A Cadastral Geodatabase for the U.S. Fish and Wildlife Service

The U.S. Fish & Wildlife Service Cadastral Data Working Group, comprised of cartographers and GIS specialists from all management regions, has produced a state-of-the-art database that stores data for all interests in real property in the U.S. National Wildlife Refuge System. The FWS Cadastral Geodatabase provides an integral component of the Refuge Lands Geographic Information System (RLGIS) by supplying boundary and parcel information to the biological geodatabases currently within the RLGIS data model. Cadastral data describes the past, current, and future right, title and interest in real property, including the spatial information necessary to describe the geographic extent. The geodatabase is the common data storage format for geographic features and attributes. A consistent and accurate cadastral geodatabase that is common across the nation and can be shared between management regions enables users to leverage the spatial data to its full potential. A web mapping application has been built utilizing the FWS cadastral geodatabase, allowing a non-GIS user to view the FWS managed lands and waters.     

Mapping Population Distribution in the Urban Environment: The Cadastral-based Expert Dasymetric System (CEDS)

This paper discusses the importance of determining an accurate depiction of total population and specific sub-population distribution for urban areas in order to develop an improved "denominator," which would enable the calculation of more correct rates in GIS analyses involving public health, crime, and urban environmental planning. Rather than using data aggregated by arbitrary administrative boundaries such as census tracts, we use dasymetric mapping, an areal interpolation method using ancillary information to delineate areas of homogeneous values. We review previous dasymetric mapping techniques (which often use remotely sensed land-cover data) and contrast them with our technique, Cadastral-based Expert Dasymetric System (CEDS), which is particularly suitable for urban areas. The CEDS method uses specific cadastral data, land-use filters, modeling by expert system routines, and validation against various census enumeration units and other data. The CEDS dasymetric mapping technique is presented through a case study of asthma hospitalizations in the Bronx, New York City, in relation to proximity buffers constructed around major sources of air pollution. The case study shows the impact that a more accurate estimation of population distribution has on a current environmental justice and health disparities research project, and the potential of CEDS for other GIS applications.