Gully monitoring at two locations in the Grand Canyon National Park, Arizona, 1996-2010, with emphasis on documenting effects of the March 2008 high-flow experiment

Abstract

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprodTo order this and other USGS information products, visit http://store.usgs.gov Suggested citation: Schott, N.D., Hazel, J.E., Jr., Fairley, H.C., Kaplinski, M., and Parnell, R.A., 2014, Gully monitoring at two locations in the Grand Canyon National Park, Arizona, 1996Arizona, -2010, with emphasis on documenting effects of the March 2008 highflow experiment: U.S. Geological Survey Open-File Report 2014-1211. ISSN 2331ISSN -1258 Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. Tables Table 1. Topographic surveys conducted at the Palisades South gully network, Grand Canyon National Park, Arizona ............................................................................................................................................ DatumsVertical and horizontal coordinate information is referenced to the 2007 realization of the National Spatial Reference System, North American Datum of 1983, NAD83 (NSRS2007), in meters.Elevation, as used in this report, refers to GPS derived ellipsoid height above the GRS80 ellipse, in meters, and not NAVD88 orthometric height. AbstractMany archeological sites in the Grand Canyon are being impacted by gully incision. In March 2008, a high-flow experiment (2008 HFE) was conducted with the intention of redistributing fine sediment (sand, silt, and clay) from the bed of the Colorado River to higher elevations along the channel margin. Deposition of fine sediment in gully mouths has been hypothesized to slow gully erosion rates and lessen impacts to archeological sites. The effects of the 2008 HFE on gullies were evaluated by comparing the topographic changes of three gullies at two study sites before and after the 2008 HFE. Comparison results indicated that sediment was deposited in gully mouths during the 2008 HFE, and that the inundated areas nearest to the river can be extensively altered by mainstream flow during high-flow events. Additionally, the history of gully evolution at the two study sites was examined between 1996 and 2010 and indicated that gullies have been subjected to thalweg incision and gully widening processes over a decadal timescale. Although the small sample size precludes extrapolating the results to other gullies, the findings contribute to the understanding of gully erosion in archeologically significant areas and have implications for future monitoring of gully erosion and evaluating the effectiveness of check dams intended to mitigate that erosion at archaeological sites in the ...