Hydrology Programs

[runoff]

I have been working on small projects lately and trying to best fit the WinTR-55 program to my projects. I am kind of new to the stormwater drainage application projects and trying to learn as much as I kind. I have found myself a little dazed by the inaccuracy or differences in program methods such as rational vs. SCS CN methods. Anyway, I have been having problems with some municipalities accepting the data from TR-55 due to the programs inability to really compare dishcarge structures (i.e weirs, piping etc..) and detention structure storage volumes. Does anyone have input to what I can do to improve my ability to use these programs or maybe a different program?

 

[BelspringKen]

HydroCAD is a good program - its fairly user friendly.
It allows you to model ponds, with pipes, weirs, etc.

I have been reading up on some USDA/NRCS training manuals that are online to fill in some gaps in my knowledge on TR-55.

http://www.nedc.nrcs.usda.gov/catalog/hydro/hydroseries.html

 

[blueoak]

WinTR-55 is a nice program, but you have to remember that it is not intended for all uses. As far as the rational equation, that is really just a guess and a correction factor.

HEC-HMS is nice because it packages most methods and lets you do as much as you want to the data, it is for larger projects typically. For urban, small projects I think SWMM and HydroCAD fit in well with development applications. They sort of assume the option of a storm drain.

 

[runoff]

Yea, I downloaded the SWMM program and tried it but it is just too busy and too much information for small water sheds. I knew the group that designed this for the EPA and they said that it was meant to be a catch all for both hydrology, hydraulics and water quality. Not very user friendly. I don't know much about HydroCad but will look it up on the web.

 

[blueoak]

I know the last two places I've lived the local agencies set up a model with defaults to make it easy to use and review.(After working with "hydrologic/hydraulic engineers" I think it might be to just get some good designs too.)

I have done that with Hec-HMS myself just because I like it and the new version is pretty solid and melds well with HEC-Ras and HEC-DSSVue(and honestly I like the price).

 

[francesca]

I could've sworn I already replied to this thread. Weird.

I used Hydraflow Hydrographs. Cheap, very easy to use, does Rational and SCS CN/TR-55 method and does detention (you have to trick it into doing retention by putting a weir above the 100-year elevation!), routing, etc.

 

[runoff]

Thanks blueoak. I will look into the HEC-HMS. I think I down loaded that program from the Army Corps. Is that where it came from? I think I looked at that program too but not sure. I had Haestad Methods at one time. Have you tried that one? I think it was Pond Pack.

 

[saruman26]

PondPack works very well, but is cumbersome when compared to other software suites and takes some time to get accustomed to.

I use Hydraflow Hydrographs from Intelisolve for all of my runoff comps for it's ease of use. The newest version allows you to enter 4 Wier structures, 4 culverts (3 orifices), and account for exfiltration and infiltration, and can compute using a tailwater condition. Storage methods include volume from contour areas, bottom area-embankment slope-depth, and pipe storage to route underground facilities.

It also has the benefit of being relatively inexpensive.

As a side note, I don't recommend HydraFlow StormSewers when it comes to hydraulic analysis of storm sewers. It works just fine, but does not interface with AutoCAD Land Desktop like StormCAD does.

 

[JasonG]

HydroCAD all the way! I love that program. TR-55 is not really appropriate for sizing basins. TR-20 is the appropriate method for detailed design. TR-55 is a simplified TR-20 method. It was originally created because TR-20 used to be a beast of a program to work with. TR-55 could be done by hand. That mattered back then when computers were rare. Now there really is no use for TR-55 anymore.

HydroCAD uses the TR-20 method with the familiar input parameters from TR-55.

 

[blueoak]

I think the HydroCAD, Hydraflow, and Pondpack suggestions are probably the best.

One point on TR-20 (WinTR-20) is that all of it can be done with HEC-HMS. The reason I love HEC-HMS is you can use just about any hydrograph method and mix and match if necessary. You can even enter your own whereas TR-20 is setup for NRCS who are "encouraged" to use that method.

One point on TR-55 is that there are some assumptions that vary by region. You have to remember that it was really designed to be used to protect farmland where a flooding event 1 out of 5 years wasn't that big a deal. It really isn't for use on storms pushing the 1% event or beyond. My designs with NRCS included letting the corn be under water for less than 48 hours and soy for less than 72(or close). A little different than a city will allow.

 

[proletariat]

Hydraflow Hydrographs (I've never used)

Hydrocad (The best I've used) Highly customizable rational hydrographs, lots of features to tweak. Also does TR-20. Makes provisions for multiple subdrainage areas contributing to a study point while using Rational.

VTPSUHM (Virginia Tech / Penn State Stormwater Urban Hydrology Model - Rough around the edges because it is not commercial, but widely accepted in PA and very good) Locked into Penn State's version of the Rational Hydrograph, also does TR-55 and TR-20.

Stormwater Manager (Abhorrent DOS-based program, but would allow you to run multiple storms at the same time when VTPSUHM couldn't. VTPSUHM now allows multiple storms, rendering SWM useless.)

 

[queque]

I am using HydroCAD extensively in Arizona. The City of Scottsdale does not accept HMS.
HYDROCAD is as smooth as silk.

 

[JasonG]

I just noticed the HydroCAD has an add in this forum. It mentions a free sampler. Give it a shot, you're sure to love it.

 

[LHA]

Another HydroCAD fan...cheap, easy to learn (I've never even used the free tutorial) with concise, clear Output.

Engineering is the practice of the art of science - Steve

 

[env21tech]

Your comments are valid.These computer models (TR-55, others) assume there is a relation between concentration time (what is happening on the ground) to rainfall duration(what is happening in the sky). Rainclouds do not care what is happening on the ground. Raincloud behavior (IDF curves) has already been established by sampling rainfall using rain gages. Concentration time recognizes that runoff rate reaching an outlet is less than the rainfall rate for the upstream area. The ratio of these two rates is the runoff coefficient. So just use the IDF curves and the Rational Method.

 

[blueoak]

env21tech,
Your post is a little confusing. IDF curves are just as much a statistical analysis as the hyetographs used by TR-55 or other programs or modeling methods.

Runoff,
If you are confused by the difference of rational and hydrograph methods you should read a good hydrology book. There are many available from the government for free or start reading the Maidment(used to be Chow) manual. Hydrology is really just trying to run statistics on a lot of different physical processes. It is important to know what you are modeling so you know if your design really is conservative. As env21tech points out, it never rains like you model, but you can play with the models so the worst expected case doesn't hurt someone.

 

[BelspringKen]

Rational method may or may not be the way to go.

Reviewing agency may require TR-55 or the area may be too large for rational method.

 

[JasonG]

The rational method is really only useful for sizing storm drains.