Negative area in subroutine convey

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Negative area in subroutine convey

Mike
I get this error from hecras :


EGATIVE AREA IN SUBROUTINE CONVEY
BETWEEN STATION      0.00 AND     164.04
1 5 45
THIS IS USUALLY CAUSED BY BAD STATION/ELEVATION DATA
IF THIS NODE HAS A WEIR (BRIDGE etc.) CHECK THE ROAD DECK DATA CAREFULLY
--PROGRAM ABORTED--
NEGATIVE AREA IN SUBROUTINE CONVEY

I have tried everything  but I can not fix the problem. (I have a long culvert with 2m drop in between which I used cross section with lid to model it).  I have imported my geometry data from 12d

I have changed the time steps. cross section spacing. number of iteration and ... but the model is not working.

Any suggestion?

Thank's
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Re: Negative area in subroutine convey

Bryan
Any luck?
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Re: Negative area in subroutine convey

SaraA
Hi,

could you solve this issue?

Thank you,

Sara
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Re: Negative area in subroutine convey

AGuiheux
Hi,

Same for me...
Can't solve the issue, I have a 1D/2D model. The 1D only works fine but when i add lat struct and 2D areas, i have this error...

I tried removing the bridges but the error spreads to the bridge upstream..

Any ideas? I'm working on HEC-RAS 5.0.4.
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Re: Negative area in subroutine convey

Gnut
Hi Mike, SaraA, Bryan, AGuiheux and others !

I've found a way to solve the same problem you encountered (1D only) : it seems be caused by the Multiple Opening Analysis conditions.

For multiple opening bridges (bridge + culvert), ONE ONLY AREA has to be set as "Conveyance". This "Conveyance" also must be on the extreme Right or Left overbank...

Be careful to set this "Conveyance" only outside of areas where the bridge can overflow (like a weir). I solved some case in putting this "conveyance" to the far right / left of the structure (a few meters is enough).

Hope it will help you !