TUFLOW Remapping - Revision history

Pavlina Monhartova at 02:22, 8 August 2024

2024-08-08T02:22:04Z

Pavlina Monhartova at 02:18, 8 August 2024

2024-08-08T02:18:23Z

← Older revision		Revision as of 12:18, 8 August 2024
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	The 2020 release of TUFLOW included new Quadtree mesh and Sub-grid Sampling (SGS) functionality. The SGS feature now supports the		The 2020 release of TUFLOW included new Quadtree mesh and Sub-grid Sampling (SGS) functionality. The SGS feature now supports the
	hydraulic analysis of partially wet cells on the flood fringe. Currently, cells that are partially wet are displayed in model output		hydraulic analysis of partially wet cells on the flood fringe. Currently, cells that are partially wet are displayed in model output
	as being fully wet. ~~Whilst~~ we ~~are~~ ~~developing~~ a ~~high~~ ~~resolution~~ ~~SGS~~ ~~map~~ ~~output~~ ~~option for a future release,~~ we ~~have~~ in the ~~meantime~~		as being fully wet. This page introduces how to use the ASC_to_ASC remap function, and discusses limitations of the method.</poem>
	added new functionality to the ASC_to_ASC utility as an interim solution to 'remap' results to a finer DEM grid. This page introduces
	how to use the ASC_to_ASC remap function, and discusses limitations of the method.</poem>
	[[File: Remap_Advice_LinkedIn.jpg \|\|450px\|right]]		[[File: Remap_Advice_LinkedIn.jpg \|\|450px\|right]]
	<br><br><br><br><br><br>		<br><br><br><br><br><br>

Pavlina Monhartova: /* Conclusion */

2020-07-21T23:43:19Z

Conclusion

← Older revision		Revision as of 09:43, 22 July 2020
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	The benefits of using the combination of Quadtree mesh and Sub-grid Sampling method are many. In this page we focused on the ability of representing the sub-grid scale geometry by SGS method, which allows the user to apply a coarser mesh to reduce the total simulation time without adversely affecting the results. However, the interpolation of map output from a coarser mesh can be challenging as illustrated in the examples above. While we are developing a high resolution output feature within TUFLOW to tackle this issue, the new remapping functions of the [[ASC_to_ASC\|ASC_to_ASC]] utility can be used to post process water level outputs to high resolution depth results. This produces smooth depth output along main flow paths and flood fringes. However, the SGS method and remapping tool is not a panacea, and a computational mesh with sufficient resolution is still needed to produce reasonable and meaningful simulation results, especially where high resolution velocity based map outputs are needed.<br>		The benefits of using the combination of Quadtree mesh and Sub-grid Sampling method are many. In this page we focused on the ability of representing the sub-grid scale geometry by SGS method, which allows the user to apply a coarser mesh to reduce the total simulation time without adversely affecting the results. However, the interpolation of map output from a coarser mesh can be challenging as illustrated in the examples above. While we are developing a high resolution output feature within TUFLOW to tackle this issue, the new remapping functions of the [[ASC_to_ASC\|ASC_to_ASC]] utility can be used to post process water level outputs to high resolution depth results. This produces smooth depth output along main flow paths and flood fringes. However, the SGS method and remapping tool is not a panacea, and a computational mesh with sufficient resolution is still needed to produce reasonable and meaningful simulation results, especially where high resolution velocity based map outputs are needed.<br>

	Tip: Run your model once with small cell size in a test mode (-t) to produce DEM_Z with all topography modifications with the same resolution as the original DEM for use in the TUFLOW Remapping function.		'''Tip''': Run your model once with small cell size in a test mode (-t) to produce DEM_Z with all topography modifications with the same resolution as the original DEM for use in the TUFLOW Remapping function.<br>

	Finally, should you have some interesting results using SGS, Quadtree or the remapping feature that you would like to share with the TUFLOW community, please feel free to email [mailto:support@tuflow.com support@tuflow.com].		Finally, should you have some interesting results using SGS, Quadtree or the remapping feature that you would like to share with the TUFLOW community, please feel free to email [mailto:support@tuflow.com support@tuflow.com].

