There are options to enter discharge data into HY-8: "Minimum, Design, and Maximum", "User-Defined", and "Recurrence". The "Minimum, Design, and Maximum" is the default option and historically was the only option available.
Minimum, Design, and Maximum
HY-8 will perform culvert hydraulic calculations based on the input minimum, design, and maximum discharge values. Calculations comprising the performance curve are made for ten equal discharge intervals between the minimum and maximum values. If desired, input a narrower range of discharges in order to examine culvert performance for a discharge interval of special interest.
Lower limit used for the culvert performance curve. Can be edited to a number greater than '0'.
Discharge for which the culvert will be designed. Always included as one of the points on the performance curve.
Upper limit used for the culvert performance curve.
First specify the number of flows they wish to enter. Then enter the flows in ascending order (smallest flows at the top, highest at the bottom). Assign a name to a flow if desired. If no name is given the name column will not be shown in the results or report.
Specifies the flow next to the recurrence interval. It is not necessary to enter flows for all the years in the table and any flows that are left at zero will not show up in the results or report.