Theme Description: National Wetlands Inventory
The National Wetlands Inventory is an inventory of wetland ecological system
found throughout the United States. It was prepared by the U.S. department
of the Interior, Fish and Wildlife Service. The wetlands were identified on
high altitude aerial photographs (1:58,000) based on vegetation, visible
hydrography, and geography in agreement with systems defined in Classificati
of Wetlands and Deep-Water Habitats of the United States, by Cowardin et al
1977.
Revisions made to data (revision number, date, description)
No revisions have been made to the data since the original collection
period in the 1970's and 1980's.
Attribute:
Attribute_Label: -
Attribute_Definition: Attribute table of NWI.
Attribute_Definition_Source: ARC/INFO
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: -
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: AREA
Attribute_Definition: Area of poly/region in square coverage units
Attribute_Definition_Source: Computed
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Positive real numbers
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: PERIMETER
Attribute_Definition: Perimeter of poly/region in coverage units
Attribute_Definition_Source: Computed
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Positive real numbers
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: NWI#
Attribute_Definition: Internal feature number
Attribute_Definition_Source: Computed
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Sequential unique positive integer
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: NWI-ID
Attribute_Definition: User-assigned feature number
Attribute_Definition_Source: User-defined
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Integer
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: FWS.CODE
Attribute_Definition: NWI code, ecological system, subsystem, class, subclass, h20 regime and other
Attribute_Definition_Source: aerial photography
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: coded characters (see narrative)
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: SYS
Attribute_Definition: ecological system code
Attribute_Definition_Source: aerial photos
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: M=marine, P=palustrine, R=riverine, L=lacustrine, E=lestuarine (see narrative)
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: SUBSYS
Attribute_Definition: Ecological subsystem code
Attribute_Definition_Source: aerial photo
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: sequential coded integers which vary according to sys. (see narrative)
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: CLASS
Attribute_Definition: class code
Attribute_Definition_Source: aerial
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: coded characters varying for each ecological system (see narrative)
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: SUBCL
Attribute_Definition: subclass code
Attribute_Definition_Source: aerial photo
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: sequential integer codes ranging from 1-7 varying for sys (see narrative)
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: WATER
Attribute_Definition: water regime code
Attribute_Definition_Source:
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: coded characters A-U, 0-9, a, t or l add to class or subclass (see narrative)
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: MODS
Attribute_Definition: modifying terms
Attribute_Definition_Source:
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: g,n,b,d,f,h,r,s,x added to class or subclass (see narrative)
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: XCLASS
Attribute_Definition:
Attribute_Definition_Source:
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value:
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: SUBXCL
Attribute_Definition:
Attribute_Definition_Source:
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value:
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Attribute:
Attribute_Label: XSYS
Attribute_Definition:
Attribute_Definition_Source:
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value:
Attribute_Value_Accuracy_Information:
Attribute_Measurement_Frequency: Unknown
Overview_Description:
Entity_and_Attribute_Overview:
NWI identifies 5 different ecological systems which contain multiple and
varying coding for subsystems, class, subclass and modifiers including
water regimes, water chemistry, soils and special modifiers.
The NWI codes found in the attribute table of this database are a
concatenation of coding for ecological systems, subsystems, class,
subclass, and modifying terms for water regime, chemistry and soil.
For example, marine, subtidal, open water body would be coded M1OW
whereas a marshy area of persistent emergent vegetation would be coded
PEM1. These codings can be found in the FWS.cod whereas individual codes
cam be found in subsequent items.
Item Definitions
sys
ecological systems (M,E,R,L,P)
M = marine systems
The marine system consists of the open ocean overlying the continental
shelf and its associated high-energy coastline. Marine habitats are
exposed to the waves and currents of the open ocean and the water regimes
are determined primarily by the ebb and flow of oceanic tides.
E = Estuarine systems
The estuarine system consists of deep water tidal habitats and adjacent
tidal wetlands that are semi-enclosed by lands but have open, partially
obstructed, or sporadic access to the open ocean, and in which open water
is at least occasionally diluted by freshwater runoff from the land.
