ANALYSIS OF THE GEOMORPHIC IMPACT OF A FLOOD SEASON ON PLEASANT CREEK, CAPITOL REEF NATIONAL PARK, UTAH

Capitol Reef National Park lies in south-central Utah on the Waterpocket Fold and has two creeks whose fluvial features and landforms are geomorphically influenced by flash floods during the annual late-summer/fall monsoon season. An investigation into the sediment distribution and mapping of this creek began in 2013 and continued in 2014. The GPS data from this work allows us to quantify the volume of material transport (work done) in this study reach over one flood season and therefore characterize the contribution of seasonal geomorphic processes in Pleasant Creek via flooding. This project highlights differences in channel form using remote sensing and GPS data from both years. We used the Geomorphic Change Detection (GCD) add-in in ArcGIS to compare (DEM of Differencing) digital elevation models (DEMs) created from high resolution GPS measurements. From this, we were able to identify where erosion and aggradation have occurred over the course of the 2013-2014 flood season. Both erosion and deposition occurred within the channel, with the greatest amount of erosion occurred at the beginning of a slight bend, which appears to have initiated migration of the bend upstream. Pleasant Creek flows through the Park adjacent to UVU’s Capitol Reef Field Station. This research has set up base data for long-term change monitoring and contributes to our understanding of how streams function within the park. This research will serve as base data for the National Park Service to manage one of the few perennial streams in the park and aid in educational purposes at the field station.