Flood Plain Boundaries 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, VA, Department of Building and Development

Publication_Date: 20140806

Title: Flood Plain Boundaries of Loudoun County, VA

Geospatial_Data_Presentation_Form: vector digital data

Description:

Abstract:

The regulatory floodplain boundary reflects the limits of flooding resulting from a storm having an occurrence probability of 1%, identified as the 100 year storm. The floodplain boundary was recompiled from the listed sources onto the County's 1:2400 scale maps with five foot interval topography. This floodplain feature class contains polygon feature classes only.

Purpose:

Floodplain data is used to establish a Floodplain Overlay District (FOD) as defined in the Zoning Ordinance of Loudoun County, which restricts the allowable uses within the regulatory floodplain. Data is used to establish flood risk factors and eligibility to participate in the National Flood Insurance Program. Floodplain data are also used in land use planning and for taxation of land.

Supplemental_Information:

Data are stored in the corporate ArcSDE Geodatabase as a polygon 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: -77.954136

East_Bounding_Coordinate: -77.323973

North_Bounding_Coordinate: 39.326187

South_Bounding_Coordinate: 38.844263

Keywords:

Theme:

Theme_Keyword_Thesaurus: none; Employee generated

Theme_Keyword: floods

Theme_Keyword: floodplain

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Categories

Theme_Keyword: inlandWaters

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 & Development

Contact_Position: Public Information, Land Management counter

Contact_Address:

Address_Type: mailing and physical

Address: MS 60A

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

Title: Various engineering studies

Geospatial_Data_Presentation_Form: vector digital data

Type_of_Source_Media: None

Source_Citation_Abbreviation: Various engineering studies

Process_Step: Occurred 2017-02-16

Process_Description:

Loudoun County has adopted amendments to the Revised 1993 Loudoun County Zoning Ordinance and Zoning Map regarding the Floodplain Overlay District (FOD). The approval of ZMAP-2016-0021 revises the mapped boundaries of the FOD (both Major Floodplain and Minor Floodplain) to conform to the updated Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS). Approval of ZOAM-2016-0015 completes the corresponding revision of the FIRM and FIS effective date provided in Section 4-1504(C) of the Revised 1993 Loudoun County Zoning Ordinance from July 5, 2001 to February 17, 2017. Additional information regarding the amendments can be found on the project website at https://www.loudoun.gov/FODZMap or in the documents for the Board of Supervisors Public Hearing for 02/07/2017 (https://lfportal.loudoun.gov/LFPortalinternet/0/fol/213127/Row1.aspx)

Process_Contact:

Contact_Information:

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

Contact_Position: GIS Administration

Contacts_role: processor

Process_Step:

Process_Description:

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

Process_Step:

Process_Description:

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 FL_MAINT_ID, FL_GIS_START_DATE, FL_GIS_END_DATE, FL_JURISDICTION, and FL_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 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_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

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

Contact_Position: GIS Analyst

Process_Step:

Process_Description:

Data derived by Department of Natural Resources from engineering studies performed by SCS or from specific engineering studies.

Process_Date: 19990101

Process_Contact:

Contact_Information:

Contact_Organization_Primary:

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

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: GT-polygon composed of chains

Point_and_Vector_Object_Count: 1279

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.FLOODS_POLY

Attribute:

Attribute_Label: FL_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

Beginning_Date_of_Attribute_Values: 20100110

Attribute:

Attribute_Label: FL_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: FL_MAINT_TASK_ID

Attribute_Definition:

The layer maintenance task id; used to ground and identify edits performed during a particalur task

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: FL_FLOOD_TYPE

Attribute_Definition: Description of flood boundary area

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: MAJOR FLOODPLAIN > 640 AC

Enumerated_Domain_Value_Definition: Major floodplain greater than 640 acres

Enumerated_Domain:

Enumerated_Domain_Value: POTOMAC FLOODPLAIN

Enumerated_Domain_Value_Definition: Potomac River floodplain

Enumerated_Domain:

Enumerated_Domain_Value: MINOR FLOODPLAIN < 640 AC

Enumerated_Domain_Value_Definition: Minor floodplain less than 640 acres

Attribute:

Attribute_Label: FL_UPD_DATE

Attribute_Definition: Date feature class created or modified

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User defined text

Attribute:

Attribute_Label: SHAPE

Attribute_Definition: Feature geometry.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: FL_GIS_END_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

Beginning_Date_of_Attribute_Values: 20100111

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: FL_UPD_USER

Attribute_Definition: Staff contact who updated data

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: FL_UPD_SOURCE

Attribute_Definition: Source that created or modified feature class

Attribute_Definition_Source: Loudoun County

Attribute_Domain_Values:

Unrepresentable_Domain: User generated text

Attribute:

Attribute_Label: DB2GSE.ST_Area(SHAPE)

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 SE, 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.