When looking at the 2,000-acre clearing on La Osa Ranch, the planned site of a residential community along the Pima-Pinal County line in Arizona's Santa Cruz River Valley, it initially resembles images of a lunar landscape or the aftermath of a nuclear blast.
Chris Mack, a geographic information systems (GIS) senior analyst in Marana, Ariz., routinely monitors changes in the land surrounding Marana's town limits that might impact the community. During one of his assessments, he noticed bulldozer tracks and extensive land scraping on the property where Scottsdale developer George Johnson, of Johnson International Inc., intended to construct 67,000 homes, a resort, golf courses and businesses.
In looking back at GIS images from 2002, 2003 and 2004, the extent of Johnson International's damage seemed apparent, and the state of Arizona sued the developer. Johnson International denies any wrongdoing, however, contending the illegal-scraping allegations don't apply to the land in question.
"We started hearing in December 2003 through various environmental groups of this proposed La Osa Ranch development and some of the allegations of illegal land clearing," Mack said. "I looked to see if our imagery covered the area, and at that time, we had two dates of imagery -- May 2002 and May 2003. I spotted the site in question fairly readily because there was a start of land clearing activities, and you could see bulldozer tracks in the area of interest."
The satellite images taken in May 2002 by Space Imaging's IKONOS satellite show the land before the damage, and provide a baseline image for reference in Arizona's lawsuit against Johnson International.
"The satellite imagery provides a time sequence of events," Mack said.
Once word spread about the scraping damage, imagery already acquired was reviewed to establish a before/after view of the site. There was no change evident in the terrain in 2002, but the 2004 image plainly shows the extent of the damage to the now-cleared area just north of Marana, Mack said.
"What we've done here in Marana is use some of the high-tech mapping and satellite imagery to sort of give a new image to the town," Mack said. "The town in the past has had an image of being a bunch of farmers."
But that image is changing. According to Mack, Marana is the only town in southern Arizona currently purchasing satellite imagery on an annual basis.
"We're a good example of a relatively small jurisdiction in Arizona that has implemented a program to purchase satellite imagery every year, and this is just one of the unexpected benefits that has come from that," he said. "It is a case where our satellite imagery proved useful in a way we hadn't foreseen."
Marana started developing an archive of high-resolution satellite imagery in 2002 with the acquisition of more than 500 square miles of IKONOS data, and is now purchasing 640 square miles of imaging yearly.
"We now go well outside of our town limits," Mack said. "We like to monitor what's going on outside of the town limits because those things impact the town."
The town's Geographic Information Systems Department also uses satellite images to provide other town departments and residents with information, such as maps and illustrations to show proposed adjoining land in rezoning cases, and for three-dimensional terrain visualization of landscapes and development plans.
The GIS Department is also involved in supporting the Traffic Operations and Water Department with asset inventories using GPS for location of their asset features.
Marana is also creating a draft Habitat Conservation Plan, the purpose of which is to protect threatened and endangered species in areas affected by growth and development. This process depends partly on the accurate GIS modeling of areas where the species might occur.