Home Forums RORB – general use ARR16 Model Hydrograph Timestep

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    I am running a model using the generated ARR16 ensemble design storms and are trying to produce hydrographs with a timestep of 0.05 hours. The default ARR16 ensemble design run outputs hydrographs with 0.5 hour data points which is too coarse for export into a hydraulic model.

    The .stm files generated by the ARR16 process default to 0.5h hydrograph datapoints on line 16. Changing this manually to 0.05h (in previously processed .stm files) is overwritten when the storm is rerun. I could manually run each .stm file however I would then have to run every storm for every AEP, duration and temporal pattern combination for multiple scenarios.

    Is there an easy way of changing the hydrograph output interval for ARR16 ensemble design storms from the default of 30min?

    I am a new user so sorry if I am missing something obvious.


    Thanks for your query.

    The timestep on the output hydrographs is controlled by the timestep of the temporal patterns written into the storm file. Thus, unless you rescale the temporal patterns to be expressed on a shorter timestep, RORB will not produce hydrographs on a shorter timestep.

    If you require hydrographs on a shorter timestep in a hydraulic model, the best approach is to manually interpolate these in a spreadsheet or other means outside RORB.

    Having said this, I’m a little surprised that your hydraulic model requires input hydrographs at a certain timestep. Most of the major hydraulic models (eg HEC-RAS, MIKE, Tuflow) I am aware of will do this interpolation for you automatically.


    Thanks for your quick response David.

    In certain temporal pattern/duration combinations the rainfall burst causes a very quick rise/fall which required a greater number of datapoints to reflect correctly. TUFLOW’s inbuilt interpolation process appears to provide linear interpolation between input datapoints, which we were concerned was not showing the full picture. We will adjust the temporal pattern file to be expressed at a shorter timestep to solve this issue.

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