U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2007–3076 

September 2007

Geographic Information Systems, Remote Sensing, and 

Spatial Analysis Activities in Texas, 2002–07

Printed on recycled paper

Geographic information system (GIS) technology has 

become an important tool for scientific investigation, resource 

management, and environmental planning. A GIS is a computer-aided system capable of collecting, storing, analyzing, 

and displaying spatially referenced digital data. GIS technology 

is particularly useful when analyzing a wide variety of spatial 

data such as with remote sensing and spatial analysis. Remote 

sensing involves collecting remotely sensed data, such as satellite imagery, aerial photography, or radar images, and analyzing 

the data to gather information or investigate trends about the 

environment or the Earth’s surface. Spatial analysis combines 

remotely sensed, thematic, statistical, quantitative, and geographical data through overlay, modeling, and other analytical 

techniques to investigate specific research questions. It is the 

combination of data formats and analysis techniques that has 

made GIS an essential tool in scientific investigations.

This document presents information about the technical 

capabilities and project activities of the U.S. Geological Survey 

(USGS) Texas 

Water Science 

Center (TWSC) 

GIS Workgroup 

from 2002 

through 2007. 

GIS Workgroup

The USGS Texas GIS Workgroup is comprised of geographers, hydrologists, and geologists in both the Water Resources 

and Geography disciplines who specialize in GIS, remote sensing, and spatial analysis. We collaborate with resident hydrologists, hydrogeologists, water-quality specialists, limnologists, 

biologists, geologists, and geographers on a diverse range of 

projects. There is emphasis on technical training to keep skills 

current with advances in software and technology. Some of our 

technical capabilities include 

Spatial data production

Spatial database administration and management

Spatial data analysis and modeling

Spatial data visualization

Land cover / Land use mapping

Watershed delineation and characterization

Programming / Custom tools 

The USGS Texas GIS Workgroup actively 

participates and collaborates with local, State, 

national, and international members of the GIS 

community. We regularly contribute to the 

knowledge base through presentations and publications. Several GIS projects have been presented at conferences such as the Association 

of American Geographers (AAG) Annual 

Meeting, Environmental Systems Research 

Institute, Inc. (ESRI) International Users 

Conference, Texas GIS Forum, and TWSC 

Technical Talk Series.

Project Activities

GIS project activities in the TWSC have steadily 

increased over the past 6 years. All projects mentioned 

below, by fiscal year, have a substantial GIS, remote sensing, 

and/or spatial analysis component. This is not a comprehensive 

list of projects, but it highlights the skills and capabilities of the 

GIS Workgroup and shows the increased importance of GIS, 

remote sensing, and spatial analysis in USGS projects over time. 

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After 

a brief 

summary 

of the GIS 

Workgroup 

capabilities, the details 

of project activities at both the national 

and local level are described. Projects are 

grouped by the fiscal year (FY) the project 

ended and include overviews, project images, 

and Internet links to additional project material and related publications or articles.
FY 2002

Texas Source Water Assessment Project

This project was developed in cooperation with the Texas Commission on 

Environmental Quality (TCEQ) to address 

the 1996 Amendments to the Safe Drinking 

Water Act which mandated that each state 

prepare source water assessment program 

(SWAP) documentation of all public water 

supplies (PWS). States were required to 

determine the drinking-water source, the origin of contaminants 

monitored and the potential contaminants to be monitored, 

and the intrinsic susceptibility of the source water. Under the 

amendments to the act, states created SWAPs to provide an 

individual source water assessment for each PWS regulated by 

the State and determined whether an individual drinking water 

source is susceptible to contamination. The USGS designed and 

developed database structures, assessment software, and technical documentation specifically designed to support staff in the 

performance of source water assessments on TCEQ computers. 

2001 USGS Fact Sheet 101–00: http://pubs.usgs.gov/fs/fs101-00/

FY 2003

Geodatabase of Texas Springs

This project was developed in cooperation with the Texas Water Development 

Board (TWDB) to aggregate and organize 

site and flow information for springs in 

Texas using selected digital and hard-copy 

data sources. Spatial and tabular data were 

organized into a geodatabase and represent 

more than 2,000 springs and 7,000 springflow measurements.

