I recently received a service request to calculate the area covered by land zoning map on a customer's property. I suspect this sort of request will arise again down the track so I should document some of my methodology and assumptions.
The service request doesn't make a lot of sense initially because land use zoning maps are just shapes and colours. They're not associated with land parcels directly. Land use zoning maps are a type of planning control in the Local Environmental Plan. It is used to govern what is permissible and can be developed on the land / property. It shouldn't have any relevance in any way to the rating of the land or its perceived value. But the customer request still needs to be resolved, so I proceed with my methodology below.
The first step was to extract the relevant land parcels from the ArcServer. This is a simple selection and data extract. Then I'll need to cut the parcels using the land use zoning maps.
To split the parcels I used the Union coverage function because it cuts the parcels and allows me to select the individual polygon areas to calculate a percentage over the total parcel area.
Then to figure out the total area covered by the land use zones, I can deduce the percentage of land covered by the land use zone, and then multiply it against the area indicated by the land title (or Section 88B Instrument) to determine an approximate area. We use the land title information because that was surveyed and registered against the State land title records. We don't use the numbers indicated by ArcGIS because there are inherited problems with our DCDB (compounded from various sources over the years).
Calculations are summarised below: