Hec-geoRas error

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07-16-2018 12:21 PM
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GiuseppeGallo
New Contributor

I have a problem with the geometric data made with HEC-geoRAs and exported to HEC-RAS. Please help me, I do all the step with geoRAS, I assigned channel ID, left rght and center to Flowpath ecc... Any idea?                                           Sorry for my english, I'm italian student.

ps: I understood that the Y and Z coordinates when I extract the sections are reversed

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2 Replies
KurtisBaron
New Contributor II

What does it look like in GeoRAS (ArcMap)?

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DANIEL_FERNANDOVALENCIA_ORTIZ
New Contributor

I know this is an older post but I got a headache trying to figure out what was wrong so I wanna leave this here in case anyone is struggling with the same issue, I found a solution in this post:

Problem with import in HEC-GeoRAS / RAS - Floodplain Mapping 

The problem is all the HEC GEO RAS files look fine in ArcGIS but when you export them and then import them as GIS data to HEC-RAS, the river displayed is completely wrong, it loses all form and shape. The core of the problem seems to be that HEC-RAS is somehow misreading the file's coordinates.

As said in the post I linked above, this may happen to some of us if our computer's regional settings use the character comma ',' as a decimal sparator, instead of the dot or period character '.' , as a result, the coordinates in our exported file will have their decimals separated by commas, but each coordinate (X, Y and Z) will also be separated by a comma, acompanied by a blank space.

Take the following set of coordinates:

X: 10.444

Y: 15.25

Z: 30

In arcmap, HEC GEO-RAS will export these coordinates as follows:

10'decimal separator'444 , 15'decimal separator'25 , 30

Normally, HEC-RAS should read these coordinates properly, however, if your decimal separator happens to be a comma, then HEC-RAS will read those coordinates the following way:

X: 10

Y:444

Z:15

So we know this is completely wrong, and it explains why the imported GIS data makes the river look like such a mess in the Geometric Data display.

The fix is to change those decimal separator commas to period characters, you can do this in a text editor, now, when you replace all commas with periods, you will also be changing the coordinate separating commas to periods as well, my fix for that problem was:

Right click your .sdf file and select 'Open with' --> Open the .sdf file with Microsoft Excel --> Select the column where the coordinates are placed (it was column B for me) and in the Start Menu, locate the Replace tool.

First, replace all commas in B column with the dot or period character '.

Now all your commas have turned into periods, but you still need each coordinate (X, Y and Z) to be separated form each other by a comma and a blank space, so you need to select B column again, use the Replace tool, and replace all Periods followed by a blank space with commas followed by a blank space, that way, your periods acting as decimal separators will not be changed back into commas, but those periods that are followed by a blank space, therefore being the coordinate separators, will become commas and now HEC-RAS will be able to properly import your data.

Again, checking the decimal separator seems like an obvious thing to do but I honestly could not figure it out by myself, so I hope this can help someone out.

Cheers!

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