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Floodplain Mapping (HEC-RAS to CAD)

Floodplain Mapping (HEC-RAS to CAD)

Floodplain Mapping (HEC-RAS to CAD)

Hi all,
I am working on hydraulic modeling of a channel for CLOMR/LOMR project, HEC-RAS model and results look fine. Right now, I am working on mapping the 100 yr floodplain boundaries. I have done one in the recent past, where I look at the results table and draft the floodplain boundary at each cross section in CAD. This is very cumbersome and time consuming process.
My question, Is there a better and faster way? Does HEC RAS 5.0 has capability to export the results back into CAD and boom you have the floodplain boundaries with one mouse click?
I am sure there is probably a quicker way of doing this. I tried downloading HEC-GeoRAS but found out quickly that you need ArcGIS with ArcView, we only have ArcMap 10.2.2.

Bit more info: I have used AutoCAD Civil 3D to create a surface from the aerial topo, then I created sample line cross sections and exported to HEC-RAS. This saved me a lot of time. Now, I am trying to learn the most efficient way of showing the floodplain boundaries in CAD without spending a lot of time on drafting.

I really appreciate your time and responses.

RE: Floodplain Mapping (HEC-RAS to CAD)

In the latest version of RAS (5.0) you can save the inundation limits polygon to a shapefile or KML, easily imported into CAD. This is done within the RAS Mapper portion of the program, under results in the study tree, where right clicking is your friend.

RE: Floodplain Mapping (HEC-RAS to CAD)

Is there an easy way to do this outside of the Civil3d environment? Port it straight to DXF or similar that less expensive cad programs can grok?

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Floodplain Mapping (HEC-RAS to CAD)

The export feature does not fit the WSE to the topo other than at the specified XSECs. If you need more detail then use a 3D model package like Civil3D or INROADS. You can overlay the two surfaces to get the intersecting lines. Please note that surfaces must be used. A second way using the 3D model packages is to create a center line of the channel and project it to intercept the topo. All are time consuming.

RE: Floodplain Mapping (HEC-RAS to CAD)

Not sure what these others guys are referencing, HEC-RAS does the surface intersection and delineation between sections natively through RAS Mapper if you have a terrain in your model. I would trust the RAS generated results more than results interpolated by third party software (e.g. inroads) not meant for the solitary purpose of hydraulic computation and analysis. RAS is very good at what it does. You can even export depth grids, water surface elevations, and a host of other output variables in geoTiff format directly from RAS.

RE: Floodplain Mapping (HEC-RAS to CAD)

Do you have to use Arc-GIS or similar to get the geometry into RAS-Mapper? I'm old-school, and learned to input all this stuff by hand. I'd be interested in reading up some sources on how to automate cutting sections and such, if it doesn't require a $7000 license from ESRI.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Floodplain Mapping (HEC-RAS to CAD)


do you remember BOSS International RiverCAD now it RiverNet. This is for use in ACAD. Not sure of their cost, however. This is the only software that I was aware of that automated xsec export to HEC-2/RAS. INROADS has the capabilities if one is using Bentley MicroStation (We use this and GIS). I googled HEC RAS automated cross section and a boat load of items popped up. civilgeo was one that came up. maybe look into these.

RE: Floodplain Mapping (HEC-RAS to CAD)

Thanks everyone for responses. Looks like I have to play with RAS Mapper in 5.0, I just did not have the time these past couple of days. I will let you guys know.

beej67, I found this great link. This I think does not need Arc-GIS.

I hope RAS Mapper 5.0 can do the job what the guy was explaining in the above link. (Without downloading SAGA etc.). Anyone who has done this without GIS in the past or played in RAS 5.0 environment and created floodplain boundaries already without help from Arc-GIS, please respond.


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