National Hydrography Dataset (NHD) Data Dictionary Miscellaneous Tables

By NGP Standards and Specifications

The data dictionary for miscellaneous tables in the National Hydrography Dataset.

ExternalCrosswalk : Contains associations of Permanent_Identifiers to external source Identifiers.

Name	Definition	Type	Allow Nulls	Length	Domain	Default Value	Comments
ExternalID	ID that identifies the feature in the source dataset.	Text	True	40
ExternalIDEntryDate	Load date of the ExternalID record.	Date	True
ExternalIDName	Field name in the external source dataset that contains the unique IDs.	Text	True	50
ExternalIDOriginator	Name of the organization or individual who developed the external dataset/features.	Text	True	130
OBJECTID	Internal feature or event number.	OBJECTID	False
OrganizationType	Administrative level code of the organization or individual who developed the external dataset/features.	Long Integer	True
Permanent_Identifier	A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map.	Text	False	40

NHDFlow : Table containing values derived from the topologic connectivity of the geometric network and values of FlowDir attribute of NHDFlowline features. This table is not populated in pre-processed subregions.

Name	Definition	Type	Allow Nulls	Length	Domain	Default Value	Comments
DeltaLevel	Numerical difference between StreamLevel for From feature and stream level for To feature.	Long Integer	True				Only populated if StreamLevel has been calculated.
Direction	Text or Code to describe direction of flow.	Long Integer	True				Flow direction domain values: In, Network Start, Network End, and Non-flowing.
From_Permanent_Identifier	Permanent_Identifier of feature from which the water flows.	Text	False	40			Feature already assigned a ComID retains that value as the Permanent_ Identifier.
OBJECTID	Internal feature or event number.	OBJECTID	False
To_Permanent_Identifier	Permanent_Identifier of feature to which the feature flows.	Text	False	40			Feature already assigned a ComID retains that value as the Permanent_ Identifier.

NHDProcessingParameters : This table lists the schema and the version of the master NHD database that was used to generate extracted NHD data. This table is most useful to USGS to verify the version used by data stewards for updates.

Name	Definition	Type	Allow Nulls	Length	Domain	Default Value	Comments
OBJECTID	Internal feature or event number.	OBJECTID	False
ParameterName	The name of the parameter.	Text	False	24	ParameterName Domain		Parameters include Version, Resolution,Processing_Organization and SchemaVersion
ParameterValue	The value for the parameter.	Text	False	100

NHDStatus : NHDStatus is used to track data changes for transaction uploads to the central repository. This table is only populated during editing. It is blank when NHD is downloaded for use.

Name	Definition	Type	Allow Nulls	Length	Domain	Default Value	Comments
ID	Temporary ID assigned to track feature edits.	Text	False	40			When edits are loaded into the national database, the temporary ID is replaced with an official PermID.
OBJECTID	Internal feature or event number.	OBJECTID	False
Permanent_Identifier	A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map.	Text	False	40
Status	Type of edit.	Long Integer	False		UpdateStatus Domain

NHDVerticalRelationship : The table documents the vertical relationship for features (i.e. streams and canals) which cross but do not exchange flow.

Name	Definition	Type	Allow Nulls	Length	Domain	Default Value	Comments
Above_Permanent_Identifier	Permanent_Identifier of feature above the vertical offset.	Text	False	40			Feature already assigned a ComID retains that value as the Permanent_ Identifier.
Below_Permanent_Identifier	Permanent_Identifier of feature below the vertical offset.	Text	False	40			Feature already assigned a ComID retains that value as the Permanent_ Identifier.
OBJECTID	Internal feature or event number.	OBJECTID	False
Permanent_Identifier	A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map.	Text	False	40