More and more of the world's population is concentrated in urban environments close to rivers and coastlines. Looked at in conjunction with changes in rainfall and sea level expected as a result of climate change, this means that an increasing number of people are exposed to flooding risks.
Sources of Data and Information
USGS Water Data for the Nation (more info) This site provides access to water-resources data collected at approximately 1.5 million sites in all 50 States, the District of Columbia, Puerto Rico, the Virgin Islands, Guam, American Samoa and the Commonwealth of the Northern Mariana Islands. Online access to this data is organized around categories: Real-Time Data, Site Information, Surface water, Groundwater, Water Quality, and Mapper.
The "1OO-Year Flood" (more info) This site describes how and when 100-year floods occur. It states that flood designations are based on statistical averages, not on the number of years between big floods. It also suggests that it would make more sense to refer to 100-year floods as 1-in-100 chance floods. This resource is a United States Geological Survey (USGS) Fact Sheet. It can be used in teaching quantitative skills.
Significant Floods in the United States During the 20th Century - USGS Measures a Century of Floods ( This site may be offline. ) During the 20th century, floods were the number-one natural disaster in the United States in terms of the number of lives lost and property damage. For more than 110 years the U.S. Geological Survey (USGS) has measured floods for the Nation's benefit while supplying additional streamflow data with its extensive stream-gaging network. Thirty-two of the most significant floods (in terms of number of lives lost and (or) property damage) in the United States during the 20th century are listed according to the various types of floods. Internet sites for acquiring near-real-time streamflow data and other pertinent flood information are provided.
USGS Surface Water Information: Flood Information (more info) This site from the USGS Office of Surface Water provides access to many resources and data sets about current and past flooding events in the United States. There are links to maps showing current water conditions, 28 day National Weather Service forecasts, Water Science Centers in the various states, as well as national and local flooding resources. There are also links to other parts of the USGS Surface Water Information site which host a variety of data and information resources.
Flood Hazards - A National Threat (more info) This USGS Fact Sheet (2006-3026) illustrates the national scope of the risk of flooding events in the US. The vast majority of counties have experienced at least one presidential disaster declaration related to flooding since 1965. The fact sheet examines the risks and how USGS scientists are studying floods in order to reduce future risks to the US population, property, and infrastructure.