1-D Modelling - Sanity Check

Been having problems trying to calibrate the TELEMAC models, both the flat and dune geometry to achieve normal flow depth. The models appear to become unstable as they approach the normal depth.  I checked that it was not a problem with the new princi.f file that I developed last week (basically ran the hotstart for a long time - still crashed).

I decided to do a quick 1-D model for comparison and as a sanity check. I know that for my model - Bed Slope = 1/600, D=1mm, Q=0.0455 cms and w=0.76m, I should get a normal depth of around 9.5cm using the Chezy equation. I set up a model in HEC-RAS to verify that I should be getting 9.5cm as my normal depth. In short - yes - after a couple of runs (adjusting mannings n against my Chezy c - which has to be done iteratively) the final normal depth was 10cm. (Note I do not think that HEC-RAS reports the depth any finer than the nearest cm). The plot is shown below. There are several profiles - the normal profile is the lowest set of lines (Profile 4).

The tabular results for the normal flow are shown below.