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GLOSSARY Water-resource terms are defined in the GLOSSARY and are italicized when first used in this report. convegance.--A measure of the carrying capacity of a channel section; it is directly proportional to channel discharge. Conveyance is that part of the Manning equation excluding the square root of the energy gradient or friction slope. correlation coefficient.--A number that expresses the relation between two variables. The value of the correlation coefficient lies between +1 and -1. A positive correlation coefficient indicates one variable increases as the other increases. A negative correlation coefficient indicates one variable increases as the other decreases. critical flow.--If the flow is critical, the Froude number is equal to unity, and the inertial forces balance the gravitational forces. This balance takes place at the depth at which flow is at its minimum energy with respect to the channel bottom. flood plain.--An area in and adjacent to the stream that is built of sediments during the present regime of the stream and which is covered with water when the stream overflows its banks. Froude number.--A dimensionless number used as an index to characterize the type of flow (subcritical, critical, and supercritical) in an open channel; the Froude nwmber is the ratio of the inertial forces to gravitational forces. It is computed as the mean flow velocity divided by the square root of the product of the hydraulic depth times the gravitational constant. high-gradient stream.--A high-gradient stream is defined as one having slopes greater than 0.01 (foot per foot). higher-gradient stream.--For this report a higher-gradient stream is defined as Gne having slopes greater than 0.002 (foot per foot). lower-gradient stream.--For this report a lower-gradient stream is defined as one having slopes less than 0.002 (foot per foot). multiple-regression analgsis.--A statistical technique by which a relation between a dependent variable and two or more independent variables can be derived. The result is usually expressed as a regression equation. recurrence interval.--The average interval of time, in years, within which a given flood will be exceeded once. standard error of estimate.--A measure of how well observed values agree with estimated values in a regression relation. The standard error of estimate is computed from the differences between the observed values and the values estimated using a regression equation. stream power.--A measure of energy transfer used in computing the regime of flow in sand channels. subcritical flow.--If the flow is subcritical, the Froude number is less than 9ne and the inertial forces are less than the gravitational forces. The flow depth in subcritical flow is greater than the flow depth in critical flow. supercritical flow.--If the flow is supercritical, the Froude number is greater than one and the inertial forces are greater than gravitational forces. The flow depth in supercritical flow is less than the flow depth in critical flow. v