SWMM 4 and SWMM 5 St. Venant Solutions Contrasted

SWMM 4 and SWMM 5 St. Venant Solutions Contrasted

 

1. Compute at time t+delta t the values of dQ/dt for the Links and dH/dt for the Nodes from the properties at time t

2 Iterate at least 2 times until either all nodes and links are converged or a maximum of 8 iterations are reached

3. Use the values of Q and H at time t+delta t for the new time step

 The SWMM5 Solution for Flow and Depth at each time step.  The new depth and new flow is always based on the old depth and old flow and normally converges fast as the flow is gradually varied.   The solution is iterative and implicitly uses the new depth and flow at each iteration.

The SWMM4 Solution for Flow and Depth is solved Explicitly at each time step.  The new depth and new flow is always based on the old depth and old flow and and a half and full time step during the time step.

The SWMM 4 Dynamic Wave Solution for ISOL=0

The SWMM 4 Dynamic Wave Solution for ISOL=0

The attached PDF file is a copy of the Extran 3 solution in the  SWMM 4 manual explaining the ISOL=0 solution in SWMM 4 / Extran 4.  The current SWMM 5 solution in its dynamic wave solution is an adaptive time step iterative solution of the ISOL=0 solution in SWMM 4.  

 

 

My History with Various Versions of SWMM: SWMM3, SWMM4, SWMM5, XP-SWMM and InfoSWMM

Subject:   My History with Various Versions of SWMM, SWMM3, SWMM4, SWMM5, XP-SWMM and InfoSWMM 

 

I first learned about SWMM in a brochure from the University of Florida when I was just a 17 year old senior in High School.  Water resources and the description of SWMM seemed to be worthy career goals at the time and I have been extremely lucky to have the opportunity to work and develop many SWMM related products in my working life.   I am especially proud that SWMM 3, SWMM 4 and SWMM 5 are both public domain and open source software.  You can open up and look at the code and add features and internal tests on your own.   You can customize the input and output of SWMM 5 if you want to but most importantly you have direct access to the source code so you can verify the computational algorithms. 

 

InfoSWMM is an Arc GIS extension that works in Arc Map but we at Innovyze are proud that we have superb import and export features to SWMM 5 from Arc Map and use the SWMM 5 engine as our engine solution.   You can look at the internal workings of the InfoSWMM engine by downloading the current SWMM 5 C code from the EPA website http://www.epa.gov/nrmrl/wswrd/wq/models/swmm/   InfoSWMM also has all of the Arc GIS programming tools, Python programming,  editing and drawing features and Table of Contents attribute features to make a better model but that model will still use the open source SWMM 5 engine inside of InfoSWMM.    When you use InfoSWMM you are using the SWMM 5 engine  but with many extra input and output features to help prepare the data for the current SWMM 5 engine and analyze the SWMM 5 engine output  in maps, tables and graphs. 

 

Best Regards, 

Robert Dickinson