Pavlina Monhartova: /* Conclusion */

2020-07-21T23:41:30Z

Conclusion

← Older revision		Revision as of 09:41, 22 July 2020
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	=Conclusion=		=Conclusion=
	The benefits of using the combination of Quadtree mesh and Sub-grid Sampling method are many. In this page we focused on the ability of representing the sub-grid scale geometry by SGS method, which allows the user to apply a coarser mesh to reduce the total simulation time without adversely affecting the results. However, the interpolation of map output from a coarser mesh can be challenging as illustrated in the examples above. While we are developing a high resolution output feature within TUFLOW to tackle this issue, the new remapping functions of the [[ASC_to_ASC\|ASC_to_ASC]] utility can be used to post process water level outputs to high resolution depth results. This produces smooth depth output along main flow paths and flood fringes. However, the SGS method and remapping tool is not a panacea, and a computational mesh with sufficient resolution is still needed to produce reasonable and meaningful simulation results, especially where high resolution velocity based map outputs are needed.<br>		The benefits of using the combination of Quadtree mesh and Sub-grid Sampling method are many. In this page we focused on the ability of representing the sub-grid scale geometry by SGS method, which allows the user to apply a coarser mesh to reduce the total simulation time without adversely affecting the results. However, the interpolation of map output from a coarser mesh can be challenging as illustrated in the examples above. While we are developing a high resolution output feature within TUFLOW to tackle this issue, the new remapping functions of the [[ASC_to_ASC\|ASC_to_ASC]] utility can be used to post process water level outputs to high resolution depth results. This produces smooth depth output along main flow paths and flood fringes. However, the SGS method and remapping tool is not a panacea, and a computational mesh with sufficient resolution is still needed to produce reasonable and meaningful simulation results, especially where high resolution velocity based map outputs are needed.<br>

			Tip: Run your model once with small cell size in a test mode (-t) to produce DEM_Z with all topography modifications with the same resolution as the original DEM for use in the TUFLOW Remapping function.

	Finally, should you have some interesting results using SGS, Quadtree or the remapping feature that you would like to share with the TUFLOW community, please feel free to email [mailto:support@tuflow.com support@tuflow.com].		Finally, should you have some interesting results using SGS, Quadtree or the remapping feature that you would like to share with the TUFLOW community, please feel free to email [mailto:support@tuflow.com support@tuflow.com].

Pavlina Monhartova: /* Remapping of Other Map Output Grids */

2020-07-03T00:42:25Z

Remapping of Other Map Output Grids

← Older revision		Revision as of 10:42, 3 July 2020
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	The utility can also remap additional map output grids (e.g. velocity, hazard and others) to the resolution of the DEM file.<br>		The utility can also remap additional map output grids (e.g. velocity, hazard and others) to the resolution of the DEM file.<br>
	<tt>asc_to_asc.exe -remap -wl lowres_h.asc -dem DEM_highres.asc lowres_v.asc lowres_hazard.asc</tt>		<tt>asc_to_asc.exe -remap -wl lowres_h.asc -dem DEM_highres.asc lowres_v.asc lowres_hazard.asc</tt>
	This command reads in an additional grids 'lowres_v.asc' 'lowres_hazard.asc' and remaps it to the finer DEM resolution. The figure below compares the original and the remapped hazard outputs from the 10/20m SGS model.<br>		This command reads in an additional grids 'lowres_v.asc' and 'lowres_hazard.asc' and remaps it to the finer DEM resolution. The figure below compares the original and the remapped hazard outputs from the 10/20m SGS model.<br>
	[[File:fig7 ZAEM1 sgs.png\|700px]]<br>		[[File:fig7 ZAEM1 sgs.png\|700px]]<br>
	'''Figure 7 Original vs remapped hazard output for 10/20m mesh SGS model.'''<br><br>		'''Figure 7 Original vs remapped hazard output for 10/20m mesh SGS model.'''<br><br>

