“Warning – An error occurred in unsteady flow data units conversion” when using IB conditions

[ns4818]

I have made a simple unsteady flow model (prismatic channel) with a flow hydrograph as an upstream boundary condition and normal depth as a downstream boundary condition. After running this model once (let’s say base run), I added 2 Internal boundaries (IB) conditions (stage hydrograph) at 2 different cross-sections for my next run. The model runs fine when I enter IB in the table but when I give IB as a DSS file (created using hec-dssvue), the model throws a warning saying ” An error occurred in unsteady flow data units conversion”. I have to manually click ‘ok’ to start/run the model. This happens only when the model is in the SI system. When I run the same model in the US customary units, I don’t get any errors.

I have checked the consistency of my input units. It looks fine to me. I don’t understand why would there be a need to convert the unit of the unsteady flow data before running a model when everything is in the same unit system.

I am doing this to run a Monte-Carlo simulation, where I would change IB values in the DSS files.

Kindly, suggest.
I am using RAS 5.0.7 and Hec-dssvue 2.0.1.

[cameron]

Are the units in the DSS data set the same as the HEC-RAS model? The values you have may be the same units, but does DSS think they are the same units?

Section 7.4 of the DSS users manual discusses how to set the units.

[ns4818]

Thank you for your reply Cameron.

Data in HEC-RAS and DSS are in the same units (SI). My DSS data are stage time-series with units Meters. I have tried to set units and even unit conversion following DSS 7.4 guidance, to make it work. But, for some reason, hec-ras is not identifying the DSS units.

[cameron]

If you look at the dss data from HEC-RAS (plot option is when you select the data) does it show it in the correct units?

If you post your files, I will take a look. If not and I have time this weekend, I may test out my own dataset to see if I get the same issue.

[ns4818]

Thanks again :). I am posting my model herewith. Project ‘run_1_c6’ has IB conditions (Dss filename = IB_conditions_stagehyd.dss).
model_IB_problm.zip

[cameron]

I would reach out to HEC to see if they think it is a bug or not.

[ns4818]

Thanks for you help. I just emailed HEC the problem. Will post their answer.

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