2003 USGS Open-File Report 03-315: http://pubs.usgs.

gov/of/2003/ofr03-315/

Digital Geologic Atlas of Texas 

This project was developed in cooperation with the Texas Water Development 

Board (TWDB) to produce a library of 38 

ESRI personal geodatabases representing 

the original 38 University of Texas Bureau 

of Economic Geology map sheets. The 

digital conversion of the original hardcopy 

map sheets began October 2002. Project 

planning among the USGS team established the need to use the personal geodatabase format for this 

procedure. This data format would allow for all the original map 

data (for example, geologic time, formation descriptions) to be 

stored in a single database location with the geographic features.

Project Web site: http://tx.usgs.gov/GAT/ 

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FY 2004

Geodatabase of Water-Level Declines in Springs Associated with 

Eurycea Salamander Habitats

This project was developed in cooperation with the U.S. Fish and Wildlife Service (USFWS) to associate projected waterlevel declines in the middle zone of the 

Trinity aquifer with Eurycea salamander 

habitats in springs and caves. Digital elevation models (DEMs) were used to assign 

elevations to individual spring locations, 

and a unique querying method was developed to determine the 

aquifer responsible for each spring, using aquifer geodatasets 

of the Source Water Assessment Program (SWAP). Projected 

water-level declines were available from a ground-water availability model (GAM) released by the Texas Water Development 

Board (TWDB). Spatial and tabular data were organized into a 

geodatabase.

2007 USGS Data Series 243: http://pubs.usgs.gov/

ds/2007/243/ 

Land-Cover and Imperviousness Data for NAWQA Effects of 

Urbanization on Stream Ecosystems (EUSE) Project

As part of the USGS NAWQA EUSE 

project, land cover and imperviousness data 

were produced primarily from Landsat-7 

ETM+ satellite imagery for 1999–2002, 

using methodologies developed by the 

USGS National Landcover Database 2001 

Program. These data are available online 

and provided as 30-meter-resolution raster 

datasets. In addition to the land-cover and imperviousness 

surface derivation, statistics for several hundred GIS-derived 

datasets were calculated to characterize population, socioeconomic, and infrastructure variables for 29 basins in the DallasFort Worth study area.

2006 USGS Data Series 221: http://pubs.usgs.gov/

ds/2006/221/

Geologic Map Compilation of the Upper Seco Creek Area, 

Medina and Uvalde Counties, South-Central Texas

This digital geologic map compilation 

presents new polygon (map unit contacts) 

and line (faults) vector data for the Seco 

Creek area in south-central Texas. The 

map database, which is at 1:50,000-scale 

resolution, shows the geology for an area 

in Medina County about 25 kilometers 

northwest of San Antonio. The impetus 

for compiling the geology of the four 7.5-minute-quadrangle 

(Comanche Waterhole, Flatrock Crossing, Sabinal NE, and 

Texas Mountain) area was to provide a digital geologic map 

database for a helicopter electromagnetic (HEM) survey flown 

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in 2002 and for ongoing 3-D EarthVision modeling of the 

boundary between the Edwards aquifer and Trinity aquifer.

2004 USGS Open-File Report 2004–1430: http://pubs.usgs.

gov/of/2004/1430/

FY 2005

Geodatabase and 3D Conceptual Model for Air Force Plant 4 and 

Naval Air Station Carswell Field, Fort Worth, Texas

The USGS, in cooperation with the 

U.S. Air Force, developed a geodatabase 

and three-dimensional model to improve 

understanding of the geology, hydrology, 

and contaminant occurrence at Air Force 

Plant 4 (AFP4) and adjacent Naval Air 

Station-Joint Reserve Base Carswell Field 

(NAS–JRB). Contaminants from the 3,600-

acre facility, primarily volatile organic compounds (VOCs) and 

metals, have entered the ground-water-flow system through 

leakage from waste-disposal sites and from manufacturing 

processes. Environmental data collected at AFP4 and NAS–JRB 

during 1993–2002 from several sources in distinct formats created the need for consolidation of the data into a comprehensive 

temporal and spatial geodatabase that supports a range of hydrologic, geologic and water quality data. A three-dimensional 

conceptual model of the hydrogeologic units integrally linked to 

the geodatabase was concurrently designed. 

