concrete surface drain

Question

Is there a way to model a concrete surface drain as a catch basin in stormcad? Essentially we are looking to see how the depth and spread change by increasing the curb opening to a concrete flume. Thanks.

Yashodhan Joshi · Answer

Hello Brian, 
 Can you share a schematic of the system you are proposing? Are you looking to model a catch-basin as a channel in StormCAD? 
 If that is the case you can try modeling the catch-basin as a box structure with a large length (the length for your surface drain) and a width equivalent to the width of the drain. However, you can try using a gutter element which essentially a surface drain which captures the overflow from the catch-basin. If you want the entire flow to be diverted to the gutter you could try setting the capture efficiency to a low value (like 0.1 %). This would divert almost all of your flow to the gutter downstream where you can measure the start and stop spread widths and the depths at both upstream and downstream. 
 I found an article which is having a similar application to what you are looking at. See the article below; 
 Modeling a Drainage Ditch 
 Let me know if this helps.

Jesse Dringoli · Answer

Hello Brian, 
 I've taken a look at the PDF but I'm still having trouble picturing what you are trying to model. 
 You can certainly use a catchbasin in StormCAD to model the inlet opening, and the gutter element to model the upstream and downstream gutter ("flume"?). If the curb opening is on-grade, then as you change the size of the curb opening, the amount of bypass flow that goes down the downstream gutter will change. The depth and spread reported at that catchbasin will stay the same since as explained here , it is measured from the upstream side of the inlet opening before any runoff is captured. To impact the spread and depth at a particular on-grade inlet, you'll need to adjust the next-upstream inlet (so that less flow bypasses it). 
 You can also use the automated design feature in StormCAD to select from a range of inlet sizes in order to meet minimum efficiency on grade as explained here . 
 If this does not help, can you explain a bit more about what you need to model? Have you tried this already and encountered a problem?