USGS TerraWeb: Flagstaff: Ground Water Resource Evaluation

CITY OF FLAGSTAFF PROJECT
Ground Water Resource Evaluation
Remote Sensing Component
USGS Open File Report OF-96-739

Click inside thumbnail images to view larger image.

[Image: Landsat TM Image of Northern Arizona]

Many regions, cities, and towns in the Western United States need new or expanded water resources because of both population growth and increased development. Any tools or data that can help in the evaluation of an area's potential water resources must be considered for this increasingly critical need. Remotely sensed satellite images and subsequent digital image processing have been under-utilized in ground water resource evaluation and exploration. Satellite images can be helpful in detecting and mapping an area's regional structural patterns, including major fracture and fault systems, two important geologic settings for an area's surface to ground water relations. Within the United States Geological Survey's (USGS) Flagstaff Field Center, expertise and capabilities in remote sensing and digital image processing have been developed over the past 25 years through various programs. For the City of Flagstaff project, this expertise and these capabilities were combined with traditional geologic field mapping to help evaluate ground water resources in the Flagstaff area. Various enhancement and manipulation procedures were applied to the digital satellite images; the results, in both digital and hardcopy format, were used for field mapping and analyzing the regional structure.

Relative to surface sampling, remotely sensed satellite and airborne images have improved spatial coverage that can help study, map, and monitor the earth surface at local and/or regional scales. Advantages offered by remotely sensed satellite image data include:

a synoptic/regional view compared to both aerial photographs and ground sampling,
cost effectiveness,
high spatial resolution and coverage compared to ground sampling, and
relatively high temporal coverage on a long term basis.

Remotely sensed images contain both spectral and spatial information. The spectral information provides various properties and characteristics about the surface cover at a given location or pixel (that is, vegetation and/or soil type). The spatial information gives the distribution, variation, and topographic relief of the cover types from pixel to pixel. Therefore, the main characteristics that determine a pixel's brightness/reflectance and, consequently, the digital number (DN) assigned to the pixel, are the physical properties of the surface and near surface, the cover type, and the topographic slope. In this application, the ability to detect and map lineaments, especially those related to fractures and faults, is critical. Therefore, the extraction of spatial information from the digital images was of prime interest in this project. The spatial information varies among the different spectral bands available; in particular, a near infrared spectral band is better than a visible band when extracting spatial information in highly vegetated areas. In this study, both visible and near infrared bands were analyzed and used to extract the desired spatial information from the images.

The wide swath coverage of remotely sensed satellite digital images makes them ideal for regional analysis and mapping. Since locating and mapping highly fractured and faulted areas is a major requirement for ground water resource evaluation and exploration this aspect of satellite images was considered critical; it allowed us to stand back (actually up about 440 miles), look at, and map the regional structural setting of the area. The main focus of the remote sensing and digital image processing component of this project was to use both remotely sensed digital satellite images and a Digital Elevation Model (DEM) to extract spatial information related to the structural and topographic patterns in the area. The data types used were digital satellite images collected by the United States' Landsat Thematic Mapper (TM) and French Systeme Probatoire d'Observation de laTerre (SPOT) imaging systems, along with a DEM of the Flagstaff region. The USGS Mini Image Processing System (MIPS) software, developed at the Flagstaff Field Center by our group during the past 16 years, was used to do all the digital image processing, manipulation, and interactive analysis. The primary information extracted from these data using the USGSMIPS were lineaments that could be related to fractures, faults, or other geologic structures. The remotely sensed satellite images helped map the area's regional structural patterns and identify areas of localized high density fractures. These results were used to help with both the geologic mapping and identifying areas that needed to be investigated in greater detail in the field, including the collection of ground penetrating radar and seismic reflection profiles of selected geologic structures. The field mapping efforts by others involved in the project have been in progress and their results will be reported separately.

The main objective of this atlas is to show some of the remotely sensed and DEM image products used in this investigation, as well as to report on the project's remote sensing component. The atlas helps show the potential that remotely sensed satellite and DEM data have for overall ground water resource evaluation and exploration. Only a subset of the image products generated for the project are shown; however, they give a good representation of the type and quality of the image data used and the information content of the remotely sensed satellite images and the DEM images. The various images in this atlas are examples showing a single representation of the digital data; more detailed analyses and information extraction can be done using the 'digital atlas' and digital image processing tools and procedures. Most of these digital data can be incorporated into a GIS type data base and made available for other projects related to the Flagstaff region.

The Flagstaff Atlas web pages were originally produced as a USGS Open File Report (OF-96-739). The figure numbers correspond to the figure numbers in the original hardcopy version.

Digital Elevation Model Images

Landsat Thematic Mapper Images

SPOT Panchromatic Stereo Images

Flagstaff Area Photo Tour

Project Team:
Pat S. Chavez, Jr.	Remote Sensing Scientist/ Team Leader
Miguel G. Velasco	Lead Image Processor on this project
JoAnn Bowell	Image Processor
Stuart C. Sides	Computer Scientist
Rosendo R. Gonzalez	Programmer
Deborah L. Soltesz	Web Page Design

References and Resources

Return to Other Land Environment Remote Sensing Research and Applications

For more information about this project, contact:
Pat S. Chavez, Jr. Email: pchavez@usgs.gov U.S. Geological Survey 2255 N. Gemini Dr. Flagstaff, AZ 86001 Tel: (520) 556-7221 FAX: (520) 556-7169
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Last Modified: Thu Oct 31 15:19:35 MST 2002

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References and Resources

Pat S. Chavez, Jr.