Dependency of chanbnkf calculation on updated chanbw (Step 2 setup)

[KaiganCodes]

Dear @StefaniaGrimaldi , @doc78,

I am currently setting up the LISFLOOD model for hydrological simulations in Sri Lanka. I have successfully prepared the static and meteorological maps following the documentation on GitHub and have generated the average discharge (avgdis.nc) for my basin using the initial channel geometry based on the upstream area.

I am writing to seek clarification regarding the iterative refinement of the channel geometry layers.

The documentation suggests that after the initial run, the Bankfull Channel Depth (chanbnkf) should be recalculated using Manning’s equation approach (Burek et al., 2014) as follows:

chanbnkf_new = 1.004 * (chanman^0.6) * (2 * avgdis^0.6) * (chanbw^-0.6) * (changrad^-0.3)

However, I note that Burek et al. (2014) also imply that the Channel Bottom Width (chanbw) should be updated using the average discharge:

chanbw_new = avgdis^0.539

Could you please clarify the correct order of operations? Specifically:

1. Are we required to recalculate the Channel Bottom Width (chanbw) using the average discharge before calculating the new Bankfull Depth?

2. If so, when calculating the new Bankfull Depth (chanbnkf), should I input the original chanbw (derived from upstream area) or the updated chanbw (derived from average discharge)?

3. Is this second step calculations are only related to the European context?

I look forward to your insights..
Thank you for your time and guidance.