Here is a table that shows the value of Q/Qfull for various levels of y/yFull or d/D in SWMM5. The full flow if you loop off the top of a circular pipe at the 0.83 level would be about 1.01 times Qfull for the whole pipe. Figure 1 shows how the flows are calculated at various values, Table 1 and Figure 2 show the values of a/aFull, r/rFull and q/qFull for various values of y/yFull.
Figure 1. How Qfull and Qmax are calculated in SWMM 5 based on the roughness, slope and a lookup table for area and hydraulic radius for a circular pipe.
Table 1. Table of y/yFull and Q/Qfull based on a/aFull and r/rFull
| y/yFull |
a/aFull |
r/rFull |
Q/qFull |
0.00000 |
0.00000 |
0.01000 |
0.00000 |
| 0.02000 |
0.00471 |
0.05280 |
0.00066 |
| 0.04000 |
0.01340 |
0.10480 |
0.00298 |
| 0.06000 |
0.02445 |
0.15560 |
0.00707 |
| 0.08000 |
0.03740 |
0.20520 |
0.01301 |
| 0.10000 |
0.05208 |
0.25400 |
0.02089 |
| 0.12000 |
0.06800 |
0.30160 |
0.03058 |
| 0.14000 |
0.08505 |
0.34840 |
0.04211 |
| 0.16000 |
0.10330 |
0.39440 |
0.05556 |
| 0.18000 |
0.12236 |
0.43880 |
0.07066 |
| 0.20000 |
0.14230 |
0.48240 |
0.08753 |
| 0.22000 |
0.16310 |
0.52480 |
0.10612 |
| 0.24000 |
0.18450 |
0.56640 |
0.12630 |
| 0.26000 |
0.20665 |
0.60640 |
0.14805 |
| 0.28000 |
0.22920 |
0.64560 |
0.17121 |
| 0.30000 |
0.25236 |
0.68360 |
0.19583 |
| 0.32000 |
0.27590 |
0.72040 |
0.22172 |
| 0.34000 |
0.29985 |
0.75640 |
0.24893 |
| 0.36000 |
0.32420 |
0.79120 |
0.27733 |
| 0.38000 |
0.34874 |
0.82440 |
0.30662 |
| 0.40000 |
0.37360 |
0.85680 |
0.33702 |
| 0.42000 |
0.39878 |
0.88800 |
0.36842 |
| 0.44000 |
0.42370 |
0.91760 |
0.40009 |