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Remote sensing aids research on effect of dam water release on natural resources in U.S.

The Department of the Interior’s U.S. Geological Survey is collaborating with partner agencies to conduct scientific experiments designed to evaluate the effect of a high-flow release from Glen Canyon Dam on the natural resources of the Colorado River in Grand Canyon National Park. Researchers from the USGS Grand Canyon Monitoring and Research Center are working with scientists and resource managers from Interior’s Bureau of Reclamation, Fish and Wildlife Service, National Park Service, as well as the Arizona Game and Fish Department, Northern Arizona University and other cooperators to prepare, conduct, and evaluate the experiments.

Research will be supported by pre- and post-release remote sensing to determine how the beaches and sediment in the system respond to the high flows. Aerial photography will be complemented by channel-bed mapping and sediment classification using sophisticated multibeam sonar. Subsequent remote sensing efforts around Memorial Day, 2005, and 18 months after the test will track changes in the system over time.

The high-flow test, began on Sunday, Nov. 21, 2004. Under the high-flow test experiment, Reclamation will open the dam’s bypass tubes for 90 hours. The peak high flows will run for two and one-half days (60 hours) at about 41,000 cubic-feet-per-second. The goal is to stir up and redistribute sediment from tributary rivers downstream from the dam to enlarge existing beaches and sandbars, create new ones, and distribute sediment into drainage channels.

The water released during the experiment will not change the amount of water to be released over the course of the 2005 Water Year. The Annual Operating Plan calls for releasing approximately 8.23 million acre-feet of water from Glen Canyon Dam. That water is sent down river and captured in Lake Mead for use by the Lower Colorado River Basin States. The test flows are factored into that annual volume. Flows later in the year will be adjusted downward to factor in the additional water released between Nov. 21 and Nov. 25, 2004.

The science experiments will focus on sediment distribution, native fish and food for aquatic animals. The results of the experiments will be used to evaluate the use of high flows to redistribute tributary sediment as a management tool for the preservation and restoration of natural and cultural resources in the Colorado River corridor below Glen Canyon Dam.