WATERSHED PERMITTING: POSTGIS PROXIMITY ANALYSIS FROM WITHIN GOOGLE EARTH
The U.S. Army Corps of Engineers, Jacksonville District administers the largest regulatory permitting program in the Corps, which provides protection for waters of the United States, including federally delineated wetlands and navigable waters.
The District has developed an application which allows both regulators and prospective applicants a convenient way to view and analyze Natural Resources at Risk (RAR) near potential permit locations. RAR data may consist of a variety of data layers such as endangered species habitats, pristine natural areas, protected lands, and wetlands.
By utilizing the fast and powerful overlay analysis available within the PostGIS Database, RAR data and resultant queries are streamed back via kmz to Google Earth (GE) clients for convenient viewing. A single web kml link loads network links to all available RAR data sets which may be viewed within the GE client. By utilizing scale dependencies, view extents, PostGIS simplify functions, and on the fly compression; massive data sets can be viewed efficiently without caching. Users are allowed to place points or upload a kml/kmz file for analysis against these resources. Several different reports and levels of detail are allowed. The input data is sent to the server where buffer, intersections, unions, and summations are computed and sent back the client as a kmz file with an HTML report, input geometries and intersected RAR geometries embedded. Thus, this single kmz file (also saved in the database) contains the entire analysis (inputs and outputs) and is maintained as part of electronic permit record. A typical analysis only takes a few seconds before the results are returned and displayed in GE.
A web base management interface allows administrators to upload new data (from shapefiles) into PostGIS, create new layers for GE, control how layers are symbolized, define report formats, and review queries of all users.
Paul Holt - U.S. Army Corp of Engineers, Jacksonville