More information on the Open Book is available. Copyright 1996, the National Academy Press. Keywords, machine extracted. Top 50 words repeated twice, next 100 once, plus phrases. The continuing industrialization and population growth of river valleys are increasing the economic cost and death toll of flood-related disasters.
Flash floods are an especially dan- gerous threat.
A single flash flood in 1976 on the Big Thompson River in Colorado claimed 139 lives. At the opposite extreme from floods, prolonged droughts also bring major economic and social disruption by losses in agriculture and food production. Low-flow conditions also impact navigation and industrial activities that are dependent on water in the river network. Drought conditions in 1996 have caused crop losses estimated in the hundreds of millions of dollars in central and southwestern regions of the United States. Many of the nation's watersheds are now managed and controlled through flood control reservoirs, storage reser- voirs, hydroelectric production, water quality and erosion control measures, and land management.