TUFLOW Output Discussion - Revision history

Abrar.Alttahir: /* Why are the values of the mapped water level results (h_max) lower than the terrain elevations (DEM_Z)? */

2026-04-08T03:15:02Z

Why are the values of the mapped water level results (h_max) lower than the terrain elevations (DEM_Z)?

← Older revision		Revision as of 13:15, 8 April 2026
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	== Why are the values of the mapped water level results (h_max) lower than the terrain elevations (DEM_Z)? ==		== Why are the values of the mapped water level results (h_max) lower than the terrain elevations (DEM_Z)? ==

	As of TUFLOW version 2025.1.1, there is a current limitation affecting result outputs for shallow sheet flow cells on steeper terrain in sub-grid~~-scale~~ (SGS) enabled models. Direct rainfall models are particularly prone to producing substantial areas of shallow sheet flow.		As of TUFLOW version 2025.1.1, there is a current limitation affecting result outputs for shallow sheet flow cells on steeper terrain in sub-grid sampling (SGS) enabled models. Direct rainfall models are particularly prone to producing substantial areas of shallow sheet flow.

	In TUFLOW HPC, the cell averaged depth is used computationally and by default in the depth outputs (see below).		In TUFLOW HPC, the cell averaged depth is used computationally and by default in the depth outputs (see below).

Abrar.Alttahir: /* Why are the values of the mapped water level results (h_max) lower than the terrain elevations (DEM_Z)? */

2026-04-08T03:13:46Z

Why are the values of the mapped water level results (h_max) lower than the terrain elevations (DEM_Z)?

← Older revision		Revision as of 13:13, 8 April 2026
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	== Why are the values of the mapped water level results (h_max) lower than the terrain elevations (DEM_Z)? ==		== 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.		As of TUFLOW version 2025.1.1, there is a current limitation affecting result outputs for shallow sheet flow cells on steeper terrain in sub-grid-scale (SGS) enabled models. Direct rainfall models are particularly prone to producing substantial areas of shallow sheet flow.

	In TUFLOW HPC, the cell averaged depth is used computationally and by default in the depth outputs (see below).		In TUFLOW HPC, the cell averaged depth is used computationally and by default in the depth outputs (see below).

Anne.Kolega: /* How to create a maximum grid for datasets without direct maximum output from a TUFLOW run? */ deleted a comma

2026-03-01T23:49:49Z

How to create a maximum grid for datasets without direct maximum output from a TUFLOW run?: deleted a comma

← Older revision		Revision as of 09:49, 2 March 2026
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	==How to create a maximum grid for datasets without direct maximum output from a TUFLOW run?==		==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), the map output interval in the TCF needs 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 cumulative datasets without direct maximum output (e.g. cumulative infiltration, cumulative rainfall etc), the map output interval in the TCF needs 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):		For non-cumulative datasets without direct maximum output (e.g., Froude number, rainfall rate etc):

Anne.Kolega: /* Why does hazard output (Z1, Z2, ...) show float values and not just integers? */

2026-03-01T23:33:20Z

Why does hazard output (Z1, Z2, ...) show float values and not just integers?

← Older revision		Revision as of 09:33, 2 March 2026
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	== Why does hazard output (Z1, Z2, ...) show float values and not just integers? ==		== Why does hazard output (Z1, Z2, ...) show float values and not just integers? ==
	The hazard values are calculated in cell corners and are in a form of an integer. When the values are processed into a grid, which has, by default, a resolution of half the cell size, the values are interpolated to the cell centres - four cell centre values per cell. Further interpolation occurs when the model has a non-zero orientation as grid files are north-south aligned.<br>		The hazard values are calculated in cell corners and are in a form of an integer. When the values are processed into a grid, which has, by default, a resolution of half the cell size, the values are interpolated to the cell centres - four cell centre values per cell. Further interpolation occurs when the model has a non-zero orientation because grid files are north-south aligned.<br>

	== Why are results from 2d_po features, POMM.csv and plots extracted from XMDF in GIS package not matching? ==		== Why are results from 2d_po features, POMM.csv and plots extracted from XMDF in GIS package not matching? ==

Anne.Kolega: /* How to create a maximum grid for datasets without direct maximum output from a TUFLOW run? */

2026-02-27T04:01:30Z

How to create a maximum grid for datasets without direct maximum output from a TUFLOW run?

