Flood Plain Cross Sections of Loudoun County, VA

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator:

Loudoun County, Virginia, Department of Building and Development

Publication_Date: 20140806

Title: Flood Plain Cross Sections of Loudoun County, VA

Geospatial_Data_Presentation_Form: vector digital data

Description:

Abstract:

Flood Plain Cross Sections are derived from hydrologic models and are used to create the flood plain boundary. They were originally compiled from the listed sources onto the County's 1:2400 scale maps with five-foot interval topography. SEE SUPPLEMENTAL INFORMATION FOR INFORMATION ON THE LAYER UPDATE THAT INDENTIFIES VERTICAL DATUMS USED FOR FLOOD LEVEL IDENFICATION.

Purpose:

Flood Plain Cross Sections are used for planning and development purposes in Loudoun County. They are used in conjunction with floodplain data (constituting the Floodplain Overlay District) and depict the flood elevation (in feet above sea level) at a given location.

Supplemental_Information:

Elevation values (CR_ELEV_29 and CR_ELEV_88) have been calculated accordingly, based on the source vertical datum. Elevation values for CR_ELEV_29 are .7 ft greater than CR_ELEV_88. FEMA Guidelines were utilized to determine the conversion factor, they can be found at <http://www.fema.gov/pdf/fhm/frm_gsab02.pdf>. For cross sections that have an update source (CR_UPD_SOURCE) of "LEGACY", the source vertical datum is assumed to be NGVD 29. Cross sections are updated periodically by County staff when detailed flood studies are submitted and approved in association with land development applications. Data are stored in the corporate ArcSDE Geodatabase as a line feature class. The coordinate system is Virginia State Plane (North), Zone 4501, datum NAD83 HARN (vertical datum, if applicable, NAVD88), US Survey foot units.

Status:

Progress: Complete

Maintenance_and_Update_Frequency: As needed

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -77.954525

East_Bounding_Coordinate: -69.499109

North_Bounding_Coordinate: 40.237174

South_Bounding_Coordinate: 38.519775

Keywords:

Theme:

Theme_Keyword_Thesaurus: none; Employee generated

Theme_Keyword: flood

Theme_Keyword: cross section

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Categories

Theme_Keyword: inlandWaters

Theme_Keyword: elevation

Place:

Place_Keyword_Thesaurus: none; Employee generated

Place_Keyword: Virginia

Place_Keyword: County

Place_Keyword: Loudoun

Access_Constraints: None

Use_Constraints:

These data were generated for use by Loudoun County and are available to the public. These data are intended for use at 1:2400 scale or smaller. Acknowledgement of Loudoun County would be appreciated in products derived from this data.

Point_of_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Loudoun County, VA, Department of Building and Development

Contact_Position: Public Information Counter

Contact_Address:

Address_Type: mailing and physical

Address: MS 60

Address: 1 Harrison Street SE, 2nd Floor

City: Leesburg

State_or_Province: VA

Postal_Code: 20175

Country: US

Contact_Voice_Telephone: (703)777-0397

Contact_Facsimile_Telephone: (703)771-5522

Contact_Electronic_Mail_Address: bad@loudoun.gov

Hours_of_Service: 8:00-5:00 EST, M-F

Native_Data_Set_Environment:

Microsoft Windows Server 2008 Version 6.0 (Build 6002) Service Pack 2; ESRI ArcGIS 10.0.5.4400

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Retention of attribute accuracy throughout the coverage to geodatabase feature class coversion process was ensured by a QA/QC programmatic check. To meet satisfactory QA/QC requirements the input coverage and output feature class must have, on a record by record basis, identical attribution when comparing all concatenated fields to all the user-defined attribution.

Logical_Consistency_Report: Topologically clean

Completeness_Report:

Features may have been eliminated or generalized due to scale and intended use. To assist Loudoun County, Virginia in the maintenance of the data, please provide any information concerning discovered errors, omissions, or other discrepancies found in the data.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Retention of coordinate accuracy throughout the coverage to geodatabase feature class conversion process was ensured by a QA/QC programmatic check. To meet satisfactory QA/QC requirements the input coverage and output feature class must have the same record total, and on a record by record basis, area, perimeter, and length differential of less than +/- 0.5%.

