Automatic dilution gaging of rapidly varying flow

Water-Resources Investigations Report 83-4088




Obtaining discharge ratings at urban gaging stations is often difficult. Results of using an automated constant-rate dye-dilution technique to measure discharge at two sites in Madison, Wisconsin, are presented. The sites selected have well-defined stage-discharge ratings, developed during previous hydrologic studies. One site is a 60-inch-diameter concrete storm sewer and the other a concrete-lined open trapezoidal channel. Equipment selected to automate the method included a portable automatic water sampler, four-channel event recorder; and for dye injection, a peristaltic pump. An electrical switching circuit was designed to coordinate the operation of the water sampler, injection pump, and four-channel recorder. During the data-collection period of 1 year, a total of 20 storms was monitored. The analyses showed that the discharges measured by dye-dilution techniques ranged from + or - 5 to + or - 10 percent of the discharges determined from ratings established by current-meter measurements. Larger differences were noted at the start of and on the rising limb of four hydrographs. Of the 20 storms monitored, 17 produced acceptable results. Peak discharges by the dilution method at the open-channel site ranged from 0 to 12 percent departures from the existing rating, whereas the peak discharge by the dilution method at the storm-sewer site ranged from 0 to 5 percent departures from the existing rating. (UGGS)

Additional Publication Details

Publication type:
Publication Subtype:
USGS Numbered Series
Automatic dilution gaging of rapidly varying flow
Series title:
Water-Resources Investigations Report
Series number:
Year Published:
U.S. Geological Survey,
v, 22 p. :ill., map ;26 cm.