DEFINITION OF A CITY OR COUNTY EXTENDED FRAMEWORK

The starting point for any city or county extended Framework is FGDC’s Framework. Therefore, a county Framework should include geodetic control, orthophoto imagery, elevation, transportation, hydrography, governmental units, and cadastral information. The geodetic control may be supplemented at the local level by local surveys, and the orthophoto imagery could also be supplemented by larger scale coverage than that collected federally. Information on the utility location is important at the local level, and is likely to become more important as the utility industry and public-sector utility services exploit new technologies that require more accurate geospatial data. More detailed elevation data may also be part of the local jurisdiction’s contribution to an LSDI. For example, we already have counties that have 0.5-foot contours derived from orthoimagery produced by the private sector under contract. For the transportation layer at the county level, it is expected that transportation features such as roads will be defined by their edges, and maybe by the spaces corresponding to the road right-of-way in addition to the road centerlines. For hydrography, additional information such as the location of each bank of the watercourse, its navigability for small craft, intakes from rivers and streams, and inputs into the same, may be monitored. For these federal Framework themes it is clear that local level data will enrich most of the layers of the NSDI.

A major difference between the local Framework and national Framework is the definition of the content for both the governmental units layer, which accurately depicts a wide range of administrative unit boundaries, and the cadastral information layer, which depicts the legal boundaries of parcels of property ownership. Whereas the cadastral information overlay from the federal NSDI could be expected to include both the Public Lands Survey System (PLSS) used in the western states and federally-owned lands managed by the Bureau of Land Management, the Park Service, and other federal agencies, the local Framework would include details of privately-owned parcels. This is an entirely different magnitude of data



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