GCD is part of the Riverscapes Consortium’s much larger family of tools for analyzing riverscapes. GCD is the Riverscapes Consoritm’s longest-standing, best developed software with the largest user base. GCD has users all over the world.
The GCD software was developed primarily for topographic change detection in rivers, but will work for simple, raster-based change detection of any two surfaces. The volumetric change in storage is calculated from the difference in surface elevations from digital elevation models (DEMs) derived from repeat topographic surveys.
As each DEM has an uncertain surface representation (which might vary in space and time), our ability to detect changes between surveys is highly dependent on surface representation uncertainties inherent in the individual DEMs. The fundamental problem is separating out the changes between the surveys that are due to topographic change as opposed to noise in the survey data. GCD provides a suite of tools for quantifying those uncertainties independently in each DEM and propagating them through to the DEM of difference. The program also provides ways for segregating the best estimates of change spatially using different types of masks. The overall suite of tools is more generically applicable to many different spatial raster-based change detection problems.
The methodological development is described in (Wheaton et al., 2010a), the Wheaton (2008) thesis, and the Wheaton et al. (2010b) RRA paper. The Matlab version of the code (DoD 3) is provided as supplemental information with the ESPL paper so that readers can test or extend the code as they see fit for their purposes.
What’s Next for GCD
GCD 7 is always in development. How active that develoment is, depends on our funding levels. We post our wish list of enhancements on our GCD GitHub Repository. If you have ideas of your own, or would like to support these efforts click below:
Note on Terminology:
DoD is an acronym for DEM (digital elevation model) of Difference (not Department of Defense). DoDs are derived from repeat topographic surveys and used in change detection studies and morphological sediment budgeting. We use GCD to mean geomorphic change detection, not Glen Cannyon Dam.