2005 USGS Open-File Report 2005–1041: http://pubs.usgs.

gov/of/2005/1041/

2004 USGS Scientific Investigations Report 2004–5062: 

http://pubs.usgs.gov/sir/2004/5062/

2004 USGS Fact Sheet 2004–3063: http://pubs.usgs.gov/

fs/2004/3063/

Geodatabase of Water Quality for Major Springs in Texas

This project was developed in cooperation with the Texas Parks and Wildlife 

Department (TPWD) to aggregate and organize water-quality information for major 

springs in Texas using selected digital and 

hardcopy data sources. Spatial and tabular 

data were organized into a geodatabase. In 

addition, water-quality data were spatially 

assessed for level III ecoregions in Texas.

2006 USGS Data Series 230: http://pubs.usgs.gov/

ds/2006/230/

Digital Geologic Atlas of Texas—Statewide Compilation

This project was developed in cooperation with the Texas Water Development 

Board (TWDB) to produce the Statewide 

Digital Geologic Atlas of Texas (GAT), 

which would combine the 38 personal geodatabases from Phase I (FY 2003–04) of this 

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project into one ESRI ArcSDE geodatabase containing more 

than 145,000 geologic features.

Project Web site: http://tx.usgs.gov/GAT/

Geologic Map of the Edwards Aquifer Recharge Zone, SouthCentral Texas

Efforts by a National Cooperative 

Geologic Mapping Program project to 

compile the geology of the Edwards aquifer 

recharge zone in south-central Texas have 

helped to refine the hydrostratigraphy of 

one of the most permeable and productive 

carbonate aquifers in the United States. 

These data illustrate the detailed geographic 

extent of the stratigraphic units and faulting for the Edwards 

aquifer recharge zone in south-central Texas.

2005 USGS Scientific Investigations Map 2873: http://pubs.

usgs.gov/sim/2005/2873/

FY 2006

Border Environmental Health Initiative (BEHI): Years 1 & 2

This multidisciplinary USGS project 

focused on developing an integrated, Webbased, environmental resource database 

for display and further analysis within a 

GIS framework. This information system 

provides the needed data and tools for furthering our understanding of the occurrence 

and distribution of disease-causing agents in 

the environment and their specific exposure pathways in water, 

air, biota, and soil. Efforts concentrated on establishing methodologies for integrating binational base data layers, developing 

a project Web site with supporting documentation and project 

information, and creating the border-wide Internet Mapping 

Service.

2004 USGS Fact Sheet 2004–3140: http://pubs.usgs.gov/

fs/2004/3140/

Project Web site: http://borderhealth.cr.usgs.gov/

Internet Mapping Service: http://gisdata.usgs.gov/website/

BorderHealth/

USIBWC Internet Map Service

The USGS, in cooperation with the 

U.S. Section, International Boundary and 

Water Commission (USIBWC), developed 

and implemented an interface between the 

USIBWC GIS and the Water Accounting 

Division’s streamflow-gaging information 

and the Texas Clean Rivers Program waterquality monitoring program. An interactive 

map displays the location of streamflow gages and water-quality 

monitoring sites, providing public access to data collected by 

both the Texas Clean Rivers Program and the Water Accounting 

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Division. The interactive map provides an open-access link to 

the data and the ability to query the data. 

Internet Mapping Service: http://gisdata.usgs.gov/website/

ibwc/

National Land Cover Database (NLCD 2001) – Zone 32

This project was developed in cooperation with the Earth Resources and 

Observation Science (EROS) Data Center 

to produce land cover data for mapping 

zone 32, which covers parts of northern 

Texas, Kansas, and Oklahoma. The NLCD 

2001 was created by partitioning the United 

States into mapping zones. A total of 66 

mapping zones were delineated in the conterminous United 

States on the basis of ecoregion and geographical characteristics, edge-matching features, and size requirement of Landsat 

mosaics. Methodology developed at EROS Data Center (http://

landcover.usgs.gov/pdf/asprs_final.pdf) was used for this effort.

