To obtain Peak Flows data

On a watershed asset card, choose the hydrology method for obtaining Peak Flows data or supply data manually.

Drainage Design supports two hydrology methods for obtaining watershed Peak Flows data: Rational or Regression. In addition, you can enter data manually. Drainage Design uses the Q100 value (100-year flow) to calculate the watershed Flow for culverts added to the model.

1. Click inside a watershed to select it and display its asset card.
2. Right-click the watershed and click Edit to enter Edit mode.
3. Choose a Hydrology Method from the drop down menu: User Defined, Rational, or Regression.
4. Provide values in editable fields to generate Peak Flows values (Q10, Q50, and Q100).

Note: Drainage Design uses US Geological Survey National Streamsflow Statistics (NSS) database to derive Peak Flows for tributaries in a watershed.

Value Fields for Hydrology Methods

User Defined	Enter values for Q10, Q50, Q100 from your data source.
Rational	Runoff Coefficient: Enter a value manually from your data source. Rainfall Intensity: Enter a value manually from your data source.
Regression	State: Choose from states with data available. Region: Choose from regions available. Depending on the State and Region, add additional values manually. Reference information is available from the USGS National Streamflow Statistics Program. Contributing Drainage Area: This value is calculated for the selected watershed and is the same as the Area value listed in the watershed asset card Summary section.