Attribute/Attribute Value
Each feature requires domain codes to be entered into the attribute table for the feature class (Elevation-Derived Hydrography Feature type description, associated geometry, and use classification table in the Elevation-Derived Hydrography Data Acquisition Specifications 2023 revision A2). See “Field Definitions and Domain Values for Attributes” section for more information on Elevation-Derived Hydrography code definitions.
Delineation
The limit of a drainageway is the topographic flowpath or the approximate overland flow path between two disconnected drainage network features. May be determined by modelling techniques, but a clearly defined channel may not be easily recognized.
Representation Rules
When delineating a feature, it must be created with the appropriate geometry, either point, line, or polygon, which is determined by the size of the feature or the length along different axes of the feature (table 8).
Special conditions:
To accommodate variations in the shortest axis of drainageway:
FOR elevation-derived hydrography: If shortest axis of drainageway is
less than 20 feet (6 meters) regardless of distance, and is connected at the downstream end to a 2-dimensional (polygon) stream/river,
then drainageway is represented as a 1-dimensional (line) basic feature object.
If shortest axis of drainageway is greater than or equal to 50 feet (15 meters) and does not meet drainageway criteria, collect as appropriate feature for capture conditions (stream/ river, playa, and others as needed).
Table 8. Drainageway Representation Rules.
| Kind of feature object |
Area |
Shortest Axis |
Longest Axis |
| 0-dimensional (point) |
-- |
-- |
-- |
| 1-dimensional (line) |
-- |
greater than 0 |
-- |
| 2-dimensional (polygon) |
-- |
-- |
-- |
Data Extraction
Capture Conditions
Drainageways have no clearly defined capture conditions. Modelling techniques (flow models, elevation surface models, logistic regression models, and so on) expose features and, therefore, require further investigation to determine their status and categorization as hydrographic features.
Attribute Information
FClass 1—Hydrography feature defined within the collection criteria of the elevation-derived hydrography specifications.
FCode 46800—Drainageway (flowlines delineated where terrain modelling indicates potential headwater drainage, but no channel is detectable).
EClass 2—Linear hydrographic features that follow the elevation surface.
Source Interpretation Guidelines
None.
