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Bedrock detection using 2D electrical resistivity imaging along the Peikang River, central Taiwan

Authors
Journal
Geomorphology
0169-555X
Publisher
Elsevier
Publication Date
Volume
114
Issue
3
Identifiers
DOI: 10.1016/j.geomorph.2009.08.004
Keywords
  • Landscape Evolution
  • Sediment Transport
  • Sediment Budgets
  • 2D Electrical Resistivity Imaging Method
  • Laplacian Edge Detection
Disciplines
  • Earth Science
  • Physics

Abstract

Abstract We use the two-dimensional (2D) electrical resistivity imaging (ERI) method to detect the contact between sediment and bedrock in a modern fluvial system. We performed eight 2D electrical resistivity surveys along the Peikang River in Kuohsing area, central Taiwan, with a pole–pole array of 1-m electrode spacing to produce a spatial resolution of about 1 m. The resistivity data were inverted into subsurface electrical structures using the least-squares inversion techniques. Then, the contact between the bedrock and sediment was found by using an image processing technique called Laplacian edge detection (LED), which represents an objective approach in interpreting various geophysical images. Numerical modeling demonstrates that isoresistivity lines are not in good agreement with the hypothetical interfaces between the bedrock and sediment, but the zero-lines of the Laplacian operation are strikingly accurate. Our results indicate a well-defined boundary in the resistivity structure that can be used to estimate the quantity of sediments covering bedrock, thus highlighting the utility of this technique in studies of landscape evolution, sediment transport, and sediment budgets.

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