Underdrain Curve Data Fields (SWMM)

An underdrain curve in a SWMM network is used to define the relationship between the depth and flow rate factor for the underdrain part of one of the following types of LID control:

• Bio-retention cell
• Infiltration trench
• Permeable pavement
• Rain barrel

Information relating to an underdrain curve can be viewed and edited on the Underdrain Curve Grid Window of the Subcatchment Grid or on the Underdrain 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 curve data, use the Property Sheet.

The table below describes all the data which can be used to define an underdrain curve. For details of results fields for subcatchments, see the Subcatchments Results Data Fields (SWMM) topic.

Underdrain Curve Data

Database Table Name: sw_curve_underdrain

Field Name	Help Text	Database Field	Data Type	Size	Units	Precision	Default	Error Lower Limit	Error Upper Limit	Warning Lower Limit	Warning Upper Limit
Curve ID	The unique name for the underdrain 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
Underrain 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_underdrain_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 Depth The depth of the underdrain element of the control type. The depth values must be positive and should be specified in increasing order. depth Double   Y 3           Factor The corresponding flow factor for this depth. factor Double     3	data	Structure