Revision as of 14:32, 13 February 2026 view source Abrar.Alttahir (talk \| contribs) Bureaucrats, Administrators 384 edits →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? Tag: Visual edit ← Older edit		Revision as of 14:56, 13 February 2026 view source Abrar.Alttahir (talk \| contribs) Bureaucrats, Administrators 384 edits →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? Tag: Visual edit Newer edit →
Line 92: 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. == When should high-resolution (HR) outputs be used, and what are their limitations? == HR outputs are intended for visualisation and presentation because they retain sub-grid terrain detail but do not improve the underlying hydraulic calculations. They are not suitable for assessment, benchmarking, or detailed analysis. Standard non-HR map outputs should be used for these purposes, and accuracy should be improved by refining the 2D cell size. {{Tips Navigation \|uplink=[[TUFLOW_Modelling_Guidance \| Back to TUFLOW Modelling Guidance]]

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