Project Web site: http://www.mrlc.gov/

Panhandle Groundwater Conservation District Geodatabase 

Development

This project was developed in cooperation with the Panhandle Groundwater 

Conservation District (PGCD) to develop 

a geodatabase that would allow PGCD to 

effectively input and manage data to distribute information to their stake holders and 

the general public. Both spatial and tabular 

data were presented in one geodatabase for data input and 

output. A data dictionary containing definitions of coded values 

was developed for data input.

Project Web site: http://tx.usgs.gov/PGCD/

Binational Networked Hydrography System for the U.S.-Mexico 

Border, Phase 1

In cooperation with the U.S. International Boundary and Water Commission 

(USIBWC), the USGS began work on 

a routable ArcHydroTM stream network 

for the U.S.-Mexico border region from 

the West Coast to the eastern boundary 

of southern New Mexico and northern 

Chihuahua. The stream network consists 

of the 1:24,000 National Hydrography Dataset stream data 

and the 1:50,000 Instituto Nacional de Estadística, Geografía e 

Informática (INEGI) stream data. Phase 1 of the project covered 

southwestern New Mexico-northwestern Chihuahua and southeastern Arizona-northeastern Sonora, and is now complete. The 

ArcHydroTM data model allows data associated with a stream 

to be related to the entire network of streams in a geodatabase. 

For instance, water-quality events and data might be related 

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to a stream and then traced upstream and downstream, allowing potential water-quality effects to be traced to a geographic 

extent.

Geologic Map of the Edwards Aquifer in Northern Medina and 

Northeastern Uvalde Counties, South-Central Texas

The southern segment of the Edwards 

aquifer in south-central Texas is one of the 

most productive subsurface reservoirs of 

ground water in the world, providing water 

to more than a million people in the San 

Antonio region. Dissolution, karst development, and faulting/fracturing directly controls aquifer geometry by compartmentalizing the aquifer and creating unique ground-water flow paths. 

The surface geology and fractures were mapped using GIS.

2006 USGS Open-File Report 2006–1372: http://pubs.usgs.

gov/of/2006/1372/

FY 2007

Geodatabase and 3D Conceptual Model for the Longhorn Army 

Ammunition Plant

The Longhorn Army Ammunition 

Plant (LHAAP) relies on historical and 

current environmental information for 

environmental management, clean-up, 

and protection. Currently (2007), various 

entities conducting work for LHAAP have 

compiled spatial and non-spatial digital 

information, including hydrologic, geologic, 

and water-quality data that can be useful for identifying data 

gaps and developing a site-wide conceptual model for LHAAP. 

The USGS, in cooperation with the U.S. Environmental Protection Agency (USEPA), is organizing the large amounts of available data to help effectively manage the data for decision-making, sampling locations, and progress at LHAAP. The spatial 

and tabular data will be compiled into a single geodatabase with 

metadata, and a three-dimensional conceptual model will be 

created to attain a geologic and hydrogeologic perspective of 

the plant.

Projected end date: September 1, 2009

Watershed Boundary Dataset

The USGS is collaborating in a 

multi-agency effort to complete the 

national Watershed Boundary Dataset 

(WBD). In Texas, the USGS, in cooperation with Natural Resources Conservation 

Service (NRCS) Texas, is using federally 

established standards (ftp://ftp-fc.sc.egov.

usda.gov/NCGC/products/watershed/hustandards.pdf) to delineate high-resolution watershed 

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boundaries for fifty 8-digit hydrologic units in eastern and 

coastal Texas.

Projected end date: October 1, 2007

Project Web site: http://www.ncgc.nrcs.usda.gov/products/

datasets/watershed/

Border Environmental Health Initiative (BEHI): Years 3 & 4

Currently (2007), a multidisciplinary 

USGS team, in conjunction with the Pan 

American Health Organization, has begun 

a 2-year research project to define linkages 

between environmental and human health. 

The objective is to use BEHI datasets 

and analyses of water quality, fish health, 

geochemistry, and land use to investigate 

linkages between regional human health issues and environmental health. A GIS-based quantitative weight-of-evidence 

and logistic regression model to associate areas of poor environmental quality with areas of impaired human health will be 

used. Additionally, binational datasets are undergoing thorough 

review and a large number of the datasets will be published 

and available for download. A download page with links, metadata, and the data in multiple formats is currently (2007) under 

construction.

Projected end date: October 1, 2008

Project Web site: http://borderhealth.cr.usgs.gov/

Internet Mapping Service: http://gisdata.usgs.gov/website/

BorderHealth/

2006 USGS Fact Sheet 2006–3054: http://pubs.usgs.gov/

fs/2006/3054/

Global Map and National Atlas 1:1M Hydrography: Production

Phase

In cooperation with the National Atlas, 

this project will produce a 1:1,000,000-

scale (1:1M) networked drainage dataset 

from the existing 1:100,000-scale (1:100k) 

National Hydrography Dataset (NHD) for 

the United States, Puerto Rico, and U.S. 

Virgin Islands. To accomplish this objective, the USGS developed specialized 

geoprocessing tools and algorithms using ESRI ArcObjects 

to partially automate generalization and simplification of the 

NHD network. The final datasets will be available through the 

USGS National Atlas in both shapefile and geodatabase formats 

(http://www.nationalatlas.gov/) and through the Global Mapping Project (http://www.iscgm.org/).

Projected end date: October 1, 2007

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Geologic Atlas of Texas (GAT)—Geodatabase Maintenance

Continuing a cooperative effort that 

began in FY 2004 with the Texas Water 

Development Board (TWDB), this project 

provides updates and revisions to the Digital Geologic Atlas of Texas (GAT) where 

needed. Using ArcGIS, in concert with 

ESRI’s Production Line Toolset, the UGGS 

will document and verify all changes to the 

Digital GAT for archival purposes. The USGS will also prototype the incorporation of high-resolution (1:24,000) geologic 

data into the current structure by using digital data recovery 

methods for the University of Texas, Bureau of Economic Geology, Geologic Quadrangle Map Series. In addition, the USGS 

will produce educational materials that will instruct end-users 

about the functionality of the Digital GAT geodatabases.

Projected end date: October 1, 2007

Project Web site: http://tx.usgs.gov/GAT/

Source Water Assessment Program Toxic Algae Study

In cooperation with the Texas Commission on Environmental Quality (TCEQ) 

Source Water Assessment program 

(SWAP), the USGS plans to investigate 

the presence of blue-green algal toxins and 

taste and odor compounds associated with 

harmful algal blooms (HABs) in drinking 

water sources. Field data and lab results 

were loaded into the USGS National Water Information System 

(NWIS) (http://waterdata.usgs.gov/nwis) and published in the 

Annual Data Report. Spatial analysis is focusing on linkages 

between drainage-area characteristics, environmental data, 

nutrient loads, and presence of HAB compounds of concern 

(algal toxins and taste and odor compounds). The water-quality 

data were pulled from NWIS and spatially enabled using the 

NWIS geodatabase snapshot schema. The schema effectively 

translates NWIS codes, establishes relationships, and formats 

data to allow for complex spatial queries.

Projected end date: September 1, 2007

Related topic USGS Fact Sheet 2006–3147: http://pubs.usgs.

gov/fs/2006/3147/

Geodatabase of Geologic and Hydrogeologic Information for the 

Brazos River Alluvium, Bosque to Fort Bend County, Texas

The USGS, in cooperation with the 

Texas Water Development Board (TWDB), 

developed a comprehensive geodatabase 

of temporal and spatial information associated with the geology and hydrogeology 

of the Brazos River alluvium in 13 counties 

in the Brazos River watershed. This 

compilation documents and provides a 

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single consolidated geodatabase of the Brazos River alluvium 

geologic and hydrogeologic data that follows the TWDB 

Groundwater Availability Model (GAM) Source Data Geodatabase format. This includes but is not limited to, top and base 

elevation point locations of alluvium data and historical hydrogeologic data such as hydraulic conductivity, specific capacity, 

and transmissivity.

Projected end date: September 1, 2007 

2007 USGS Open-File Report 2007–1031

Extreme Bed-Material Mobility, Edwards Plateau: Year 4

The USGS, in cooperation with 

the Texas Department of Transportation 

(TxDOT), is generating and analyzing 

fluvial geomorphic data to understand 

frequency of bed-material entrainment in 

stream reaches in the Edwards Plateau, 

associated with extensive maintenance 

issues for the TxDOT at bridges and lowwater crossings. Digital elevation models (DEMs) and digital 

orthophoto quarter-quadrangles (DOQQs) are analyzed in GIS 

to produce a variety of geomorphic metrics including drainage area, channel slopes, and channel widths. Trend analysis 

investigates linkages between road crossings with considerable 

problems and geomorphic metrics.

Projected end date: September 1, 2007

2005 USGS Open-File Report 2005–1234: http://pubs.usgs.

gov/of/2005/1234/

Watershed and Land-Use/Land-Cover Geodatabase for NAWQA 

Lake/Reservoir Coring Project

The USGS National Water Quality 

Assessment (NAWQA) program coordinates a study that examines sediment cores 

from selected lakes and reservoirs across 

the United States. Laboratory analysis of 

sediment cores provides information to 

determine relative constituent loadings and 

concentrations for each water body since the 

1950s. GIS has been used for this project to determine drainage 

areas and land-use/land-cover change in watersheds over time.

2003 USGS Water-Resources Investigations Report 03–4169: 

http://pubs.usgs.gov/wri/wri034169/

2004 USGS Scientific Investigations Report 2004–5184:

http://pubs.usgs.gov/sir/2004/5184/

2006 USGS Data Series 166: http://pubs.usgs.gov/

ds/2006/166/

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Water-Level Altitudes 2007 and Water-Level Changes in the 

Chicot, Evangeline, and Jasper Aquifers and Compaction 1973–

2006 in the Chicot and Evangeline Aquifers, Houston-Galveston 

Region, Texas

The USGS, in cooperation with the 

Harris-Galveston Subsidence District, the 

City of Houston, the Fort Bend Subsidence 

District, and the Lone Star Groundwater 

Conservation District, prepares an annual 

series of reports that depicts water-level 

altitudes and water-level changes in the 

Chicot, Evangeline, and Jasper aquifers, 

and compaction in the Chicot and Evangeline aquifers in the 

Houston-Galveston region. Beginning in 2007 a multi-user 

geodatabase was designed that allows the USGS to effectively 

input, generate, and manage data from both the Houston and 

Austin offices. The use of map templates streamlines the annual 

map series production.

Project Web site: http://tx.usgs.gov/subsidence/

Colonia Health Infrastructure Platting Status (CHIPS) Tool 

In cooperation with the Office of the 

Texas Secretary of State (SOS) and the 

Office of the Attorney General of Texas, 

the USGS created CHIPS to monitor the 

progress of projects oriented towards the 

improvement of colonia infrastructure. 

CHIPS is a relational database housed in 

Microsoft Access that includes a customizable report generator. Although CHIPS was developed for the 

SOS in response to Senate Bill 827 (SB827), this project is part 

of a larger project involving the USGS, the U.S. Department 

of Housing and Urban Development, and Mexico’s Instituto 

Nacional de Estadística Geografía e Informática.

2004 USGS Fact Sheet 2004–3070: http://erg.usgs.gov/isb/

pubs/factsheets/fs307004.html

SOS Final Report: http://www.sos.state.tx.us/border/forms/

sb827_111706.pdf

2007 USGS Open-File Report 2007–1230: http://pubs.usgs.

gov/of/2007/1230/

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Information regarding water resources in Texas is available at

http://tx.usgs.gov/