Drop Pipe Spillway Design

This program calculates the spillway discharge at different water elevations. When the water is lower than the top of the riser, the Riser Inlets would take water when the water rise above the inlet's invert elevation. As the water elevation initially rises above the riser, the flow is controlled by weir flow. The program uses the perimeter of the riser for the weir length for the weir flow calculation. The riser can be either circular or box. At higher water elevations the flow is under orifice control. When the barrel flows full, the flow is controlled by full pipe flow. Given the water elevation and spillway dimensions, the program calculates the type of flow and discharge.

The Riser Inlets are orifice/weir openings on the riser and discharge into the riser box, and then to the culvert. There are two methods to calculate culvert discharge - Carlson Legacy and HDS-5.

Riser Parameters: Indicate the dimension of the vertical riser pipe, and the orifice and weir coefficients which are used in orifice and weir flow calculations.

Culvert Parameters: Indicate the culvert dimension and profile. The Friction Coefficient is the manning's n for calculating the pipe friction loss. The Entrance Loss Coefficient is used to calculate the energy loss at the culvert inlet end.

Headwater Elev: Indicate the water (pool) elevation.

Discharge: Discharge value at the end of the culvert.

Calc Discharge: Causes the routine to read the values in the dialog and calculate the Discharge flow at the current headwater elevation.

Calc Headwater Elevation: Causes the routine to read the values in the dialog and calculate the headwater elevation that's required to handle the known discharge flow.

Report Setup: Chooses between a Standard Report and a PDF Report. The Standard Report is a simple text report of the parameters and calculations. The PDF Report adds some text formatting and has the option to draw a schematic of the pipe detail and draw the stage-discharge graph.

Report: Creates a report for the current spillway.

Load/Save: Store and recall the parameters to a .drop file.

Stage-Discharge Result: Displays the following dialog box that allows you to indicate the water elevation range and increment to report:

Write Stage-Discharge File: Creates a Stage-Discharge (.STG) file that can be used in other Carlson Hydrology commands.

Draw: Allows a graphic representation of the Stage-Discharge data to be placed into the drawing.

Draw Grid: When enabled, this option creates a grid that accompanies the Stage-Discharge curve. Click the Setup button to access the grid settings which are discussed in detail in the Draw Grid section of the Draw Profile command.

Output to Separate Drawing: When enabled, this option draws the hydrograph to a separate drawing. Click the Set button to specify the name/location of the external drawing.

Horizontal Scale: Specify the discharge scale (in CFS).

Vertical Scale: Specify the stage scale (in Ft).

The Layers, Colors, Text Styles/Sizes and Linetypes buttons provide access to settings for each of these features of the Stage-Discharge curve.

Load Settings: Loads a saved collection of Draw Stage-Discharge settings, saved in a (.PFS) file.

Save Settings: Saves all Draw Stage-Discharge settings in a (.PFS) file.

Pulldown Menu Location: Structure
Keyboard Command: spillway
Prerequisite: None