Model Unstable for Low Flows

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Model Unstable for Low Flows

sanjeewa
Dear Friends,

I developed  HEC-RAS dynamic model which has two main reaches and both reaches meet at the junction and after that it goes down to the sea.Downstream of the model has lateral structures and bridges etc.

I gave two hydrographs for both up steams of the two reaches. My problem is that the model have Run for High flows. But when I  included low flows model got unstable.



Please can you give me advice to avoid this instability for Low unsteady flow.
Thank you very much.

Sanjeewa

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Re: Model Unstable for Low Flows

Luis Partida
In 1D unsteady state models one of the most common causes of failure is the modeling drying out. Try creating a small pilot channel using a high mannings value and for your inflow hydrographs enter a minimum flow at the bottom left (something small in comparison to the inflow that will just keep the model wet withiin the pilot channel)
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Re: Model Unstable for Low Flows

sanjeewa
Thank you very much..