Laboratory experiments were conducted to study solute transport along preferential flow paths in unsaturated, inclined fractures. Qualitative aspects of solute transport were identified in a miscible dye tracer experiment conducted in a transparent replica of a natural granite fracture. Additional experiments were conducted to measure the breakthrough curves of a conservative tracer introduced ...

Many of the world's megacities depend on groundwater from geologically complex aquifers that are over-exploited and threatened by contamination. Here, using the example of Dhaka, Bangladesh, we illustrate how interactions between aquifer heterogeneity and groundwater exploitation jeopardize groundwater resources regionally. Groundwater pumping in Dhaka has caused large-scale drawdown that exten...

Water repellency of soils near the surface leads to preferential flow and transport, because it prevents water from entering hydrophobic areas and concentrates water fluxes in hydrophilic areas. Heterogeneity in the flow field is the main problem for the prediction of contaminant transport. To investigate the flow patterns in a sandy soil, which was contaminated with hydrophobic tar oils and he...

Preferential flow in unsaturated porous media, in the form of fingers and channels, has been observed to take place in different types of media and at different scales. The preferential flow is caused by fluid instabilities, created by density or viscosity differences, or because of heterogeneities in the geological media. In this study, two very different types of preferential flow problems ar...

2 FOREWORD The Russell Creek Research Project is a joint multi-year project between the University of British Columbia and the B.C. Ministry of Forests, with an objective of increasing our understanding of hydrological processes by focusing on subsurface flow, spatial variation of climate data and snow accumulation and ablation dynamics. This process based experimental setup will provide data t...

A preferential entailment is defined by a binary relation, or “preference relation”. This relation can be either among interpretations or among sets of interpretations. The relation can be also among “states” which are “copies of interpretations”, or “copies of sets of interpretations”. This provides four kinds of preferential entailments. The paper deals mainly with propositional logic, howeve...

Discrete fracture network (DFN) model simulations, where a fracture network can have a natural heterogeneity, is one of the most effective approaches in fluid flow analyses for naturally fractured and enhanced geothermal reservoirs. In the DFN model simulations, fractures are modeled by a pair of parallel smooth plates although real fractures have rough surfaces. Numerous field and laboratory o...

Soil and crop management practices have been found to modify soil structure and alter macropore densities. An ability to accurately determine soil hydraulic parameters and their variation with changes in macropore density is crucial for assessing potential contamination from agricultural chemicals. This study investigates the consequences of using consistent matrix and macropore parameters in s...