Rating Curve Data Fields (SWMM)

A rating curve in a SWMM network is used to define the relationship between either the head difference across the outlet or the freeboard depth above its opening, and its flow rate.

Information relating to a rating curve can be viewed and edited on the Rating Curve Grid Window of the Links Grids or on the Rating Curve Property Sheet.

Most data can be edited on the grid, but some fields cannot be displayed in the grid format.

To view and edit all rating curve data, use the Property Sheet.

The table below describes all the data which can be used to define a rating curve. For details of results fields for links, see the Link Results Data Fields (SWMM) topic.

Database Table Name: sw_curve_rating

Field Name	Help Text	Database Field	Data Type	Size	Units	Precision	Default	Error Lower Limit	Error Upper Limit	Warning Lower Limit	Warning Upper Limit
Rating curve ID	The unique name for the rating curve, up to 254 letters, numbers and underscore characters. Upper and lower case letters are treated as being the same. This name cannot be used by any other curve in the same SWMM network.	id	Text	254		0
Rating array	This field contains a series of records defining the data for this curve. These are entered on the Curve Editor which is displayed by clicking on the button. Database Table Name: sw_curve_rating_data Show Columns Database Names Size, Type and Units Defaults and Error Limits Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit Head difference Depending on which Rating curve type is chosen in the relevant outlet's properties, this is either the head difference across the outlet or the freeboard depth above its opening. head Double   Y 3           Outlet flow The corresponding flow from the outlet at this head difference. outflow Double   Q 3	data	Structure