The Synthetic Roadcut -- A Nuherical Technique For The Multiple-Scale Integration Of Surface And Borebole Data

Integration of geophysical soundings or tomograms with geophysical logs<br>and hydraulic test data from boreholes is complicated by the very different<br>scales of investigation of each of these techniques. We present a numerical<br>approach designed to optimize the comparison of large-scale geophysical<br>measurements with data from borehole arrays. This technique addresses four<br>important requirements: 1) borehole data are projected into a single vertical<br>plane or “synthetic roadcut”; 2) projections between boreholes are adjusted in<br>the representation plane within specified limits to improve spatial<br>correlations between boreholes; 3) borehole data are subjected to a range of<br>spatial averaging and smoothing techniques; and 4) soundings or tomograms and<br>borehole data sets are kept rigorously separate until the processed data are<br>formally compared. The technique is illustrated using data from the FSE<br>borehole array at the Mirror Lake, New Hampshire fractured rock hydrology<br>research site. The Mirror Lake data show that comparisons of borehole logs<br>and borehole packer test data with tomograms can indicate how discontinuous<br>fractures are organized into larger scale conductive zones, and how the<br>distribution of those zones may be related to the lithologic fabric of the<br>bedrock.