RDII or RTK UH's in the SIM and SWMMSIM Engines of ICM InfoWorks and SWMM Networks

InfoWorks ICM uses two different engines for its hydraulic and hydrologic calculations: the SIM engine and the SWMM engine.

The SIM engine is proprietary to InfoWorks and includes two versions of RDII (Rainfall-Dependent Infiltration/Inflow) from the SWMM (Storm Water Management Model) platform, specifically SWMM5 and SWMM4.

The SWMM5 is the latest version of the EPA's stormwater management model, while SWMM4 is the previous iteration. Both are used to simulate the quantity and quality of runoff generated within urban areas and to predict the response of complex drainage systems over time.

i was referring to the implementation of RDII within the SWMM components of the SIM engine. In InfoWorks ICM, RDII is treated differently compared to SWMM5. In SWMM5, RDII is typically associated with a specific node in the system. However, in InfoWorks, RDII is treated as part of a Subcatchment, which represents a specific area of land.

The difference in treating RDII can lead to certain limitations when using InfoWorks ICM, as Kyle pointed out. Specifically, when more than one RDII stream needs to be associated with a single node, the software's code had to be modified to accommodate this. The change was necessary because the original SWMM5 code didn't allow for multiple RDII streams to be linked to a single node.

This distinction highlights the complexity of modeling water systems and how different software tools handle the same processes in different ways. When working with InfoWorks ICM, it's essential to understand these differences and how they might affect your modeling and analysis.