Dilution of non-reactive tracers in variably saturated sandy structures |
| |
| Institution: | 1. Norwegian University of Life Sciences (NMBU), Universitetstunet 3, 1430 Ås, Norway;2. Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, United Kingdom;3. Norwegian Institute of Bioeconomy Research (NIBIO), Høgskoleveien 7, 1430 Ås, Norway;1. Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, IN 46556, USA;2. Hydrologic Science and Engineering, Colorado School of Mines, Golden, CO 80401, USA |
| |
| Abstract: | Based on a dye tracer experiment in a sand tank we addressed the problem of local dispersion of conservative tracers in the unsaturated zone. The sand bedding was designed to have a defined spatial heterogeneity with a strong anisotropy. We estimated the parameters that characterize the local dispersion and dilution from concentration maps of a high spatial and temporal resolution obtained by image analysis. The plume spreading and mixing behavior was quantified on the basis of the coefficient of variation of the concentration and of the dilution index. The heterogeneous structure modified the flow pattern depending on water saturation. The shape of the tracer plumes revealed the structural signature of the sand bedding at low saturation only. In this case pronounced preferential flow was observed. At higher flow rates the structure remained hidden by a spatially almost homogeneous behavior of the plumes. In this context, we mainly discuss the mechanism of re-distributing a finite mass of inert solutes over a large volume, due to macro- and micro-heterogeneities of the structure. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
