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Found 5 results

  1. Question: When running a direct rainfall model using the TUFLOW HPC solver and applying an IL/CL using the materials layer, the results in the RFML map output are showing that the losses continue to accumulate after the rainfall has stopped i.e. for a 1 hour storm event, the cumulative loss continues to increase after the model time has passed the 1 hour mark. Is the model working, and am I able to use the other output results? Answer: Yes, the model is working and you can still use TUFLOW HPC to model direct rainfall with IL/CL applied using the materials layer. There is a bug in TUFLOW build 2017-09-AC in the RFML map output when running with the HPC solver that continues to report rainfall loss after the rainfall has ceased. This bug is confined to this map output only and does not affect the hydraulic computations or other outputs (depth, velocity, hazard etc). Please do not use the RFML output when using the HPC solver in TUFLOW build 2017-09-AC or earlier. This is not an issue when using the Classic solver.
  2. Q: When using a Global Rainfall boundary (via the "Global Rainfall BC == " command) do the spatially varying losses via the materials file apply, or only the Global Rainfall losses ("Global Rainfall Continuing Loss == " and "Global Rainfall Initial Loss == " commands)? A: When using a Global Rainfall BC the approach is more simplistic than the one than used for a 2d_rf layer. No memory is allocated for spatial losses and the global rainfall losses are the only ones that apply. These global losses are subtracted from the rainfall before the simulation and each cell gets the same rainfall applied. Therefore: The global rainfall losses commands only apply to global rainfall boundaries and not to 2d_rf polygons. The material losses do not apply to global rainfall boundaries. We will issue an updated 2016-03-AE manual in the coming weeks and this behaviour has been clarified. For future versions we will likely; add some warnings if either of the above configurations is specified, we will also look at supporting spatial losses for global rainfall, but will likely make a new command for doing so, to keep the existing behaviour.
  3. Q: "What are some suggestions for checking direct rainfall boundaries have been applied to my model correctly? For example, I wanted to verify that the correct rainfall depth of 90 mm was applied across the model. I divided the “total volume in” by the total area of active cells, and came up with only 72mm. I cannot track how the histogram relates to the hyetograph." A: There are a number of things that can be looked at, depending on the type of rainfall boundary being applied, and if rainfall losses are applied to the model. Rainfall losses applied through the Materials Definition file (.tmf or .csv format) removes the loss depth from the rainfall before it is applied as a boundary on the 2D cells. Soil infiltration losses however remove water from wet cells, after the rainfall source has been applied. Is the model health (mass balance, negative depths etc) acceptable? If using TUFLOW classic (as opposed to TUFLOW GPU) direct rainfall models should be run with double precision and the recommendation is to lower the cell wet / dry depth to 0.2mm. For 2d_rf boundaries, the rainfall time-series data must be in mm versus hours, and is converted to a hydrograph to smooth the transition from one rainfall period to another (the converted hydrograph is reported in the .tlf log file for cross-checking). After subtraction of rainfall losses, this is applied to the model cells as a source volume. The Map Output Data Types RFR and RFC (see Table 9-10 of the 2016-03-AE TUFLOW Manual) may be used to view the rainfall rate (mm/hr) and cumulative rainfall (mm) over time respectively. As these are model outputs, they are inclusive of the rainfall losses and any adjustments made in the BC Database (eg. multiplication factors/time shift). For rainfall grids generated from point rainfall data with a Rainfall Control File .trfc, the rainfall control file is processed during model initialisation and a series of rainfall grids are output, which are then used by the simulation to vary the rainfall over the 2D domain(s). This feature may also be useful simply to generate the series of rainfall grids for other purposes or display. The rainfall grids are pre-processed to reduce memory usage whilst TUFLOW is running. Whilst there isn’t a specific check file for the rainfall distribution when using generated rainfall grids, another advantage of the pre-processing of rainfall grids is that they can be interrogated prior to the end of the simulation to allow for checks. Note that the generated rainfall grids are inclusive of adjustments made in the BC Database (e.g. multiplication factors used for climate change) and of adjustment factors in the input GIS layer’s attributes, but because they are an input to the model, they are not inclusive of rainfall losses that may be specified in a materials file. Again, the Map Output Data Types RFR or RFC can be specified, these are inclusive of the rainfall losses, however these results are output as the simulation progresses. To confirm the rainfall losses applied across the model, use the grd_check file with the Materials Definition file .tmf.
  4. We have recently become aware of an issue affecting TUFLOW GPU simulations using the new gridded rainfall inputs. If the map output interval exceeds the interval in the rainfall grids, then the applied rainfall boundary condition is not updated. Choosing a map output interval that matches or divides into the boundary rainfall data interval will alleviate the issue. For example, if the gridded rainfall has a grid every 30 minutes, a Map Output Interval of 30, 15 or 10 minutes will all work. It is also important that the start map output time matches the gridded rainfall input start time. This will occur by default, though may be altered if a user defined Start Map Output time is specified. This does not affect TUFLOW “classic” simulations and the issue will be corrected in the 2016-03-AB release which will be available within the next month. If you're concerned about large file sizes resulting from your map output interval being reduced to fit your rainfall data interval you can use an output zone. For example with a 10 minute rainfall interval an output zone can be defined with an output interval of 10 minutes and the entire model output can be 1 hour. Again this work-around will only be required until the 2016-03-AB release. The 2016-03-AA release has the option to output the instantaneous rainfall rate and cumulative rainfall can be output with the RFR and RFC output types respectively. These can be used to cross-check the results. For example to output the depth, levels, velocities, rainfall rate and cumulative rainfall the .tcf command would be: Map Output Data Types == d h V RFR RFC Please contact support@tuflow.com if you have any queries relating to the above. Regards TUFLOW Support Team
  5. Hi, I have run a 2D only model with combined rainfall and hydrograph inflow and I'm getting a higher peak outflow (1003 m3/s) than a peak inflow (851 m3/s). When looking at the Qo value at the stated time of peak outflow, it is only 753 m3/s. I was wondering if this may be because the rainfall loss is not included in the Qo column calculation but is reported in the peak outflow? Additionally I can't find an explanation of the Mx column represents on the output file? Any help would be much appreciated. Cheers
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