Report of the status of the Georgia Coastal Geographic Information System [1991]

REPORT ON THE STATUS OF THE GEORGIA COASTAL
GEOGRAPHIC INFORMATION SYSTEM
by
Dennis B. O'Connell
OPEN-FILE REPORT 91-1
DEPARTMENT OF NATURAL RESOURCES Joe D. Tanner, Commissioner
ENVIRONMENTAL PROTECTION DIVISION Harold F. Rebels, Assistant Director GEORGIA GEOLOGIC SURVEY
William H. McLemore, State Geologist
ATlANTA 1991

REPORT ON THE STATUS OF THE GEORGIA COASTAL
GEOGRAPHIC INFORMATION SYSTEM
by Dennis B. O'Connell
Open-File Report 91-1
Prepared in cooperation with Minerals Management Service U.S. Department of the Interior Continental Margins Study Program Subagreement No. 14-12-0001-30432-GA
Department of Natural Resources Joe D. Tanner, Commissioner
Environmental Protection Division Harold F. Reheis, Assistant Director
Georgia Geologic Survey William H. McLemore, State Geologist
Atlanta 1991

CONTENTS Page
SUMMARY ................................................................................................................................ 1 IN'1R.ODUcriON .......................................................................................................................... 1 OBJECTIVE AND APPROACH................................................................................................ 2 PROORESS OF Tiffi GEORGIA COASTAL GIS .................................................................... 2
Acquisition and Installation of GIS Workstation Hardware .................................................. 3 Acquisition and Installation of GIS Workstation Software .................................................... 3 Training of Two Staff Members in the Use of the GIS Software ........................................... 3 Compilation of Database Inventory ........................................................................................ 4 Inventory of Databases Needed for Making Environmental and Mineral Resource
Decisions ..... .................................................................... ............................ ..................... 5 Acquisition of Some of the Databases Identified in the Inventory ........................................ 7 Establishment of QNQC Policy and Procedures.................................................................... 7 Development of Archiving and Backup Strategies ................................................................. 8 APPENDIX A: Catalog of Available Databases as of 12/31!89 ....................~............................ 9 APPENDIX B: Quality Assurance Testing Procedures and Accuracy Assessment ................... 24 APPENDIX C: Computer File Backup Proc~ures and Policy ..................................................27 REFERENCE ..............................................................................................................................28
TABLE
Table 1. Databases included in the Year Six Inventory .............................................................. 6
iii

REPORT ON THE STATUS OF THE GEORGIA COASTAL GEOGRAPIDC INFORMATION SYSTEM
SUMMARY
The Georgia Department of Natural Resources, Environmental Protection Division has initiated the installation of a PC-compatible Geographic Information System (GIS) for the coastal region of Georgia. The Coastal GIS will be used to assist in the management of Georgia's coastal and offshore geologic resources and will also be used to manage information related to coastal geology. The work is being performed under the Continental Margins Program as a part of the Year Six Subagreement between the Georgia Department of Natural Resources, the U.S. Minerals Management Service, and the University of Texas.
Work performed during Year Six has focused on the establishment of a GIS workstation and the development of an inventory of databases which are relevant to coastal geology. The present PC workstation consists of an ffiM Model 80 computer with peripherals for storing and retrieving data on magnetic tape, plotting maps, and digitizing data from pre-existing maps. PC ARC/INFO has been installed as the primary software for the Coastal GIS. Two Georgia Geologic Survey staff members have been trained in the use of this software for performing basic GIS tasks (digitizing, editing, database management, map overlay techniques, spatial analysis and routing analysis). A catalog of databases containing information related to coastal geology and resources has been compiled (see Appendix A). The compilation ofthis catalog is an ongoing process and will continue into Year Seven. Priorities for acquiring these databases have been established. The majority of the identified databases will be acquired during Year Seven or later.
Policies and procedures have been established for assuring the quality of data sets that have been prepared in-house. Detailed procedures for quality assurance and accuracy assessment are presented in Appendix B. Policies have been established for archiving important data sets and backing up working files to protect them from accidental loss (see Appendix C). The current GIS facility is sufficient for most basic GIS functions, provided that the coverages which are being modified are of limited aerial extent and complexity.
INTRODUCTION
Geologic studies in the Georgia marine environment can be divided primarily into two domains, the coastal barrier islands and the continental shelf. Work in these areas cover a broad range of topics, including environmental, geologic framework, and mineralogic resources studies. The very diversity of these studies, their objectives, and their results have created a major problem for researchers. The information presented, the formats used, and the results are as varied as the researchers who have developed them. To date, a readily accessible, comprehensive, and uniform database is lacking. What is needed for thorough and effective resources management and research is a generalizable and "user-friendly" Geographic Information System (GIS) which can combine, reconcile, and collate the information presently available, as well as incorporate data from future studies. Such a system would insure that the data collected and information gained would be preserved with the greatestdegree ofapplicability toward an informed and comprehensive program of marine resources management.
1

The Georgia Geologic Survey has initiated the installation of a personal computer (PC)compatible Geographic Information System (GIS) for the coastal region of Georgia. The work is being performed under the Continental Margins Program as a part of the Year Six Subagreement between the Georgia Department of Natural Resources, the U.S. Minerals Management Service, and the University of Texas. This report describes the work performed under the subagreement during the period from January 1, 1989 to December 31, 1989.
OBJECTIVE AND APPROACH
The objective of the Year Six Project is to initiate the development of a PC-compatible GIS for the coastal area and continental shelf of Georgia. This PC-based GIS will be used for natural resource and information management in the coastal and continental shelf regions of Georgia. GIS technology has the following advantages:
1 It preserves attribute (descriptive) information related to spatial features.
2. It maintains topological relationships between features.
3. It allows the user to rapidly perform spatial analysis by merging information from unrelated sources, once this information has been digitized.
In order to meet the project objective, the following approach was implemented:
1. Establish a PC-compatible GIS workstation at the Georgia Geologic Survey. This workstation will include facilities for digitizing, high-capacity data storage and retrieval, data file management, spatial analysis, and graphics output.
2. Compile an inventory ofdatabases that will be integrated into the GIS, and establish priorities for their incorporation into the Coastal GIS.
3. Acquire databases that have been identified in the inventory, and maintain an archive of these databases.
4. Establish procedures to insure the quality of databases which are digitized by the Georgia Geologic Survey, and develop strategies for protecting the database archive and computer working files through the creation of backup copies.
S. Train Georgia Geologic Survey personnel in the use of the GIS.
PROGRESS OF THE GEORGIA COASTAL GIS
As of December 31, 1989, the following accomplishments toward the establishment of the Georgia Coastal GIS have been achieved:
1. Acquisition and installation of GIS workstation hardware.
2. Acquisition and installation of GIS workstation software.
2

