Identification_Information: Citation: Citation_Information: Originator: Hitt, Kerie J. Publication_Date: 200504 Title: NAWQA GIS ancillary data: 2000 block group weighting table for ground water study areas (Land Use Studies and Subunit Surveys) Online_Linkage: Description: Abstract: This data set consists of area weighting factors for 2000 Census block groups for NAWQA LUS and SUS areas. The weighting factors can be used to calculate population and housing statistics for data compiled by block groups. Purpose: This is one of the ancillary GIS data layers developed to characterize NAWQA ground water studies for national synthesis of water-quality data. Supplemental_Information: The weighting factors are used to compute Census statistics for LUS and SUS study areas. The 2000 block group input layer did not include Alaska and Hawaii. Sites that fell outside the extent of the block group data layer are coded as -9999. Time_Period_of_Content: Time_Period_Information: Multiple_Dates/Times: Single_Date/Time: Calendar_Date: 1991 Single_Date/Time: Calendar_Date: 2001 Currentness_Reference: The data set is intended to represent conditions for the early 1990's to late 1990's. Status: Progress: Complete Maintenance_and_Update_Frequency: NAWQA cycle 2 study areas will be added as their boundaries become available. Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -125 East_Bounding_Coordinate: -66 North_Bounding_Coordinate: 50 South_Bounding_Coordinate: 24 Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: Ground water Theme_Keyword: Water quality Theme_Keyword: Land use study Theme_Keyword: Subunit survey Theme_Keyword: Major aquifer Theme_Keyword: Census block group Theme_Keyword: Block group Theme_Keyword: Census of population and housing Access_Constraints: The data set is for internal USGS access only. Use_Constraints: The data set is for internal USGS use only. Data_Quality_Information: Logical_Consistency_Report: None. Completeness_Report: None. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Hitt, K. Publication_Date: 20030220 Title: 2000 generalized block groups for the conterminous United States Edition: 1 Geospatial_Data_Presentation_Form: vector digital data Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Type_of_Source_Media: digital files Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2000 Source_Currentness_Reference: Represents boundaries for 2000 census Source_Citation_Abbreviation: USBG00 Source_Contribution: Generalized boundaries of the 2000 block groups, which provide the basis for the 30-m grid of block group boundaries used to make the weighting table. Source_Information: Source_Citation: Citation_Information: Originator: Hitt, K.J. Publication_Date: 2004 Title: Boundaries of the land use study (LUS) and subunit survey (SUS) ground-water studies conducted by the National Water-Quality Assessment (NAWQA) study units Edition: 3 Geospatial_Data_Presentation_Form: vector digital data Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Type_of_Source_Media: digital files Source_Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1991 Ending_Date: 2004 Source_Currentness_Reference: current Source_Citation_Abbreviation: GWPOLYS Source_Contribution: The boundaries of the LUS and SUS ground water study areas, as submitted by the NAWQA study units. Process_Step: Process_Date: 20040510 Process_Description: Ground water study boundaries are gridded at 30 meters and snapped to the NLCDE. Data processing occurs at 30 meters resolution. The block group weighting factors were created by overlaying each study area with the Census block group boundaries. The weighting factors show all block groups (BG) comprising the ground water study area and what fraction of the ground water study area each BG covers. The weighting factors are used to compute statistics for population and housing variables. This avoids doing multiple overlays of the study area and block groups (i.e., avoids doing an overlay for each Census variable). Here is an example of part of a block group weight table: !GW STUDY BGI AREAKM2 AREAF USBG00_KM2 USBG00_F !ucollusrc1d_trg 080519638001 0.1 0.072 654.8 0.000 !ucollusrc1d_trg 080519638002 0.4 0.537 135.7 0.003 !ucollusrc1d_trg 080519638003 0.3 0.392 2.6 0.117 ! ______ _____ ! 