Elevation-Derived Hydrography Data Acquisition Specifications: Feature Codes and Values Requirements

Feature Codes and Values

3D Elevation Program Light Detection and Ranging Base Specification Required Hydroflattening Features

Additional User-Defined Features

Feature Codes and Values

Hydrographic features collected under the scope of this specification document represent a subset of the features included within the NHD. Where appropriate, the FCode values and descriptions match the NHD specifications. Elevation features used as breaklines for hydroflattening, or for other elevation surface treatments, are identified with an elevation class as well as a hydrography FCode. The complete set of domain values required with this specification is provided in table 4, table 5, table 6, table 7, and table 8. The companion document “Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation rules” (READ Rules) further defines the fields, domains, and minimum feature collection requirements for each required feature (Archuleta and Terziotti, 2020).

3D Elevation Program Light Detection and Ranging Base Specification Required Hydroflattening Features

A subset of the features collected for the lidar source projects meeting the Lidar Base Specification (LBS) hydroflattening requirement (U.S. Geological Survey, 2019) can be used directly for waterbody polygon delineations. The elevation-derived hydrography FCodes that correspond to hydroflattening features are cross-referenced in table 11.

Additional User-Defined Features

The primary use for the UserCode field: to identify features that are outside the scope of this specification but are required by the user.

• Additional features (not defined within table 4, table 5, and table 9) may be collected but will be given unique codes in UserCode.

• If the feature is outside the scope of this specification, the following guidelines apply:

  • FClass, EClass, and FCode will be coded as 2, 0 (unless collected to produce an elevation derivative, then 2), and 0, respectively.

  • The Desc field may be used to describe the additional feature.

  • A unique code per feature type will be added to the UserCode field.

  • Codes will not duplicate other defined features or coding used for NHD conflation.