Pavlina Monhartova: /* Remapping of Other Map Output Grids */

2020-07-03T00:42:02Z

Remapping of Other Map Output Grids

← Older revision		Revision as of 10:42, 3 July 2020
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	=Remapping of Other Map Output Grids=		=Remapping of Other Map Output Grids=
	The utility can also remap additional map output grids (e.g. velocity, hazard and others) to the resolution of the DEM file.<br>		The utility can also remap additional map output grids (e.g. velocity, hazard and others) to the resolution of the DEM file.<br>
	<tt>asc_to_asc.exe -remap -wl lowres_h.asc -dem DEM_highres.asc lowres_hazard.asc</tt>		<tt>asc_to_asc.exe -remap -wl lowres_h.asc -dem DEM_highres.asc lowres_v.asc lowres_hazard.asc</tt>
	This command reads in an additional ~~grid~~ 'lowres_hazard.asc' and remaps it to the finer DEM resolution. The figure below compares the original and the remapped hazard outputs from the 10/20m SGS model.<br>		This command reads in an additional grids 'lowres_v.asc' 'lowres_hazard.asc' and remaps it to the finer DEM resolution. The figure below compares the original and the remapped hazard outputs from the 10/20m SGS model.<br>
	[[File:fig7 ZAEM1 sgs.png\|700px]]<br>		[[File:fig7 ZAEM1 sgs.png\|700px]]<br>
	'''Figure 7 Original vs remapped hazard output for 10/20m mesh SGS model.'''<br><br>		'''Figure 7 Original vs remapped hazard output for 10/20m mesh SGS model.'''<br><br>

Pavlina Monhartova: /* Remapping of Other Map Output Grids */

2020-07-03T00:40:10Z

Remapping of Other Map Output Grids

← Older revision		Revision as of 10:40, 3 July 2020
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	=Remapping of Other Map Output Grids=		=Remapping of Other Map Output Grids=
	The utility can also remap additional map output grids (e.g. hazard) to the resolution of the DEM file.<br>		The utility can also remap additional map output grids (e.g. velocity, hazard and others) to the resolution of the DEM file.<br>
	<tt>asc_to_asc.exe -remap -wl lowres_h.asc -dem DEM_highres.asc lowres_hazard.asc</tt>		<tt>asc_to_asc.exe -remap -wl lowres_h.asc -dem DEM_highres.asc lowres_hazard.asc</tt>
	This command reads in an additional grid 'lowres_hazard.asc' and remaps it to the finer DEM resolution. The figure below compares the original and the remapped hazard outputs from the 10/20m SGS model.<br>		This command reads in an additional grid 'lowres_hazard.asc' and remaps it to the finer DEM resolution. The figure below compares the original and the remapped hazard outputs from the 10/20m SGS model.<br>
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	''Tip: multiple file names or wildcard are allowed for the extra grid files for remapping.''		''Tip: multiple file names or wildcard are allowed for the extra grid files for remapping.''


	=Model Mesh Size vs Remap Result=		=Model Mesh Size vs Remap Result=

Chris Huxley: /* Introduction */

2020-06-02T12:48:45Z

Introduction

← Older revision		Revision as of 22:48, 2 June 2020
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	[[File:Fig2 H nonsgs.png\|700px]]<br>		[[File:Fig2 H nonsgs.png\|700px]]<br>
	'''Figure 2 Water level simulation results without SGS. Left: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>		'''Figure 2 Water level simulation results without SGS. Left: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>
	These examples show how the mesh size sensitivity are significantly reduced if using TUFLOW's implementation SGS. Therefore, modellers can confidently use a coarser mesh at areas away from the area of interest without adversely affecting the results. However, this has created a challenge on how to map results in areas of coarser mesh. For example, the images below show that whilst the 10/20m mesh and the 2.5/5/10/20m mesh SGS models produce similar water levels, the depth output is much 'smoother' in the 2.5/5/10/20m model due to the finer computational mesh. <br>		These examples show how the mesh size sensitivity are significantly reduced if using TUFLOW's implementation of SGS. Therefore, modellers can confidently use a coarser mesh at areas away from the area of interest without adversely affecting the results. However, this has created a challenge on how to map results in areas of coarser mesh. For example, the images below show that whilst the 10/20m mesh and the 2.5/5/10/20m mesh SGS models produce similar water levels, the depth output is much 'smoother' in the 2.5/5/10/20m model due to the finer computational mesh. <br>
	[[File:Fig3 D sgs zoom.png\|700px]]<br>		[[File:Fig3 D sgs zoom.png\|700px]]<br>
	'''Figure 3 Water depth simulation results with SGS. Left: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>		'''Figure 3 Water depth simulation results with SGS. Left: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>

