3-DIMENSIONAL DIGITAL IMAGING OF ENVIRONMENTAL DATA - SELECTION OF GRIDDING PARAMETERS

Three-dimensional imaging is a powerful technique for the visualizatio n and interpretation of environmental data. The success of the process is linked to careful, technically-justifiable selection of variable p arameters during the gridding and imaging process. The impacts of vari ous approaches to gridding and possible setting of parameters on the f inal image and volume calculations were examined by generating alterna tive images for a very well characterized contaminated site in layered coastal plain sediments. To image properly scattered data collected a t close intervals in wells from layered geological media, a higher gri d density in the z direction is required along with a weighting factor to emphasize the influence of data in the x and y directions. For ste eply-varying contaminant concentration data, the best results were obt ained by gridding the log of the property value; an anti-log transform ation is carried out to restore property values to the correct value b efore the visualization file is prepared. The techniques and recommend ations made in this article were designed for modelling contaminant va lues with very steep gradients dispersed in a strongly anisotropic med ia. These recommendations may not apply directly to other sites but th e process of selecting parameters should be similar.