National Hydrography Dataset (NHD) Data Dictionary Miscellaneous Tables
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 |