Curves (SWMM)
Curves are used in a SWMM network to define the functional relationship between two quantities.
The following types of curves, and the network object that uses them, are listed below:
- Storage - defines how the surface area of a tabular type of storage node varies with water depth.
- Tidal - defines how the tide elevation at an outfall type of node changes during a 24 hour period.
- Pump - defines the relationship between a pump's flow rate and conditions at its inlet and outlet sides of the pump.
- Rating - relates flow through an outlet to the freeboard depth or head difference across the outlet.
- Weir - defines the relationship between the head difference and the discharge coefficient for a weir
- Control - determines how the control setting of a pump or other flow regulator, such as a weir, varies as a function of some control variable (such as water level at a particular node) as specified in a SWMM control rule.
- Shape - describes how the width of a cross section shape varies with height for a conduit with a custom type of shape.
- Underdrain - defines the relationship between the depth and flow rate factor for the underdrain element of a Bio-retention cell, Infiltration trench, Permeable pavement or Rain barrel type of LID control.
Each curve must be given a unique name and can be assigned any number of data pairs. Curve parameters are edited in the grid window of either the Nodes Grid (Storage curve and Tidal curve), the Links Grids (Shape curve, Pump curve, Rating curve, Weir curve and Control curve), or the Subcatchment Grid (Underdrain curve), or the relevant Property Sheet.
