This paper proposes groundwater flow simulation models based on explicit finite difference method (FDFLOW) and Galerkin finite element method (FEFLOW) and solute transport simulation models based on Galerkin finite element method (FESOLUTE), random walk method (RWSOLUTE) and modified method of characteristic (MMOCSOLUTE). These coupled flow and transport models are aimed at simulation of solute...

Whole-system denitrification in the South Platte River was measured over a 13-month period using an open-channel N2 method and mass-balance measurements. Concentrations of dissolved N2 were measured with high precision by membrane-inlet mass spectrometry and estimates of denitrification were based on the mass flux of N2, after correction for reaeration and groundwater flux. Open-channel estimat...

[1] This paper presents a framework for studying regional water balance in which the physical processes are first described at the local instantaneous scale and then integrated to the annual, basin-wide scale. The integration treats the relative soil saturation (i.e., the soil moisture divided by the porosity) and precipitation intensities as stochastic variables in space and time. A statistica...

We used the natural geochemical tracers radon-222 and radium isotopes (223Ra, 224Ra, 226Ra, 228Ra) to assess exchange rates between the Chao Phraya River and the Gulf of Thailand, and the magnitude of groundwater discharge in the estuary. We performed tracer surveys during two periods in 2004, in January (dry season, gauged river discharge 47 m3 s21) and in July (wet season, 430 m3 s21). The is...

The sustainability of irrigated agriculture in many arid and semiarid areas of the world is at risk because of a combination of several interrelated factors, including lack of fresh water, lack of drainage, the presence of high water tables, and salinization of soil and groundwater resources. Nowhere in the United States are these issues more apparent than in the San Joaquin Valley of Californi...

The feasibility of phytoremediation of groundwater contamination with methyl-tert-butyl ether (MTBE) was examined experimentally using a six-channel soil system with or without plants. Two bacterial strains capable of degrading MTBE were each added to two out of six channels. A solution of 0.84 mM MTBE was continuously fed into each channel at 1 L/day until a stable MTBE concentration level in ...

Mixed and Mixed Hybrid Finite Elements (MHFE) methods have been widely used in the last decade for simulation of groundwater flow problem, petroleum reservoir problems, potential flow problems, etc. The main advantage of these methods is that, unlike the classical Galerkin approach, they guarantee local and global mass balance, as well the flux continuity between inter-element sides. The simple...