ShuangGao: /* Steep Catchments */

2020-06-02T01:36:20Z

Steep Catchments

← Older revision		Revision as of 11:36, 2 June 2020
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	==Steep Catchments==		==Steep Catchments==
	In direct rainfall models, substantial benefits are being realised from applying SGS. The cell faces now correctly capture the lowest elevations along the gullies to preserve the sub-cell scale flow paths, which can significantly improve the hydrologic response for a whole catchment model (see Kitts ~~et. al., 2020, will add link to Duncan~~'s ~~paper~~ in https://www.~~tuflow~~.com/~~Library.aspx when it is uploaded~~). However, if the cell size becomes too large in areas of significant topographic change, only a small portion of the cell may be wet. This makes the depth plotting extremely challenging and the remapped depth may become negative even though water is flowing through the cell. The blue contour below shows the remapped water depth of a 60m mesh direct rainfall model. As can be seen the flow paths are not continuous along some valleys. The remapped water depth from a 20m mesh model is also plotted as the pink contours underneath the 60m result demonstrating that how the flow paths have become clearer as the mesh size is refined even though the results from these two models are very similar when using SGS. <br>		In direct rainfall models, substantial benefits are being realised from applying SGS. The cell faces now correctly capture the lowest elevations along the gullies to preserve the sub-cell scale flow paths, which can significantly improve the hydrologic response for a whole catchment model (see Duncan Kitts' LinkedIn post: https://www.linkedin.com/pulse/sub-grid-sampling-step-change-way-we-create-apply-hydraulic-kitts/). However, if the cell size becomes too large in areas of significant topographic change, only a small portion of the cell may be wet. This makes the depth plotting extremely challenging and the remapped depth may become negative even though water is flowing through the cell. The blue contour below shows the remapped water depth of a 60m mesh direct rainfall model. As can be seen the flow paths are not continuous along some valleys. The remapped water depth from a 20m mesh model is also plotted as the pink contours underneath the 60m result demonstrating that how the flow paths have become clearer as the mesh size is refined even though the results from these two models are very similar when using SGS. <br>
	[[File:Fig11 Innisfall remapped D.png\|600px]]<br>		[[File:Fig11 Innisfall remapped D.png\|600px]]<br>
	'''Figure 11 Remapped depth at upstream catchment from different mesh size models.'''		'''Figure 11 Remapped depth at upstream catchment from different mesh size models.'''

Chris Huxley at 00:51, 2 June 2020

2020-06-02T00:51:23Z

← Older revision		Revision as of 10:51, 2 June 2020
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			<poem lang="fr" style="float:left;">
			The 2020 release of TUFLOW included new Quadtree mesh and Sub-grid Sampling (SGS) functionality. The SGS feature now supports the
			hydraulic analysis of partially wet cells on the flood fringe. Currently, cells that are partially wet are displayed in model output
			as being fully wet. Whilst we are developing a high resolution SGS map output option for a future release, we have in the meantime
			added new functionality to the ASC_to_ASC utility as an interim solution to 'remap' results to a finer DEM grid. This page introduces
			how to use the ASC_to_ASC remap function, and discusses limitations of the method.</poem>
			[[File: Remap_Advice_LinkedIn.jpg \|\|450px\|right]]
			<br><br><br><br><br><br>
			__TOC__

	= Introduction =		= Introduction =
	With the release of TUFLOW 2020, the combination of Quadtree mesh and Sub-grid Sampling (SGS) method has offered great flexibility for rapidly building flood models of varying resolution and increased topographic detail. Now a wide range of mesh sizes can be applied in a model based on the geographic feature and the area of interest in a project. Especially with the SGS method, cells and faces can be treated as 'partially wet', and the impact of the sub-grid scale geometry may be represented by cells with larger sizes.<br>		With the release of TUFLOW 2020, the combination of Quadtree mesh and Sub-grid Sampling (SGS) method has offered great flexibility for rapidly building flood models of varying resolution and increased topographic detail. Now a wide range of mesh sizes can be applied in a model based on the geographic feature and the area of interest in a project. Especially with the SGS method, cells and faces can be treated as 'partially wet', and the impact of the sub-grid scale geometry may be represented by cells with larger sizes.<br>
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	[[File:Fig2 H nonsgs.png\|700px]]<br>		[[File:Fig2 H nonsgs.png\|700px]]<br>
	'''Figure 2 Water level simulation results without SGS. Left: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>		'''Figure 2 Water level simulation results without SGS. Left: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>
	These examples show how the mesh size sensitivity are significantly reduced if using SGS. Therefore, modellers can confidently use a coarser mesh at areas away from the area of interest without adversely affecting the results. However, this has created a challenge on how to map results in areas of coarser mesh. For example, the images below show that whilst the 10/20m mesh and the 2.5/5/10/20m mesh SGS models produce similar water levels, the depth output is much 'smoother' in the 2.5/5/10/20m model due to the finer computational mesh. <br>		These examples show how the mesh size sensitivity are significantly reduced if using TUFLOW's implementation SGS. Therefore, modellers can confidently use a coarser mesh at areas away from the area of interest without adversely affecting the results. However, this has created a challenge on how to map results in areas of coarser mesh. For example, the images below show that whilst the 10/20m mesh and the 2.5/5/10/20m mesh SGS models produce similar water levels, the depth output is much 'smoother' in the 2.5/5/10/20m model due to the finer computational mesh. <br>
	[[File:Fig3 D sgs zoom.png\|700px]]<br>		[[File:Fig3 D sgs zoom.png\|700px]]<br>
	'''Figure 3 Water depth simulation results with SGS. Left: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>		'''Figure 3 Water depth simulation results with SGS. Left: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>

