Assigning Property Zones using Shapefile Data

This post describes how to use the zones from arcview for chosen elements command to define property zones using shapefile (.shp) data. This method is particularly useful for projects involving spatially distributed properties in both the porous media and surface domains.

Conceptually, this command assigns zone numbers to chosen elements in the active domain based on a selected attribute from a shapefile. Since shapefiles are two-dimensional, elements sharing the same x- and y-coordinates will receive the same zone number, regardless of their z-coordinates.

We find this command especially useful when working with property zoning in HydroGeoSphere models. A sample problem demonstrating its application, based on the Abdul verification problem, is available for download. In this example, porous media properties are assigned using this approach, with the zone_offset instruction applied to distinguish between upper and lower model layers.

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A user recently requested some guidance on the use of shapefile data to help with the definition of property zones. This is a very common problem for any projects dealing with spatially distributed properties, whether they be in the porous media or surface domain.

So we’d like to highlight one potentially useful command: zones from arcview for chosen elements

This command uses chosen elements from the active domain and assigns zone numbers based on the selected attribute from an available shapefile (.shp). Since these files are two-dimensional, elements with the same x- and y-coordinates will be assigned the same zone number, regardless of their z-coordinates within the chosen element set.

Figure 1: Command description

Zones from arcview for chosen elements requires four instructions, as described in the Reference Manual (see section 2.8.1.3 for further details):

This command is demonstrated in a simple sample problem which you can download here:
Abdul_AlgoMesh_zones from arcview.zip

The sample problem is a variation of the familiar Abdul verification problem, but porous media properties have been applied in the Channel and Field zones using the Zones from arcview for chosen elements command.

Figure 2: Porous media property zones

The relevant section of the grok file is reproduced below. Please note that the abdul.mprops file has been modified to include two materials: channel and field (Figure 2).

Also note that the porous media domain has been divided into a total of four zones, with the channel and field zones being applied separately to upper and lower model layers. The 2nd instance of the Zones from arcview for chosen elements command illustrates the proper use of the zone_offset instruction.

!--------------------------  Porous media properties
use domain type
porous media

properties file
abdul.mprops

clear chosen zones
clear chosen elements
choose elements by layer
   1 10 !select layers 1 to 10
zones from arcview for chosen elements
   ./mesh/Property_Zones
   3
   Zone_ID
   0

clear chosen zones
clear chosen elements
choose elements by layer
   11 15 !select layers 11 to 15
zones from arcview for chosen elements
   ./mesh/Property_Zones
   3
   Zone_ID
   2

clear chosen zones
choose zone number
   1
read properties
channel

clear chosen zones
choose zone number 
   2
read properties
field

clear chosen zones
choose zone number 
   3
read properties
channel

clear chosen zones
choose zone number 
   4
read properties
field

Finally, I will note here that many similar commands exist to apply complex property zones using other file types (e.g. raster, ASCII files). If you want to learn more you could search for the following commands in the Reference Manual:

• Read zones from raster for chosen elements

• Read overland zones from raster

• Read pm zones from voxet file

• Zones from arcview ascii grid