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TUFLOW Boundary Conditions


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I am modelling a very large floodplain area 30,000 acres using 10m cell TUFLOW grid. I am having a hard time setting my flow boundary conditions and need some advice for my input data.

Over a single flood event my flow will rise from 90 cms up to 4,000 cms over a two-three week period. I only have mean daily data leading up the the event and a peak value for the flood crest. It is unreasonable to model the full real-time two week period, and I am trying to establish an arbitrary timescale for my BC hydro data and model controls. I am using time vs flow for my upstream boundaries and water surface elevation vs flow for my downstream boundaries.

I have tried treating each mean daily value as a half an hour. For an event that spans 28 days, there are 14 hrs in the time series, with the map output interval to 1800 seconds, and the start time to 0, end time to 15.0 hrs. I am using a time step of 2.0. The model runs for about 8 hrs cpu time and upon completion, only a quarter of the floodplain is flooded. The flood is drastically underestimated by the TUFLOW model. I am quite sure it is an issue with my BC parameters and model control specifications.

Are there rules for relating the time series inflow to the size of the event if you can not model real-time data?

I do not mind the long run times, I just wish I could figure out an appropriate time period to let the model respond to the in flow.

My terrain and bathymetry data is very good, so it is not a problem and my manning's n are specified correctly. Also the Mass Error % in the log file is always less than 1%. So my model is running fine, I just need help calibrating my inflows, and specifications in the model control interface.

Please advise.

Many Thanks,


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