FLOOD11629 ‎(2)‎

• County: Statewide
• Basin: Statewide
• Title: Hydrologic Basin Response - Phase II B - Parameter Estimation Guidelines
• Date: 3/1/2007
• Floodplain - Doc Type: Floodplain Report/Masterplan

11. Use Table 7 to select the appropriate dimensionless unit hydrograph and for
guidance in selecting K~,.
033
12. Calculate Lag = 26 Kn ~ L o 5) •
S
D~nration: The duration of the unit hydrograph (or all unit hydrographs in a multiple
subbasin model) is specified in HEC-1 in the IT record as NMIN. In general, NMIN will be
selec:ted according to the following criteria:
1. NMIN equal to or less than 0.15 T~ or 0.15 Lag provides adequate definition
of the hydrograph peak with an optimum number of hydrograph coordinate
calculations.
2. NMIN = 0.25 T~ or 0.25 Lag is the maximum value for NMIN.
3. NMIN for a multiple subbasin model should be selected based on the smallest
T~ value for any of the subbasins in the model.
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