Glossary of Terms

Base Flow Streamflow coming from ground-water seepage into a stream.

Cubic Feet Per Second A rate of the flow in streams and rivers. It is equal to a volume of one foot high and one foot wide flowing a distance of one foot in one second. One "CFS" is equal to 7.48 gallons of water flowing each second.

Discharge The volume of water that passes a given location within a given period time. Usually expressed in cubic feet per second.

Drainage Basin Land area where precipitation runs off into streams, rivers, lakes, and reservoirs. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge. Large drainage basins usually contain many smaller drainage basins. Also called a "watershed".

Flood An overflow of water onto lands that are used or usable by man and not normally covered by water.

A Flood Plain A strip of relatively flat and normally dry land along side a stream, river or lake that is covered by water during a flood.

Flood Stage The elevation at which overflow of the natural banks of a stream or body of water begins in the reach or area in which the elevation is measured.

Gage Height The height of the water surface above the gage datum (zero point). Gage height is often used interchangeably with the more general terms, stage, although gage height is more appropriate when used with a gage reading. Just like everything else we adhere to USGS standards, we spell "Gage" like the USGS, too!

Gaging Station A site on a stream, lake, reservoir or other body of water where observations and hydrologic data are obtained.

Peak Flow The maximum instantaneous discharge of a stream or river at a given location. It usually occurs at or near the time of maximum stage.

Rating Curve: A drawn curve showing the relation between gage height and discharge of a stream at a given gaging station.

Streamflow: The water discharge that occurs in a natural channel. A more general term than runoff, streamflow may be applied to discharge whether or not it is affected by diversion or regulation.

Watershed: The land area that drains water to a particular stream, river, or lake. It is a land feature that can be indentified by tracing a line along the highest elevations between two areas on a map.