Allocating land use demand to nodes

Land Use Demand can be allocated to nodes:

• Manually by entering data in the Land Use Page of the node property sheet
• Automatically by using the Land Use Allocation tool

In both cases the Land Use demands should be defined in the Land Use Grid View of the Polygons Grid prior to allocation.

Manual Allocation of Land Use Demand to Nodes

Land Use Demand can be allocated to a node manually by editing the Land Use Page of the node property sheet:

1. Open the Property Sheet of the node to be edited.
2. On the Land Use Page of the property sheet:
• Select a Land Use Demand object from the Land Use Demand ID dropdown list.
• Enter the contributing Area to which the Land Use demand applies and a Land Use Area if the Land Use calculation method is Land Use Demand.
• Select a land use Polygon from the Polygon ID field to use demand values specified at the selected polygon in preference to the demand values specified at the Land Use Definition.

The read only cells on the Land Use Page of the Node property sheet contain values derived from either the selected Land Use Definition or Land Use Polygon (if one has been selected). These values are used to calculate the land use demand assigned to the node, which can be viewed in the Node Demand Page of the Node property sheet.

See the Calculation of Land Use Demand at Nodes topic for more information.

Land Use Allocation Tool

The Allocate Land Use Demand to Nodes option allows automatic calculation of the contribution of land use area demands to nodes in the network.

The following are required when allocating land use demand to nodes:

• A checked out network which has Node Polygons and Land Use Definitions included
• A set of Land Use polygons

The Land Use polygons represent geographical areas of demand, for example, Farms or Industrial Estates.

The Land Use area data is incorporated into the model by selecting Node Polygons | Allocate Land Use Demand to Nodes from the Model menu. This displays the Allocate Land Use Demand to Nodes dialog.

The dialog allows the digitised GIS Land Use Polygon data to be read by:

• Browsing for a GIS file
• Selecting a Layer in the GeoPlan Window
• Selecting polygons (imported from GIS or digitised in the GeoPlan Window) by Category field

Using the Allocate Land Use Demand functionality

To allocate land use demands to nodes:

1. If only a selection of nodes are to be updated, make a selection of nodes on the GeoPlan Window.
2. Select Node Polygons | Allocate Land Use Demand to Nodes from the Model menu. This displays the Allocate Land Use Demand to Nodes dialog.
3. Select the source of the Land Use Polygon data to be used. This may be a GIS file, a layer displayed on the GeoPlan Window, or polygons that have already been imported from the GIS file.
• If using a GIS File or Layer as the source file, select the field in the GIS table that contains the polygon Land Use definition name from the Land Use Field dropdown list.
• If using Polygons in the network, select a category from the Polygon Category dropdown list.
• Only polygons with the selected category will be considered as land use polygons during the allocation process.
• A Land Use definition is associated with the polygon via the polygon Land Use field.
4. Select other options as required:
• Check the Update Selected Nodes Only box to carry out the allocation process for the currently selected nodes only.
• Check the Keep existing Land Use Demands box to retain Land Use demand that has already been allocated. Demands generated by the current allocation process will be added to the existing Land Use Demands. If this option is not checked, existing Land Use demands at nodes to be updated will be overwritten.
• Check the Allow Polygon values to Override Land Use Values box to allow demand information specified at the Polygon to be used in preference to the demand information specified at the Land Use. (This option is only available when using Polygon objects in the network as the source of the Land Use polygon data.)
• Check the Create Log of Process box to display a log file summary after the allocation process is complete.
5. Click OK to complete the process.

At each node to be updated:

• All existing land use demands will be removed from the node (unless the Keep existing Land Use Demands option has been selected).
• For each Node Polygon associated with the node, any overlapping land use polygons are found.
• The area of the land use polygons that intersect the node demand polygons is calculated to determine a contributing area.
• The Land Use definitions and calculated contributing area are added to the Land Use Page of the node property sheet. (Note that a single Land Use definition may be made up of any number of Land Use Demand objects.)
• If the Allow Polygon values to Override Land Use Values option has been selected, the ID of the land use polygon is added to the Polygon ID field in the Land Use Page of the node property sheet. Demand information specified at the land use polygon will be used in preference to demand information specified at the Land Use Definition and is used to calculate the values displayed in the read only cells in the Land Use Page.
• Demand to be applied to the node is calculated from the values displayed in the Land Use Page of the node property sheet and can be viewed in the Node Demand Page of the property sheet.

See Calculation of Land Use Demand at Nodes for more information.