Beaches were formed or enlarged throughout the system, even in Marble Canyon where the sand supply was thought to be most depleted. The USGS preliminary findings suggest that the majority of sediment redeposition occurred in the first 2-3 days of the experiment. This finding, when verified, will have valuable management implications that may permit future controlled floods to be of much shorter duration and therefore substantially less costly. Understanding how sand and sediment move through our river systems is a major concern across the country for many reasons, including preservation of depositional features like the Colorado River beaches, maintenance of navigational channels, and retention and movement of pollutants such as DDT long after their use has stopped. The controlled flood experiment on the Colorado River will have benefits across the country, as it will yield information that is needed to expand the usefulness of models employed to predict the effects of higher flows on other rivers in the country.
Dams have profound but varied impacts on the rivers that they harness.
Remote Sensing Aids Cleanup A recently completed study at the California Gulch Superfund Site in Leadville, Colo., has demonstrated the application of a new technology capable of locating and pinpointing sources of acid mine drainage and a tremendous variety of other surface materials. Mineral maps produced by the USGS are cutting costs and accelerating cleanup of hazardous mine waste over a large area. Imaging spectroscopy is used for mapping minerals at hazardous waste sites to help in remediation, saving time and money, and proving imaging spectroscopy is a robust and accurate tool. Scientists at the USGS are producing these specialized maps using a new tool called imaging spectroscopy, the latest in remote sensing science. All materials, whether gaseous, liquid, or solid, contain chemical bonds that give rise to unique spectroscopic signatures.