3. Training of two staff members in the use of the GIS software.
4. Compilation of a database inventory.
5. Acquisition of some of the databases identified in the inventory.
6. Establishment of quality assurance and quality control (QA/QC) procedures.
7. Development of archiving and back up strategies.
Each of these accomplishments is discussed in detail below.
Acquisition and Installation of GIS Workstation Hardware
Establishment of the workstation which will be used for GIS tasks has been completed. The present workstation consists of the following:
1. ffiM PS/2 Model 80 computer with 2MB user memory, 115MB fixed disk storage, 20 MHz math co-processor, mouse, VGA color monitor, 3.5 inch diskette drive and multi-protocol communications adapter. DOS version 3.30 has been installed as the operating system.
2. IBM model 6157-002 streaming tape drive. Compatible data storage tapes are capable of storing 125 MB of data. An adapter for the streaming tape drive has been installed on the ffiM PS/2 Model 80.
3. Hewlett Packard model 7570A Draft ProD-size plotter.
4. Calcomp model95360 digitizing table, 36.5 x 48.5 inches, with a compatible 16 button digitizing cursor. This digitizing table is capable of resolving up to 10,160 lines per inch, with an accuracy of+ or - .005 inches.
Acquisition and Installation of GIS Workstation Software
The PC version of ARC/INFO was selected as the primary software for the Coastal GIS. PC ARC/INFO includes modules for data capture through digitizing, interactive graphic data editing, data transfer, relational database management, map overlay, spatial analysis, and network analysis for optimum routing. ARC/INFO software is widely used by a number of Federal, State, and local agencies. Because ofits widespread use in government, databases generated by these agencies may be easily imported. In addition, databases that have been compiled using most of the common relational database management system programs may be easily imported and converted into ARC/ INFO flles. The PC ARC/INFO software has been acquired and installed and is currently operational.
Training of Two Staff Members in the Use of GIS Software
Two staff members attended a PC ARC/INFO starter course sponsored by the Center for
3

.Remote Sensing and Mapping Science (CRMS) at the University of Georgia. Topics addressed in the lectures and exercises included:
1. GIS applications and future trends in GIS;
2. basic functions and operations with PC ARC/INFO software;
3. data capture and editing, using the digitizer;
4. relational database construction, manipulation, and management with INFO;
5. relationship between INFO data files and graphic map features;
6. map overlay functions and map composition;
7. utilization of map overlay functions for spatial analysis, including environmental monitoring, resource management and urban planning applications;
8. optimum routing analysis. Compilation of Database Inventory
A catalog of available databases which contain spatial information for the coastal region of Georgia has been compiled (see Appendix 1). The catalog includes a yariety of earth science information (geologic maps, soils maps, digital elevation models, etc.), environmental data (wetland inventory maps, vegetation maps, etc.), and planimetric data (political boundaries, roads, etc.). Many of these databases are not directly related to mineral resource management issues and will not be included in the inventory of databases that will be imported. Additional databases that were not found during Year Six will be added to the catalog as they are identified.
Priorities for incorporation into the Georgia Coastal GIS have been assigned to all databases which were entered into the catalog. The priority categories are as follows:
1. Databases identified during Year Six that already exist in digital form and can be acquired without cost.
2. Databases identified during Year Six that do not currently exist in digital form but that can be readily digitized.
3. Databases identified during Year Six that already exist in digital form and for which there is a charge for acquisition. These data will be acquired as funds become available.
The following priorities for incorporation into the Georgia Coastal GIS will be assigned to databases identified after the end of Year Six:
4. Databases identified after Year Six which are relevant to coastal geology, that
4

already exist in digital form, and can be acquired without cost.
5. Databases identified after Year Six which are relevant to coastal geology, that do not currently exist in digital form, but that can be readily digitized.
6. Databases identified after Year Six which are relevant to coastal geology, that already exist in digital form, and for which there is a charge for acquisition. These data will be acquired as funds become available.
Inventory of Databases Needed for Making Environmental and Mineral Resource Decisions
An inventory of databases that will be entered into the GIS during Year Seven was selected from the catalog of databases listed in Appendix 1. The inventory includes those databases which will be immediately useful in the preparation of other maps and coverages, plus basic geologic framework data for the coast and continental shelfofGeorgia. The databases that will be imported are described below and are also summarized in Table 1.
Databases that have been incorporated into the Year Six Inventory include:
Priority 1: databases already in digital form
1. Base map showing coastal counties and approximately 200 miles of the continental shelf. This base map will be compiled from pre-existing digitized databases on the PRIME computer and imported to the PC-based GIS.
2. Digital Line Graph (DLG) files (hydrography and major roads), currently in digital form at a scale of 1:100,000. DLG ftles will be used alone or in combination to construct coverages of limited aerial extent. Manipulation of individual DLG files is more efficient in terms of computer storage than trying to manipulate a large base map. Less than one week should be necessary to import all coastal DLG files.
3. County boundaries and other political boundaries in the coastal region, currently in digital form at a scale of 1:250,000. Less than one week should be necessary to import these files.
4. Land use and land cover for the coastal region, currently in digital form at a scale of 1:250,000. Less than one week should be necessary for importing these files.
5. Geology digitized from the state geologic map at a scale of1:500,000. Less than one week should be needed for importing these files.
Priority 2: databases not currently in digital form
6. Lease tract/block boundaries, also known as "Official Protraction Diagrams," available through Minerals Management Service. This task may require up to one month.
5

Table 1. Databases included In the Year 81% Inventory.

CoveraRe_Name

Covera~e 'IVDe

Data TvDes

Prioritv

Scale (Ul

Source of Ua1a

Required Time

Coastal Counties Base Map

Composite

County outlines,

1

(line and

hydrography and

polygon data)

roads

1:100,000 and
1:250,000

USGS, compiled byGGS

1 month

Digital Une Graphs

Line data: DLGs

Hydrography and

1

roads

1:100,000

USGS

1week

County Boundaries

Polygon data

County boundaries

1

1:250,000

USGS

1 week

Land Use and Land Cover

Polygon data

Land use and land cover

1

1:250,000

USGS

1week

Geology
0\
Official Protraction Diagrams

Polygon data Polygon data

Digitized state geologic map
Boundaries for offshore lease tract blocks

1

1:500,000

GGS

2

1:250,000

MMS

1week 2months

Offshore

Une data

Offshore

2

NA

Georgia

2months

Geophysical

geophysical

State

Tracklines

tracklines

Univ.

