TR-55 Hydrograph 1

[urbanresource]

All,

I am new to using the TR-55 software and have a few questions. Please see below. My goal is to use the hydrograph data in the input file for HEC-1, so that I may determine storage volume. I would need to do so for the 100 year 6hr and 24 hr storm.

1. Where can I find Unit Hydrograph data for input? I am using the "standard" UH, as provided by the software.

2. Storm Data - The software only allows for rain data on the 24 hr duration storm. Can I input 6 hr rainfall data here to produce the corresponding hydrograph?

3. Once all data is input, I can run TR-55, and plot the hydrograph. Is there a way to get hydrograph data for input into the HEC-1 input file? All I am receiving is the graph, and could not find the points for the hydrograph.

Thanks very much.

 

[psmart]

When you say "storage volume", are you referring to pond storage?

What UH data do you want to use?

Why type of 6-hour storm do you want to use? Type II or III, or something else?

I'm also curious as to why you're using TR-55 and HEC-1 together. Why not use one or the other? Or some other program that can more easily meet the needs you've outlined.



Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[urbanresource]

I am referring to pond storage. I am not sure what you mean by which UH data I would want to use. Are there specific ones to choose from, or should I be referring to the local hydrology manual? I would be using the TYPE II distribution.

I am using TR-55 because I am not sure how to run HEC-1 without the inflow hydrograph. Typically, I use a software, which would provide me the inflow hydrograph for the HEC-1 Input File. However, the software is not applicable to this project location (Colorado). So I am trying to determine the inflow hydrograph data, so that I may run HEC-1 iterations, to determine detention basin sizing. I believe there are multiple HEC-1 input format available, but I am only familiar with the input format requiring the "QI" inflow hydrograph. Do I have other format options with HEC-1, that would be simpler? I have the rainfall data for this project, imperviousness, and CN number. Your feedback would be much appreciated. Thanks.

 

[psmart]

The Unit Hydrograph (UH) is characterized by a "peak factor", which is 484 for most applications. Other peak factors are sometimes used, such as 284 for the Delmarva unit hydrograph. If your stormwater regulations don't specify the peak factor, it's probably safe to assume 484. Most programs (including TR-55) have a default peak factor or 484 already built-in.

In any case, the UH curve is completely independent of the (Type II) rainfall distribution. Both curves are required for the SCS/NRCS runoff method.

The Type II rainfall is normally a 24-hour duration. If a shorter version is required, your stormwater regulations should provide details on the curve.

You can probably use HEC-1, TR-55, or one of the commercial alternatives for your purposes. But using HEC-1 and TR-55 together seems unnecessarily complicated.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[puzzler77]

TR-55 is a hydrology modeling software as are HEC-1 and HEC-HMS. FEMA requires matching an existing HEC-1 model with a HEC-HMS model. I typically use TR-55 to obtain all the variables needed for input into HEC-HMS but this is done manually. Are you trying to compare the hydrographs?

 

[RWF7437]

"TR-55 is a hydrology modeling software as are HEC-1 and HEC-HMS. FEMA requires matching an existing HEC-1 model with a HEC-HMS model"


Where and for what reason does FEMA "require" such matching ?

 

[RWF7437]

The following is from a list of locally approved hydrology models approved by FEMA:



"Colorado Urban
Hydrograph Procedure
(CUHPF/PC)
(May 1996 and May 2002) Denver Urban Drainage
and Flood Control District Denver Urban Drainage and Flood Control District
2480 West 26th Avenue, Suite 156-B
Denver, CO 80211 Flood hydrographs at different locations along streams. Hydrographs are routed using UDSWM2-PC (a modified version of the Runoff Block of EPA's SWMM).

Only accepted for usage and the default parameters in the model applicable within the Denver, Colorado, metro area.

Public Domain: Yes"

 

[puzzler77]

It's HEC-2 and HEC-RAS that should match, my apologies. It would be extremely difficult to match hydrographs.

 

[RWF7437]

It is also difficult in many cases to get HEC-II and HEC-RAS to match and FEMA does NOT require that they do.