Modeling Pipe Flow in HEC-HMS

[Scott Horowitz]

I am working to analyze the impacts of a proposed development within a previous storm water design. I have the report that was prepared for the original design and the report includes the HEC-HMS output results and basins schematic, which shows an upstream pond conveying metered storm water through a pipe and into another pond. I do not have the HEC-HMS files to use. There is quite a bit of input data available for me to start building my HEC-HMS model and am waiting for additional information regarding the HEC-HMS model to come my way, hopefully the HEC-HMS files which will be a big help on my end. The HEC-HMS basins schematic shows a junction immediately downstream of the first pond and a pipe connecting to the downstream pond. The only flow to the pipe is from the upstream pond. A couple of questions:

1. What would be the purpose of placing a junction between the pond and the pipe?

2. I assume the pipe is used for routing the storm water through a reach; how are pipes modeled in HEC-HMS, particularly in situations like this, and is it possible to model pressure pipes in the software?

Thank you very much for any help.

 

[gbam]

From your description I interpret the junction joining one pond to an existing storm drain system so to try to answer your questions:

1 - Junction, the junction is required to combine flows from different sources and you will need this junction to model the combining of flow hydrographs.
2 - Modeling Pipes, Look into the documentation of HMS to see how to route hydrographs through pipe. It's been a while but I think Kinematic Wave have pipe options for routing. I suggest that you read the HMS manual.