Identification_Information
Abstract
Purpose
Supplemental Information
Data_Quality_Information
Spatial_Data_Organization_Information
Entity_and_Attribute_Information
Detailed Description
Overview
Distribution_Information
Metadata_Reference_Section
Identification_Information
Citation_Information
Originator: Derosier, Brakebill, Denis, & Kelley
Publication_Date: 1998
Title: Water Quality Assessment of the Potomac River Basin:
Water Quality and Selected Spatial Data, 1992 - 1996.
Scale_Denominator: 500,000
Description
Abstract
The National Water-Quality Assessment (NAWQA) Program's Potomac River Basin
study unit is an integrated water-quality assessment designed to address a
broad array of water-quality properties in several environmental media at
various spatial and temporal scales. These properties are then related to
natural and human factors that can influence the quality of water. During
a 3-year period of intensive data collection and analysis, hundreds of
water-quality characteristics were measured in five environmental media within
surface-water and ground-water systems. Sampled surface-water media include
streamwater, streambed sediment, aquatic biological communities, and aquatic
biological tissues. This investigation was conducted as part of a nation-
wide study to help assess the Nation's water-quality conditions.
Physiography and geology, the two most influential natural factors responsible
for most of the water-quality variability within the Potomac River Basin, were
used to develop a framework within which to assess the water quality of the
basin (Gerhart and Brakebill, 1996). Eight major subunits were created based
on the geographic distribution of physiographic and geologic characteristics
within the basin. The resulting distribution of subunits resembles the distribution
of physiographic provinces in most cases. Differences in rock type were
considered important enough in the Valley and Ridge (Great Valley section)
to further subdivide this province into Great Valley carbonate and siliciclastic
subunits.
Keywords:
Potomac NAWQA, Subunits, Geology, Lithology, Physiography, NAWQA, Poto,
stratification
Purpose
The purpose of this data set is to provide the Potomac NAWQA study unit with
a geographic distribution of important natural factors that influence water
quality within the basin. This subdivision was used with other data sets
representing natural conditions and human activities to produce subunits of
relatively distinct environmental settings consisting of relatively
homogeneous combinations of natural and human factors. These subunits were
used as a framework to design a sampling approach to an integrated
water-quality assessment.
Supplemental_Information
Procedures_Used
Surficial geology was compiled and digitized from state geologic maps for the
entire area within the Appalachian Valleys-Piedmont Regional Aquifer System
(APRASA) study area by APRASA personnel (T. Mesko, U.S. Geological Survey,
written commun. 1992). Linework for geologic contacts were digitized into
a Geographic Information System (GIS) using an electronic image-scanner and
translated into ARC/INFO spatial data vector coverages. The geologic maps of
Maryland, Pennsylvania, Virginia, and West Virginia were appended into a
single coverage and a 1:100,000 boundary of the Potomac River basin was
overlayed onto the coverage areas within the study unit.
Physiographic Province boundaries were modified from physiographic regions as
defined by Fenneman and Johnson, 1946.
Surficial geologic contacts represented by ARC/INFO arcs were used as
boundaries to determine the five physiographic provinces within the Potomac
River basin. They are: Appalachian Plateau, Valley & Ridge, Blue Ridge,
Piedmont, and the Coastal Plain. The Valley & Ridge province was sub-divided
into the Great Valley, and the Piedmont province was sub-divided
into the Triassic Lowlands to create a total of seven divisions. Surficial
contacts were also used as boundaries for the divisions. The PUT command
was used to place the selected arcs into an ARC/INFO coverage PHYPROV.
Interpretation of geologic formations was done to determine rock types
(lithologic composition) (Blomquist and others, 1995). An item called
TYPE was added to a copy of the geologic coverage and attributed with the
proper lithologic code. A coverage called LITHOLOGY was created with the
INFO item TYPE and polygons with the same lithologic code were merged together.
The combination of coverages PHYPROV and LITHOLOGY resulted in a subunit
coverage (Gerhart and Brakebill, 1996). An INFO item called SUBUNIT was added
to the coverage and attributed with the appropriate code representing its
combination of lithology and physiography.
Revisions
As needed
Reviews_Applied
Colleague, District Chief Approval
The data you have secured from the USGS have not received Director's
approval and as such are provisional and subject to revision. The data
are released on the condition that neither the USGS nor the United
States Government may be held liable for any damages resulting from
their authorized or unauthorized use.
Related_Spatial_and_Tabular_Data_Sets
SUBUNIT.LUT
Other_References_Cited
Berg, T.M., chief compiler, 1980, Geologic Map of Pennsylvania:
Pennsylvania Topographic and Geological Survey, 4th series, 1 map
on 2 sheets, scale 1:250,000.
Blomquist,J.D., Fisher,G.T., Denis,J.M., Brakebill,J.W., and Werkheiser,W.H.,
1996, Water-Quality Assessment of the Potomac River Basin: Basin Description
and Analysis of Available Nutrient Data, 1970-90. U.S. Geological Survey
Water-Resources Investigations Report 95-4221, 88 pp.
