Check Files 2d grd

Introduction

This pages contains information on the attributes of the _grd_check file. This GIS contains a region object for each active (cell code 1) or null (cell code -1) cell. A number of the output attributes are only written if certain model features are enabled. For example, the Soil_ID attribute is only included if any soil features are used in the model.

There are a number of attributes that are only output for TUFLOW GPU models, as the GPU model is a cell centred scheme certain properties such as Manning's roughness and Form Loss are applied at the cell centre, whilst in TUFLOW these are applied at the cell side (refer to the TUFLOW Manual for a more detailed explanation). These GPU only attributes are noted in the table below.

Attributes of grd_check

General Attributes

Attribute Name	Attribute Description
n	Row number in the TUFLOW domain.
m	Column number in the TUFLOW domain.
Code	The cell code status. This is 1 for active cells and -1 for null cells that are included in the mesh. Refer to the TUFLOW Manual for more information on the cell codes.
Material	The material ID.
ZC	The elevation within the cell.
IWL	The initial water level value. If the initial water level set in the model is below the cell elevation (ZC) or if no initial water level has been set, the cell elevation plus the model wet / dry depth is output. Note, this value is rounded to 3 decimal places.
Domain_Index	The index of the model domain. This is the order with Start 2D Domain == <Domain Name> commands appears in the TCF control file. For a single domain model this will be 1.
SRF	The Storage Reduction Factor for the cell.
Soil_ID (only if soil feature used)	The Soil ID for the cell. This is only output if a Set Soil, Read GIS Soil or Read GRID Soil command is specified for the simulation.
GW_Z_L1 (only if soils are used)	The groundwater level for each cell. This is equal to the elevation in the cell minus the soil thickness. If no soil thickness is specified (using the Set Soil Thickness TGC command), the attribute will be set to -99999. This attribute is only output if using soils, i.e. if the Set Soil, Read GIS Soil and/or Read Grid Soil TGC command(s) have been used.
IGW_Lvl_L1 (only if soils are used)	The initial groundwater level for each cell. This is equal to the elevation in the cell minus the initial groundwater depth. If no initial groundwater depth is specified (using the Set IGW Depth TGC command), the attribute will be set to the GW_Z_L1 value. This attribute is only output if using soils, i.e. if the Set Soil, Read GIS Soil and/or Read Grid Soil TGC command(s) have been used.

Example _grd_check attribute table:

SGS Specific Attributes

Attribute Name	Attribute Description
ZMin	The minimum elevation within the cell.
Z_Map_Cutoff	The map output cutoff elevation for each cell. This is equal to the minimum cell elevation plus the map cutoff depth (specified by the TCF command Map Cutoff Depth).
SGS_Delta	This attribute is output only if the SGS Breakline Detection Delta TCF command has been used. The SGS breakline detection check processes each 2D cell to identify the minimum water surface elevation needed for a continuous wet connection through the cell traversing between left to right and between top to bottom. The maximum invert elevation of the left and right faces is subtracted from the left-right minimum water level and reports it as “uDelta”. Similarly, the top to bottom value is reported as “vDelta”. uDelta and vDelta represent the depth of water over the cell face inverts by which a natural ridge (break) line would block any flow. This attribute reports the maximum of uDelta and vDelta.

Example _grd_check attribute table (using SGS):

Quadtree specific attributes

Attribute Name	Attribute Description
qpc_id	The quadtree cell ID.
dx	The size of the cell. This value is dependent on the base cell size and the quadtree nesting level. For example, for a base cell size of 5m and nesting level 2, the dx attribute would be 2.5m.

Example _grd_check attribute table (using Quadtree):

Features

This file is very useful to apply a style or thematic map to. See the Tips for visualising check files.
This allows a very easy way to visualise the final properties for large models.

A grd_check file styled by the soil ID is below (in QGIS).



An example of a grid check file shaded by Material ID is below (in MapInfo).

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TUFLOW Check Files