WMS:HEC-1 Parameters

File:Image190.jpg

Attributes or parameters for all HEC-1 hydrograph stations are defined and/or later edited using the Edit HEC-1 Parameters dialog. This dialog is accessed by selecting the Edit HEC-1 Parameters command from the HEC-1 menu or by double-clicking on basin, outlet, or diversion icon from the Graphics Window.

If a basin, outlet, or diversion is selected before issuing the command then data for that object appears in the text window at the bottom of the dialog. The top portion of the dialog lists the HEC-1 cards that can be edited by selecting the corresponding button. When a hydrograph station is selected (basins/outlets/diversions) only the buttons that edit parameters associated with that hydrograph station are active, all others are dimmed. In addition to using the appropriate button, HEC-1 attributes can be edited by clicking on the HEC-1 card in the text display window. Using this method, job control parameters can be edited by first toggling their display using the Display Job Control Cards toggle box, and then selecting a job control card from the text display window.

Once the dialog appears it becomes part of the main screen until you select the Done button. Therefore, you can continue to select additional, or other hydrograph stations so that data for that object may be edited without exiting the dialog. You can use the previous and next hydrograph station buttons to cycle through hydrograph stations in the order they are computed by HEC-1. Since the dialog is part of the main screen, all menu commands are active while this dialog is present.

Basin HEC-1 Cards

Unit Hydrograph Method...

One of several different unit hydrograph methods can be chosen when generating synthetic hydrographs. A method is assigned to a basin by first selecting the basin and then choosing the Unit Hydrograph Method button from the Edit HEC-1 Parameters dialog. As with other basin options the same parameters can be assigned to several basins by selecting multiple basins before accessing the Unit Hydrograph Method dialog.

Snow Melt Data...

When snow needs to be considered in the runoff analysis, snow melt data for a basin needs to be defined. HEC-1 has two different methods for computing snowfall/melt simulations: the Degree-Day method, and the Energy-Budget.

To define data for a selected basin, choose the Snow Melt Data button from the Edit HEC-1 Parameters dialog. The toggle at the top of the dialog turns snow calculations on. For both methods the elevation or zone data, the coefficients, and temperature data must be defined.

The Degree-Day method is set up once these parameters have been defined. If the Energy-Budget method is toggled on then the Dew point, Short-wave radiation, and Wind speed data must be defined as well. Losses should be defined when either method is used. These losses are used in conjunction with the LU or LE cards for normal basin losses. The check box at the bottom of the dialog allows losses to be turned on or off for a given simulation.

Routing HEC-1 Cards

Output Control...

See Output Control... section under Basin HEC-1 Cards.

Related Topics

• Job Control Data
• Basin Data
• Loss Method
• Unit Hydrograph Method
• Precipitation
• Snowmelt
• Routing
• Reservoirs
• Diversions
• Output Control
• Model Check
• Running an HEC-1 Analysis