Elevation-Derived Hydrography READ Rules: Sea/Ocean
A Sea/Ocean is the great body of saltwater that covers much of the Earth.
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 sea/ocean is the approximate line of mean high water.
In areas where rivers enter sea/ocean, the limit is where the conformation of the land and water makes the division obvious, or, if the land and water do not suggest an obvious limit, the limit is where the river reaches a width of 1 nautical mile (6,076.1 feet or 1.15 statute miles) with no further constrictions.
A boundary waterbody is any waterbody that contains the boundary of the collection (that is, the actual opposite bank or shore is not being mapped). Boundary waterbodies may be a single water surface elevation (for example, lake) or gradient (for example, river). Boundary waterbodies will contain either a centerline or an Elevation Terminus line, depending on circumstances.
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 14).
Special conditions: none.
Table 14. Sea/Ocean Representation Rules.
| Kind of feature object | Area | Shortest Axis | Longest Axis |
| 0-dimensional (point) | -- | -- | -- |
| 1-dimensional (line) | -- | -- | -- |
| 2-dimensional (polygon) | greater than 0 | -- | -- |
Data Extraction
Capture Conditions
Capture all.
Attribute Information
FClass 1—Hydrography feature defined within the collection criteria of the elevation-derived hydrography specifications.
FCode 44500—Sea/ocean (the great body of saltwater that covers much of the Earth).
EClass 11— Polygon created from breakline—Polygon derived from the breaklines used for hydroflattening the elevation surface (3D polygon).
OR
FClass 1—Hydrography feature defined within the collection criteria of the elevation-derived hydrography specifications.
FCode 44500—Sea/ocean (the great body of saltwater that covers much of the Earth).
EClass 12— Polygon created from hydroflattened surface—Polygon corresponding to a hydroflattened surface, but breakline is either not available or not horizontally or vertically aligned appropriately with the DEM surface. For use in Alaska or where breaklines do not meet cartographic or horizontal requirements.
OR
FClass 1—Hydrography feature defined within the collection criteria of the elevation-derived hydrography specifications.
FCode 44500—Sea/ocean (the great body of saltwater that covers much of the Earth).
EClass 13—Polygon created without using elevation breakline and the surface of the waterbody is not hydroflattened in the source DEM.
Source Interpretation Guidelines
The minimum size for islands within sea/ocean is 1 acre (4,000 square meters).
For lidar base specification hydroflattening, permanent islands 1 acre (4,000 square meters) or larger shall be delineated within all waterbodies.
For examples of islands and intermittently submerged islands, which may be apparent on elevation surface, see “Additional Elevation-Derived Hydrography Treatments and Elevation Specific Features” section.
