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Evaluation of wet-line depth-correction methods for cable-suspended current meters

Water-Resources Investigations Report 85-4329

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Abstract

Wet-line depth corrections for cable-suspended current meter and weight not perpendicular to the water surface have been evaluated using cable-suspended weights towed by a boat in still water. A fathometer was used to track a Columbus sounding weight and to record its actual depth for several apparent depths, weight sizes, and towed velocities. Cable strumming, tension, and weight veer are noted. Results of this study suggest possible differences between observed depth corrections and corrections obtained from the wet-line correction table currently in use. These differences may have resulted from test conditions which deviated from the inherent assumptions of the wet-line table: (1) drag on the weight in the sounding position at the bottom of a stream can be neglected; and (2) the distribution of horizontal drag on the sounding line is in accordance with the variation of velocity with depth. Observed depth corrections were compared to wet-line table values used for determining the 0.8-depth position of the sounding weight under these conditions; the results indicate that questionable differences exist. (Lantz-PTT)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Evaluation of wet-line depth-correction methods for cable-suspended current meters
Series title:
Water-Resources Investigations Report
Series number:
85-4329
Edition:
-
Year Published:
1986
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
iv, 31 p. :ill. ;28 cm.