HMR 52 Probable Maximum storm 2

[jaredrall]

I am trying to use HMR 52 to get the probable maximum frequency, but I am very unfamiliar with the program, if anyone has any user manual for it or ideas on another program to use please let me know. Does the NFF Program from USGS give you a rainfall frequency or is there a module within HEC HMS that achieves the same results. I am trying to find a program that will also calculate a dam breach, as of right now i am using DOS based Dambrk or Breach

Thanks,
Jared
jrall@larsondesigngroup.com

 

[RWF7437]

The NFF ( National Flood Frequency) program will calculate the Probable Maximum Flood ( PMF ), not Frequency. I believe HEC-RAS now includes the simplified dam break program. Both are free.

I don't know about HMS.

good luck

 

[blueoak]

With all your dam talk I assume you want the Probable Maximum Precipitation event. Just read your local HMR. It is very straight forward.

HMS has a break module just like RAS. I really think you need to look into your dam. While RAS has always given me good results there are a lot of empirical methods out there that are really the defensible way to analyze a dam. The RAS seems a little voodoo to me that it works so well. Also you have to look at your dam and the downstream channel to get a guess. My favorite hydrograph method is to figure out just how bad I think it will be. I call this Peak at time 20 minutes or so and I draw a triangle with the breaching reservoir volume under it. If I just barely miss a house or something I consider adding some more water. I use an HP calculator. I like to run a few models.