Base question on HydroCAD runoff Volume question

[tsli001]

Hi guy:

I got a question regard HydroCAD report. In the report, there are always got two lines list out the summary of the model out come such as total run are, and precent of the previous or Impervious and are, etc. Is the reach in the model affect the 'Runoff volume'. I think there is a separate calcution to do those calculation.

thank you

 

[psmart]

The runoff volume is associated stricty with the subcatchment. A reach routing is a completely separate calculation.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[tsli001]

So are you tell me that if I want to do something to the runoff volume is to do something to the subcatchment instead?

 

[tsli001]

This is just a follow up question. Let say has 30% of increased of the pervious area under a post development condition. And, are you saying no matter what storage I use I have no control the runoff volume on the HydroCAD?

 

[psmart]

Assuming that you're are using the SCS/NRCS method, the runoff volume is strictly a function of the area, CN and rainfall depth. The only way to change the runoff volume is to change these parameters.

The final discharge volume from your site will be the sum of all the runoff, unless you retain or infiltrate some of the volume.

Peak flow reduction is another matter. This is easily achieved by detention.

Which of these are you asking about? Please be clear about your terminology.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[tsli001]

Well, that is a good question. On the report(which I had enclosed a Pdf file with it) which one is the run volume and which one is the final discharge volumn. Is it the the bold statement at the end page is my 'Finela dischage volume form my site"? or just a runoff volumn. Cause someone think the bolded statments at the end page is the final discharge volume leave the site.

thanks many

 

[psmart]

That wording doesn't sound like a standard HydroCAD report. You'll have to ask the person who created the report.

FYI, all HydroCAD reports will have a standard HydroCAD page heading, including the software version, serial number, copyright, date prepared, etc.



Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[tsli001]

Hey my friend I had print out the wrong page. And I print out other one call "report" Can you take a look of it again please.

thanks

 

[psmart]

There was no report attached to your post...


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[tsli001]

thats funny, I will upload again see you can find it is call 'report'PDF file
many thanks

 

[psmart]

At the bottom of the report you will find the total "runoff volume". This is the total RUNOFF produced by all subcatchments before any routing.

Pond 6P is labeled "Stone infiltration", and has an inflow that matches the runoff. It appears that all the runoff is being infiltrated, producing zero discharge from the pond. This zero flow is presumably routed to Reach 5R which is labeled "Total Runoff".

To be sure of this, you really need to examine the routing diagram, and not just the node summary you provided. If in doubt, ask the person who prepared the report. This is a matter of how they chose to model the site, rather than a HydroCAD question per se.




Peter Smart
HydroCAD Software

http://www.hydrocad.net