|
Notes:
The hydrography layer consists of flowing waters (rivers and streams),
standing waters (lakes and ponds), and wetlands -- both natural and manmade.
Two separate feature types are represented: polygons (areas) and lines.
Polygon features have attribute codes that identify water bodies such as
lakes, wide river segments, or swamps. Line features have attribute codes
that represent streams or shorelines.
The hydrography layer was assembled from data originally published by the
U.S. Geological Survey (USGS) in Digital Line Graph (DLG-3) format.
DLG-3 data were generated by USGS from 1:100,000-scale maps by manual
digitizing and raster scanning. Approximately 3200 original USGS DLG files
were processed by Teale to create the statewide hydrography data layer.
Edits to the original linework have been made during the data
conversion by Teale from the original DLG-3 format to the ARC/INFO(tm)
GIS format. Such changes include line movements (due to the map
edge-matching process), minor corrections of attribute coding, and the
closing of open polygons. Flow direction for streams (feature type
line) has also been added. Stream arcs are flagged (where item FLOW =
1) to indicate whether or not the direction of a given stream (line)
has been defined and/or verified by Teale.
Changes:
|
