In this work, we present a two-dimensional mixed-hybrid nite element model of variably saturated ow on unstructured triangular meshes. Velocities are approximated using lowest order Raviart-Thomas (RT 0) elements with piecewise constant pressure. The resulting nonlinear systems of algebraic equations are solved using Picard or Newton iterations. Theroretical superconvergence properties of the R...

Environmental gas tracers allow inferring groundwater travel times and mixing ratios. Their concentrations are commonly interpreted with simplified indirect approaches that conceptually at odds the high degree of complexity found in natural systems. However, information content can potentially be fully explored through explicit simulation an advection-dispersion transport equation, for example ...

Tortuosity has a significant impact on flow and transport characteristics of porous media plays major role in many applications such as enhanced oil recovery, contaminant aquifers, fuel cells. Most analytical theoretical models for determining tortuosity have been developed ideal systems with assumptions that might not be representative natural media. In this paper, geometric was directly deter...

We extend our recent work on higher-order time integration of Richards' equation to layered heterogeneous porous media, using a diierential-algebraic-equation-based method of lines (DAE/MOL) approach. We show that the DAE/MOL approach is robust and eecient compared to standard low-order time integration methods for heterogeneous media. We also show the advantage of using an integral representat...

The gas push-pull test (GPPT) is a single-well gas-tracer method to quantify in situ rates of CH4 oxidation in soils. To improve the design and interpretation of GPPT field experiments, gas component transport during GPPTs was examined in abiotic porous media over a range of water saturations (0.0 < or = Sw < or = 0.61). A series of GPPTs using He, Ne, and Ar as tracers for CH4 were performed a...

Relatively small changes in the shape of the soil water retention curve near saturation can signi®cantly a€ect the results of numerical simulations of variably saturated ̄ow, including the performance of the numerical scheme itself in terms of stability and rate of convergence. In this paper, we use a modi®ed form of the van Genuchten±Mualem (VGM) soil hydraulic functions to account for a very ...

7 Abstract Streambed drainage was measured at the 8 cessation of 26 ephemeral streamflow events in Rillito 9 Creek, Tucson, Arizona from August 2000 to June 2002 10 using buried time domain reflectometry (TDR) probes. An 11 unusual drainage response was identified, which was char12 acterized by sharp drainage from saturation to near field 13 capacity at each depth with an increased delay betwee...

The VMPC function is a combination of triple permutation composition and integer addition. It differs from a simple triple permutation composition with one integer addition operation performed on some of the elements of the permutation. The consequence of this addition operation is corruption of cycle structure of the transformed permutation the fundamental source of the function's resistance t...

contaminant transport and degradation in soils have represented biodegradation as a first-order decay proAn experimental and numerical investigation was conducted to cess, without actually considering microbial processes and study interactions between microbial dynamics and transport processes in variably saturated porous media. Experiments were contheir interactions with other transport proces...