Questions Emerge About CRMP Validity

October 2004. A team of reviewers continues to be highly concerned with analyses presented in the 900 page just released Colorado River Management Plan for the Grand Canyon National Park Draft Environmental Impact Study (Draft EIS).

Tom Robey, Ph.D. mathematician and computer scientist, has been reviewing the eight alternatives in terms of wilderness and solitude. Robey is concerned with the validity of the results from some of the complex computational models.

According to Robey, the Draft EIS has two major measures that are used: river encounters between groups and time within sight. Robey points to the EIS analysis and shakes his head.

"Looking at the number of river encounters in summer in the Draft EIS, the report says that all alternatives have 2-4 Encounters Per Day for non-motorized trips. Then, looking at the Time In Sight analysis, we see that all alternatives have 30-45 minutes listed."

"It just doesn't make sense for all the alternatives to have no differences in terms of wilderness and solitude values" says Robey, who goes on to point out "the alternatives range from some with motorboats and some without, from 9 launches per day to 4 launches per day and 171,000 user days to 280,000 user days. How could such big changes in the use have no effect on Encounters Per Day and Time In Sight?"

Robey has been doing simple calculations to compute a group size-invariant measure of average daily number of people encountered. He then looked at the underlying physics of group launch patterns using the principles of convection and Brownian motion.

According to Robey, "The results show that the two no-motors alternatives have daily encounters of 51 and 64 people per day for standard sized noncommercial groups, and the preferred alternative has the highest daily encounters at 146 people per day, exceeded only by the no-action alternative."

"It looks like the Park Service may have managed to defy the underlying physics. I wonder how the calculations in the Draft EIS can be so ...different."

According to Robey, the most important management objectives should be a wilderness river trip experience that is appropriate for a national park, especially one with the stature of Grand Canyon National Park, internationally recognized as a World Heritage Site, and preserving the unique area's resources.

To take a look at the data crunching, see where the formulas can be found by looking at the source for that page. Robey intends to run the park's river trip simulator computer model on the park's alternatives as well.