Locations

Point data

Locations for

2

NA

GGS, USGS, 1 month

for Cores

COST and TACI'S

and NOAA

and Wells

cores, oil and

gas wells

Location of

Point data

Vibracore,

2

NA

Several

3months

Shallow

piston core,

different

Geologic

dredge and grab

sources

Samples

sample locations

Approximate time required for incorporation of the database into the GIS.

7. Location of offshore geophysical tracklines. This data will be obtained from various sources. The acquisition process may take several weeks. Digitizing this data at the required accuracy should take no more than one month.
8. Locations of COST wells, oil and gas test wells, TACTS cores, and wells drilled by the Georgia Geologic Survey, plus related information (e.g., types of lithologic and geophysical logs associated with each well). Acquiring the exact locations for these wells and cores should require no more than two weeks. Digitizing these points should require less than two weeks.
9. Location of offshore vibracore, piston core, dredge and grab samples relevant to studies of heavy minerals; not yet digitized. Acquiring this data may take up to two months, except for data which is already in GGS files. Actually digitizing this data and assigning attributes to the digitized points should require no more than one additional month.
Acquisition of Some of the Databases Identified in the Inventory
The acquisition of databases identified in the inventory began during the last quarter of 1989. Activities during Year Seven will be directed mostly toward acquiring the remainder of the databases that are listed in the inventory. Procurement of the bulk of the remaining databases will be an ongoing process. Emphasis will be placed on acquiring those databases directly related to mining and minerals, rather than on data related to other aspects ofcoastal geology, hydrology, and non-economic earth resources. Priority 1 databases listed above should be acquired during the first half of 1990. The materials from which the priority 2 databases will be digitized (including maps and reports from various sources) will also be acquired during the fli'st half of 1990. Digitizing of these materials will begin during the first quarter of 1990. Priority 3 databases will be acquired as they are needed, and as funds become available for their purchase. The present acquisition status of each database in the catalog of available databases is given in Appendix A.
Establishment of QA/QC Policy and Procedures
In order to maintain the accuracy, logical consistency and completeness of spatial data sets which are digitized at the Georgia Geologic Survey, standards for digital cartographic data quality have been established and will be maintained. The standard of acceptance should be based on an assessment of the fitness of a spatial data set for use (i.e., whether or not the accuracy of the data set meets its intended purpose), rather than on an arbitrary numerical threshold of quality. The development of quality assurance procedures will be an ongoing process, and the procedures outlined in this report will be revised as needed.
All data sets compiled by the GGS will be accompanied by a brief quality assessment statement (this will be stored on disk, along with the data set, as an ASCII text file). Topics addressed in this statement will include:
1. References to all data source materials (including dates), methods of derivation (e.g., whether the data was obtained by digitizing or through some other method) and transformation (e.g., rescaling, conversion from one projection to another, etc.),
7

where applicable, and dates of all information used to update the original source materials. Specific information on the map projection and geodetic control information used will also be reported.

2. Assessment of the positional accuracy of digitized map features (e.g., do locations for points, lines, arcs, and polygons on the digitized coverage match the locations of these features on the source materials), plus a description of the test employed to assess positional accuracy.

3. Determination of the topological consistency of digitized map features (e.g., do lines intersect only at permitted points, are there any duplicate arcs, etc., see Appendix B), plus a description of the method employed to assess topological consistency.

4. Assessment of the accuracy ofattributes associated with digitized map features, plus a description of the method used to assess attribute accuracy.

5. A description of the completeness of the data set, including relevant mapping criteria (e.g., minimum size thresholds for areas, widths, and lengths to be digitized.)

6. The report should indicate the person responsible for assessing the accuracy of each database. In most cases, accuracy assessment will be performed by the GIS specialist's supervisor.

The form of the quality assessment statement, as well as many of the testing procedures used to assess accuracy, are derived from standardsestablished by the National Committeefor Digital Cartographic Data Standards (1987). Specific testing procedures are described in Appendix B.

Development of Archiving and Backup Strategies

In order to protect data tiles from accidental loss, strategies have been developed for

archiving data tiles obtained from outside sources, as well as completed data flies and map

coverages which are compiled in-house. Backup procedures were also developed to protect working

flies from accidental loss. A summary of the current file backup and archiving strategy is presented

in Appendix C.



8

APPENDICES

APPENDIX A

Catalog of Available Databases as of 12/31/89

The following catalog contains a list ofdatabases that are relevant to various aspects ofcoastal geology. Many of these databases are only marginally useful in the management of coastal resources, and will not be imported into the Coastal GIS unless they are needed for specific projects. Databases that will be imported into the Coastal GIS are listed in the Compilation of Database
Inventory.

Each entry in the catalog contains the following information:

Title

title of the document, report, or file that contains the data

Priority: priority category, as previously defmed ~Compilation of Database Inventory)

Data type: a brief description of the most significant data types contained in the database

Source: agency or individual that compiled the data contained in the database

Scale (l:X): map scale of the database, expressed as a ratio (NA =not applicable)

Status:

information regarding the processing and acquisition of the data in each database (status as of December 31, 1989)

GEOLOGIC DATA

Geophysical Data

Title:

Bulletin 109: Seismic Investigation of the Phosphate-bearing, Miocene-age

Strata of the Continental Shelf of Georgia

Priority: 2

Data type: Offshore geophysical tracklines; analog data: single-channel, high-resolution

uniboom seismics, isopach and structure contour maps, references for core loca-

tions

Source: Georgia Geologic Survey (also Georgia State University)

Scale (l:X): Several different scales

Status: Report acquired, not digitized. Original data should be acquired from Georgia

State University.

Title:

MGG File Numbers 02010077 (Cruise CH051), 02010078 (Cruise CH052),

02010089 (Cruise CH001), 02130001 (Cruise AT251), 02130003 (Cruise

AT266), 02210001 (Cruise BE140)

Priority: 2

Data type: Offshore geophysical tracklines; analog data: navigation, bathymetry

Source: Woods Hole, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired.

