Damming Grand Canyon
The 1923 USGS Colorado River Expedition
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Robert Webb has worked on long-term changes in natural ecosystems of the southwestern United States since 1976. He is a research hydrologist with the U.S. Geological Survey and has authored, co-authored, or edited nine books, including Grand Canyon: A Century of Change; and Floods, Droughts, and Changing Climates (with Michael Collier).