hydraulic grade line


Also found in: Acronyms.

hydraulic grade line

[hī′drȯ·lik ′grād ‚līn]
(fluid mechanics)
In a closed channel, a line joining the elevations that water would reach under atmospheric pressure.
The free water surface in an open channel.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.