Controlled flooding on the Colorado River: using GIS methods to assess sandbar development

To replenish and restore sandbars and thus preserve aquatic and riparian habitats along the Colorado River, four high-flow controlled floods were conducted as part of the Glen Canyon Dam Adaptive Management Program. While studies of the most recent flood event in November 2012 are not yet available, scientific research has been completed on the March-April 1996, November 2004, and March 2008 artificial floods. Ground based research on pre- and post-dam sediment-transport has yielded insights into the process of sedimentation, the types of sediments conducive to sandbar formation, the significance of antecedent sand supply, and the effect of high-flow discharges from Glen Canyon Dam along seven reaches of the Colorado River where substantial data were collected over the years. On the basis of GIS data collected before and after the 2004 flood and assembled into an overall image in ArcGIS, this study tests the hypothesis that the post-flood sandbar area and volume show substantial increases over the pre-flood measurements. Analyzing extensive reaches along the main stem of the river allows a comprehensive overview of sandbar movement and development that may serve as a predictive tool for future high-flow experiments.