Reply To: Initial Loss Sensitivity

[Benson Liu]

Hi Grant,

I can’t view any of the files you have uploaded as I think the websites security has blocked it but there are a few things to consider that could be causing this issue.

How the initial/continuing loss model works is that the initial loss is applied first and wipes out the rainfall until the initial loss is satisfied, continuing loss then kicks in after that. So what you could be seeing is that even if you lower the IL, the CL is still wiping out the rainfall and so the hydrograph doesn’t change but this is dependent on the rainfall depths and temporal pattern.

A second thing to note, while losses are catchment and event specific and can vary quite a bit between these things, a CL value of 9.6mm/hr I would consider extremely high, almost unreasonable. Again, this is catchment and event specific so it could be possible but I think you would need a good justification for applying such a high CL. This feeds into another point about the fit routine. The fit routine is generally no longer used as computers now have enough power to run RORB very quickly. The design routine is recommended as this allows you to specify the losses, gives you greater control of the parameters and allows you to see the incremental changes with changing parameters.

Kind regards,

Benson