute transport parameters from transient m...

Chlorofluorocarbons CFC-11 (CCl(3)F), CFC-12 (CCl(2)F(2)), and CFC-113 (CCl(2)F-CClF(2)) are used in hydrology as transient tracers under the assumption of conservative behavior in the unsaturated and saturated soil zones. However, laboratory and field studies have shown that these compounds are not stable under anaerobic conditions. To determine the degradation rates of CFCs in a tropical envi...

Journal of Environmental Hydrology Volume 17 Paper 7 February 2009 1 A parallelized large-scale regional hydrologic soil model (RHSM) is developed as a tool for large-scale unsaturated zone investigations. It is applied to simulate the temporal and spatial responses of the unsaturated zone and the regional water budget under the forcing of realistic precipitation and evaporation scenarios. The ...

In recent years, researchers have focused on modeling of multicomponent reactive transport and have developed models to study the mobility of potentially toxic heavy metals in the subsurface. In this study, a mathematical model for understanding the fate of a typical heavy metal (lead) in unsaturated soil is developed. The entire modeling activity comprises of three parts. During the first part...

The majority of hydraulic processes under a natural condition in a field are carried out under unsaturated flow conditions. The soil moisture retention curve (SMRC) is the most important hydraulic characteristic of an unsaturated soil whose knowledge is of prime importance in soil-water studies such as soil conservation, soil erosion, land evaluation, soil reclamation, and water resources manag...

the determination of soil wetting front which caused by emitters is one of the important issues in designing trickle irrigation system. in this study, a mathematical model introduced in order to study the position of soil wetting front during irrigation by point emitters in homegenious soil in unsteady condition. the model solves governing differential equation of unsaturated flow in cylindrica...

In this study, displacement experiments of isoproturon were conducted in disturbed and undisturbed columns of a silty clay loam soil under similar rainfall intensities. Solute transport occurred under saturated conditions in the undisturbed soil and under unsaturated conditions in the sieved soil because of a greater bulk density of the compacted undisturbed soil compared to the sieved soil. Th...