Coweeta Hydrological Laboratory continues to serve as a premier facility for studying rainfall and watersheds in the mountains, its data made all the more relevant by Hurricane Helene.
Dr. John Walker, project leader, said the lab is located in what was historically Cherokee territory before Coweeta Valley was purchased by logging companies and extensively logged in the early 1900s. The United States Forest Service bought the area in 1918, rejoined it with the Nantahala National Forest in 1923 and set aside the station’s territory in 1934 as Coweeta Experimental Forest to begin collecting long-term hydrological data. The forest was renamed the Coweeta Hydrological Laboratory in 1948.
The facility’s most well-known experiment remains the rainfall study, in which daily records of rainfall, streamflow and atmospheric measurements are taken. These show trends of how rain affects the local watershed, how rainfall and climate change over time and how vegetation and wildlife use the water falling on a region. The hydrological lab also collects data on land management, soil, fire and the ecology of the region.
The lab’s territory can be separated into a collection of small watersheds that all drain through a single stream leaving the valley, allowing the lab’s scientists to set up experiments in different areas to collect data. Though Coweeta is one of 19 experimental forests in the southeastern region, the Smoky Mountains’ high rainfall and unique climate puts the lab in a position to collect data that might not be available anywhere else in the U.S. The data is used to develop models to predict and simulate watershed processes such as flooding and landslides.
Likewise, the clearcutting seen in the region in the early 20th century puts the lab in a position where it can monitor how forests and forest composition grows and changes as the region recovers from century-old land management techniques.
Data from the lab has earned it recognition from international scientific facilities and programs. Walker said its data is being used to develop a model in Asheville to assess the risk of future storms impacting water quality following extreme flooding events. Another post-Helene model is looking at how stormwater culverts can be designed to better withstand flood conditions. Walker also noted 20 million people in the southern U.S. get drinking water from National Forest lands, and the data on forest management collected at the lab can be vital to ensuring people retain safe water access.
On a brief tour of the facility, Walker pointed out an instrument yard in which rainfall indicators, atmospheric instruments and other equipment allow the facility to monitor everything from rain, wind and temperature to microplastics and rain composition.
The microplastics research is in collaboration with Jason Love at the Highlands Biological Station. Walker said, “We collect the rainfall and then, each week, we come out, we pour it off. Some of it we analyze in our laboratory and some of it we send off to other laboratories to analyze the chemistry of the precipitation. That’s kind of a new line of research, looking at these emerging pollutants in rainfall and trying to better understand how they move through the environment once they are deposited.”
Both modern and traditional equipment is used to take rainfall and atmospheric measurements, which Walker said allows the facility to reduce the risk of lost data in the event of equipment failure and ensure modern data can be effectively compared to historic data taken at the lab.
Also essential in monitoring watershed input and output are weirs, set up like little dams around the forest to measure water flowing out of the valley’s watersheds. Walker said by measuring rainfall and streamflow through the weirs, researchers have the ability to calculate measures like transpiration and evaporation and how different kinds of plants in the forests use different amounts of water.
One study has gone on since the 1940s, in which a section of forest was clearcut and kept clear until 1955. After recording that streamflow increased 60% without trees on the land, researchers then planted Eastern White Pines on the land in 1956 and compared the resultant data with other forests to demonstrate pine forests use more water than hardwood forests. This is due, at least in part, to the evergreens’ needles transpiring more water into the atmosphere.
Moving up into the forest, Walker pointed out dormitories that allow students and visiting scientists to come on site to conduct research. In the last year, the dorm has seen more residents after a COVID-19-era slowdown in visitation.
“Collaboration with universities and international partners and academics really has been an important aspect of the work that we’ve done here over the years,” he said. “Recently, we had a few nights where the entire dorm was full … that’s really great to see those things. Activity obviously slowed down during COVID.”
“One of the things that we’re working on is related to prescribed fire and the use of prescribed fire as a management tool to reduce fuel loads, return nutrients to the soil and help with forest productivity and to restore the forest,” Walker continued. “In particular, oaks have declined due to a number of factors and forest management can play an important role in their regeneration.”
Another prescribed fire experiment involved the removal of rhododendron from the forest understory, which Walker said affected nutrient cycling and other forest processes, and resulted in a short-term increase in water yield, which later returned to normal as the vegetation returned.
“Forest management calls for a certain frequency of prescribed fire, and so we’re kind of following that schedule of a fire every three to five years,” he said. “So we’re going to see how that influences those questions over the very long term.”
The lab is preparing to begin some new experiments next year and hopes to refresh some of its long-term hydrological experiments in the next few years. One experiment will examine the introduction of biochar to a landscape. Walker said the biochar has shown some nutrient-adding, nitrogen-sequestering, pollutant-absorbing properties and could be useful in facilitating the return of oak trees to the area.
Reorganization plan
In July, a memo from Secretary of Agriculture Brooke L. Rollins outlined a reorganization plan for the U.S. Department of Agriculture which would close nine research stations and consolidate them into one station in Fort Collins, Colorado. The Southern Research Station of Asheville, which operates the Coweeta Hydrological Laboratory, would be among those closed due to the shift. The fate of Coweeta Lab was not discussed in the memo and has not yet been addressed by public-facing USDA communications, leaving the future of the station uncertain.
Though Dr. Walker did not address the proposed reorganization plan, he stressed the value and importance of the lab and the unique data it is able to collect due to its geography and historical datasets collected over the past 90 years.