SWMM Pollutograph
A SWMM Pollutograph database item is a type of event which defines a water quality input to the system. In a SWMM network, a pollutograph can be created for each inflow type of pollutant, and during a simulation, its time-varying input is applied at a particular node, using the information specified in the Profile Properties Dialog.
SWMM Pollutographs can be used in conjunction with an Inflow or Level event. The Inflow or Level event provides flow measurement and the two together define actual pollutant inflow. For every point that has a pollutant input defined in the Pollutograph, a hydrograph must also be defined in the Inflow or Level event.
- Level hydrographs can only be used to provide inflow information for outfall types of nodes. This represents changing level in the body of water (river or sea for example) into which the sewer network discharges. Once this level rises above the level of the outfall, backflow into the system can occur.
- Inflow hydrographs can be used at junction or storage node types but cannot be used at outfall nodes.
To use one or more pollutographs in a simulation, include the required SWMM Pollutographs in the Pollutograph box on the SWMM Schedule Hydraulic Run View, and ensure that Water quality box is checked in the Run Options dialog.
Remember that volume inflow data must be present for each water quality pollutant input. An Inflow and/or a Level event must be included in the run. There must be a hydrograph for each object that has a pollutant input in the SWMM Pollutograph. If there is no volume inflow data the pollutant input at that point is ignored.
Pollutograph components
SWMM Pollutographs are viewed and edited in the Event Editor, where a single tab represents the inflow for the pollutant. The name on the tab is specified when the pollutograph database item is added to a model group.
Sub-Events and Profiles
SWMM pollutograph events, like many other types of event, are divided into:
- sub-events - a time period during which input to the system takes place
- profiles - describing the input at a single point
For more details on how ICM deals with sub-events and profiles, see the main Events topic.
Each pollutant is treated separately when carrying out simulations. A different number of sub-events, with different start and end times can be defined for each type of pollutant, and each pollutant type can have more than one profile.
