The Trick to Applying 1D Initial Conditions to ICM Simulations

In InfoWorks ICM, it is possible to assign initial node levels or inflows as well as initial depths and flows along a river reach. If you have attempted this by creating an Initial Conditions 1D object and applying it to your Hydraulic Run only to find that the initial conditions specified were not applied, you might have been missing a few crucial steps. This only occurs if the initial conditions have been partially applied, ie, not all nodes/links have had initial conditions specified.

Simply applying your Initial Conditions 1D object to your run here may not ensure that the initial conditions will be applied if some of the adjacent nodes/sections do not have their initial conditions set.  In which case there will be a message in the log file:

Warning 1124: Some nodes and links in the network are not in the state.  SIM will fill in levels from known state nodes.

There will then be an initialization phase which propagates any defined levels from the 1D initial conditions object throughout the network.


To prevent this error and the subsequent initialization phase, you should  first run a short simulation with the ‘Save State at End’ option specified in the run (this is essentially creating a hotstart for the run with Initial Conditions):  This will create an initial state for all nodes/links within the model based on the boundary conditions applied.

The state file will provide an initial state for all nodes/links.  This will then be overwritten by the 1D Initial Condition object for those objects where an initial condition is defined.  As all nodes/links have a defined state, either by the state file or the 1D initial conditions object, there will be no subsequent initialization phase. Be aware, however, that if the initial conditions are incompatible with neighboring nodes/sections in the state file, your simulation might have instability problems.

In the Hydraulic Run window of the simulation where you apply your Initial Conditions 1D object, drag the simulation where you saved the state at the end into the Sim box and tick the ‘Always use state without re-initialization’ option:


The results from this run should reflect the 1D Initial Conditions specified.

Share this post!
    This entry was posted in InfoWorks ICM and tagged , , , , , . Bookmark the permalink.