FMA Challenge 2: Difference between revisions
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= Introduction =
The FMA Challenge
This Wiki page assumes an intermediate to advanced user level. If you haven't already completed FMA Challenge 1, please see
This model specifically shows:
*Tidal influences on floodplains and riverine systems;
*Variation in results due to 2D cell resolution and whether or not the model should contain a 1D component;
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*The differences between two different 2D solvers, TUFLOW classic and TUFLOW GPU.<br>
Data for this model is provided
*[https://www.tuflow.com/Download/TUFLOW/Demo_Models/FMA_Challenge_Model_2_QGIS.zip QGIS Data Download]
*[https://www.tuflow.com/Download/TUFLOW/Demo_Models/FMA_Challenge_Model_2_MapInfo.zip MapInfo Data Download]
*[https://www.tuflow.com/Download/TUFLOW/Demo_Models/FMA_Challenge_Model_2_ArcGIS.zip ArcGIS Data Download]
=Relevant Tutorials=
It may be useful to revisit some of the following tutorials:<br>
*General 2D modelling - <u>[[
*2D topography modification - <u>[[
=Model Setup=
This section provides an overview and discussion of the model domain setup.
It is at your discretion which GIS package, text editor and method of model simulation to use (batch mode or within the text editor). All files required to setup and run the models are available within the download package. You have the choice of running with shape file or mif for usage in ArcGIS/QGIS or Mapinfo respectively.<br> <br>
This model does not require a licence dongle to run.
==Grid Setup and Cell Size==
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| 30m (grid) || 80,842
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=== Note on Runtimes ===
There is a series of batch files provided with the demo model that give the choice of running only the 15m and 30m grid resolutions or all three. Due to the size of the model and large number of cells for the CPU only 10m case, it may take up to 24hrs of 'real time' to run on your computer. If you don't want to run the 10 m case then just run either 'run_all_001.bat' or '_run_all_CPU_001.bat'. Further details are provided in the Readme.txt within the runs directory.
Current benchmarching of runtimes for the CPU vs GPU respectively has found that the GPU simulations are typically 20-30 times faster than the CPU for this demo model. For models with a much larger number of cells >10 million the benefit of the GPU increases dramatically with CPU/GPU runtime speed increases over 100. Further detail on the hardware benchmarking conducted on FMA Demo Model 2 is provided [[Hardware_Benchmarking | here]].
==Simple Manning’s n / Topography Test==
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<ol>
<li>Recorded levels can themselves be quite uncertain. They should preferably be rated as to their accuracy and the type of flood mark noted with the recording. For example, a water mark in the wall of a house is a reliable, accurate mark of the peak water level; while a debris level is simply an indication that the flood was at least this high (debris marks may not be at the peak of the flood). Scanning through the high water marks in this study would indicate some inconsistencies. For example, in the northern end of the study area the 5.35 HWM in the image below is upstream of the 5.66 HWM. Either the 5.35 is low and/or the 5.66 is high. If the accuracy of the HWMs can’t be established, then as a generalization, the modeler should err on the high side in case the flood mark was not recorded at the flood peak.<br>
[[File:Critical_Embankment5.jpg|600px]]
<li>The modeller should NOT adopt unrealistic parameter values (eg. excessively low or high Manning’s n values) for the sole purpose of achieving a good calibration. It is invariably the fact that there are other uncertainties causing the discrepancy when unrealistic Manning’s n values are used. Unrealistic Manning’s n values or other parameters (eg. high eddy viscosity) distort the results and are a sure sign that there is something else wrong.
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==Caveats==
In summary, the TUFLOW 15m No Embankments simulation provided the best calibration
=Conclusion=
In this challenge, we explored a tidally influenced floodplain and riverine system. From this, we gained a better understanding of how cell resolution affects results and when it is suitable to neglect 1D components, how to use a looped batch file to run through scenarios, and an understanding of comparison between the
Congratulations on finishing Challenge 2! Please click [[Main_Page | here]] to return to the main page.
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