Input Hydrograph+highly regulated catchment

[Anonymous]

Hi everyone, I am not sure if here is a good place to put may comment.
I want to prepare a 2d model for downstream of highly regulated catchment (There are 2 dams and their reservoirs in the upstream catchment) . I have 40 years river gauging station time series at the upstream boundary of the 2d model. The the biggest flood happened in this period has 50 years return period. I need to prepare an inundation map for 100 years event .
How can I prepare this input hydrograph? Do I need an rainfall run off Hydrological model for upstream catchment? what if i do not have enough data for calibration of my Model?
Cheers

[Vince Moody]

With 40 years of data you should be able to estimate the 100 year flow with a reasonable degree of certainty. If you don’t have enough observed data for calibration, you do the best you can and clearly and emphatically state the analysis limitations; maybe present reasonable bounds of your results. You don’t need a rainfall-runoff model, but it certainly seems like it might help you if you have sufficient data. The new version of HEC-HMS has some very powerful uncertainty analysis features you may find helpful (User’s Manual Chapter 16).

An important thing to think about is what the “100 year event” means for your analysis. Is this the regulated discharge from the system, or the “natural” discharge of the system were the dams not in place? One of those will require a lot more work than the other.

[Author]

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