What should be the optimum range for External and Internal outflow for SWMM 5.0 result ?
Is there any book available for understanding EPA SWMM 5.0 applications and basic concepts/mechanism apart from the User and Application manual ?
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While allowing ponding I am getting all the conduits in surcharging condition. Generally what should be the ponding depth at the nodes if we are going for allow ponding option.
If I dont allow ponding then I am facing too much of internal flow.
I have used a rainfall of 543 mm for 24 hours of period and running the simulation 36 hours.
The average and maximum depth at the nodes in "Node Depth Summary" are coming too high 20 to 27 m respectively, though I have given the max depth of 0.6 m in the input dialogue box of Junction property.
Please tell me how can I reduce these numbers ?
It is better if the ponded depth is not many meters. I would suggest making the ponded area larger so that the while the flooded volume is the same the ponded depth is smaller. The ponded area will be larger in square meters.
In case we have given 3 outfall in a system and after running the model we go for the graphical results, the what the "Total Inflow" indicates in the graph (for System), as Total Inflow would be different for different nodes as well as as for the three outfalls.
Whether the "Storage" term in graph for the "System" infers the stored water in the conduits ?
Total Inflow = the Runoff from all Subcatchments + the Dry Weather flow at all Nodes + The Time Series inflow at all nodes
Storage = the final volume in the links + the volume in storage ponds or wet wells
Thanks for the clarification.
Thanx for the reply.
I have a little confusion regarding Internal Outflow, as it is the flow which leaves the system through flooding at non-outfall nodes.
What is mean by non-outfall nodes here, if the non outflow nodes are Junction then it means whenever there is a flooding at a node (i.e. Junction) there will be a internal outflow,
similarly no flooding at any nodes will result into no Internal outflow in the Status report.
Is it correct...?
There are two type of flooding:
1. Flooding when the HGL reaches the Rim Elevation of the Junction and there is no surface ponding the excess flow is called flooding and is shown in the node flooding table and is summed into internal outflow
2. Flooding when the HGL reaches the Rim Elevation of the Junction and there is surface ponding the excess flow is called flooding and is shown in the node flooding table and but is NOT summed into internal outflow
3. If it is still flooded in the surface pond at the end of the simulation the flooded volume is considered ending or final storage
I hope this helps and you are correct in your statement
For the final say I always refer to the code
// --- otherwise node is an interior node and any overflow is considered as system outflow and flooding
{
if ( Node[j].newVolume <= Node[j].fullVolume)
outflow = Node[j].overflow;
if ( outflow > 0.0 ) *isFlooded = TRUE;
Other than the runoff is normally between 0 and 100 percent of the rainfall there are no rules for the optimal range of SWMM 5 results. However, if you have flow from another Subcatchment, even that rule can be exceeded. Do you really mean rules for acceptable Continuity Error? If so then we developed these rules in the past for XP-SWMM:
1. Less than 1 percent absolute continuity error is Excellent
2. 1-2 percent absolute continuity error is Great
3. 2-5 percent absolute continuity error is Good
3. Greater than 5 percent absolute continuity error is Bad
It does not matter if the continuity error is positive or negative