GIS METHODS FOR TECTONIC GEOMORPHOLOGY

Morphometric indices are powerful tools for investigating landscape expressions of active tectonism. Geographic Information Systems (GIS) and digital elevation models (DEM) have greatly improved the quality and efficiency of investigations into the paired processes of tectonic uplift and erosional denudation. Modern GIS tools are capable of working with very large datasets (4 GB or more), but geomorphology-specific extensions to popular software packages do not yet exist. A review of 65 long-format articles on tectonic geomorphology published in 23 different journals between 2000 and 2009 also revealed a significant gap in the literature. Methods sections rarely provide details on the data processing methods used to derive the results reported, though notable exceptions exist (Jordan et al. 2005, Lin and Oguchi 2006, Wobus et al. 2006, Crosby and Whipple 2006, Perez-Pena et al. 2009). In an attempt to fill that gap, we wrote a set of step-by-step instructions for calculating 25 geomorphometric indices in ArcGIS 9.x and tested them on a section of the Wasatch Mountains in northern Utah. Most of the routines utilize framework elements of ArcGIS (pull-down menus, simple scripts, buttons), however, some calculations require the user to push beyond the standard menus and buttons. None of the techniques described here are proprietary. The instructions are intended to aid the geomorphology research community in its investigations of surficial processes, landscape evolution, channel response, fault scarp growth, relict surfaces, and landform delineation.