Hi everyone,

I am currently having problems with calibrating/finding my RTK parameters and derive a unit hydrograph for my wet period simulations, so any help is more than appreciated!!  

I have set up my DWF and flow patterns, and I have calibrated my model using my field flow measurements and the SRTC tool implemented within PCSWMM. I have followed all the steps to derive an RTK unit hydrograph and I have implemented it in my simulations. I have also tried to calibrate the RTK parameters for short, medium and long-term responses. Everything works nicely in my calibration for DWF and all the steps work well for the RTK unit hydrograph creation, however, when I use the SRTC tool I see no response in my hydrographs (comparing my simulated and observed hydrographs), implying that my RTK parameters have no effect on my hydrograph response. How should I understand that my sensibility analysis results in no response from changing my RTK values?

Please note that I am ignoring initial abstractions and that I am using typical values for TK. As for the R values, I can calculate this and are in the order of 1/10 - 3/10 for all the sites I consider. 

Any piece of advice or explanation as to why my RTK parameters have no effect on my simulations is more than welcome. Thanks! 



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  • A simple question, is the raingage you are using for your RDII the same period as your simulaiton time?

    • Hi all,

      Thank you very much for the reply Robert. Indeed my raingage and simulation dates share the same time period. 

      I would like to update you all on the subject as I found my problem (part of being novel to SWMM). I missed entering my tributary area for the unit hydrograph so there was no I/I flows coming to my system. 

      I look forward to keep exchanging my experience of using SWMM, thanks.

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