0.9 1.00 (AREAF should add to 1.) !BGI is the block group identifier (12-digit number). Three BGIs ! occur in this particular study area. !AREAKM2 is the square kilometers of each block group in the ! study area. !AREAF is the fraction of the ground water study represented by each ! block group. (AREAF = AREAKM2/total AREAKM2 for study area) !USBG00_KM2 is the total square kilometers of a BLOCK GROUP. !USBG00_F is the fraction of the block group represented in the study area. ! (USBG00_F = AREAKM2 / USBG00_KM2) The values of 2000 population density for each BLOCK GROUP (from CENSUS data) are: !BLOCK GROUP POP DENSITY !080519638001 1.8 !080519638002 9.8 !080519638003 362.2 The weighted average of population density for ucollusrc1d_trg is calculated as: ! ! BG BG BG BG BG BG TOTAL OF ALL ! AREAF * POPDENS AREAF * POPDENS AREAF * POPDENS AREAF's !POPDENS = (.072 * 1.8) + (.537 * 9.8) + (.392 * 362.2) / (.072 + .537 + .392) Processing routines are from the NAWQA area characterization toolbox. Process_Step: Process_Date: 20040701 Process_Description: Ground water study boundaries were re-gridded to correct a problem. (Previous version did not account for interior areas that are excluded from the study area.) The procedure to calculate the weighting factors was repeated. Process_Step: Process_Date: 20040722 Process_Description: Received new boundary for cycle 1 SANJLUSOR1A_TRG, SANJLUSOR1B_TRG. Recalculated weighting factors for these areas. Process_Step: Process_Date: 20050412 Process_Description: Recalculated data for several cycle 2 areas. For the previous calculations, the doughnut holes in the some of the study areas had not been removed in the gridded versions of the study areas. This affects seven study areas: with doughnuts without doughnuts cut out (correct) not cut out (incorrect) AREAID GRID AREA (M2) GRID AREA (M2) cnbrluscr1_bnd 7,044,202,800.000 7,392,941,100.000 cnbrluscr1_trg 5,706,866,700.000 6,766,256,700.000 connlusrc1_bnd 1,756,677,600.000 2,064,634,200.000 connlusrc1_trg 587,594,700.000 610,191,000.000 connsus2_bnd 6,848,918,100.000 7,617,282,300.000 nvbrlusrc1_trg 155,431,800.000 155,443,500.000 spltluscr2_trg 207,267,300.000 228,433,500.000 Also added studies that are resampled studies, but do not have the same boundaries in cycle 2 as were used in cycle 1: albelusag1, nvbrsus2, trinsus3, sanjluscr1a, sanjlusor2a. Also added willlusag3, which has the same boundaries as cycle 1 willlusag2. Process_Step: Process_Date: 20050622 Process_Description: Replaced data for santlusrc1_bnd. The study area santlusrc1_bnd should be the same as santsus1_bnd, not the same as santsus2_bnd. Spatial_Data_Organization_Information: Indirect_Spatial_Reference: The data set is referenced by SUCODE (NAWQA study unit/network code) and AREAID (ground water study boundary coverage). Two kinds of ground water network polygon coverages exist: 1) BND coverages, which represent the entire areal extent of the hydrogeologic unit defined for study, and 2) TRG coverages, which delineate the targeted land use within the BND. Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: The data set is organized by AREAID. Missing data is indicated by -9999. An example of using the weighting factors to calculate average POPDENS for a ground water study area is shown under Process_Step. Fields in the block group weighting table are: !SUID NAWQA study unit !SUCODE NAWQA study unit/network code !AREAID Ground water boundary coverage !USBG00G Numeric representation of block group id (BGI) from 30m block group grid !AREAG Flag indicating area is within a ground water study area (= 1) !AREAKM2 Square kilometers of block group in the study area !AREAF Fraction of the study area represented by the BLOCK GROUP !USBG00_KM2 Total area of block group !USBG00_F Fraction of block group in the study area (AREAKM2/USBG00_KM2) !BGI Block group identifier Entity_and_Attribute_Detail_Citation: None Distribution_Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: Kerie Hitt Contact_Organization: USGS NAWQA Nutrients National Synthesis Contact_Address: Address_Type: Mailing address Address: 413 National Center City: Reston State_or_Province: VA Postal_Code: 20192 Country: USA Contact_Electronic_Mail_Address: kjhitt@usgs.gov Contact_Voice_Telephone: 703 648-6854 Contact_Instructions: Contact via email Distribution_Liability: USGS assumes no liability for the use of this data set. Metadata_Reference_Information: Metadata_Date: 20050622 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Kerie Hitt Contact_Organization: USGS NAWQA Nutrients National Synthesis Contact_Address: Address_Type: Mailing address Address: 413 National Center City: Reston State_or_Province: VA Postal_Code: 20192 Country: USA Contact_Electronic_Mail_Address: kjhitt@usgs.gov Contact_Voice_Telephone: 703 648-6854 Contact_Instructions: Contact via email Metadata_Standard_Name: Content standards for digital geospatial metadata Metadata_Standard_Version: FGDC-STD-001-1998