Lancaster EPrints

Monitoring unsaturated flow and transport using geophysical methods.

Looms, Majken C. and Jensen, Karsten H. and Binley, A., Andrew and Nielsen, Lars (2008) Monitoring unsaturated flow and transport using geophysical methods. Vadose Zone Journal, 7 (1). pp. 227-237. ISSN 1539-1663

Full text not available from this repository.

Abstract

Improved understanding of unsaturated flow and transport processes is limited by the lack of appropriate in situ measurement techniques. This study was conducted to determine whether two noninvasive cross-borehole geophysical methods combined could be used to estimate two important unsaturated zone transport parameters, namely the pore water velocity and longitudinal dispersivity. Cross-borehole electrical resistivity tomography and ground penetrating radar were used to estimate temporal and spatial variation of electrical resistivity and water content, respectively, during a 20-d forced infiltration experiment. The resulting one-dimensional profiles and two-dimensional images of moisture content and electrical resistivity were subsequently combined to estimate solute tracer concentration. The results were used to analyze the downward migration and vertical spreading of water and tracer mass. The two geophysical methods provided independent estimates of soil moisture content and electrical resistivity that were spatially and temporally consistent. The observed changes in moisture content and electrical resistivity were, as a first approximation, used in a one-dimensional moment analysis. The transport behavior was found to be very susceptible to layering of the subsurface. Even slight reductions in grain size apparently lead to flow barriers and associated lateral flow, resulting in tracer mass loss, reduced vertical pore water velocity, and increased longitudinal dispersivity. Synthetic data showed that the estimated unsaturated transport parameters (i.e., pore water velocity and longitudinal dispersivity) and the mass estimate were influenced by the selected electrical resistivity tomography inversion routine. In effect, an overprediction of all three parameters was observed.

Item Type: Article
Journal or Publication Title: Vadose Zone Journal
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 475
Deposited By: Prof Andrew Binley
Deposited On: 27 Apr 2009 16:48
Refereed?: Yes
Published?: Published
Last Modified: 06 Sep 2013 20:54
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/475

Actions (login required)

View Item