Overflow routes
These are surface paths along which overflows from pits travel. Commonly they will be along street gutters and designated flow paths, but they may run through properties and areas such as car parks. (Surface flows from sub-catchments draining to pits are dealt with in sub-catchment flow calculations. They may be combined with overflows using a procedure related to the percentage of a sub-catchment through which an overflow route runs.)
In Lite hydraulic model runs, a fixed travel time is used to translate hydrographs. In the Full Unsteady hydraulic model, the full unsteady flow solution is used in overflow routes. Therefore, invert levels are required. Water level profiles are calculated along overflow routes at each time step.
In all cases you must select a cross-section from the Overflow route data base.
Overflow routes can be divided into segments with different characteristics (slopes, cross-sections, roughness, invert levels). The segments are separated by nodes, as shown below:
When using storage routing models, DRAINS can perform routing calculations along the stream routing reaches.
Following a run, peak flowrates are presented in the Main Window. If multiple storms are used, the results for a particular storm can be selected using the pull-down menu that appears in the top-left corner of the drawing area. The Customise Text option in the View menu allows you to vary the on-screen display.
Flows along overflow routes can be examined using the Pop-Up (right mouse button) menu that provides options for plotting flowrates calculated during a run, or for displaying the numerical values.
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Weirs as alternatives to overflow routes
The special weir object in DRAINS can be used as an alternative to an overflow route at sag pits when the hydraulic control is a parabolic weir. For example, if a user has access to the Full unsteady hydraulic model option in DRAINS, the overflow ...Property sheet for overflow routes from pits
The appearance of this property sheet will vary depending on whether: you are operating the Full Unsteady hydraulic model, the storage network routing module is enabled, or you have started to specify extra data for the Full Unsteady hydraulic model. ...Overflow route property sheet
This is used to define the hydraulic characteristics of the flow paths along which overflows from pits, headwalls and detention basins may flow. It takes different forms depending on the type of node from which the route comes, and on the options ...Overflow route characteristics calculator
After a DRAINS run has been made, and peak flowrates and hydraulic grade line levels are displayed in the Main Window, it is possible to examine the flow characteristics of overflows from pits and detention basins in the page of the Overflow Route ...Overflow Route drawing tool
This tool, , is used to draw lines or poly-lines in the the Main Window, representing the paths of overflows from pits and detention basins to downstream pits and nodes, or those going out of the system. It is also used to define flow paths or ...