Title:

MGG File Number 03030016 (Cruise AMC1167)

Priority: 2

Data type: Offshore geophysical trackline; analog data: navigation, bathymetry, magnetics,

gravity

9

APPENDIX A (Continued)

Source: NOAA, through National Geophysical Data Center Scale (l:X): NA Status: Not yet acquired

Title:

MGG File Number 04990020 (no cruise given)

Priority: 2

Data type: Offshore geophysical trackline; analog data: navigation, single-channel seismics

Source: U.S. Army, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

"Offshore LORAN Log" = working title (not yet published; publication expected

in July, 1990)

Priority: 2

Data type: Point data: LORAN locations for hardbottom environments

Source: Georgia DNR, Coastal Resources Division

Scale (l:X): NA

Status: Not yet acquired; in press

Title:

MGG File Numbers 01010001 (Cruise C0101), 01010002 (Cruise C0102)

Priority: 3

Data type: Offshore geophysical tracklines; digital data: navigation; analog data: naviga-

tion, single-channel seismics

. Source: Lamont (LOGO), through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number 01010141 (Cruise C1902)

Priority: 3

Data type: Offshore geophysical trackline; digital data: navigation, bathymetry, magnetics,

gravity; analog data: navigation, single-channel seismics

Source: Lamont (LDGO), through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number 01030135 (Cruise V2807)

Priority: 3

Data type: Offshore geophysical trackline; digital data: navigation, bathymetry, magnetics,

gravity; analog data: navigation, single-channel seismics

Source: Lamont (LOGO), through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title: Priority:

3MGG Flle Number020100.23 (Cruise CH046L01)

Data type: Offshore Geophysical Trackline; digital data: navigation, bathymetry, magnetics,

gravity; analog data: navigation, bathymetry, single-channel seismics

Source: Woods Hole, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number 302030014 (Cruise KN031L05)

Priority: 3

10

APPENDIX A (Continued)

Data type: Offshore Geophysical Trackline; digital data: navigation, bathymetry Source: Woods Hole, through National Geophysical Data Center Scale (l:X): NA Status: Not yet acquired

Title:

MGG File Numbers 02300002 (Cruise FA017L01), 02300006, (Cruise

FA025101), 02310001 (Cruise FL001L01), 02310002 (Cruise FL001L02)

Priority: 3

Data type: Offshore Geophysical Tracklines; digital data: navigation, gravity

Source: Woods Hole, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number 04990009 (no cruise given)

Priority: 3

Data type: Offshore Geophysical Trackline; digital data: navigation (unprocessed); analog

data: single-channel seismics

Source: U.S. Army, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number06280003 (Cruise FAY-018)

Priority: 3

Data type: Offshore Geophysical Trackline; digital data: navigation; analog data: naviga-

tion, bathymetry, single-channel seismics

Source: U.S. Geological Survey, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Numbers 06910003 (Cruise P483AT), 06910004 (Cruise P583AT)

Priority: 3

Data type: Offshore Geophysical Tracklines; digital data: navigation, bathymetry, gravity

Source: U.S. Geological Survey, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number 06990006 (Cruise TD1-6)

Priority: 3

Data type: Offshore geophysical trackline; digital data: navigation; analog data: navigation,

common depth point seismics.

Source: U.S. Geological Survey, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired.

Title:

MGG File Number 09050041 (Cruise KA939014)

Priority: 3

Data type: Offshore geophysical trackline; digital data: navigation, bathymetry

Source: U.S. Navy, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number 09100001 (Cruise KEATHLEY)

Priority: 3

11

APPENDIX A (Continued)

Data type: Offshore geophysical trackline; digital data: navigation, bathymetry, magnetics; analog data: bathymetry, magnetics
Source: U.S. Navy, through National Geophysical Data Center Scale (l:X): NA Status: Not yet acquired

Title:

MGG File Numbers 09100013 (Cruise KEA 07-68), 09100014 (Cruise KEA 08-

68)

Priority: 3

Data type: Offshore geophysical trackline; digital data: navigation, bathymetry, gravity

Source: U.S. Navy, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Numbers 09100021 (Cruise KEA 02-69), 09100022 (Cruise KEA

03-69), 09100026 (Cruise KEA 07-69)

Priority: 3

Data type: Offshore geophysical trackline; digital data: navigation, gravity

Source: U.S. Navy, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number 10020004 (Cruise IG1501)

Priority: 3

Data type: Offshore geophysical trackline; digital data: navigation, bathymetry, magnetics

Source: University of Texas, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number 60000018 (Cruise LSSALE56)

Priority: 3

Data type: Offshore geophysical trackline; digital data: navigation; analog data: navigation,

bathymetry, single-channel seismics, common depth point seismics, sidescan sonar

Source: Minerals Management Service, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Title:

MGG File Number 60090001 (Cruise ECOASTI9)

Priority: 3

Data type: Offshore geophysical trackline; digital data: navigation; analog data: navigation,

single-channel seismics, common depth point seismics

Source: Minerals Management Service, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

Maps

Title:

Geology

Priority: 1

Data type: Polygon data: geology

Source: USGS-WRD, GA District (GGS)

Scale (l:X): 500,000

Status: Processed, acquired by the Georgia Geologic Survey

12

APPENDIX A (Continued)

Title:

Geology

Priority: 1

Data type: Polygon data: geology

Source: USGS-WRD, GA District

Scale (l:X): 2,500,000

Status: Processed, acquired by DNR, Information Management

Title:

Soils- County

Priority: 1

Data type: Polygon data: soils

Source: USGS-WRD, GA District (originally from Georgia DNR)

Scale (l:X): Several different scales

Status: Currently being processed by USGS, some acquired by DNR.

Title:

Open-file Atlas of Mines, Pits, and Quarries for Georgia: Coastal Plain

Priority: 2

Data type: Point locations: mines, pits, and quarries

Source: Georgia Geologic Survey

Scale (l:X): 24,000

Status: Acquired, not digitized.

. / Title:

Bulletin 104: A Revision of the Lithostratigraphic Units of the Coastal Plain of

Georgia: the Miocene Through the Holocene

Priority: 2

Data type: Maps of marine terraces (generalized), outcrop/ subcrop of formations, type and

reference localities,structural and physiographic features, core and well sites

Source: Georgia Geologic Survey

Scale (l:X): Several different scales

Status: Acquired, not digitized

Title:

Information Circular 31: A Subsurface Study of Pleistocene Deposits in Coastal

Georgia

Priority: 2

Data type: Analog data: isopach map of Pleistocene sediments

Source: Georgia Geologic Survey

Scale (l:X): 2,000,000

Status: Acquired, not digitized

Title:

Environmental Impact Statement ES 52: Proposed 1981 Outer Continental Shelf

Oil and Gas Sale No. 56

Priority: 2

Data type: Maps related to physical oceanography, meteorology, environmentally sensitive

areas, undersea features, sea bottom sediments, geology, offshore leases, and

offshore drill sites.

