GIS Mapping Program Peels Back Newtown Layer By Layer

By Andrew Gorosko

In his corner office on the topmost level of Edmond Town Hall, Scott Sharlow, the town’s geographic information systems (GIS) coordinator, has been doing research on the Cedarhurst section of Sandy Hook, in the town’s continuing project to establish a timely and accurate computer database of information keyed to local geography.

Unlike more recent residential development in town, much of the property in Cedarhurst does not generally conform to local land use rules, posing a special set of indexing problems in compiling such a computer database.

The densely built Cedarhurst, which centers on Lakeview Terrace, is one of the town’s several “lakeside communities,” along the western shore of Lake Zoar.

Cedarhurst is but one of the scores of neighborhoods that are being integrated into the GIS mapping project.

Since he started working for the town in the spring of 2002, Mr Sharlow has been developing the town’s GIS project, an electronic mapping system designed to provide a wealth of planning information to its users through a digitized cross-indexing system. Mr Sharlow is responsible for developing, implementing, and maintaining the town’s GIS mapping, including software upgrades, system training, and troubleshooting.

To demonstrate the potential townwide capabilities of GIS, Mr Sharlow has completed a pilot project, which focuses on Sandy Hook Center, a business district at the intersection of four major streets — Church Hill Road, Washington Avenue, Riverside Road, and Glen Road. The pilot project has thoroughly mapped the various features in the 1,100-acre area surrounding Sandy Hook Center.

The pilot project area contains developed land, undeveloped land, land with sewer and water utilities, and land served by septic systems and domestic water wells. The pilot project depicts the local spectrum of development density, ranging from densely built areas to undeveloped areas in order to demonstrate how GIS can be used in municipal planning.

GIS mapping seeks to collect and unify both broad geographical information, such as the course of rivers and layout of road networks, as well as fine details, such as the location of individual utility poles, utility holes, and stormwater catch basins.

Electronic Layers

The system incorporates many electronic “layers” of information within a unified format, within which layers may be added, subtracted, or recombined to produce customized electronic maps. Those maps depict the desired level of detail and also the type of detail that is required for a particular planning project.

When complete, about 60 types of information will be incorporated into about 20 mapping layers, Mr Sharlow said. Holding the number of layers down to 20 makes the system more practical to use, he said.

GIS mapping stores information on individual land parcels, roads, railroads, brooks, ponds, wetlands, open space, trails, public utilities, industrial development, and land use zones. It also includes information on property boundaries, zoning lines, topographic contours, tax assessments, property ownership, building square footages, and land record references, plus other data. Computerized GIS mapping may be used by every municipal department that stores information that can be keyed to geographic locations, such as street addresses, or lines of latitude and longitude.

The GIS mapping includes topographic features depicted with a two-foot elevation contour interval to illustrate the lay of the land in relation to manufactured features. The mapping seeks to reduce the vertical distortion inherent in the aerial photography that serves as a basis for the mapping. That aerial photography was flown for the town on April 7, 2002.

GIS mapping is intended to be generally accurate, not critically accurate, because the system is designed for land use planning purposes, not legal purposes, Mr Sharlow explained.

One of Mr Sharlow’s tasks has been creating a geographic referencing system for land parcels of unknown ownership. Also, local open space land is being cataloged.

Tax Mapping

A key aspect of GIS mapping is tax mapping, which provides a cross-indexed visual and informational reference system for the town’s tax assessor. GIS tax mapping is expected to be complete in about two months, Mr Sharlow said.

Initially, GIS mapping will be used on the town’s internal computer network. Eventually, aspects of the system will be available on the Internet, Mr Sharlow said.

Within a few months, a “public map kiosk” should be in use. It will provide the public with maps and information on individual land parcels.

Mr Sharlow has said he expects that virtually every town agency will find the GIS mapping helpful in managing government affairs. The major users of the GIS mapping will include the tax assessor, the building department, land use agencies, public works, and the health department. GIS mapping will be continually updated to reflect changing conditions.

The recently completed Town Plan of Conservation and Development is digitized, allowing its content to be stored by the GIS project.

GIS mapping will be used to document the significant growth that has occurred in Newtown. The town’s population grew by 20.5 percent from 1990 to 2000, rising from 20,779 to 25,031 residents. Between 1991 and 2000, the town approved 164 subdivision applications for a total of 1,326 new building lots and 46 new roads. The town approved approximately 1,828 permits for new housing during that period.