St. Venant Terms in SWMM 5 and how they change for Force Mains
Note : An explanation of the four St . Venant Terms in SWMM 5 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 +...