Source: U.S. Department of the Interior, Bureau of Land Management

Scale (l:X): 1,000,000

Status: Acquired; not digitized

Cores, wells, and shallow samples

Title:

Project Report 14: Georgia Offshore Minerals Assessment Database

Priority: 1

13

APPENDIX A (Continued)

Data type: Point locations; associated depth, grain size, and heavy mineral percentage values
Source: Zellars-Williams Co. (produced for the Georgia DNR and MMS) Scale (l:X): NA Status: Acquired by the Georgia Geologic Survey

Title:

USGS OFR 89-559 (Preliminary) Phosphorite Potential in the Continental Shelf

off Georgia: Results of the TACI'S Core Studies

Priority: 2

Data type: Point locations: TACI'S cores, plus locations for other offshore deep stratigraphic

tests and associated data

Source: U.S. Geological Survey

Scale (l:X): NA

Status: Data acquired; not digitized

Title:

GGS Well Inventory

Priority: 2

Data type: GGS well identification number, county, driller, owner, and sample interval for

wells drilled in Georgia (see also GGS Well Record Book)

Source: Georgia Geologic Survey

Scale (l:X): NA

Status: Data acquired; not digitized

Title:

GGS Well Record Book

Priority: 2

Data type: Point locations (wells): GGS well identification number, county, driller, lease,

sample interval, location, elevation, and "elevation depth"(= depth below land

surface?) for wells in Georgia

Source: Georgia Geologic Survey

Scale (l:X): NA

Status: Acquired; not digitized

Title:

MGG File Number 01035007

Priority: 2

Data type: Point locations: offshore cores, by latitude and longitude, with descriptions

Source: Lamont-Doherty Geophysical Observatory, Through National Geophysical Data

Center)

Scale (l:X): NA

Status: Not yet acquired, except for locations

/ Title:

Bulletin 110: Distribution of Heavy Mineral Sands Adjacent to the Altamaha

Sound: a Possible Exploration Model

Priority: 2

Data type: Point data: location of grab, auger, and trench samples, with mean percentages of

constituents; depositional environment maps

Source: Georgia Geologic Survey

Scale (l:X): NA

Status: In preparation, not digitized

J Title:

Evaluation of Heavy Mineral-bearing Nearshore Sands, Altamaha and the adjacent

Nearshore Zone, Georgia

Priority: 2

Data type: Point data: vibracore locations, heavy mineral percentages (total by mineral)

14

APPENDIX A (Continued)

Source: Georgia Geologic Survey Scale (l:X): 250,000 Status: In preparation; not digitized

Title:

Information Circular 77: Petroleum Exploration Wells in Georgia 1979-1984

Priority: 2

Data type: Point locations: oil test wells drilled between 1979 and 1984, plus related data

Source: Georgia Geologic Survey

Scale (l:X): Several different scales

Status: Acquired, not digitized

Title:

Information Circular 51: Petroleum Exploration Wells in Georgia

Priority: 2

Data type: Point locations: oil tests (map, locations by latitude and longitude, miscellaneous

well information)

Source: Georgia Geologic Survey

Scale (l:X): 1,095,957

Status: Acquired, not digitized

Title:

Information Circular 38: Petroleum Exploration in Georgia

Priority: 2

Data type: Point locations: oil and gas tests 1903-1970

Source: Georgia Geologic Survey

Scale (l:X): 1,095,957

Status: Acquired, not digitized

Title:

Information Circular 19: Oil Tests in Georgia

Priority: 2

Data type: Point locations: oil test wells (map)

Source: Georgia Geologic Survey

Scale (l:X): 1,030,244

Status: Acquired, not digitized

Title:

MGG File Number 03995999

Priority: 2

Data type: Point locations: piston cores and grab samples; lithology and geologic age

Source: Atlantic Oceanographic and Meteorological Labs (through National Geophysical

Data Center)

Scale (l:X): NA

Status: Not yet acquired, except for locations

Title:

MGG File Number 01995999

Priority: 2

Data type: Point locations: offshore cores, by latitude and longitude, with age and lithology

of cores in MGG File 01035007

Source: Lamont-Doherty Geophysical Observatory (through National Geophysical Data

Center)

Scale (l:X): NA

Status: Not yet acquired, except for locations

Title:

MOO File Number 06025001

Priority: 2

15

APPENDIX A (Continued)

Data type Point locations: dredge or grab samples, with texture data Source: USGS-Woods Hole, through National Geophysical Data Center Scale (l:X): NA Status: Not yet acquired, except for locations

Title:

MGG File Number 60925001

Priority: 2

Data type: Point location: core, with core description, organic geochemistry, paleontology,

geologic age, well logs, and geotechnical information

Source: Minerals Management Service, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired, except for location

Title:

MGG File Number 66995999

Priority: 2

Data type: Point locations: sediment drill (with lithology and age), and grab samples

Source: USGS, Atlantic-Gulf Branch ofMarine Geology, through National Geophysical

Data Center

Scale (l:X): NA

Status: Not yet acquired, except for locations

Title:

Bulletin 70: Well Logs of the Coastal Plain of Georgia

Priority: 2

Data type: Point locations: well locations, plus well logs

Source: Georgia Geologic Survey

Scale (l:X): 1,003,723

Status: Acquired, not digitized

Title:

Bulletin 74: Logs of Selected Wells in the Coastal Plain of Georgia

Priority: 2

Data type: Point locations: well locations, plus well logs of varying accuracy

Source: Georgia Geologic Survey

Scale (l:X): 3,060,407

Status: Acquired, not digitized

Title:

Bulletin 76: Subsurface "Basement" Rocks of Georgia

Priority: 2

Data type: Point Locations: wells penetrating to basement, plus lithologic logs

Source: Georgia Geologic Survey

Scale (l:X): 1,000,000

Status: Acquired, not digitized

Title:

Information Circular 56: Geologic Data of the Gulf Trough Area, Georgia

Priority: 2

Data type: Point Locations: well locations by latitude and longitude, well descriptions

location map

Source: Georgia Geologic Survey

Scale (l:X): 500,000

Status: Acquired, not digitized

Title:

Information Circular 25: Subsurface Geology of the Georgia Coastal Plain

Priority: 2

16

APPENDIX A (Continued)

Data type: Point data: locations of logged wells; Line data: thickness distribution (isopach)
and structure contour maps Source: Georgia Geologic Survey Scale (l:X): 1,000,000 Status: Acquired, not digitized

Title:

MGG File Number 02045001

Priority: 2

Data type: Point location: dredge sample, with location and description

Source: Woods Hole Oceanographic Institute, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired, except for location

Title:

Manganese Phosphorites of the Blake Plateau (in Marine Mineral Deposits)

Priority: 2

Data type: Point data: sample location, bathymetry, geochemistry, mineralogy (manganese),

geologic age, sediment chemistry and properties

Source: Data available through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired, except for location

Title:

Assorted Papers Associated with Cruise SP-AMC-11-67 Aboard Discoverer

Priority: 2

Data type: Point data: sample location, bathymetry, geochemistry (manganese)

Source: Data available through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired, except for location

Title:

MMBffi: USGS WH 8602

Priority: 2

Data type: Point data: sample locations, bathymetry, geochemistry (manganese)

Source: USGS, through National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired, except for locations

Multiple data types

Title:

COST Well GE-l

Priority: 3

Data type: Well logs, COST (Continental Offshore Stratigraphic Test) Well GE-l; depth, well

logs, core and sidewall cores, lithology, petrography, grain density, paleontology,

biostratigraphy, Rb-Sr ages, DST reports, miscellaneous additional data,

location

Source: NOAA Environmental Data and Information Service

Scale (l:X): NA

Status: Not yet acquired

J Title:

Bulletin 111: Heavy Mineral-bearing Sands from the Wicomico to Princess Anne

Paleobarrier Complexes along the Georgia Coastal Plain

Priority: 2

Data type: Analog maps: paleobarrier island shorelines, Pleistocene barrier complexes,

geomorphology of Pleistocene - Recent barrier islands, sample locations (with

17

APPENDIX A (Continued)

heavy mineral percentages), traverses Source: Georgia Geologic Survey Scale (l:X): Several different scales Status: In preparation: not digitized

Title:

Bulletin 87: Symposium on the Petroleum Geology of the Georgia Coastal Plain

Priority: 2

Data type: Maps (basement configuration, well location, isopach, structure contour. bouguer

gravity anomaly), tracklines for shallow, high-resolution seismics

Source: Georgia Geologic Survey

Scale (l:X): Several different scales

Status: Acquired; not digitized

Title:

Bulletin 82: Stratigraphy and Economic Geology of the Eastern Chatham County

Phosphate Deposit

Priority: 2

Data type: Point locations: cores; maps: structure contour, isopach, and economic

phosphate; lithologic core logs

Source: Georgia Geologic Survey

Scale (l:X): 177,408

Status: Acquired, not digitized

Title:

Bulletin 108: Construction Material Potential of the Coastal Plain of South-

eastern Georgia: An evaluation

Priority: 2

Data type: Polygon data: sandy soil areas, physiographic provinces. potential for aggregate

production, geology. geomorphic features; point locations: deposits, sampling

localities

Source: Georgia Geologic Survey

Scale (l:X): Several different scales

Status: Acquired; not digitized

Title:

Information Circular 53: Second Symposium on the Geology of the Southeastern

Coastal Plain

Priority: 2

Data type: References for information on geophysical tracklines, deep stratigraphic tests,

geologic hazards, pipeline corridors, structure contour and isopach maps

Source: Georgia Geologic Survey

Scale (l:X): NA

Status: References only; data not acquired

HYDROLOGY AND HYDROGRAPHY

Title:

Digital Line Graph Data for Georgia: Hydrography

Priority: 1

Data type: Line data: DLG, hydrography

Source: USGS-WRD, GA District (NCIC)

Scale (l:X): 100,000

Status: Processed, acquired by Georgia Geologic Survey

Title:

Water Use Sites- Withdrawals

Priority: 1

18

APPENDIX A (Continued)

Data type: Point locations: water use sites Source: USGS-WRD, GA District Scale (l:X): NA Status: Processed, acquired by DNR, Information Management

Title:

Clayton, Claiborne, and Floridan Depth to Aquifer

Priority: 1

Data type: Line data: depth to aquifer

Source: USGS-WRD, GA District, and GGS

Scale (l:X): 500,000

Status: Processed, acquired by DNR, Information Management

Title:

Floridan Aquifer Potentiometric Surface I Flow Direction

Priority: 1

Data type: Line data: potentiometric and flow

Source: USGS-WRD, GA District

Scale (l:X): 500,000

Status: Processed, acquired by DNR, Information Management

Title:

Most Significant Recharge Areas

Priority: 1

Data type: Polygon data: recharge areas

Source: USGS-WRD, GA District (originally from GGS)

Scale (l:X): 500,000

Status: Processed, acquired by DNR, Information Management

Title:

Stream Gaging Stations

Priority: 1

Data type: Point locations: stream gaging stations

Source: USGS-WRD, GA District

Scale (l:X): NA

Status: Processed, acquired by DNR, Information Management

Title:

Surface Water Quality Stations

Priority: 1

Data type: Point locations: surface water quality stations

Source: USGS-WRD, GA District (NWIS)

Scale (l:X): NA

Status: Processed, acquired by DNR, Information Management

Title:

Water Use Sites- Discharges

Priority: 1

Data type: Point locations: water use sites

Source: USGS-WRD, GA District (NPDES)

Scale (l:X): NA

Status: Processed, acquired by DNR, Information Management

Title:

Public Lands: Lakes, Reservoirs

Priority: 1

Data type: Polygon data: lakes

Source: USGS-WRD, GA District (NCIC)

Scale (l:X): 2,000,000

19

APPENDIX A (Continued)

Status: Processed, acquired by DNR, Information Management

Title:

USFWS Wetlands Maps

Priority: 2

Data type: Paper maps: land classified as wetlands for the following 1:100,000 scale quad-

rangles: Beaufort, Brunswick, Fernandina Beach, Hazlehurst, Jesup, Okeefenokee

Swamp, Savannah, Wassaw Sound, Waycross

Source: U.S. Fish And Wildlife Service

Scale (l:X): 100,000

Status: Distribution maps available; not yet acquired

Title:

Digital National Wetland Inventory Maps

Priority: 3

Data type: Line and polygon data: wetland areas, for the following 1:24,000 scale quad-

rangles: Burroughs, Cumberland Island South, Fernandina Beach, Garden City,

Glennville, Glennville NE, Glissons Millpond,Harrietts Bluff, Hinesville, Letford,

Limerick NW, Meldrim SE, Me:ldrim SW, Richmond Hill, Savannah, Taylors

Creek, Trinity, Waltherville, Willie

Source: U.S. Fish And Wildlife Service

Scale (l:X): 24,000

Status: Not yet acquired

Title:

NOS Digital Shoreline Data: Georgia (C8)

Priority: 3

Data type: Line data: shoreline

Source: NOAA/NOS, Carting and Geodetic Service

Scale (l:X): "Large scale,. (see product information)

Status: Not yet acquired

Title:

NOS Digital Shoreline Data: Small Scale, East Coast, (Dl)

Priority: 3

Data type: Line data: shoreline

Source: NOAA/NOS, Carting and Geodetic Service

Scale (l:X): "Small scale" (see product information)

Status: Not yet acquired

Title:

NOS Digital Shoreline Data: South Carolina (Cl)

Priority: 3

Data type: Line data: shoreline

Source: NOAA/NOS, Carting and Geodetic Service

Scale (l:X): "Large scale" (see product infonnation)

Status: Not yet acquired

INFRASTRUCTURE

Title:

Digital Line Graph Data for Georgia: Major Roads

Priority: 1

Data type: Line data; DLGs, major roads

Source: USGS-WRD, GA District

Scale (l:X): 100,000

Status: Processed, acquired by Georgia Geologic Survey

20

APPENDIX A (Continued)
Title: Digital Line Graph Data for Georgia: Roads, Trails Priority: 1 Data type: Line data; DLGs, roads and trails Source: USGS-WRD, GA District (NCIC) Scale (l:X): 100,000 Status: Processed, acquired by Georgia Geologic Survey
Title: Digital Line Graph Data for Georgia: Pipelines Priority: 1 Data type: Line data; DLGs, pipelines Source: USGS-WRD, GA District (NCIC) Scale (l:X): 100,000 Status: Processed, acquired by Georgia DNR, Information Management
Title: Digital Line Graph Data for Georgia: Railroads Priority: 1 Data type: Line data; DLGs, railroads Source: USGS-WRD, GA District (NCIC) Scale (l:X): 100,000 Status: Processed, acquired by Georgia DNR, Information Management
LAND USE AND LAND COVER
Title: Land Use and Land Cover - Level I Priority: 1 Data type: Polygon data; land use Source: USGS-WRD, GA District Scale (l:X): 250,000 Status: Processed, acquired by DNR, Information Management
Title: Land Use and Land Cover- Level II Priority: 1 Data type: Polygon data; land use Source: USGS-WRD, GA District Scale (l:X): 250,000 Status: Processed, acquired by DNR, Information Management
POLITICAL DATA: GEOGRAPHIC NAMES AND BOUNDARIES
Title: Geographic Names Priority: 1 Data type: Point locations: geographic names Source: USGS-WRD, GA District (NCIC) Scale (l:X): NA Status: Processed, Acquired by DNR, Information Management
Title: County Boundaries Priority: 1 Data type: Polygon data: county boundaries Source: USGS-WRD, GA District (NCIC) Scale (l:X): 250,000
21

APPENDIX A (Continued)

Status: Processed, acquired by DNR, Information Management

Title:

Public Lands: Military Reserves

Priority 1

Data type: Polygon data: military reserves

Source: USGS-WRD, GA District (NCIC)

Scale (l:X): 2,000,000

Status: Processed, acquired by DNR, Information Management

Title:

Public Lands: State Parks

Priority: 1

Data type: Polygon data: state parks

Source: USGS-WRD, GA District (EPD- GNHI)

Scale (l:X): 24,000

Status: Processed, acquired by DNR, Information Management

Title:

Public Lands: National Parks

Priority: 1

Data type: Polygon data: national parks (includes Ft. Pulaski, Ft. Frederica)

Source: USGS-WRD, GA District (originally from NPS)

Scale (l:X): 24,000

Status: USGS is acquiring maps: not digitized

Title:

Official Protraction Diagrams (OPDs)

Priority: 2

Data type: Polygon data: OPDs (boundaries for offshore lease tracts)

Source: Minerals Management Service

Scale (l:X): 250,000

Status: Data acquired; not yet digitized

TOPOGRAPHY AND BATHYMETRY

Title:

Digital Elevation Model Data for Georgia: Elevation Data

Priority: 1

Data type: Polygon data: Digital Elevation Model (OEM), elevation, 60 m. resolution

Source: USGS-WRD, GA District (NCIC)

Scale (l:X): 250,000

Status: Some processed in-house at USGS, none acquired (Note: the Coastal GIS does not

currently have the correct PC ARC/INFO module for processing OEM data. This

software is available, and could be acquired if needed.)

Title:

Digital Elevation Model Data for Georgia: Elevation Data

Priority: 1

Data type: Polygon data: Digital Elevation Model (OEM), elevation, 2700 ft. resolution

Source: USGS-WRD, GA District (NCIC)

Scale (l:X): 250,000

Status: Processed, acquired by DNR, Information Management (see note, above)

Title:

Digital Elevation Model Data for Georgia: Slope Class

Priority: 1

Data type: Polygon data: Digital Elevation Model (OEM), slope class

Source: USGS-WRD, GA District (NCIC)

22

APPENDIX A (Continued)

Scale (l:X): 250,000 Status: Some processed in-house at USGS, none acquired (see note above)

Title:

Bulletin 98: Historical Changes in the Mean High Water Shoreline of Georgia,

1857- 1982

Priority: 2

Data type: Nearshore and shelf bathymetry, shelf topography, shoreline changes and net

erosion/accretion maps

Source: Georgia Geologic Swvey

Scale (l:X): Several different scales

Status: Acquired; not digitized

Title:

NOS Hydrographic Database

Priority: 3

Data type: Point data: bathymetry

Source: NOAA, National Geophysical Data Center

Scale (l:X): NA

Status: Not yet acquired

23

APPENDIXB
Quality Assurance Testing Procedures and Accuracy Assessment
Assessment of Positional Accuracy
An assessment of the positional accuracy ofpoints, lines, and polygons should be made for each map coverage digitized in-house. The assessment should include an assessment of the accuracy of the source or sources from which the coverage was digitized, as well as an evaluation of the accuracy of the digitizing process used to create the coverage (including any testing procedures employed). The relationship of map coordinates to a specific map projection should be clearly expressed. The geodetic standards, datum and map scale used should be recorded. Any transformations used to produce the final product should be documented. Digital map coverages that were prepared using different projections, scales, geographic data, and values of magnetic declination should be transformed to the same projection, etc. before being merged in order to reduce errors.
Whenever possible, the magnitude of errors and uncertainty associated with the field location of points (e.g., core and sample locations), lines (contours, faults, formation contacts), and polygonal areas should be estimated. Any assumptions made concerning error propagation during the field mapping process should be stated. Methods used for locating points and elevations on maps (e.g., surveying, LORAN, deductive estimate) should be reponed if this information is available.
Positional accuracy for digitized coverages can be assessed using one or more of the tests listed below. The most rigorous testing procedure is listed first, and the least rigorous test is presented last (this format will be used throughout the remainder of this appendix). Whenever possible, the most rigorous test feasible should be used to determine fitness for use. The results of each test, as well as any geometric or numerical thresholds of tolerance applied, should be reported.
1. Comparison to an Independent Source of Higher Accuracy.
This test is generally applicable to only well-defined points. For example, it may be possible to check the location ofpoints digitized from a map (such as benchmarks, political boundary intersections, etc.) against the location of these points as determined by an accurate survey. Refer to the National Committee for Digital Cartographic Data Standards (1987) for test guidelines.
2. Comparison to the Original Data Source.
In cases where the coverage has been digitized from a drafted map (or maps), the positional accuracy can be checked visually by overlaying the digitized coverage onto the original map. If the coverage contains points that have been plotted from a tabular database of map coordinates, the coordinates of the points that have been plotted should be compared to the original coordinates in the database. Where feasible, all such points should be checked. If this is impractical, points that will be spot checked should be randomly selected, recorded, and the test result for each point reported.
3. Deductive Estimate.
For coverages where methods 1 and 2 (above) are not practical, a deductive estimate of the accuracy of the coverage may be acceptable. For instance, it may not be possible to directly compare a final map coverage to the original data source (e.g., another map) if the map has been rescaled or has been otherwise transformed since it was first digitized. Such estimates are usually based on the knowledge and experience of the individual assessing the accuracy of the coverage. Whenever the accuracy of a coverage is assessed by deductive estimate, the specific basis for the deduction should be explained. Errors inherent in each production step, assumptions concerning propagation of errors, and calibration tests employed in the digitizing process should be addressed.
24

APPENDIX B (Continued)
Assessment of Attribute Accuracy
Attributes are descriptive data that are assigned to each point, line, or polygon on a map. Examples of attributes include lengths associated with line segments, areas associated with polygons, and descriptive tenns that can be associated with points,lines, orpolygons to distinguish them from other points, lines and polygons. Specific tests which can be used to determine attribute accuracy are described below.
1. Comparison to a Source of Higher Accuracy.
Attributes of digitized features whose real-world values have been accurately surveyed or otherwise determined, such as the length of political boundaries and the areas enclosed by these boundaries, can be compared to the values calculated from the survey. All tolerance thresholds should be reported, and the source of higher accuracy should be adequately referenced. This test is valid only for quantitative attribute information. Non-quantitative, descriptive attributes must be checked using another method.
2. Comparison to the Original Data Source.
Comparison of the attributes of digitized features to attributes in the original data source is an appropriate test for both quantitative and non-quantitative atttibutes. For example, this procedure might be used to determine whether polygonal areas that represent specific land use categories have been correctly classified and labeled, and whether the area enclosed by each digitized polygon agrees with previous area calculations.
3. Deductive Estimate.
In some cases, it may not be possible to directly compare attributes in a coverage to either an independent source of higher accuracy or to the original source of the data used to create the coverage. This may often be true for coverages created as the end product of spatial analysis. In such cases, an estimate ofattribute accuracy based on the knowledge and experience ofthe individual may be sufficient. When the deductive method is used, the basis for the deduction, including acceptance or rejection criteria, must be explained.
Determination of Topological Consistency
Tests for topological consistency are used to determine the fidelity of geometric relationships among lines (arcs), nodes (endpoints and intersection points of arcs), and polygons. These relationships include connectivity of arcs and nodes and the contiguity (adjacency) of polygons. A coverage is topologically consistent (or "clean") if all of the following conditions are met:
1. Arcs intersect only at nodes.
2. No lines are entered twice.
3. There are no arcs that overshoot or undershoot intended intersections.
4. All areas are completely described by arcs (i.e., the polygon is closed).
5. No polygons or lines are below minimum size thresholds.
25

APPENDIX B (Continued) 6. Cycles ofchains (arcs with a directional component) and nodes are consistent around polygons, or cycles of chains and polygons are consistent around nodes. PC ARC/INFO software contains procedures for insuring that the above conditions are met, and these procedures should be used whenever a coverage is created or modified. All of these procedures for building and maintaining topology require that tolerances are specified for minimum lengths of overshoots ("dangling arcs"), minimum distances between inter-arc and intra-arc coordinates, and minimum distances between nodes. These tolerances should be specified in the quality assessment report.
26

APPENDIXC

Computer File Backup Procedures and Policy

Archiving of "source" databases

(Coverages/files imported from outside sources; not digitized "in-house".)

a. Two separate copies should be made of all such files for archival purposes. One copy should be made for use as a "working copy: and will be kept at the Coastal GIS facility. A separate copy should be stored in another location, possibly in the Information Management Office ofthe Environmental Protection Division, Georgia Department of Natural Resources, or at the U.S. Geological Survey office in Doraville. This will insure the security of the "source" files in the event of a fire or other disaster. Maintaining a third copy at yet another location is recommended.

b.
protected.

Tapes and diskettes on which these "source" files are maintained should be write-

c. The GIS specialist will be responsible for maintaining the database archives.

Backup of coverages digitized "in-house"

a. While map coverages are being digitized, all files that are being modified should be backed up at the end of the day. If work is interrupted for an extended period of time (more than 1/2 hour) during a GIS work session, the files that are being used should be backed up.

b. Global backups of the entire hard disk should be made at the end of every week, preferably more frequently.

c. Backup copies (for archival purposes) should be made (as in part 1, above) for every coverage completed in-house.

d. The GIS specialist will be responsible for backing up files in accordance with the procedure outlined above.

27

REFERENCE
National Committee for Digital Cartographic Data Standards, 1987, Digital Cartographic Data Quality,
inMoellering, Harold, ed., ADraft Proposed Standardfor Digital Cartographic Data: Issues inDigital
Cartographic Data Standards, Report No. 8, Part ill, Nat Comm. Digital Cartog. Data Standards, Columbus, OH, p. 1-6.
28