Lineage:

Source_Information:

Source_Citation:

Citation_Information:

Originator: Loudoun County, VA, Department of Building and Development

Publication_Date: 19900101

Title: Engineering studies

Geospatial_Data_Presentation_Form: vector digital data

Source_Scale_Denominator: 2400

Type_of_Source_Media: None

Source_Citation_Abbreviation: Engineering studies

Source_Contribution: Engineering studies to generate cross sections

Process_Step:

Process_Description:

Three new attributes were added to the layer and one existing attribute deleted to enhance its spatial by differentiating between NAVD (North America Vertical Datum) 29 & 88 elevation values. CR_SRC_VERTICAL_DATUM, CR_ELEV_88, & CR_ELEV_29 were added. The existing CR_ELEV was deleted, as it didn't indicate the vertical datum used. Five new attributes were added to the layer to provide immediate maintenance history and jurisdictional information for all of the features. These new attributes are CR_MAINT_ID, CR_GIS_START_DATE, CR_GIS_END_DATE, CR_JURISDICTION, and CR_APP_NM.

Process_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Loudoun County, VA, Department of Building and Development

Contact_Position: GIS Administration

Process_Step:

Process_Description:

This layer undergoes occassional updates from County staff that are not individually documented

Process_Step:

Process_Description:

Data derived from engineering studies performed by SCS or from specific engineering studies onto the County's 1:2400 scale maps with five foot interval topography.

Process_Date: 19900101

Process_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Loudoun County, VA, Department of Building and Development

Process_Step:

Process_Description:

This data set was part of a batch process that converted legacy data from ArcInfo coverage in Librarian to a single-tiled ArcInfo coverage in preparation for a final coversion to ArcSDE Geodatabase Feature Classes. Data were extracted from Librarian using the EXTRACT TOPOLOGICAL command. Multi-tiled data sets were extracted into multiple coverages and then combined based on the feature type(s). Layers with both polygon and arc feature classes were processed with the Arc commands, MAPJOIN and DISSOLVE. Arc feature classes alone were processed with the Arc commands, APPEND and DISSOLVE. Layers with both arc and point feature classes and point feature classes alone were processed with the Arc command, APPEND. When used, the Arc command, DISSOLVE, was given with the <#all> option. All coverages were then reprojected to HARN 83 using the following .prj file specifications: INPUT PROJECTION STATEPLANE UNITS FEET ZONE 5551 DATUM NAD27 NADCON PARAMETERS OUTPUT PROJECTION STATEPLANE UNITS FEET FIPSZONE 4501 DATUM HPGN NADCON PARAMETERS END This dataset was then converted to a feature class in a geodatabase in ArcSDE.

Process_Date: 20040101

Process_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

Loudoun County, VA, Office of Mapping and Geographic Information (OMAGI)

Contact_Position: GIS Systems Analyst

Spatial_Data_Organization_Information:

Indirect_Spatial_Reference: Loudoun County

Direct_Spatial_Reference_Method: Vector

Point_and_Vector_Object_Information:

SDTS_Terms_Description:

SDTS_Point_and_Vector_Object_Type: String

Point_and_Vector_Object_Count: 7252

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Map_Projection:

Map_Projection_Name: Lambert Conformal Conic

Lambert_Conformal_Conic:

Standard_Parallel: 38.03333333333333

Standard_Parallel: 39.2

Longitude_of_Central_Meridian: -78.5

Latitude_of_Projection_Origin: 37.66666666666666

False_Easting: 11482916.66666666

False_Northing: 6561666.666666666

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: coordinate pair

Coordinate_Representation:

Abscissa_Resolution: 0.001

Ordinate_Resolution: 0.001

Planar_Distance_Units:

Geodetic_Model:

Horizontal_Datum_Name: D North American 1983 HARN

Ellipsoid_Name: GRS 1980

Semi-major_Axis: 6378137.0

Denominator_of_Flattening_Ratio: 298.257222101

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: GISDBB.GISBROW.FLOOD_CROSS_SECTIONS_LINE

Attribute:

Attribute_Label: CR_MAINT_TASK_ID

Attribute_Definition: Internal field for use in maintenance records

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: CR_SRC_VERTICAL_DATUM

Attribute_Definition:

The vertical datum cited in the source material for the feature.

