Task 2. Create and Parameterize a Bulletin 17 Analysis

The Bulletin 17 analysis allows the user to fit a Log Pearson Type III analytical distribution to an annual maximum series of flow. This analysis allows for one of two procedures to be used:

1. Bulletin 17B, which was published by the Interagency Advisory Committee on Water Data in 1982
2. Bulletin 17C, which was originally released by the Subcommittee on Hydrology in 2018

Create a new Bulletin 17 Analysis

• Click Analysis | New | Bulletin 17 to create a new Bulletin 17 analysis.
• Name the analysis "Aquashicola_B17C".
• Select the Aquashicola Creek peak flow data set within the Flow Data Set drop down menu.

The data set will be named "Aquashicola Creek-Palmerton, PA-FLOW-ANNUAL PEAK".

• On the General tab, ensure the "17C EMA" radio button is selected within the Method for Computing Statistics and Confidence Limits panel. Leave all other options unchanged.
• Move to the Options tab. Take note of the options that are available within this tab.
• Move to the EMA Data tab. This is where perception thresholds and flow ranges are entered which are then used within the Bulletin 17C procedures.

Compute and Visualize the Results

• Click the Compute button at the bottom of the Bulletin 17 editor. A window informing you that the computations are complete should appear. Click OK to close this window.
• Click Plot Curve at the bottom of the Bulletin 17 editor to view the results. A window similar to the figure below should appear.

• Notice that there are four data sets plotted within this window. Click on each data set in the legend to better identify which data set is associated with each legend item in the plot.
• When you are done, close the plot and move to the Tabular Results tab. Take note of the tabular information that is contained within this tab including the compute curve, confidence limits, distribution parameters, and details of the selected data set.
• Click the View Report button to open the report.
• Within the report window, take note of the expanded information that can only be found within the report file. When you are finished scrolling through the report, close the window by clicking the "X" button in the upper right corner of the window.

Question 2: Within the report file, what is the reported Grubbs-Beck Critical Value for the Aquashicola_B17C analysis?

• Click OK to close the Bulletin 17 editor.
• Click the Save button (  ) to save the study.

Continue to Task 3. Create and Parameterize a General Frequency Analysis.