← Older revision		Revision as of 14:01, 27 February 2026
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	*Confirm the dataset's output ID number in the resulting (maxmax).xmdf file:		*Confirm the dataset's output ID number in the resulting (maxmax).xmdf file:
	<pre>"C:\TUFLOW\Releases\res_to_res\res_to_res_w64.exe" -xnfo (maxmax).xmdf</pre>		<pre>"C:\TUFLOW\Releases\res_to_res\res_to_res_w64.exe" -xnfo (maxmax).xmdf</pre>
	*Convert the resulting dataset to a preferred grid format for GIS ~~use~~ using the <u>[[TUFLOW_to_GIS#Introduction \| TUFLOW to GIS]]</u> utility.		*Convert the resulting dataset to a preferred grid format for GIS using the <u>[[TUFLOW_to_GIS#Introduction \| TUFLOW to GIS]]</u> utility.

	:Note: For non-cumulative datasets, this method does not capture the true maximum, however can be close enough with a fine map output interval.		:Note: For non-cumulative datasets, this method does not capture the true maximum, however can be close enough with a fine map output interval.

Anne.Kolega: /* Why are grids processed with TUFLOW_to_GIS different from TUFLOW grids? */

2026-02-27T03:51:32Z

Why are grids processed with TUFLOW_to_GIS different from TUFLOW grids?

← Older revision		Revision as of 13:51, 27 February 2026
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	The differences can also be amplified when the rotation of the model is a non-zero value.		The differences can also be amplified when the rotation of the model is a non-zero value.
	The extent of the grids is also different. When TUFLOW starts it removes any redundant areas (if any) outside of 2d_code layer to reduce the calculation time:		The extent of the grids is also different. When TUFLOW starts, it removes any redundant areas (if any) outside of 2d_code layer to reduce the calculation time:
	* The extent of grids written directly from TUFLOW works with the unreduced area, encapsulating the entire rotated model domain in a north-south orientated rectangle.		* The extent of grids written directly from TUFLOW works with the unreduced area, encapsulating the entire rotated model domain in a north-south orientated rectangle.
	* The extent of XMDF (or DAT) results is based on the reduced area. When the TUFLOW_to_GIS utility is used the post-processed north-south aligned grids encapsulate the reduced model extent. The origin coordinates of such grids doesn't match the origin of the model (model domain), neither the grids written out from TUFLOW directly.		* The extent of XMDF (or DAT) results is based on the reduced area. When the TUFLOW_to_GIS utility is used, the post-processed north-south aligned grids encapsulate the reduced model extent. The origin coordinates of such grids doesn't match the origin of the model (model domain), neither the grids written out from TUFLOW directly.

	In general, a better interpolation of results is achieved when the grids are written directly from TUFLOW than when post-processed with TUFLOW_to_GIS utility. Importantly, when comparing results the recommendation is to be consistent and to use the same method for the duration of a project to ensure there are no differences as a consequence of the post-processing method.<br>		In general, a better interpolation of results is achieved when the grids are written directly from TUFLOW than when post-processed with TUFLOW_to_GIS utility. Importantly, when comparing results the recommendation is to be consistent and to use the same method for the duration of a project to ensure there are no differences as a consequence of the post-processing method.<br>

Abrar.Alttahir: /* How should below ground water surface elevation (WSE) in wet SGS cells be interpreted or presented? */

2026-02-17T23:56:27Z

How should below ground water surface elevation (WSE) in wet SGS cells be interpreted or presented?

← Older revision		Revision as of 09:56, 18 February 2026
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	[[File:SGS_Sheetflow_Waterlevel.jpg\|600px]]		[[File:SGS_Sheetflow_Waterlevel.jpg\|600px]]

	== ~~How~~ ~~should below ground~~ water surface ~~elevation~~ ~~(WSE)~~ in ~~wet~~ SGS ~~cells~~ be interpreted or presented? ==		== The modelled water surface level is below the SGS cell elevations. How should this result be interpreted or presented? ==
	Below ground WSE in wet SGS cells is a known output behaviour in SGS enabled models and does not indicate an error in the hydraulic solution.		Below ground WSE in wet SGS cells is a known output behaviour in SGS enabled models and does not indicate an error in the hydraulic solution.

Abrar.Alttahir: /* How should below ground water surface elevation (WSE) in wet SGS cells be interpreted or presented? */

2026-02-14T07:46:56Z

How should below ground water surface elevation (WSE) in wet SGS cells be interpreted or presented?

← Older revision		Revision as of 17:46, 14 February 2026
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	Below ground WSE in wet SGS cells is a known output behaviour in SGS enabled models and does not indicate an error in the hydraulic solution.		Below ground WSE in wet SGS cells is a known output behaviour in SGS enabled models and does not indicate an error in the hydraulic solution.

	This occurs because TUFLOW reports water level assuming water fills from the lowest part of the SGS cell during output. As a result, cells may be wet while the reported ~~water surface elevation~~ remains below the cell centre ground level.		This occurs because TUFLOW reports water level assuming water fills from the lowest part of the SGS cell during output. As a result, cells may be wet while the reported WSE remains below the cell centre ground level.

