HydroCAD Hydrograph Peak Issues in Link Nodes
HydroCAD Hydrograph Peak Issues in Link Nodes
(OP)
In HydroCAD, I am using a Link to manually enter an exactly triangular shaped hydrograph. My problem is that HydroCAD uses a best fit line to "match" my hydrograph data and calculates a "rounded" hydrograph peak that is inevitably higher than my actual peak. Is there a way to stop HydroCAD from using a best fit, rounded type of a line instead of using a linear rising and falling leg?
In the attached example file, the peak should be 94.30 cfs at 0.38 hours, but HydroCAD says it is 94.33 cfs at 0.38 hours.
Thanks!
In the attached example file, the peak should be 94.30 cfs at 0.38 hours, but HydroCAD says it is 94.33 cfs at 0.38 hours.
Thanks!





RE: HydroCAD Hydrograph Peak Issues in Link Nodes
There's no provision for disabling the peak flow calculation. It's always calculated and reported. But keep in mind this has no effect on the routing calculations, which are always preformed using the exact values you have entered.
However, you could reduce the number of decimal places in the flow values, so it only reports to 1/10 CFS.
As a side note, I'm curious as to why you're entering a triangular hydrograph, rather than generating the hydrograph within the software. This is a rather unusual application of the software, so perhaps there's a better way to address your underlying goal.
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: HydroCAD Hydrograph Peak Issues in Link Nodes
For example, if the three highest values are: 10.0 11.0 10.1
Change them to: 10.1 11.0 10.1
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: HydroCAD Hydrograph Peak Issues in Link Nodes
Yes, this method is a little odd, but we are trying to follow the requirements of the jurisdiction we are working in. All hydrographs are supposed to be triangular, starting at 0 at time 0, peaking at the Tc Time, and then ending at 0 at time 1-hour. When I have multiple subcatchment areas with different Tc times, I have trouble getting HydroCAD to create the triangular hydrograph that I want for each subcatchment because the intensity values are different for each Tc. I've found that by using the Link node, I can force it to use the exact hydrograph that I want. Good to know that this is just a reporting issue and doesn't affect the calculations. The reviewers sometimes question the little details like the hydrograph peaks not matching other reports. Thanks for your suggestion of limiting the decimal places. Also the idea of matching the point values on either side of the peak is a good one.
RE: HydroCAD Hydrograph Peak Issues in Link Nodes
I would expect the end results would be darn nearly the same whether the triangular or interpolated hydrograph were used...
RE: HydroCAD Hydrograph Peak Issues in Link Nodes
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: HydroCAD Hydrograph Peak Issues in Link Nodes
;)
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