hydromaj_arc

The NC Center for Geographic Information and Analysis, developed this digital Major Hydrography data to enhance planning, siting and impact analysis in areas directly affecting surface waters consisting of streams and rivers, lakes, reservoirs, and shorelines. The data is a subset of the 1:24,000-scale detailed hydrography data. This file is updated as changes occur.

This data was created to assist governmental agencies and others in making resource management decisions through the use of a Geographic Information System (GIS) where information on general hydrographic features is needed.

system filename: hydromaj      file size = 6.40 mb
Revisions and updates to this layer include:
3.) Previous 1:100,000-scale version was used to select hydro features from 1:24,000-scale coverage to create a new subset of the detailed hydro for purposes of larger scale mapping and making additional attributes available in the major hydrography coverage.  Arcs and polygons were created as major_hydro_arcs.shp and major_hydro_polys.shp.  In the shapefile version of the polygons, label = 216 was excluded (water offshore) to make the shapefile more suitable for cartographic purposes.
2.) filename: hydromaj299  The February 9, 1999 updates include:
a.) Projecting the data from NAD27 datum, State Plane projection, units of measure feet TO: NAD83 DATUM, State Plane PROJECTION, UNITS OF MEASURE METERS.  This was done to comply with the NC Geographic Information Coordinating Council's "Statement of Direction for North Carolina Corporate Geographic Database Horizontal Reference, Datum and Unit of Measure".  This reprojecting was done in various ways depending on the data type and content. Vector data was projected using the 'project' command in ESRI's Arc software and topology was cleaned and built based on coverage needs.  Raster data was projected using ESRI's Grid module
and various steps as applicable.
b.) Replaced the lake boundary for Falls Lake.  Corrected lake boundary digitized from US Army Corps of Engineers 251.5 foot contour overlay that was transferred onto 1:24,000-scale topo sheets.  (The original lake contours were surveyed incorrectly and the lake level has since been raised to the correct 251.5 ft level.)
c.) Added more detailed stream annotation (anno level 1 - primary streams; anno level 2 - secondary streams).
1.) filename: hydromaj997  The original version was dated September 1997. (perviousl named majhydro) Any previous versions were not offical database releases.

Hydrography 1:100,000-scale features were taken from the USGS 1:100,000-scale DLGs. Supplemented hydrographic features were digitized from 1:24,000-scale bases and the linework checked against the bases to within a linewidth.