Need HEC-HMS Assistance
Need HEC-HMS Assistance
(OP)
I am pretty new to HEC-HMS and I seem to be having many problems with it. I am trying to model a watershed of about 1700 acres. There are many basins, ditches and culverts in my watershed. I am having a huge problem modeling the culverts. Can I model culverts in HEC-HMS or should I leave them out of HMS and input them into HEC-RAS? Any ideas? If I should include them in HEC-HMS, then how should I model them?





RE: Need HEC-HMS Assistance
I have used many approaches in my models. It really depends on your point of concentration and what you plan to do with the model results.
Good Luck & Have Fun!
RE: Need HEC-HMS Assistance
RE: Need HEC-HMS Assistance
Good luck.
RE: Need HEC-HMS Assistance
RE: Need HEC-HMS Assistance
RE: Need HEC-HMS Assistance
Reference: h
RE: Need HEC-HMS Assistance
Ia = 0.2 S
S = (1000/CN)-10 [inches]
The Ia/S ratio is sometimes adjusted for specialized situations, such as low-volume events, but should not be changed unless you know exactly what you're doing.
RE: Need HEC-HMS Assistance
RE: Need HEC-HMS Assistance
RE: Need HEC-HMS Assistance
The input prompt should indicate what is expected...
RE: Need HEC-HMS Assistance
S=(1000/CN)-10
IA= (S)x(0.2)
RE: Need HEC-HMS Assistance
RE: Need HEC-HMS Assistance
RE: Need HEC-HMS Assistance
See page 102 of the user manual. A 100-year storm has a 1% exceedence probability annually. It should be set to 10% for your 10-year storm.
RE: Need HEC-HMS Assistance
RE: Need HEC-HMS Assistance
A "25 year storm" has a probability of being equaled or exceeded of 1 in 25 in any one year. Thus its annual exceedence probability (AEP) is 1/25 = 0.04 = 4%.
If n= 50 the AEP is 1/50 = 0.02 0r 2%
If n= 100 the AEP = 1/100 = .01 = 1%
Good luck
RE: Need HEC-HMS Assistance