HR: 1330h
AN: NS23A-03    [Abstracts]
TI: Electrical Resistivity Inversion Constrained by Resistivity Cone Penetrometry (RCPT): Application to Landfill Site Characterisation
AU: * Catt, L M
EM: lcatt@earth.leeds.ac.uk
AF: School of Earth and Environment (Earth Sciences), University of Leeds, LEEDS, LS2 9JT United Kingdom
AU: West, L J
EM: j.west@earth.leeds.ac.uk
AF: School of Earth and Environment (Earth Sciences), University of Leeds, LEEDS, LS2 9JT United Kingdom
AU: Clark, R
EM: r.clark@earth.leeds.ac.uk
AF: School of Earth and Environment (Earth Sciences), University of Leeds, LEEDS, LS2 9JT United Kingdom
AU: Murray, T
EM: t.murray@geog.leeds.ac.uk
AF: School of Geography, University of Leeds, LEEDS, LS2 9JT United Kingdom
AB: Areas of clay-rich tills in the UK are attractive sites for landfills. The relatively impermeable clays act as a barrier between landfill contents and surrounding permeable materials, but tills often contain sand and gravel deposits, which may be water-bearing and/or hydraulically connected to aquifers or surface water bodies. The sands and gravels may be missed by borehole and trial-pit led site investigations but cause flooding of landfill excavations or act as leachate flow routes. Electrical resistance tomography (ERT) is potentially an appropriate subsurface imaging tool for landfill site characterisation, due to its ability to distinguish permeable sand and gravel from clays.. However, engineers want more accurate identification of interface depth than standard ERT inversions supply. Here, the use of reference geoelectrical models based on Resistivity Cone Penetrometry (RCPT) data is investigated. The use of RCPT data can potentially guide the inversion algorithm towards improved solutions. A series of synthetic electrical resistivity and RCPT data from model profiles with various shaped sand bodies within a clay background were generated, and inverted with and without RCPT constraints. The ability of the guided inversion to reconstruct the original geoelectrical model was assessed quantitatively. Preliminary results indicate that using RCPT data as a constraint can significantly improve interfacial depth accuracy in the inverted data. The use of depth information to constrain 1-D layer models in resistivity sounding is already well established. Hence, an alternative approach to the incorporation of depth information is construction of a pseudo-2D resistivity profile from 1-D soundings extracted from ERT data, inverted using depth-constrained layer models. The accuracy and limitations of this approach will be compared with the reference model approach described above. Future work will include the acquisition and processing of field RCPT and ERT data.
DE: 0925 Magnetic and electrical methods
DE: 1832 Groundwater transport
DE: 3210 Modeling
SC: Near-Surface Geophysics [NS]
MN: 2005 Joint Assembly