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TUFLOW Output Discussion: Difference between revisions

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==How to create a maximum grid for datasets without direct maximum output from a TUFLOW run?==
 
For cumulative datasets without direct maximum output (e.g., cumulative infiltration, cumulative rainfall etc), ensure that the map output interval in the TCF matchesneeds to match the simulation end time (in seconds). The end time output is when the maximum occurs for cumulative datasets, as it represents the cumulative results over the entire simulation duration.
 
For non-cumulative datasets without direct maximum output (e.g., Froude number, rainfall rate etc):
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*Specify XMDF for <font color="blue"><tt>Map Output Format</tt></font>.
*Identify the output ID number of the desired dataset within the .xmdf file:
<pre>“C"C:\TUFLOW\Releases\res_to_res\res_to_res_w64.exe”exe" -xnfo results.xmdf</pre>
*Extract maximum values using the <u>[[https://wiki.tuflow.com/RES_to_RES#Introduction res_to_res| RES to RES]]</u> utility.
*Confirm the dataset’sdataset's output ID number in the resulting (maxmax).xmdf file:
<pre>“C"C:\TUFLOW\Releases\res_to_res\res_to_res_w64.exe”exe" -xnfo (maxmax).xmdf</pre>
*Convert the resulting dataset to a preferred grid format for GIS use using the <u>[[https://wiki.tuflow.com/TUFLOW_to_GIS#Introduction TUFLOW_to_GIS| TUFLOW to GIS]]</u> utility.
 
:Note: For non-cumulative datasets, this method dependsdoes onnot capture the chosentrue map output intervalsmaximum, andhowever truecan maximumsbe mayclose notenough bewith captureda iffine themap intervals are toooutput largeinterval.
 
== Why are the values of the mapped water level results (h_max) lower than the terrain elevations (DEM_Z)? ==
 
As at TUFLOW Build 25.1.1, there is a current limitation for result outputs at shallow sheet flow cells on steeper terrain in sub-grid-scale (SGS) enabled models. Direct rainfall models are particularly prone to result in substantial extents of shallow sheet flow.
 
In TUFLOW HPC, the cell averaged depth is used computationally and by default in the depth outputs (see below).
 
Water level outputs, however, assume that water fills from the bottom of the SGS cell’s storage curve. This water level result is recorded at the cell centre, interpolated to the cell corners, and then the gridded outputs are triangulated from these points (orange line). In sheet flow situations when the volume in that cell is small, the cell-centered water level may sit below the terrain (blue dot on diagram) if the cell is steep enough. This can result in a water level results sitting below the DEM_Z, even when there is a positive depth result. Note this does not affect the simulation computationally, only how the water level results are output. <br>
[[File:SGS_Sheetflow_Waterlevel.jpg|600px]]<br>
 
== Why the high resolution (HR) mapped results have a significantly smaller extent than the standard (non-HR) grid outputs for a sub-grid-scale (SGS) enabled direct rainfall HPC model? ==
 
The high resolution (HR) outputs are based on <u>[[TUFLOW_HR_Output | intersecting]]</u> the standard water level output results with the HR DEM_Z. Due to the <u>[[TUFLOW_Output_Discussion#Why_are_the_values_of_the_mapped_water_level_results_.28h_max.29_lower_than_the_terrain_elevations_.28DEM_Z.29.3F | output limitation]]</u> for sub-grid-scale (SGS) enabled models with shallow sheet flow (particularly direct rainfall models) on sufficiently steep terrain, water levels can be output lower than the DEM_Z terrain elevations. This is due to the assumption (for output purposes) that water fills the SGS cell’s storage curve from the bottom, which differs from the approach of cell-average depth used computationally in TUFLOW HPC and by default in depth outputs. When the HR water level results are processed, the full extent of the water level results are intersected with the HR DEM_Z and any water level results that are lower than the HR DEM_Z elevations due to the above effect are trimmed. The extent of the HR water level results are then used to trim the HR depth outputs.
 
 
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