GIS helps link Grand Canyon's ecosystems
- By Allan Holmes
- May 19, 1996
In a project conducted this spring to replenish the Grand Canyon's river beaches and habitat for endangered fish, the Bureau of Reclamation used geographic information systems (GIS) to begin measuring for the first time how the many different components of an ecosystem are linked.
In March and April, the bureau created a controlled flood on the Grand Canyon's Colorado River by increasing by nearly six times the flow of water through the Glen Canyon Dam. The flood was designed to mimic the river's spring floods that occurred before the dam was built in 1963 and to assess the impact the dam has had on the Grand Canyon's ecosystem.
The flood, which occurred over seven days, deposited sediment from the river bottom onto eroded beaches of the river's banks, removed vegetation and sediment from backwater habitats to increase breeding areas for endangered fish and removed cobbles and boulders that blocked tributaries.
The bureau used numerous computers to measure the changes to the river and its effect on wildlife and the environment, including the rate and amount of sediment removed from the river bottom, the movements of endangered fish and the changes in water quality.
The data was downloaded into a Sun Microsystems Inc. workstation running the GIS software Arc/Info. The system maps the river's ecosystem using 40 resource layers, including water quality, topography, sediment deposits, spawning areas and nesting sites, locations of endangered fish and birds, weather and cultural resources such as burial grounds and special vegetation used in Native American ceremonies. It will allow scientists to spatially analyze and link the effects of one variable in the Colorado River ecosystem with other variables.
"This has never been done before," said Dave Wegner, program manager for the Glen Canyon Environmental Studies in Flagstaff, Ariz. "It allows us to make significant steps in our analyses of these systems. We can link the physical system with the biological system, the biological system with the area's cultural resources [of the Native Americans living in the area], or the spatial water quality can be linked to all of these."
The GIS system will be the basis for long-term monitoring of 17 sites, or "reaches," in a 280-mile stretch of the Grand Canyon.
"They have developed one of the most advanced GIS systems in all of government," said Dan Beard, commissioner of the Bureau of Reclamation from 1993 to 1995 and now the Rocky Mountain regional vice president of the National Audubon Society. "It's going to be a fantastic resource."
Louis Hecht, a GIS consultant in Silver Spring, Md., called the bureau's effort a "notable application of merging science data with spatial systems.
"This is the kind of stuff that you're going to see more and more often," he said.
To collect the flood data, the bureau relied on numerous technologies. These included:
* Six boats, each equipped with laptop 486 computers to collect real-time data that mapped more than 70 miles of the river bottom and Lake Powell, the 180-mile long lake created by the Glen Canyon Dam.
* Videos shot from a helicopter and downloaded into computers to measure the changes in the river's beaches.
* Laptops to follow schools of endangered fish, such as the humpback chub. Devices on boats tracked the movements of fish that had surgically implanted transmitters. The data was downloaded to the on-board computers.
* Water samples at 12 sites, taken periodically to measure the water quality, with the results downloaded into the laptops.
The laptops "gave us the ability to look at real-time data," Wegner said. "Instead of bringing the data back to the lab and saying, `If I just would have taken another measurement every 10 minutes instead of every 20 minutes, I would be able to do this,' we could make the adjustment right there and get the data that we needed."
Because each trip into the Grand Canyon costs the bureau $10,000, not including scientists' time, the ability to make the adjustments saved tens of thousands of dollars, Wegner said.
The data and analyses will be available on the bureau's home page on the World Wide Web at http://www.usbr.gov/.