Elevation-Derived Hydrography READ Rules: Canal/Ditch

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 canal/ditch is the top of the banks of the artificial waterway.

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 2).

Special Conditions

To accommodate variations in the shortest axis of canal/ditch:

If the shortest axis of canal/ditch is:

• less than or equal to 50 feet (15 meters) but greater than or equal to 20 feet (6 meters) for a distance less than 1 mile (1.6 kilometers), and is connected at both ends to a 2-dimensionalcanal/ditch,

then canal/ditch is represented as a 2-dimensional basic feature object.

• less than or equal to 50 feet (15 meters) but greater than or equal to 20 feet (6 meters) for a distance greater than 1 mile (1.6 kilometers), or less than 20 feet (6 meters) regardless of distance, and is connected at both ends to a 2-dimensional (polygon) canal/ditch,

then canal/ditch is represented as a 1-dimensional (line) basic feature object.

• greater than 50 feet (15 meters) but less than 80 feet (24 meters) for a distance less than 1 mile (1.6 kilometers), and is connected at both ends to a 1-dimensional (line) canal/ditch,

then canal/ditch is represented as a 1-dimensional (line) basic feature object.

• greater than 50 feet (15 meters) but less than 80 feet (24 meters) for a distance greater than or equal to 1 mile (1.6 kilometers), or greater than or equal to 80 feet (24 meters) regardless of distance, and is connected at both ends to a 1-dimensional (line) canal/ditch,

then canal/ditch is represented as a 2-dimensional (polygon) basic feature object.

Table 2. Canal/Ditch Representation Rules.

Data Extraction

Capture Conditions

If canal/ditch is named, or

if canal/ditch is greater than or equal to 984 feet (300 meters) along the longest axis,

then capture.

If canal/ditch is needed to provide network connectivity,

then capture.

If canal/ditch is within agricultural fields and drains to another canal/ditch or other hydrologic feature,

then do not capture (see following exception).

The exception is if a project has a special need for canals and ditch features that are within agricultural fields and drain to another canal/ditch or other hydrologic feature, then these features should be coded with a separate FCode (user defined) so that they can be excluded from features ingested into the 3DHP.

Note that a hydrologic network should not be broken if features are excluded.

Attribute Information

FClass 2— Nonhydrography feature.

FCode 33600—Canal/ditch (an artificial open waterway constructed to transport water, irrigate or drain land, connect two or more bodies of water, or serve as a waterway for watercraft).

EClass 0—Not used for elevation derivatives.

OR

FClass 1— Hydrography feature defined within the collection criteria of the elevation-derived hydrography specifications.
FCode 33600—Canal/ditch (an artificial open waterway constructed to transport water, irrigate or drain land, connect two or more bodies of water, or serve as a waterway for watercraft).
EClass 2— Linear hydrographic features that follow the elevation surface.

OR

FClass 1— Hydrography feature defined within the collection criteria of the elevation-derived hydrography specifications.

FCode 33600—Canal/ditch (an artificial open waterway constructed to transport water, irrigate or drain land, connect two or more bodies of water, or serve as a waterway for watercraft).

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 33600—Canal/ditch (an artificial open waterway constructed to transport water, irrigate or drain land, connect two or more bodies of water, or serve as a waterway for watercraft).

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 33600—Canal/ditch (an artificial open waterway constructed to transport water, irrigate or drain land, connect two or more bodies of water, or serve as a waterway for watercraft).

EClass 13— Polygon created without using elevation breakline and the surface of the waterbody is not hydroflattened in the source DEM.

Source Interpretation Guidelines

Do not capture underground aqueducts as canal/ditch. See “Pipeline” section.

Do not capture rivers that have been channelized to control flooding or erosion, or to maintain flow for navigation as canal/ditch. See “Stream/River” section (for example, Los Angeles River is a large, channelized river, and coded as stream/river).

Do capture as canal/ditch only those inland navigation waterways that are cut through land to bypass outcrops or rapids, or to connect two bodies of water.

If a canal or ditch passes through a siphon that meets capture conditions for pipeline, then do not capture canal/ditch. See “Pipeline” section.

Do not capture canal/ditch associated with a cranberry bog or rice paddy.