Map Creation
Tips and Technical Information
- Wetland features will display at 1:144,000 scale or
larger.
- As a function of the mapping display software, not all
wetlands will be labeled.
- Linear wetlands are not displayed on the mapper. Linear
wetlands are wetland features captured as line segments
rather than polygons. In certain situations, it is necessary
to capture a wetland as a linear feature; when the size
and shape of the wetland and the source scale are such that
defining the wetland as a polygon is not possible. These
linear data are kept as a separate feature class.
About the Wetlands Maps
The Service's topical wetland maps are graphic
representations of the type, size and location of the wetlands
and deepwater habitats in the United States. These maps have
been prepared from the analysis of high altitude imagery in
conjunction with collateral data sources and field work. The
maps represent reconnaissance level information on the location,
type, size of wetlands habitats such that they are accurate
at the nominal scale of the 1:24,000 base map and the 1:63,360
base map for Alaska. A margin of error is inherent in the use
of imagery; thus, detailed on-the-ground inspection of any particular
site, may result in revision of the wetland boundaries or classification
established through image analysis. The Service uses the Cowardin
et al. (1979) definition of wetland. This definition is
the standard for the agency and is the National Standard for
wetland mapping, monitoring, and data reporting as determined
by the Federal Geographic Data Committee in 1996.
For the purposes of adapting the wetland classification
system to map form, a series of letter and number codes has
been developed. These alpha-numeric codes correspond to the
classification nomenclature that best describes the habitat.
An example of how this mapping code is used is shown below:
Lacustrine Aquatic Bed
NWI Map Classification Code: L 2 AB G
Lacustrine (L) Littoral (2)
Aquatic Bed (AB) Intermittently exposed (G)
Other Names/Identifiers: Lake Edge, Aquatic Bed
Forested Wetland, Deciduous
NWI Map Classification Code: P FO 1 C
Palustrine (P) Forested (FO)
Broad leaved deciduous (1)
Seasonally flooded (C)
Other Names/Identifiers: Hardwood Swamp