How to Map a Floodplain in 10 minutes using Civil 3D, HEC-RAS, and a spreadsheet.

[@ajliu2168]

Hi Tom, what's the purpose to use weedfeatures to read?

[@TomHaws]

I decided to use weedfeatures to make the final polyline look smoother.

[@TomHaws]

I'm a bit embarrassed about the Weeding method at the end. Video would have been better without it. Sorry.

[@ajliu2168]

@@TomHaws eh.....I forgot why I asked that :)

[@michaelhaidee]

Thanks for the video! Last 6 years i had to be on Bentley In-Roads 😭. Had to juggle three programs by using In-roads and HEC Geo in GIS. Since I am on Civil 3d now it will only takes 20 minutes in slow motion, this will save me half a day. Now i can sleep underneath my desk the rest of the day... LOL.

[@SewingZee]

Thank you SO much for this tutorial, Tom. It was really helpful, wow! Thank you.

[@altoroos]

Awesome Video. Short and Sweet - Much Appreciated.

[@TomHaws]

Thanks, Alto.

[@ChristopherSchmittgplus]

Awesome tutorial. It's going to save me a lot of time!

[@TomHaws]

I hope so!

[@sethmckilla4913]

Awesome video, thank you so much!!!

[@TomHaws]

Glad it helped!

[@DanieJvR100]

Thank you for this. Now how also know how to do it!

[@emmanueladewumi8651]

Please, I have a question, I tried to import geometry files (XML and GML) to Civil 3D 2018 through VBS routines-RASgeoTOCAD2011.dvb, but it was not successful. Which other way can I import them?

[@TomHaws]

I would assume you can import them as "maps" (.shp files) after using "Create/update stored maps" in RAS Mapper. Am I understanding your question.

[@emmanueladewumi8651]

@@TomHaws Thank you for your response. I did use "Mapimport" command, but nothing was imported. I emailed the author (Andy Carter) of the manual presented at AU University 2011, but I have not received any response from him. Let me rephrase my question, once you are done with your floodplain mapping in Hec-Ras 4.1.0. you want to import your water surface elevation to Civil 3D 2018, how do you go about it? The manual suggests " File - Export Geometry and Results (Ras Mapper)". once that is done, it gives you two file outputs, which are XML and GML. Which other way can you import your water surface elevation to Civil 3D 2018?

[@TomHaws]

@@emmanueladewumi8651 I don't know how to import water surface elevation. I have only imported inundation limits.

[@emmanueladewumi8651]

@@TomHaws Thanks for the response, much appreciated!!!! When it comes to cross-section in Civil 3D, they always say draw it from left to right looking downstream but when it gets to Hec-Ras. it would be flipped the other way. How best can someone do it? I drawn polylines in Civil 3D, then use Mapexport command to Hec-Ras...

[@TaraLynn218]

Do you wanna ad spatial reference, “noooo” 30 seconds later “yessssss” hahahahahahah

[@TomHaws]

:-D

[@AlexEdstrom]

Nice video Tom!

[@TomHaws]

Thanks, Alex. Long time no see.

[@iliasmachairas4466]

Thanks for the video! It was helpful! When I imported the .geo file to HEC RAS, I got the following error: "None of the XS's are Geo-referenced". I have set the projection in Civil 3D via adesetcrdsys command though. How can I fix it? The river is imported in geometry but the cross-sections not. Any idea about it?

[@TomHaws]

My memory may be fuzzy, but is it possible that your alignment or cross sections are not fully contained within the surface extents or that your cross sections are not all crossing the alignment?

[@JamesBaleLA]

I've run into a similiar issue before where my cross sections were extending beyond the surface extents.

[@yuleroy2019]

hi Tom, I do have a question regarding the polyline your talking about in cross-section, is it just a PL? and the site, is it necessary to assign a site? I've tried it exporting as geo file and itwas zero bytes, and could not load up to HEC-RAS

[@TomHaws]

The cross section polylines are just polylines. I don't think site matters. The most common reason I have found for getting a geo file of zero bytes is having an alignment or cross sections that go beyond the terrain surface.

[@noone1722]

thank you for teaching

[@TomHaws]

:-)

[@58naguilar]

Hi Tom; thanks for you video. I´m following the routine in my computer with a file I´ve got but at 7:40 minute Ras Mapper couldn´t find the C3D-transfer file (minute 7:57) where de .hdf is located. do you have an idea how can I get the terrain file?

[@TomHaws]

I am not completely sure I understand your question correctly, but it sounds like you misplaced the GEOTIFF fiile you exported from C3D. Is that right? Were you unable to browse to it and choose it, or was HEC-RAS subsequently unable to do something after you chose it?

[@58naguilar]

Exactly; I can`t find it. Probably it wasn`t created by HEC-RAS.

[@TomHaws]

You have to export it from C3D at 1:33 and put it where you can find it.

[@58naguilar]

Great!!!!!!!! Thanks Tom.

[@TomHaws]

I added an annotation at 1:33. Thanks to you!

[@vas.milivoj]

this is how i was doing it too. but today i found out about ENCROACHMENT methods.. what is it for, I cant understand that comparing to this?

[@TomHaws]

Encroachment methods are tools to help establish a FEMA regulatory floodway in the middle of a floodplain. They are different ways to decide where the regulatory floodway (future encroached stream) will be.

[@emadnadi152]

how did you assign the location of the streamline, left bank and right bank, to begin with? Are these streamlines FEATURE LINES created from surface???

[@TomHaws]

They are simply polylines.

[@emadnadi152]

Tom Haws I was not asking about the type. I was asking how did you define their station on the station line. How did you determine LOB and ROB

[@hikmet933]

emad nadi when you exporting to hec-ras, you can specify the lob and rob in the c3d export dialogue window

[@TomHaws]

It is best, if possible, for the banks to be the natural division between regions of deep narrow flow and wide shallow flow. You could choose a top of bank breakline or snap to TIN endpoints that you feel best represent "banks".

[@ajliu2168]

Thank you! There should be several ways to revise river direction instead of using spreadsheet, right?

[@TomHaws]

Yes. You could also enter arbitrary River stations with the smallest at the downstream end. I suppose that creativity is the only limit.

[@ajliu2168]

+Tom Haws thank you, I remember there is a button you can click on Hecras to fix that; and an engineer in Half associates has wrote a small tool to do it before.

[@TomHaws]

The HEC-RAS command to reverse River stationing does not really work the way you think it will. The HEC-RAS Flipper tool from Robert Half and Associates should do the same thing that you can do in a spreadsheet.

[@ajliu2168]

+Tom Haws thanks Tom! Hope to meet you in person one day.

[@TomHaws]

Likewise!

[@williamrihani]

Hi Tom thank you for the helpful video, please can you tell me how you drew the right and left over banks ?

[@TomHaws]

Just polylines. Is that the answer you needed?

[@emadnadi152]

@@TomHaws did you estimate locations? Did you convert them to feature lines that match the topo surface???

[@TomHaws]

@emad nadi No conversion to feature lines. I would drawing them from point to point along triangle lines after showing Triangles on the surface. I actually don't usually export them from AutoCAD as I did in this video. I normally set them using the Graphical Cross Section Editor in HEC-RAS.

[@Juanbrujo1971]

Hi Tom, error JIT, what can I do?...

[@TomHaws]

Sorry. I don't know.