← Older revision		Revision as of 12:22, 8 August 2024
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	The 2020 release of TUFLOW included new Quadtree mesh and Sub-grid Sampling (SGS) functionality. The SGS feature now supports the		The 2020 release of TUFLOW included new Quadtree mesh and Sub-grid Sampling (SGS) functionality. The SGS feature now supports the
	hydraulic analysis of partially wet cells on the flood fringe. Currently, cells that are partially wet are displayed in model output		hydraulic analysis of partially wet cells on the flood fringe. Currently, cells that are partially wet are displayed in model output
	as being fully wet. This page introduces how to use the ASC_to_ASC remap function, and discusses limitations of the method.</poem>		as being fully wet. This page introduces how to use the ASC_to_ASC remap function, and discusses limitations of the method.</poem><br><br>
	[[File: Remap_Advice_LinkedIn.jpg \|\|450px\|right]]		[[File: Remap_Advice_LinkedIn.jpg \|\|450px\|right]]
	<br><br><br><br><br><br>		<br><br><br><br><br><br>
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	[[File:Fig4 sgs depth interporation.png\|500px]]<br>		[[File:Fig4 sgs depth interporation.png\|500px]]<br>
	'''Figure 4 TIN interpolation used for water depth map output with SGS.'''<br><br>		'''Figure 4 TIN interpolation used for water depth map output with SGS.'''<br><br>
	Whilst we are developing a high resolution SGS map output option for a future release, we have in the meantime added new functionality to the [[ASC_to_ASC\|ASC_to_ASC]] utility to 'remap' a water level grid to a finer DEM grid. This page introduces how to use the [[ASC_to_ASC\|ASC_to_ASC]] remap function, and discusses limitations of the method.		This page introduces how to use the [[ASC_to_ASC\|ASC_to_ASC]] remap function, and discusses limitations of the method.

	=Remapping Water Level to a Finer DEM=		=Remapping Water Level to a Finer DEM=
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	'''Figure 9 Remapped depths over a road crest from models of different mesh resolutions.'''<br><br>		'''Figure 9 Remapped depths over a road crest from models of different mesh resolutions.'''<br><br>

	As illustrated in the chart below, the DEM has a much finer resolution and the elevation changes rapidly across the road crest, so when interpolating a coarser water level grid to the finer DEM, the interpolated water level may become lower than the local DEM level. In the 2D solver, this type of location is treated as upstream controlled weir flow with the upstream depth used for the calculation. However, the information that the flow is upstream controlled is not known when remapping, hence the appearance of dry patches on the downstream face of the road crest~~. Consideration of this effect will be addressed during the development of the high resolution SGS output feature scheduled for a future TUFLOW release~~.<br>		As illustrated in the chart below, the DEM has a much finer resolution and the elevation changes rapidly across the road crest, so when interpolating a coarser water level grid to the finer DEM, the interpolated water level may become lower than the local DEM level. In the 2D solver, this type of location is treated as upstream controlled weir flow with the upstream depth used for the calculation. However, the information that the flow is upstream controlled is not known when remapping, hence the appearance of dry patches on the downstream face of the road crest.<br>
	[[File:Fig10 road mesh size2.png\|500px]]<br>		[[File:Fig10 road mesh size2.png\|500px]]<br>
	'''Figure 10 Modelled water level line over the road crest.'''<br>		'''Figure 10 Modelled water level line over the road crest.'''<br>