Abstract - Development of Cadastre-Based Applications in Local Government

Track: Local/State Government, Cadastral, Land Records

Shafi Khan
Engineering Systems
355 S. Grand Avenue Suite 2530
Los Angeles, CA 90071

Telephone: 703-324-3594
Fax: 703-324-3937
E-mail: xxctc.1@co.farifax.va.us

Ping He, Douglas Scott, Swapan, Nag

Development of Cadastre-Based Applications in Local Government

Cadastral data is a key component in the implementation of GIS in local government. At the City of Falls Church, Virginia, the relationship between the City's cadastral data and all other data categories was established during the database design stage of the City's GIS implementation program in 1994. Since then, several applications have been developed around the cadastral base, including analysis of value assessments of property within the City jurisdiction, automated cadastral map generation, parcel area reconciliation zoning, historical building inventory and management, automated property owner notification, water and sewer utility management, and so forth. These applications have helped the City to collect and assess taxes; disseminate information on cadastre; manage zoning, parcels, and historical sites; notify property owners of planned new development; manage their water and sewer utilities; and analyze impervious surfaces for watershed management.The City maintains detailed and comprehensive information on real estate, zoning classification, individual property ownership and addresses, historical sites, and business and utility customer billing data on their ABM AS/400 system. This information was downloaded into a set of relational tables conforming to the database design on the City's IBM RS/6000-based ArcInfo GIS platform. Indices were created to establish relational joins between the various tables to facilitate a seamless implementation of various cadastre-related applications. During this linkage process, several problems pertaining to specification of parcels, buildings, roads, zoning and businesses were identified and resolved. The paper discusses the various situations encountered and resolution of the problems to attain accurate reconciliation with the conventional (real property code) RPC numbers traditionally maintained at the City. Parcel areas calculated within the GIS were compared with recorded values within the City's real estate database and parcels differing by more than 25% were identified and mapped for further investigation and correction. An automated routine was developed to generate a series of standard cadastral maps at both 1"=100' and 1"=200' scales throughout the City's jurisdiction. Several planimetric layers, such as buildings, parking lots, driveways, and other paved surfaces (obtained from aerial photogrammetry), were overlaid with the cadastral data and an analysis of impervious surfaces performed. Real property was classified as commercial and residential for the validation of assessed values throughout the tax jurisdiction. Availability of spatial parcel ownership and address information enabled the development of an automated home owner notification application around a 150-foot annulus surrounding a parcel to speed up the related administrative processes.Historic buildings are attributed within the building attribute table, with relational links established to parcel and other real estate data, thereby facilitating the rapid retrieval of data on these facilities. The cadastral base is also being used to develop a comprehensive automated mapping, facilities management system for the City's water and sewer utilities. Automated water distribution and sewer facility maps will automatically be generated throughout the utility territory, which includes a large part of the neighboring County of Fairfax. The resulting AM/FM/GIS is to be used for inventory management of City water and sewer facilities, rapid retrieval of facility documents and sketches, and as an accurate interface for the modeling of the water distribution system via network analysis.The paper provides a description of the relational aspect of the database design with specific reference to relationships between the cadastre and other data categories, including metadata and processes developed to support various cadastre-based applications developed at the City over the last two years. Various map products are included to illustrate the utility of GIS as an analytical tool to support the administration of a typical city government.