R = Riverine systems
The riverine system incudes all wetlands and deep water habitats contained
within a channel, with two exceptions:(1)wetlands dominated by trees, shrubs
persistent emergents, emergent mosses, or lichens, and(2)habitats with water
containing ocean-derived salts in excess of .5 parts per thousand.
L = Lacustrine systems
The lacustrine system includes wetlands and deep water habitats with all
of the following characteristics:(1)situated in a topographic depression or
a dammed river channel:(2)lacking trees, shrubs, persistent emergents, emergent
mosses, or lichens with greater than 30% areal coverage: and(3)total area
exceeds 8 ha (20 acres).
P = Palustrine systems
The palustrine system includes all nontidal wetlands dominated by trees,
shrubs, persistent emergents, emergent mosses or lichens, and all such
wetlands that occur in tidal areas where salinity due to ocean-derived
salts is below .5 parts per thousand.
subsys
ecological subsystems
Marine, Riverine, Lacustrine, and Estuarine ecological systems have subsystem
with varying codes while Palustrine systems do not.
Marine and Estuarine
1 = subtidal
2 = inter tidal
Riverine
1 = tidal
2 = lower perennial
3 = upper perennial
4 intermittent
5 unknown perennial
(emergents found only in riverine tidal and riverine lower tidal subsy
Lacustrine
1 = limnetic
2 = littoral
class and sclass
class and subclass
subclass have repetitive coding according to class therefore an area of subclass
1 could be one of many types including bedrock, submergent coral et.
RB = rockbottom
1 = bedrock
2 = boulder
UB = unconsolidated bottom
1 = cobble/gravel
2 = sand
3 = mud
4 = organic
AB = Aquatic bed
1 = submergent alga
2 = submergent vascular
3 = submergent moss
4 = floating leaved
5 = floating
6 = unknown submergent
7 = unknown floating
FL = flat
1 = cobble/gravel
2 = sand
3 =mud
4 = organic
5 = vegetated pioneer
6 = vegetated non pioneer
RS = rocky shore
1 = bedrock
2 = boulder
6 = vegetated non pioneer
BB = beach bar
1 = cobble/gravel
2 = sand
EM = emergent
1 = persistent
2 = nonpersistent
3 = narrow leaved nonpersistent
4 = broad leaved nonpersistent
5 = narrow leaved persistent
6 = broad leaved persistent
SS = scrub/shrub and FO = forested
1 = broad leaved deciduos
2 = needle-leaved deciduous
3 = broad-leaved evergreen
4 = needle-leaved evergreen
5 = dead
6 = deciduous
7 = evergreen
ML = moss/lichen
1 = moss
2 = lichen
SB = stream bed
1 = cobble/gravel
2 = sand
3 = mud
4 = organic
OW = open water
wat
water regimes
non-tidal
A = temporary
B = saturated
C = seasonal
D = seasonal well drained
E = seasonal saturated
F = semipermanent
G = intermittently exposed
H = permanent
J = intermittently flooded
K = artificial
Z = intermittently exposed permanent
W = intermittently flooded temporary
Y = Saturated/semipermanent/seasonal
U = unknown
tidal
K = artificial
L = subtidal
M = irregularly exposed
N = regular
P = irregular
R = seasonal tidal
S = temporary tidal
T = semipermanent tidal
V = permanent tidal
U = unknown
water chemistry
coastal salinity
1 = hyperhaline
2 = eualine
3 = mixohaline (brackish)
4 = polyhaline
5 = mesohaline
6 = oligohaline
0 = fresh
inland salinity
7 = hypersaline
8 = eusaline
9 = mixosaline
0 = fresh
pH modifiers for all fresh water
a = acid
t = circumneutral
l = alkiline
mod
soil
g = organic
n = mineral
special modifiers
b = beaver
d = partially drained/ditched
f = farmed
h = diked/impounded
r = artificial
s = soil
x = excavated
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