Q/Qp-T/Tp is a dimensionless unit hydrograph that is used with the SCS Unit Hydrograph method. The Qp and Tp are determined based on subarea characteristics. Typically, the SCS method uses a default curvilinear unit hydrograph. Drainage and Utilities allows you to assign your own Q/Qp-T/Tp hydrograph to better suit your local conditions.

To create a new Q/Qp-T/Tp Unit Hydrograph:

1. Highlight a catchment in the model.
2. In the Property Editor, change the value in the Runoff Method field to Unit Hydrograph.
3. Change the Unit Hydrograph Method to SCS Unit Hydrograph.
4. Change the Unit Hydrograph Method Type to Dimensionless Unit Hydrograph.
5. Click the Dimensionless Unit Hydrograph field and select the Edit Dimensionless Unit Hydrograph command.
6. In the Dimensionless Unit Hydrographs dialog that appears, click the New button.

To import a Q/Qp-T/Tp Unit Hydrograph from an Engineering Library:

1. Highlight a catchment in the model.
2. In the Property Editor, change the value in the Runoff Method field to Unit Hydrograph.
3. Change the Unit Hydrograph Method to SCS Unit Hydrograph.
4. Change the Unit Hydrograph Method Type to Dimensionless Unit Hydrograph.
5. Click the Dimensionless Unit Hydrograph field and select the Edit Dimensionless Unit Hydrograph command.
6. In the Dimensionless Unit Hydrographs dialog that appears, click the Synchronization Options button and select the Import From Library command from the menu that appears.
7. In the Engineering Libraries dialog that appears, find the desired library, highlight it, and click the Select button to import it.