In this blog we example the St Venant terms used in SWMM5 as equations, table, graphs and units. We use a QA/QC version of SWMM 5 that lists many more link, node, system and Subcatchment variables than the default SWMM 5 GUI and engine. This also applies to #InfoSWMM
This help file topic contrast the St Venant Solution for InfoSWMMH2OMap SWMM 
, InfoSewer/H2OMap Sewer
and ICM/ICM SE
.
The assumptions behind Lumped and Distributed … Read the rest
How to Tell how Long Normal Flow is used in a Link in #InfoSWMM, H2OMap SWMM w/ #SWMM5
| Find the Fraction of Normal Flow Limited in the Flow Classification Table and copy it to the Link Information Table – the value of FLM can then be Displayed in a |
This blog contrasts the St Venant Solutions for InfoSewerH20Map Sewer (1), InfoSWMM/H2OMap SWMM and ICM/ICM SE.
The assumptions behind Lumped and Distributed Models along with the assumptions of the St Venant equations. InfoSewerH20Map Sewer, InfoSWMM, H2OMap SWMM, SWMM5, ICM and ICM SE … Read the rest
SWMM5 Link Upstream Weighting
Purpose: The purpose of this note is to explain a significant dynamic wave routing difference between EPA SWMM 5.0.013 and EPA SWMM 5.0.011 and before. A few people have detected a difference. The previous solution(s) would use only the midpoint area (Amid) and hydraulic radius (Rmid) … Read the rest
Note: Four cross sectional areas are used in a link of SWMM 5. The weighted hydraulic radius (Rwtd) is a function of the Froude Number of the link and the upstream and downstream hydraulic radius. The Rwtd value is used in the computation of the friction slope or … Read the rest
Subject: SWMM 5 Culvert Data from FHWA, HDS No. 5, Hydraulic Design of Highway Culverts, 1985
If you use the culvert option in later versions of SWMM 5 then when the inlet control equation flow is less than the computed St Venant flow then the FHWA equations will be used
The SWMM 4 Dynamic Wave Solution
The attached PDF file is a copy of Appendix C of the SWMM 4 manual explaining the three St Venant solutions in SWMM 4 / Extran 4. The current SWMM 5 solution in its dynamic wave solution is an adaptive time step iterative solution
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 … Read the rest
Subject: Non Linear Term in the Saint Venant Equation of SWMM 5
The flow equation has six components that have to be in balance at each time step:
1. The unsteady flow term or dQ/dt
2. The friction loss term (normally based on Manning's equation except for full force mains),… Read the rest
Subject: How is the St Venant Equation Solved for in the Dynamic Wave Solution of SWMM 5?
An explanation of the four St. Venant Terms in SWMM 5 and how they change for Gravity Mains and Force Mains. The HGL is the water surface elevation in the upstream … Read the rest
Note: The Keep and Dampen options and their effect on the four main terms of the St Venant equation.
The four terms are are used in the new flow for a time step of Qnew:
Qnew = (Qold – dq2 + dq3 + dq4) / ( 1 + dq1)… Read the rest
Subject: Surcharged Node and the Link Connection in SWMM 5
A surcharged node in SWMM 5 uses this point iteration equation (Figure 1):
dY/dt = dQ / The sum of the Connecting Link values of dQ/dH
where Y is the depth in the node, dt is the time step, … Read the rest
Note: How to Search These Blogs for Information
In each of the blogs search for a term or a set of terms using the search button. For example, here is http://swmm5.blogspot.com with a search for venant
An equivalent Search in http://www.swmm2000.com
An equivalent Search in http://swmm5.org/
An equivalent Search in … Read the rest
Subject: Link Simulated Parameters used in either the Normal Flow or St Venant Equation of SWMM 5
St. Venant equation – this is the link attribute data used when the St. Venant Equation is used in SWMM 5. Simulated Parameters from the upstream, midpoint and downstream sections … Read the rest
Note: Four cross sectional areas are used in a link of SWMM 5. The weighted hydraulic radius (Rwtd) is a function of the Froude Number of the link and the upstream and downstream hydraulic radius. The Rwtd value is used in the computation of the friction slope … Read the rest