Stormwater Management Model (SWMM) Information for watershed water quality, hydrology and hydraulics modelers (Note this Blog is not associated with the EPA). You will find Blog Posts and Twitter Embeds on the Subjects of SWMM5, InfoSWMM, InfoSewer, SWMMLive, InfoSWMM SUSTAIN, SWMM4 and SWMM in general.
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Surcharged Node and the Link Connection in SWMM 5
Subject:SurchargedNode and the LinkConnection in SWMM5
A surchargednode in SWMM5 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, H is the head across the link (downstream – upstream), dQ is the net inflow into the node and dQ/dHis the derivative with respect to H of the link St Venant equation. If you are trying to calibrate the surchargednode depth, the main calibration variables are the time step and the link roughness:
1. Mannings's N 2. Hazen-Williams or 3. Darcy-Weisbach
The link roughness is part of the term dq1 in the St Venant solution and the other loss terms are included in the term dq5. You can adjust the roughness of the surchargedlink to affect the node surcharge depth.
Figure 1. The Node Surcharge Equation is a function of the net inflow and the sum of the term dQ/dH in all connecting links. Generally, as you increase the roughness the value of dQ/dH increases and the denominator of the term dY/dt = dQ/dQdH increases.
Figure 2. The value of dQ/dH in a link as the roughness of the link increases.
World-Renowned Urban Drainage Modeling Authority Robert Dickinson Joined Innovyze in January, 2008Broomfield, Colorado USA, January 16, 2008/altered 20142008/2014 Robert E. Dickinson, one of the world’s leading experts in wastewater and urban drainage modeling, has joined Innovyze as Product Sector Leader. Dickinson, who comes to the company from CDM now CDMSmith, will be charged with maintaining, enhancing and supporting Innovyze's flagship SWMM5-based product line (InfoSWMM and H2OMAP SWMM as well as the GIS based InfoSewer and H2OMap Sewer), which are some of the industry’s leading wastewater and urban drainage systems design and modeling software. He will also be responsible for coordinating vital collaborative research and technology transfer with key universities and government organizations as well as developing business strategies that advance Innovye’s overall growth objectives in wastewater and stormwater systems management and heighten its initiatives in both U.S. and i…
Engine Error NumberDescription ERROR 101: memory allocation error. ERROR 103: cannot solve KW equations for Link ERROR 105: cannot open ODE solver. ERROR 107: cannot compute a valid time step. ERROR 108: ambiguous outlet ID name for Subcatchment
These warning and error messages were added in SWMM 184.108.40.206 to 5.0.016 to trap questionable raingage, link and node data. Correcting these errors does make a better model . The list shown below has the major new warnings and errors and help on interpreting the messages. WARNING01: wet weather time step reduced to recording interval for RainGage Explanation: The user selected hydrology time step is automatically reduced by the engine to match the rain gage interval. The smallest rainfall interval among all of the gages will be used during the simulation. WARNING 02: maximum depth increased for Node Explanation: The rim elevation of a node has to be at least equal to the crown elevation of the highest connecting link to the node. The maximum depth of the node is increased to match the highest crown elevation. WARNING03: negative offset ignored forLink Explanation:Negative Offsets are set to offsets of 0.0 WARNING 04: minimum elevation drop used forConduit Explanation: If the elevation acro…