T38 Hydrogeomorphic and Ecohydrologic Consequences of Extraordinary Sediment Loading (Posters)

Sunday, 18 October 2009
9:00 AM - 6:00 PM
Hall A

RESULTS OF A RECENT GROUND PENETRATING RADAR (GPR) SURVEY ALONG THE HITE DELTA, LAKE POWELL, UTAH

Paper number: T38-11
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

The Hite Delta is a 60 km-long, highly dynamic river delta that is forming from sediments transported by the Colorado River system within Glen Canyon and some of its inner gorges in southeast Utah. Its rate of advance had been approximately 1.2 km/year for about a quarter century, but increased significantly to about 2.7 km/year between 1999 and 2005. This was due in large part to a lengthy drought throughout the upper Colorado River drainage basin and the consequential lowering of water levels in Lake Powell. The Colorado River responded to this change by increased cutting of its channel into the Hite delta, which exposed large volumes of deltaic sediments. Increased water levels in Lake Powell during the spring and summer of 2009 have resulted in regression of the delta and infilling of the incised channel in the area around the Hite Marina.

In this project, GPR was employed in the month of June 2009 in the area of the abandoned Hite marina to characterize newly deposited sediments along the Hite delta during regression. Special attention was given to post-depositional features such as slump blocks, lateral spreads, and fluid escape structures. The 25 MHz surveys were carried out using a floating platform towed across the width of the Colorado River in the vicinity of the marina. Results indicate that incised portions of the channel have been completely filled with recent sediments and the areas of the channel that contain slump blocks and lateral spreads were also infilled. Slump blocks are discernable on the GPR profiles as are sections of the Cedar Mesa (Permian age) structural bench and large vertical fluid escape conduits that have been buried by the recent sediments. This information is intended for use in identifying and improving interpretations of similar environments that have been preserved in the rock record.