Cardwell, D.H., chief compiler, 1968, Geologic Map of West Virginia:
West Virginia Geological and Economic Survey, 2 sheets, scale 1:250,000.
Cleaves, E.T., chief compiler, 1968, Geologic Map of Maryland: Maryland
Geological Survey, 1 sheet, scale 1:250,000.
Fenneman and Johnson, 1946, Physical Divisions of the United States
USGS map, scale 1:7,000,000.
Gerhart, J.M., and Brakebill, J.W., Design and Implementation of a Sampling
Strategy for a Water-Quality Assessment of the Potomac River Basin. U.S.
Geological Survey Water-Resources Investigations Report 96-4034, 31 pp.
Mesko, Thomas, U.S. Geological Survey, Richmond, Va. Appalachian-Piedmont
Regional Aquifer System Analysis (APRASA) Written Commun (Provisional data),
1992.
Milici, R.C., chief compiler, 1963, Geologic Map of Virginia:
Virginia Division of Mineral Resources, 1 sheet, scale 1:500,000.
Notes
The use of trade, product, or firm names is for descriptive purposes only and does not
imply endorsement by the U.S. Government.
Time_Period_of_Content
Currentness_Reference
N/A
Status
Progress:
Maintenance_and_Update_Frequency
as needed
Spatial_Domain
Bounding_Coordinates
West_Bounding_Coordinate: -79.7418877
East_Bounding_Coordinate: -76.17953691
North_Bounding_Coordinate: 40.22693586
South_Bounding_Coordinate: 37.85990691
Keywords
Theme
Theme_Keyword_Thesaurus: None
Theme_Keyword: NAWQA, Subunits, Geology, Physography, Lithology
Place
Place_Keyword_Thesaurus: None
Place_Keyword: Potomac River Basin
Stratum
Stratum_Keyword_Thesaurus: None
Stratum_Keyword:
Temporal
Temporal_Keyword_Thesaurus: None
Temporal_Keyword:
Access_Constraints
The data you have secured from the USGS have not received Director's
approval and as such are provisional and subject to revision. The data
are released on the condition that neither the USGS nor the United
States Government may be held liable for any damages resulting from
their authorized or unauthorized use.
Use_Constraints
1) Original geologic coverages released as provisional data.
2) Multiple map scales used in digitizing.
3) Edgematch problems at state boundaries due to mapping inconsistencies.
4) Use at map scales of 1:250,000 or smaller.
Data_Set_Credit
Security_Information
Security_Classification_System: None
Security_Classification: UNCLASSIFIED
Security_Handling_Description: None
Native_Data_Set_Environment: dgux UNIX, ARC/INFO version 7.0.4
Cross_Reference
Originator: Derosier, Brakebill, Denis, & Kelley
Publication_Date: 1998
Publication_Time:
Title: Water-Quality and Selected Spatial Data, 1992- 1996, Potomac River Basin NAWQA
Edition:
Geospatial_Data_Presentation_Form:
Series_Information
Series_Name:
Issue_Identification:
Publication_Information
Publication_Place:
Publisher:
Other_Citation_Details:
Online_Linkage:
Larger_Work_Citation:
Data_Quality_Information
Attribute_Accuracy
Attribute_Accuracy_Report: See Entity_Attribute_Information
Quantitative_Attribute_Accuracy_Assessment
Attribute_Accuracy_Value: See Explanation
Attribute_Accuracy_Explanation:
Attribute accuracy is described, where present, with each
attribute defined in the Entity and Attribute Section.
Logical_Consistency_Report: Polygon topology present.
Completeness_Report
Positional_Accuracy
Horizontal_Positional_Accuracy
Created from Scale stable 1:250,000 and 1:500,000 state geologic maps.
Vertical_Positional_Accuracy
N/A
Lineage: See Supplemental_Information for overview.
