LAUSR

Fractures rarely occur individually but more usually as networks of numerous fractures whose arrangement, abundance, and interaction control the mechanical and transport properties of rock masses. Of particular importance are the distributions and spatial variations of different geometric (locations, orientation, length, etc.) and topological (intersections, connectivity, etc.) attributes of fractures in a network. Geographical Information Systems (GIS) provide a means to map and digitize two-dimensional fracture networks from a variety of field and remote sensing data and to display the results in the form of quality maps. We introduce NetworkGT, an open-source toolbox for ArcGIS capable of efficient sampling, analysis, and spatial mapping of geometric and topological attributes of two-dimensional fracture networks. The toolbox helps to extract and plot geometric and topological information from a given two-dimensional fracture network including: rose diagrams, plots of frequency distribution and topology, and maps of topological parameters. Using a fracture network example from offshore NW Devon, United Kingdom, we illustrate the practicality and effectiveness of the toolbox. This includes computing a contour grid with 1326 subsampled regions within the fracture network, which is used to demonstrate the quantitative capabilities of the toolbox and the ability to spatially map important network properties. The toolbox will help to facilitate the increasing application of geometry and topology in the analysis and comparison of fracture networks at a range of scales. Furthermore, the integration of the NetworkGT toolbox into ArcGIS allows two-dimensional fracture networks to be interpreted, mapped, and fully analyzed within the same software package.