SSA 2012 - Rational Method - Pipe peak flow exceeds inlet flow

[mfc731]

I think I must be missing something obvious. I create a new layout for a pipe network consisting of inlets, pipes, and an outlet. Using the Rational Method for runoff, the connected drainage area to the first (highest) inlet has peak runoff of 3.58 cfs. The inflow into the inlet (set as 'in sag' for 100% capture) is 3.58 cfs. The peak flow in the first (highest) pipe is 4.95 cfs. Why is there a difference? 

If I look at the time series plot for this pipe the flow is all over the place. The flow from the drainage area and into the inlet are the expected triangle.

If I switch the nodes to junctions rather then inlets, the resultant flow is the expected triangle. The unexpected results appear to be liminted to the use of inlets. No external flows are listed.

[amit1304in]

Can you please share your model? I think peak in pipe can be higher but voulme of water should be same.

[mfc731]

File attached.

[amit1304in]

Just increase the ponded area of the from 10 to 50. You will get the good results