Three-dimensional groundwater flow and contaminant transport in medium-scale highly heterogeneous environments.

摘要

Laboratory hydrology studies are often limited to one of two dimensions and often suffer from edge flow, which results in data that is not characteristic of the porous media. A large, minimally disturbed, heterogeneous aquifer sample in a laboratory allows the study of small-scale processes in a controlled setting. We present the design of this collection apparatus and use it to collect and study a large sample, called a mesocosm, from a glacial debris-flow deposit. A simulation regression algorithm was used to estimate effective aquifer properties and produce a numerical model which is used to illustrate that it is crucial to understand small scale processes that result from aquifer heterogeneity in order to accurately describe data collected over larger scales. Additionally, high-resolution tracer data is used to investigate effects of diffusion on flow and transport of two conservative tracers with different molecular weights. The data is used to demonstrate that fluorescein travels faster than tritium in highly heterogeneous environments as a result of its higher molecular weight which caused it to also be less diffusive.