The behaviour of a network under particular conditions is modelled by running simulations. The simulations test the effects of a given flow of water through the network over a period of time and identify weaknesses in the system, such as nodes that are liable to flood under given conditions.

The details of particular simulations are held on the database as runs. When a run is set up, one or more time varying inputs - rainfall events, flow surveys or time series database objects - can be specified for use in calculations. The system creates one simulation for each time varying input therefore each run may contain one or more simulations. In addition, if the run includes any scenarios and/or episode collections (InfoWorks networks only), then simulations will also be created for each scenario and/or each episode for all time varying inputs included in the run.

Simulation parameters

The simulation parameters govern how the engine performs the model calculations in the hydraulic simulation. The default values have been chosen for optimum accuracy and performance, and therefore do not normally need to be amended. However, the parameters can be edited if necessary.

From the Model menu, select Model parameters | Simulation parameters to display the simulation parameters values in the Object Properties Window for the currently active InfoWorks network.


If monthly RTK hydrographs are to be included in simulations for InfoWorks networks, then ensure that the Use SWMM5 RDII option is checked in the simulation parameters. This option is checked by default for any new network created using InfoWorks ICM version 8.5 onwards.

For SWMM networks, the model parameters also include options which determine how the hydraulic simulation is performed. To change any of these options, select Model parameters | Options from the Model menu to display the model parameter values for the currently active SWMM network.

Simulation diagnostics

Diagnostic checks can be set up as part of a run for InfoWorks networks. Thresholds for various parameters are set. If the simulation engine exceeds these thresholds during a simulation, the icon used for the simulation in the Explorer Window is displayed in a different colour.

If sensible threshold values are exceeded, this could mean that numerical instabilities have occurred in the simulation engine.


Simulation diagnostics are not currently available for SWMM networks.

To set up run diagnostics for a run:

  1. Click Diagnostics in the Schedule Hydraulic Run View. The Run Diagnostics dialog is displayed.
  2. In the Run Diagnostics dialog, set threshold values for the parameters available. If a threshold of zero is set, the parameters is ignored and no checks are made.
  3. Click OK to return to the Schedule Hydraulic Run View.

See Computational Instabilities for further information.

Simulation status

The colour of the simulation icon provides information on the status of the simulation after it has been run:


Hydraulic Theory

2D Simulations

Runoff Only Simulations

Water Quality Simulations

Initial State Simulations

Simulation Parameters

Dry Weather Flow Mode

Computational Instabilities