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Hi SMAIH, Your explanation of calibration looks a lot more valid that what I had proposed. I'll do that next. I actually have over 50 years of storm data. This is just the largest storm during that entire period and it produced no runoff except for the uppermost of five culverts which got...

I have a question about ‘calibrating the model’ in HEC-HMS. I have pretty strong evidence that a storm of 1.8 inches produced no runoff in a desert gully in Eastern Washington. (State and county highway departments plus personal observation.) The 100 year storm is 3.2 inches. I believe...

Thanks for all the good answers. Your latest made me realize I should probably size the culvert on this property as if someday the drainage areas above will also have culverts and fill and therefore higher veolcity flows than they do now. dpajr

beej67, All the world's philosphers could not have come up with better advice than that. Thanks goodness I didn't do it for a fixed fee. Thanks, dpajr froude, 500 year flood yikes What set of codes governs cleanouts and other structural details, bedding etc of putting in a culvert? I am...

Thanks for all the good comments. I think you are right on the money about the CLOMR-F being the best approach. My project is similar to froude's except most of the stream will stay above ground and only a small portion will go underground. You are right about FEMA being hard to convince...

Expensive as it sounds a storm drain down the entire ravine is the plan. This is very pricey real estate with a spectacular view and only 18 miles from a ski area. We already requested an LOMR using a log-Pearson Type III analysis which was based on 52 years worth of daily rainfall data. A...

I am dealing with a ravine that will experience runoff during a 100 year flood. Can installing a culvert and adding fill over the top be a justification for changing the flood zone designation? I am interested in hearing from people who have experience with FEMA in cases like this Thanks

I need to find the curve number for a couple of gravel parking lots. All I can find in the curve number tables of Hydrocad and TR-55 is gravel with right of way included. The numbers for that have to be lower than for just plain gravel pavement. I am guessing close to 98 but I don't want to...

You need to get a copy of the "Civil Engineering Reference Manual". The one that is specifically published for the CE license exam. Most university book stores should have one. I would send you the equations but I am on the wrong computer right now. Just sending you the equations would not...

Hi SMIAH, I found several tutorials for log-Pearson. Thanks, dpajr

Hi SMIAH, That is a great suggestion. As usual you are always ready to help. I have read a lot of your answers to other people's questions too. Yes I have the daily 24 hour rainfall peaks for every day since May 1, 1958 except for a few rare days when the gage did not get read for some...

Hi, Has anyone out there had any luck convincing NOAA that in certain cases their rainfall Atlas might be a bit too aggressive. We have a project that requires a 100 year storm. The value from the NOAA Atlas for the area in question says the 100 year 24 hour storm value is 3.2 inches. The 10...

For the benfit of anyone else who comes across this post I forgot to add: Windows will tell you it cannot open this file but just select the button for pick the software to open from a list and either MS Word or Notebook will open it. WordPerfect probably will too. Thanks again, dpajr

Hi SMIAH, Just a quick update. It worked like a champ. You really saved my bacon. Hope I can help you out sometime. Thanks, dpajr

Thanks SMIAH, This is a GREAT idea. Thanks, dpajr

Thanks SMIAH, I have not had this problem previously but it drove me crazy for a couple of hours yesterday. I eliminated everything from the model except the subbasins and started over, new reaches, culverts etc. Now it is mostly in English units except for the reaches. In the optional tab...

God tips everyone, This is a series of five culverts in a large ravine some concrete, some corrugated. There are about nine soil types. Several are HSG "A" but some are "D". Vegetation also varies throughout with grass in the upper reaches and desert shrubs, and grass in the lower reaches...

Two problems with HEC-HMS 3.3 1. I change the units to US Customary and they just keep changing back to metric. Any way to stop this? I just loaded HEC-HMS 3.4. Apparently the manual did not get upgraded to the latest perversion. Items that were in the menu sytem in HEC-HMS 3.3 such as how...

Hi beej67, You are right. That is exactly what I have. NRCS listed the Te soil but it only gave about half the information it gives for other soil types like CIB, CkE, MgD, EnF etc. Those list storage capacity, infiltration rates etc. Te only lists elevation, frost free period, and a...

Hi, I am working on a drainage project which has a large ravine running down the middle. The NRCS soil map classifies it as Te Terrace Escarpments. Every reference to Te I have found on the internet leaves all the characteristics such as available water capacity, depth to restrictive layer...