Process_Steps
Process_Step
Available in download Arc/Info export file
Spatial_Data_Organization_Information
Direct_Spatial_Reference_Method: Vector
Point_and_Vector_Object_Information
SDTS_Terms_Description
SDTS_Point_and_Vector_Object_Type: Point
Point_and_Vector_Object_Count: 569
SDTS_Point_and_Vector_Object_Type: String
Point_and_Vector_Object_Count: 1042
SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains'
Point_and_Vector_Object_Count: 570
Spatial_Reference_Information
Horizontal_Coordinate_System_Definition
Planar
Map_Projection:
Map_Projection_Name: ALBERS
Longitude_of_Central_Meridian: -78
Latitude_of_Projection_Origin: 23
Latitude_of_First_Standard_Parallel: 29.5
Latitude_of_Second_Standard_Parallel: 45.5
False_Easting: 0.00000
False_Northing: 0.00000
Geodetic Model
Horizontal_Datum_Name:
Ellipsoid_Name: Clarke 1866
Semi-major_Axis: 6,378,206.4
Denominator_of_Flattening: 294.98
Entity_and_Attribute_Information
Detailed_Description
Entity_Type
Entity_Type_Label: SUBUNIT.PAT
Entity_Type_Definition: Polygon attribute table
Entity_Type_Definition_Source: Arc/Info
Attribute:
Attribute_Label: -
Attribute_Definition: Polygon attribute table
Attribute_Definition_Source: Arc/Info
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: -
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: AREA
Attribute_Definition: Area of poly/region in square coverage units
Attribute_Definition_Source: Computed
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Positive real numbers
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: PERIMETER
Attribute_Definition: Perimeter of poly/region in coverage units
Attribute_Definition_Source: Computed
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Positive real numbers
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: SUBUNIT#
Attribute_Definition: Internal feature number
Attribute_Definition_Source: Computed
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Sequential unique positive integer
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: SUBUNIT-ID
Attribute_Definition: User-assigned feature number
Attribute_Definition_Source: User-defined
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Integer
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: PROV
Attribute_Definition: Physiographic Province Code
Attribute_Definition_Source: USGS
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Character, AP,VR,GV,BR,PD,TR,CP
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: TYPE
Attribute_Definition: Lithology type
Attribute_Definition_Source: USGS
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Character C,CS,S,X,U
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: SUBUNIT
Attribute_Definition: Primary Subunit
Attribute_Definition_Source: USGS
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Character AP,VR,GVC,GVNC,PD,TR,BR,CP
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Entity_Type
Entity_Type_Label: SUBUNIT.LUT
Entity_Type_Definition: look up table
Entity_Type_Definition_Source: USGS
Attribute:
Attribute_Label: -
Attribute_Definition: look up table
Attribute_Definition_Source: USGS
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: -
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: SUBUNIT
Attribute_Definition: Primary subunit, used as relate item
Attribute_Definition_Source: USGS
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Character
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: SYMBOL
Attribute_Definition: Colornames.shd symbol number
Attribute_Definition_Source: assigned
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Integer
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Attribute:
Attribute_Label: NAME
Attribute_Definition: Subunit Name
Attribute_Definition_Source: USGS
Attribute_Domain_Values
Enumerated_Domain
Enumerated_Domain_Value: Character
Enumerated_Domain_Value_Definition
Enumerated_Domain_Value_Definition_Source:
Overview_Description
Entity_and_Attribute_Overview
Three items of PROV, TYPE, and SUBUNIT are listed below. The description
of these three items can be found in lookup tables Prov.lut, litho.lut,
and subunit.lut respectively.
PROV
AP Appalachian Plateau
BR Blue Ridge
CP Coastal Plain
GV Valley & Ridge (Great Valley)
PD Piedmont
TR Piedmont (Triassic Lowlands)
VR Valley and Ridge
TYPE
C Carbonate
CS Carbonate Siliciclastic Undivided
S Siliciclastic
U Unconsolidated Sediments
X Crystalline
SUBUNIT
AP APPALACHIAN PLATEAU
VR VALLEY AND RIDGE
GVC GREAT VALLEY CARBONATE
GVNC GREAT VALLEY NONCARBONATE
BR BLUE RIDGE
TR Piedmont (TRIASSIC LOWLANDS)
PD PIEDMONT
CP COASTAL PLAIN
Entity_and_Attribute_Detail_Citation: Not Available
Distribution_Information
Arc/Info Export format:
Use Load to local disc:
Physical settings.e00
Gunzipped SDTS Topological Vector Profile (TVP) format:
Use Load to local disc:
Physical settings.tgz
PC Zipped SDTS Topological Vector Profile (TVP) format:
Physical settings.zip
STDS files were created from ARC/INFO ARCSDTS
If the end user of an ARCSDTS file does not have access to the
SDTSARC command, the file can be converted into an Arc coverage
by first uncompressing it with the UNIX gzip command, which will
create a UNIX tar file. If the compressed ARCSDTS file does not have
a .tgz or .gz suffix, it must be renamed (UNIX mv command) to have
one. Second, the user must perform a UNIX tar xvof command on
the tar file and all SDTSEXPORT .DDF files will be loaded into the
workspace the "tar xvof" command is issued. Last, the user must
issue the Arc SDTSIMPORT command with the < in_transfer_prefix >
being the first four characters of the prefix to the .DDF files and the
< out_cover > being the prefix to the tar file. PC users can use unzip
to create STDS .DDF files from downloaded .zip files.
Contact
John W Brakebill
Geographer
U.S. Geological Survey
8987 Yellow Brick Road
Baltimore, Maryland 21237
Phone: 410-238-4200
Fax: 410-238-4210
email: jwbrakeb@usgs.gov
Metadata_Reference_Section
Metadata_Date: 19980128
Metadata_Contact: jwbrakeb
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: 19940608
Metadata_Time_Convention: Local Time
Metadata_Security_Information:
Metadata_Security_Classification_System: None
Metadata_Security_Classification: UNCLASSIFIED
Metadata_Security_Handling_Description: None
Last modified: 98-02-05.15:53:01.Thu