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.
Note: An explanation of the four St. VenantTerms in SWMM5 and how they change for Force Mains. The HGL is the water surface elevation in the upstream and downstream nodes of the link. The HGL for a full link goes from the pipe crown elevation up to the rim elevation of the node + the surcharge depth of the node. dq1 is calculated differently based on full or partially full force mains and gravity mains
dq2 = Time Step * Awtd * (Head Downstream – Head Upstream) / Link Length or
dq2 = Time Step * Awtd * (HGL) / Link Length
Qnew = (Qold – dq2 + dq3 + dq4) / ( 1 + dq1)
when the force main is full dq3 and dq4 are zero and
Qnew = (Qold – dq2) / ( 1 + dq1)
The dq4 term in dynamic.c uses the area upstream (a1) and area downstream (a2), the midpoint velocity, the sigma factor (a function of the link Froude number), the link length and the time step or
dq4 = Time Step * Velocity * Velocity * (a2 – a1) / Link Length * Sigma
the dq3 term in dynamic.c uses the current midpoint area (a function of the midpoint depth), the sigma factor and the midpoint velocity
Soffit Level (pipe technology)The top point of the inside open section of a pipe or box conduit. The soffit is the highest point of the internal surface of a pipe or culvert at any cross-section. The soffit is also referred to as the pipe obvert. So it is not quite the Crown of the Pipe. Here is an image I found that hopefully explains it better.
Comment: A really nice water analogy for the field properties Divergence, Curl and Gradient from the Blog Starts With a Bang
....it's pretty mathematically intensive, but what's missing from most textbooks and E&M courses are physical explanations of what the mathematics means. For instance, I've started teaching about fields, and pretty much every textbook out there goes on and on about the properties of fields. They say you can do three things to fields, take the gradient, divergence, orcurl of them. (Are you asleep yet? I'm sorry!) What do these things mean? An easy way to picture it is in terms of water. If you placed a drop of water anywhere on, say,Earth, the magnitude and direction of how it rolls down is the gradient of the Earth's elevation. If you let that drop of water flow, as it goes downhill, it can either spread out or converge to a narrower stream. When we quantify that, that's what the divergence of the field is. And finally, when that water is …
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