	This behaviour commonly occurs in the following situations:		This behaviour commonly occurs in the following situations:
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	* Partially wet cells along channel banks may contain water that does not reach the cell centre elevation.		* Partially wet cells along channel banks may contain water that does not reach the cell centre elevation.
	* In this case, compare the standard ~~water surface elevation~~ with the standard ~~DEM Z~~ check file to confirm consistency with terrain levels.		* In this case, compare the standard WSE with the standard DEM_Z check file to confirm consistency with terrain levels.

	'''Shallow sheet flow from rainfall or side inflow'''		'''Shallow sheet flow from rainfall or side inflow'''

	Cells may be wet but still report ~~water surface elevation~~ below the cell centre ground level because the depth is small and distributed across the SGS terrain.		Cells may be wet but still report WSE below the cell centre ground level because the depth is small and distributed across the SGS terrain.

	'''Presentation and reporting considerations'''		'''Presentation and reporting considerations'''

	* A presentation method is to post process results by adding the cell averaged depth output <font color="blue"><tt>SGS Depth Output</tt></font> <font color="red"><tt>==</tt></font><tt> CELL AVERAGE</tt></font> to the DEM elevation to derive an above ground water level.		* A presentation method is to post process results by adding the cell averaged depth output <font color="blue"><tt>SGS Depth Output</tt></font> <font color="red"><tt>==</tt></font><tt> CELL AVERAGE</tt> </font>to the DEM elevation to derive an above ground water level.
	* This approach can improve the visual representation of shallow flooding in sheet flow areas but may produce unrealistic water levels in fully wet or partially wet cells.		* This approach can improve the visual representation of shallow flooding in sheet flow areas but may produce unrealistic water levels in fully wet or partially wet cells.
	* Conditional IF logic may be required to choose where to present cell averaged depth plus DEM and where to retain the standard TUFLOW water level output.		* Conditional IF logic may be required to choose where to present cell averaged depth plus DEM and where to retain the standard TUFLOW water level output.

Abrar.Alttahir: /* How should below ground water surface elevation (WSE) in wet SGS cells be interpreted or presented? */

2026-02-14T07:44:26Z

How should below ground water surface elevation (WSE) in wet SGS cells be interpreted or presented?

← Older revision		Revision as of 17:44, 14 February 2026
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	'''Presentation and reporting considerations'''		'''Presentation and reporting considerations'''

	* A presentation method is to post process results by adding the cell averaged depth output <font color="blue"><tt>SGS Depth Output == CELL AVERAGE</tt></font> to the DEM elevation to derive an above ground water level.		* A presentation method is to post process results by adding the cell averaged depth output <font color="blue"><tt>SGS Depth Output</tt></font> <font color="red"><tt>==</tt></font><tt> CELL AVERAGE</tt></font> to the DEM elevation to derive an above ground water level.
	* This approach can improve the visual representation of shallow flooding in sheet flow areas but may produce unrealistic water levels in fully wet or partially wet cells.		* This approach can improve the visual representation of shallow flooding in sheet flow areas but may produce unrealistic water levels in fully wet or partially wet cells.
	* Conditional logic may be required to ~~determine~~ where ~~the standard water surface elevation~~ or a ~~derived~~ depth plus DEM ~~level~~ ~~should~~ be ~~presented~~ ~~based~~ on ~~the~~ ~~local~~ ~~flow~~ ~~condition~~.		* Conditional IF logic may be required to choose where to present cell averaged depth plus DEM and where to retain the standard TUFLOW water level output.

	== Why do the high-resolution (HR) mapped results have a significantly smaller extent than the standard (non-HR) grid outputs for a sub-grid-scale (SGS) direct rainfall HPC model? ==		== Why do the high-resolution (HR) mapped results have a significantly smaller extent than the standard (non-HR) grid outputs for a sub-grid-scale (SGS) direct rainfall HPC model? ==

Abrar.Alttahir at 07:38, 14 February 2026

2026-02-14T07:38:04Z

@@ Line 54: / Line 54: @@
 == How do I apply high resolution (HR) output and what are the options? ==
 See the <u>[[TUFLOW_HR_Output | TUFLOW HR Output]]</u> Wiki page for details.<br>
 == Why are there differences between high resolution grid from TUFLOW and remapped outputs generated by the asc_to_asc utility? ==
@@ Line 86: / Line 85: @@
 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>
+[[File:SGS_Sheetflow_Waterlevel.jpg|600px]]
 == Why do the high-resolution (HR) mapped results have a significantly smaller extent than the standard (non-HR) grid outputs for a sub-grid-scale (SGS) direct rainfall HPC model? ==