FY27 DCA - Instructions for Creating 3DHP Project Boundaries 1

US Geological Survey
3D National Topography Model Data Collaboration Announcement 3D Hydrography Program

3DHP-B: Instructions for Creating 3DHP Project Boundaries Collection of data for 3DHP data must be follow a set of collection requirements to achieve a consistent national dataset. These requirements include: 1. Hydrographic features will be collected within whole hydrologic units (HU) as defined by the Watershed Boundary Dataset (WBD)
2. The hydrologic unit(s) that form the Defined Project Area (DPA) must be whole 10digit or larger HU (e.g 8-digit HU) from the final, static published version of the WBD.
3. DPA comprised of or including stand-alone 12-digit HU are discouraged and must be approved in advance by the 3DHP Data Acquisition Lead by emailing [email protected] .
4. The DPA must be whole HU and must not be clipped to administrative or political boundaries except where HU cross over the international boundary with Canada or Mexico or to remove areas of open water area where a HU extends to the NOAA 3 Nautical Mile Line.
5. The DPA attribute table must include the following fields: LoadDate, AreaAcres, AreaSqKm, States, HU# (where # is the HU level 2,4,6,8, or 10), and Name. 6. Data collection is required for the full extent of the DPA. However, the WBD is created from base data of varying scales and vintages and may contain delineation errors which could result in the actual data collection area expanding or contracting. 7. 3DHP will be produced in NAD 1983 (2011) Contiguous USA Albers (EPSG 6350). Background
The WBD is comprised of HU polygons arranged in a nested, hierarchical system with each polygon identified by a unique hydrologic unit code (HUC). The number of digits in the code denote the hydrologic unit’s place in the hierarchy. For each successive level in the hierarchy, two digits are added to the HUC in which the smaller unit is nested so that more digits in a HU code identify smaller HU.

FY27 3DHP-B: Instructions for Creating 3DHP Project Boundaries

US Geological Survey
3D National Topography Model Data Collaboration Announcement 3D Hydrography Program

An HU may represent all or only part of the total drainage area to its outlet so that multiple HUs may be required to define the entire drainage area to a given outlet. More detailed information about the WBD is available in the most recent version of the WBD Standards. Information about DPA for 3DHP can be found under the "Collection Area” heading of the Elevation-Derived Hydrography Acquisition Specification available at: