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Keywords:

  • acoustic;
  • seismic;
  • fragipan;
  • mapping;
  • geophysics

Abstract

Agricultural, hydrological and civil engineering applications have realized a need for information of the near subsurface over large areas. In order to obtain this spatially distributed data over such scales, the measurement technique must be highly mobile with a short acquisition time. Therefore, some type of remote sensing or geophysical technique must be utilized. Geophysical measurements are sensitive to the distribution of physical properties, such as the electrical conductivity, dielectric constant, mass density, mechanical properties, etc., of the ground. In most instances, the geophysical properties must be reconciled with physical properties used by the soil scientist. This paper presents a preliminary investigation of the use of acoustic to seismic (A/S) coupling measurements for measuring the depth to the top of the fragipan horizon. Fragipans influence the hydrology and ecohydrology of the soil on a field scale. A suite of traditional geophysical measurements was taken to characterize the soils at two sites with different depths to the fragipan horizon. Data at these two field sites indicate that this A/S technique is sensitive to the spatial variability of the depth to the fragipan horizon. At present, inversion of the A/S data for the fragipan depth requires use of data from a separate geophysical measurement or soil cores to provide a field calibration. Copyright © 2009 John Wiley & Sons, Ltd.