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But how do you collect water that's racing by? Dams. These giant barriers trap river water in reservoirs. Dams can also generate electricity and help control floods. There are about 75,000 dams in the U.S. alone. Yet dams create problems of their own. Investigate the site with your transit to find out more about dams and how they affect our world. ©1997 National Geographic Society. All rights reserved. |
All river water, from icy mountain streams to the
wide Mississippi, is on a downhill journey. It may surge into a sea or lake, or it may seep underground to refresh wells and springs. As they travel, rivers can provide water for cities, suburbs, factories,
and farms.