Natural Disaster. A geographical area which contributes surface water runoff to a particular point. The terms "drainage basin," "tributary area," and "watershed" can be used interchangeably
The Flood Control District of Maricopa County, Glossary of Flooding Terms, AZ, USA 2009. http://www.fcd.maricopa.gov/Education/glossary.asp x, (ND/ Flood - Amer) {477}