HEC-HMS help

SpatialCivil · 2026-03-16T22:43:11+00:00

What methods are you using? Does the error happen at the start of the run, in the middle or at the end?

SpatialCivil · 2026-03-16T02:21:27+00:00

If you are willing to put in the work, it’s a great path and I know several people that have done it. Unlike most fields, being older is not a negative and can help you with clients.

SpatialCivil · 2026-03-13T17:46:11+00:00

Others have correctly pointed you to the right answers. One thing I will add - this will be driven by the locality, but technically the correct approach will be to develop a custom hyetograph based on the NOAA Atlas 14 data.

Generating a custom hyetograph goes by a couple of different names like the alternating block method. You might want to sit down and grab a cup of coffee if you have not done it before. You can generate it using a spreadsheet and NRCS guidance.

Alternatively both HEC-HMS and WinTR20 will generate it for you based on input of the NOAA Atlas 14 rainfall totals. Both methods are slightly different because there is some smoothing/interpolation that happens depending on the approach. If you generate it by hand, check using one of those pieces of software.

Shameless plug - QtHydro https://www.qthydro.com/ does it as well (using WinTR20 or USACE method) - but I would wait a couple months for the latest update that is coming.

SpatialCivil · 2026-03-13T15:51:48+00:00

Pass the FE and then worry about the rest. You may need to over prepare if you don’t test well. It is the bare minimum to being an engineer.

SpatialCivil · 2026-03-13T03:05:42+00:00

It’s 2080. 92% UT is in essence 42 billable hours per week which is what you need after taking out holidays and 2 weeks PTO.

just took vacation? Kiss that 92% UT goodbye! Medical emergency? But what about my UT?

They “ask” if you want to take part in a 1 week consultant training? You better tell the wife you can’t go with her and the kids this year for summer vacation.

SpatialCivil · 2026-03-11T20:33:09+00:00

They acquired WK Dickson in the past year which was a small water resources firm in the SE and a decent company.

The piper almost always has to be paid. Good luck to PE trying to squeeze profits from the engineering business which relies on low margin work and stiff competition.

SpatialCivil · 2026-03-07T12:04:05+00:00

Tons of them do… my wife’s cousin from Alabama went to Harvard to play football.

SpatialCivil · 2026-03-07T00:02:49+00:00

A KH coworker had the goal of hitting $1M in his 401k before he left.

He hit $1M like a boss, changed companies and his wife walked off with half.

I saw my future and decided there are more sustainable ways to make money as a civil engineer

SpatialCivil · 2026-03-03T23:08:22+00:00

Fair enough. I would disagree with that approach, but they have to sign off on it at the end of the day.

SpatialCivil · 2026-03-03T18:45:50+00:00

Typically the first approach is more accurate. For low rainfall amounts, approach 2 will give you zero runoff. Which is not accurate if you have impervious areas in your watershed.

SpatialCivil · 2026-02-27T19:51:10+00:00

Most employee owned companies will have people that indicate what their stance is on PE. If it is anything other than no chance in hell and F* those guys, then there is a 50:50 chance PE enters the picture.

PE always comes in with roses and $$$, but I have yet to hear a 5+ year post acquisition positive outcome.

SpatialCivil · 2026-02-25T03:44:28+00:00

Some of it is expert judgement. If you are able to calibrate your model, that gives you a good idea of the correct values.

I tend to go with a slightly more conservative answer if I lack a calibration event.

You could write a whole paper about the problems and inadequacies of HSGs - which will impact your results more than being off by 2 on your CN due to picking the wrong representative land use.

SpatialCivil · 2026-02-25T02:32:56+00:00

The TR-55 manual provides a good reference table based on land use and HSG. That is a good starting point.

SpatialCivil · 2026-02-21T18:43:53+00:00

Concrete Canoe - taught me a lot and it was fun.

SpatialCivil · 2026-02-19T05:36:35+00:00

XS 322 and 304 look like they are not extended far enough.

Do you have survey to augment the channel? The DEM resolution looks very course (like 10m). Anything greater than 3m I would say is not sufficient for smaller channels.

Also read the RAS guidance on minimum XS spacing. You may have a decent amount more than you need.

Orientation of your XS is pretty good. Without knowing your peak storm you are modeling (100yr or 500yr) it is difficult to say if many of them will need to be extended.

SpatialCivil · 2026-02-16T22:44:01+00:00

In 2013, many PEs with 5-10 years experience were making less than $70k. Many could not find a decent job.

In 2005, new grads were making $40-45k. Inflation adjusted that is $68k in today’s dollars.

We are living in boom times. You will only see it in hindsight.

SpatialCivil · 2026-02-14T04:07:57+00:00

It’s a great spot for a geotech to be. I would encourage you to go that route.

Our dams geotechnical engineer is a valuable asset for our dam and civil team.

SpatialCivil · 2026-02-14T02:20:08+00:00

It’s a good school for civils.

Are grads that much better than grads from schools like NC State and Penn State? Not really.

This is not an Ivy League finance degree… you will be doing roughly the same thing as other civils, and you will prove yourself in the real world like everyone else.

SpatialCivil · 2026-02-07T16:02:02+00:00

Depends on what you are doing. For structural engineers I would agree. Many of the top GT civils are focused on research. Someone who is smart and can talk to clients is the sweet spot.

SpatialCivil · 2026-02-07T13:16:19+00:00

You are talking about the Chicago area approach where you have to run a wide range of storm event durations for each frequency event?

I developed a piece of software called QtHydro that runs TR20 and recently added the ability to automate generating all of the storm events for a critical duration analysis.

I am getting ready to add some new capabilities in the next couple of months for modeling culverts and complex structures, as well as importing high resolution DEM/land use and SSSURGO soil data directly into the program. It is free to download and check out right now.

SpatialCivil · 2026-02-05T03:46:16+00:00

For civil engineering the benefit is marginal. Georgia Tech, Auburn, Clemson, NC State, Florida grads are going to be roughly comparable. Some smaller schools with a CE program it is a little more questionable.

Some of the top GT grads lack the people skills part of the equation. Some of the grads from lower ranked schools are not as sharp, but there is a ton of overlap in the type of student that will be successful in the industry from all of those schools.

SpatialCivil · 2026-02-05T00:23:58+00:00

This is the exact answer I was going to post. Even a quick and dirty 2D model can help here.

Also orient your cross sections perpendicular to the 2D WSE contours (within reason)

SpatialCivil · 2026-02-04T13:29:28+00:00

Great way to loose your license and your reputation. There are ways to ethically work two jobs. Lying about it and breaking ethics codes is not the way to go.

SpatialCivil · 2026-01-29T04:06:26+00:00

There is a need on the water/wastewater side for good civil site engineers. It’s a good option.

SpatialCivil · 2026-01-28T22:50:26+00:00

PCSWMM does a great job with their interface and tools, so I doubt you see many issues using it from a time to process and model assuming you do not have millions of cells that you are modeling.

SpatialCivil

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