Roughness Zone Data Fields (SWMM)

Roughness Zone data can be edited on either the Roughness Zone Grid Window of the Polygons Grid or the Roughness Zone Property Sheet.

Most data can be edited on the grid, but some fields cannot be displayed in the grid format.

To view and edit all Zone data, use the Property Sheet.

The following describes all the data which can be used to define a Roughness Zone.

Common Data Fields

Fields that are common to the majority of objects can be found in the Common Fields topic.

Roughness Zone Data

Database Table Name: sw_roughness_zone

Show Columns	Database Names
	Size, Type and Units
	Defaults and Error Limits

Field Name

Help Text

Database Field

Data Type

Size

Units

Precision

Default

Error Lower Limit

Error Upper Limit

Warning Lower Limit

Warning Upper Limit

The name of the zone.

polygon_id

Text

Area

Zone area. Default value calculated from polygon geometry.

area

Double

Roughness (Manning's n)

Manning roughness (n), used when creating a 2D mesh. The roughness value assigned to mesh elements within the Roughness Zone.

This field is automatically disabled if a Roughness definition object is selected in the Roughness definition field.

roughness

Double

Roughness definition

The name of the Roughness definition associated with the Roughness Zone.

Any Roughness definition objects already defined can be selected from the dropdown list. Alternatively, a new one can be added or an existing one modified using the button located to the left of the field. This displays the non-visual object menu, from which you can select the appropriate option.

roughness_definition_id

Text

Exclude roughness zone boundary when creating 2D mesh

Determines whether the boundary of the roughness zone is enforced as a break line when Creating 2D Meshes:

Checked: Do not enforce roughness zone boundary as a break line. The roughness of the roughness zone will be assigned to 2D mesh elements for which the centroid falls within the roughness zone.
Unchecked: Enforce roughness zone boundary as a break line. The roughness of the roughness zone will be assigned to all 2D mesh elements within the roughness zone.

exclude_from_2d_mesh

Boolean

Priority

Used for clip meshing only.

The priority assigned to this zone.

If this zone overlaps another roughness zone, the intersecting part of the zone with the lowest priority value will have precedence over a zone with a higher priority value.

When you create a 2D mesh, the roughness value that is assigned to each mesh triangle depends on what priority has been set for the roughness zone the triangle is located in. Any mesh triangles, whose centroid falls within an overlapping zone, will be assigned the roughness of the lowest priority overlapping zone if Exclude roughness zone boundary when creating 2D mesh is unchecked. If checked, all mesh triangles that fall within the overlapping zones will be assigned the roughness of the lowest priority overlapping zone. See the following example for further information.

This example shows 3 roughness zone polygons before the mesh is generated.

The roughness zone with the lowest priority value of 1 (shown with a green boundary) will have overlapping precedence over the roughness zones with higher priority values of 2 (shown with a pink boundary) and 3 (shown with a purple boundary). The roughness zone with the priority value of 2 overlapping precedence over the zone with a value of 3.

If Exclude roughness zone boundary when creating 2D mesh is checked, the zone boundary will not act as a break line when the mesh is generated. If the centroid of a mesh triangle falls within an intersection of any zone polygons, it will be assigned the roughness value of the zone with the lowest priority value. The example below shows how the roughness zones are attributed.

If Exclude roughness zone boundary when creating 2D mesh is unchecked, the zone boundary acts as a break line and mesh triangles will be generated up to the boundary. This may result in some very small mesh triangles around the boundary.

If a mesh triangle falls within an intersection of any zone polygons, the mesh triangle will be assigned the roughness value of the zone with the lowest priority value. The example below shows how the roughness zones are attributed.

Clip meshing will not occur if roughness zones with the same priority intersect or a value is not assigned to a zone.

priority

Long integer