A groundbreaking, high-tech research project could not only save the watershed of the C.C. Cragin Reservoir — but boost the odds forest restoration projects can save forested communities like Payson and Show Low from the next megafire.
The $198,000 project involves use of remote-sensing LiDAR systems to figure out how many trees of what types and sizes timber companies can harvest to restore a healthy forest. Moreover, the tool can help answer a host of questions from watershed yields to the mysterious movements of Mexican spotted owls.
“There are almost endless applications of how we can use this data to inform our understanding of forest structure, wildlife, watersheds, wildfires — you name it,” said lead researcher Elvy Barton, who is both a researcher for Salt River Project and an adjunct faculty member at Northern Arizona University’s Ecological Research Institute.
“We can understand how the watershed works and how stream channels change over time. We’re at a very exciting point in this technology,” she said.
SRP is funding the research in partnership with NAU’s Ecological Research Institute. The effort to document the condition of the 64,000-acre watershed of the C.C. Cragin Reservoir will serve as a pilot project for using the radar-like reflections off the landscape to provide a quick, cost-effective view of the landscape in unprecedented detail.
“This collaboration is an exciting opportunity to further our understanding of important watershed and wildlife-habitat attributes,” said NAU professor Andrew Sanchez Meador, who serves as executive director of the institute. “It’s a great example of the pioneering ways researchers are working together to solve Arizona’s wildfire and forest health problems.”
The research could also finally become a critical tool in the long-stalled efforts to restore millions of acres of forests in northern Arizona. Tree densities in the past century have increased from about 100 per acre to more like 1,000 per acre due to grazing, logging and fire suppression. Those forests are now desperately vulnerable to the kinds of megafires that this year consumed millions of acres in California and killed dozens of people, while destroying more than 10,000 homes.
The crowded, sickly condition of the forest on the C.C. Cragin watershed could also spawn a wildfire that would end up causing erosion that would fill the 15,000 acre-foot reservoir with mud in the aftermath of a giant fire. Both SRP and Payson depend on the reservoir for their future water supply and have spent more than $50 million on now-vulnerable pipeline infrastructure running through the forest.
Since 2002, some 3 million acres of national forest land in and around the Salt, East Verde and East Clear Creek watersheds have been impacted by high-severity crown fires. SRP provides 244 billion gallons of water to 2 million Valley residents. That water drains off the 13,000-square-mile watersheds of the Salt and Verde rivers — including all of Rim Country and the White Mountains.
The research will combine three types of images created by the radar-like pulses of LiDAR devices — one in airplanes, one in drones below the forest canopy and one using hand-held devices deployed by a researcher tromping through the forest.
The airplane surveys have covered 5,000 acres, providing an image based on 12 data points per square yard — mostly tree tops and ghostly images of the ground in the gaps in the canopy.
The drone-mounted transmitters produce about 50 pulses per square yard, providing a much more detailed image from beneath the canopy.
The hand-held devices produce 1,000 pulses per square yard, producing a far more detailed image — which also costs much more to acquire and process than the airplane mounted LiDAR devices.
The research project will compare and combine the images from 5,000 acres of airplane survey, 100 acres of drone survey and 35 acres of hand-held survey on foot. The researchers will spend the next nine months processing all the data to create an astonishingly detailed, three-dimensional picture of the forest. The project allows researchers to essentially ground test the measurements made from the air, greatly refining the accuracy of the airplane-based survey.
This could prove invaluable when it comes time for timber companies to bid on restoration projects — which remain the only currently plausible way to restore millions of acres to balance and protect forested communities from crown fires.
“So if I could tell you there are 100 ponderosa pine trees on this acre and I need 50 removed — and here are the sizes and lengths of each tree — you know everything you need to know to bid that sale,” said Barton.
The data could also provide a precise estimate of the amount of biomass consisting of downed wood and saplings in need of removal. If connected to other computerized systems, the data could even tell loggers how many 2x4s or beams or biomass or particle board materials or other products a given tract of land would produce.
But the data would provide tremendous benefits beyond preparing timber sales, currently an expensive, time-consuming process limited by Forest Service manpower. The data could also provide a much more precise blueprint for restoring forest health and protecting endangered species like the Mexican spotted owl.
For instance, right now biologists don’t have a precise idea of where the small forest owls forage. The endangered birds prefer to nest in thick stands dominated by old-growth trees. But where do they spend their time when they’re not nesting? If you combine the results of radio collaring a spotted owl with a LiDAR analysis of the areas through which it moves, you can calculate much more precisely what the owl needs.
Barton just hopes they get results which can boost the speed of thinning projects before a wildfire does permanent damage to the watershed — killing residents and consuming whole towns like Paradise, Calif.
“I’m very much, ‘oh, man, I wish we could move faster on these research questions.’ But it’s a fascinating level of detail we can get from this technology,” she said. “The LiDAR is not the difficult part — it’s the processing of the data — billions of data points. But we hope this will provide a cost effective way to move restoration projects forward.”