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: user generated text

Beginning_Date_of_Attribute_Values: 20090110

Attribute:

Attribute_Label: CR_APP_NM

Attribute_Definition: The associated Loudoun County Application Number

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: CR_ELEV_88

Attribute_Definition: NAVD 88 flood elevation in feet above sea level

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: OBJECTID

Attribute_Definition: Internal feature number.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: SHAPE

Attribute_Definition: Feature geometry.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: CR_UPD_USER

Attribute_Definition:

Not for public distribution. Internal User ID of editor creating or modifying a feature

Attribute:

Attribute_Label: CR_UPD_DATE

Attribute_Definition: Date feature class created or modified

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: CR_GIS_START_DATE

Attribute_Definition:

Future enhancement. For GIS maintenance use to determine when a feature was first added to the layer.

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: CR_ELEV_29

Attribute_Definition: NGVD 29 flood elevation in feet above sea level.

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Beginning_Date_of_Attribute_Values: 20090110

Attribute:

Attribute_Label: CR_UPD_SOURCE

Attribute_Definition: Source that created or edited feature class

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: CR_CROSS_ID

Attribute_Definition:

Identifies the source engineering study or associated floodplain study or alteration application

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: CR_GIS_END_DATE

Attribute_Definition:

Future enhancement. For GIS maintenance use to determine when a feature was first added to the layer.

Attribute:

Attribute_Label: DB2GSE.SdeLength(SHAPE)

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Loudoun County, VA, OMAGI

Contact_Position: Public Information Counter

Contact_Address:

Address_Type: mailing and physical

Address: MS 65

Address: 1 Harrison Street S.E., 2nd floor

City: Leesburg

State_or_Province: VA

Postal_Code: 20175

Country: US

Contact_Voice_Telephone: (703)771-5778

Contact_Facsimile_Telephone: (703)771-5075

Contact_Electronic_Mail_Address: mapping@loudoun.gov

Hours_of_Service: 8:00-4:30 EST, M-F

Distribution_Liability: See access and use constraints information.

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: DXF

Format_Specification: AutoCad Digital Exchange File

Digital_Transfer_Option:

Offline_Option:

Offline_Media: dvd

Fees:

Loudoun County distributes spatial data in ArcGIS database or shapefile and DXF format for the cost of reproduction. Countywide spatial datasets may be purchased for $22 per DVD for up to 4.5 GB of data. There is a $100 surcharge to purchase countywide topography, and a $3 charge if the item is to be mailed. If the customer wants the data in DXF format and/or would like OMAGI to custom select specific geographic areas of the County, there is an additional $7 per 15 minute increment labor charge. Select aerial imagery is also available.

Ordering_Instructions:

Size limit: 4.5 GB. Visit our website at: <http://www.loudoun.gov/omagi>, click on "Loudoun County Mapping Documents & Order Forms." The "Forms" directory will lead you to custom & standard (countywide) data order forms. Hardcopy maps may also be available; please contact the Mapping Office Public Information Counter for more information regarding all data requests.

Metadata_Reference_Information:

Metadata_Date: 20140806

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

Loudoun County, VA, Office of Mapping & Geographic Information (OMAGI)

Contact_Position: Metadata Specialist

Contact_Address:

Address_Type: mailing and physical

Address: MS 65

Address: 1 Harrison Street SE

City: Leesburg

State_or_Province: VA

Postal_Code: 20175

Country: US

Contact_Voice_Telephone: (703)771-5778

Contact_Facsimile_Telephone: (703)771-5075

Contact_Electronic_Mail_Address: mapping@loudoun.gov

Hours_of_Service: 8:00-4:30 EST, M-F

Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time

Metadata_Use_Constraints:

This metadata reflects the source Geodatabase format and specific elements may not apply if your data is exported to SHP or DXF products. User must be aware that changes to data schema occur during data export that may not be reflected in this metadata, which represents Loudoun County's corporate geodatabase. Acknowledgement of Loudoun County would be appreciated in the use of this metadata.