Used GIS to implement a parcel and farmland assessment system for county assessor
New government regulations required farmland to be assessed in a new and different fashion than it had been done in the past. Fulton County required a Geographic Information System (software and data) to be implemented to successfully accomplish this assessment. The GIS was needed in order to run a series of queries that would analyze georeferenced parcel data with various government-produced land surveys and coverages, and provide output on County land assessment per government regulations.
In order for the GIS to perform the new assessments, some data acquisition and creation was necessary. The biggest task was to create the digital parcels layer from the source Mylar sheets. About 250 Mylar sheets were scanned by the County to a raster format (TIF) and sent to Great Arc. Using ESRI’s ArcView software, each raster sheet was georeferenced to a projected layer of the Public Land Survey System grid. Each parcel boundary was then digitized to a new digital layer, about 4,500 in total. Parcel Identification Numbers were assigned as each parcel was digitized.
Other parcel attributes were needed to successfully accomplish the assessment. Using ArcView’s table joining method, the attributes stored in a relational database needed for the assessment were then collected and attached to each parcel using database linking.
In conjunction with Fulton County, Great Arc acquired all available digital data that was potentially necessary for the project’s land assessment process. Data included Soil and Land Surveys, Land and Flood Zone Coverages, Aerial Photos or DOQQs, Digital Layers of Roads, Streams, or Wetlands.
The next step was data re-projection. Since the data needed for assessment was coming from a number of different sources, the projections of each data layer needed to all be the same, and a single projection was chosen.
After the acquired and created data went through a process of Quality Control and Assurance, we were able to perform the farmland assessment process. This process included:
* Review and determination of which parcels were to be assessed as a farm (land use.) (Done with aerial photo interpretation and on-site inspection as needed.)
* Determined the acreage of each soil mapping unit within each land use category.
* Assigned Productivity Indexes
* Assigned slope and erosion factors
* Assigned flood debasement factors
* Developed drainage district debasements
* Assigned adjusted PIs
* Assigned Department of Revenue values
* Rolled values to the assessment roll vendor Devnet
Using ArcObjects code development, we created a Parcel Query Tool that provides a menu of available standard queries that can be used when viewing the Parcel Layer in ArcView. The queries allow the user to quickly search on Parcel PIN numbers, Townships, Parcel Classes, Tax Codes, and Owner name.
Great Arc also conducted on-site training for the Fulton County staff involved with the project. Basic ArcGIS training was necessary so that the Fulton County staff were able to learn GIS concepts as well as how to use the ArcGIS software. Real World training was important so that the Fulton County staff can maintain the parcel data using GIS as well as continue to perform the farmland assessment on an ongoing basis.