Hi everyone,
Fisrt of all, I know that HEC-RAS V5.0.3 cannot compute sediment transport in 2D areas and that is not my goal !
A 1D/2D model was built for a study in order to compute WSE, Velocities and overflows. But the next step is to analyse the sediment transport.
Knowing that HEC-RAS sediment module does’nt work for 2D, I used simple cases to test 1D/2D sediment transport before trying it on the model. I noticed that the sediment transport module was actually working well as long as the water remains in the 1D reach. But as soon as the water is overflowing, instabilities are coming in the 2D part. I tried to make it stable reducing the Computation interval (until 0.1 seconds !), adding cross-sections, taking a higher tolerance… Sometimes the calculation finishes but with a big amount of instabilities and a demential time of calculation (sometimes HEC-RAS is showing errors equal to 0.0000 !)
I thought that the software was using the remaining flow in the reach to calculate the sediment transport and that the flow leaving has no incidence but apparently I was wrong.
Does anyone manage to compute sediment transport on a 1D/2D model ?
Thanks for your attention,
Benoît