The computation of channel flow is similar to that of shallow flow. TR-55 again points to the use
of Manning’s equation as the basis of the computation. Again, the actual T5-55 manual is silent on
the assumption that should be used for hydraulic radius when using Manning’s equation. StormShed3G™
follows the same procedure to develop a set of k coefficients that are suitable for channel flows.
In this case, two conditions have been developed. They are intermittent channel flow (R=0.2) and
continuous channel flow (R=0.4). The following table lists the values of k available in StormShed3G™.
| "k" Values Used in Travel Time/TC Channel Flow computations |
|---|
| Kc values for Intermittent Channel Flow (R=0.2) |
|---|
| Forested swale with heavy ground litter (n=0.100) | 5 |
| Forested drainage course/ravine with defined channel bed (0.050) | 10 |
| Rock lined waterway (n=0.035) | 15 |
| Grassed waterway (n=0.030) | 17 |
| Earth lined waterway (n=0.025) | 20 |
| CMP pipe (n=0.024) | 21 |
| Concrete pipe (n=0.012) | 42 |
| Other waterways and pipes | 0.508/n |
| Kc values for Continuous Channel Flow (R=0.4) |
|---|
| Meandering stream with some pools (n=0.040) | 20 |
| Rock lined stream (n=0.035) | 23 |
| Grass lined stream (n=0.030) | 27 |
| Other streams, man-made channels and pipes | 0.807/n |