Developed by T. Endreny at SUNY ESF in the Department of Environmental Resources Engineering
Fluvial Geomorphology
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Estimate Bankfull Width Exercise

Exercise Objective

To estimate Bankfull Width given Bankfull Discharge data and the 9-207 geometric measurements.

Exercise Process

Form 9-207 data can be used to plot a width to discharge relationship. You can either view the graph on this FGM Module page, or use Excel to view the relationship. In Excel, if you downloaded the completed workbook, the graph is already plotted. If you would like to create the graph, the Excel columns to use in the 9-207 worksheet are channel_width and discharge.

With the Bankfull Discharge estimated earlier, find the associated width. To get width, read the nearest graphical data point or use the shown equation.

  1. Recall the Bankfull Discharge value found earlier in this FGM Module Section.
  2. Find the Bankfull Discharge (x axis) on the graph to locate the associated Bankfull Width, W, (y axis) point.
  3. Consider the scatter of the data versus the narrowness of the regression line, and choose the most representative for your estimate.
  4. Record the W in feet from the log plot.

Note that the width does not change much between flows of 400 and 10,000 cfs, likely due to a constriction at the bridge.

geometric graph

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