The United States Geological Survey (USGS) is responsible for studying the landscape, natural resources, and natural hazards of the United States. Founded in 1879, the current motto of the agency is “Science for a Changing World”. Over the many decades that the USGS has been functioning, they have continued to change along with the scientific and technological demands of modern times. The USGS was one of the first nonmilitary government agencies to begin using drone technology.
Today, more than ever, drones are playing an important role in the investigations conducted by USGS researchers. Joel B. Sankey leads the remote sensing group for the USGS at the Grand Canyon Monitoring and Research Center (GCMRC), in Flagstaff, Arizona. At GCMRC, Joel uses data collected by drones to study changes in land surfaces of river ecosystems. His research has him looking for changes from natural events, like climate change, and those influenced by humans, like pollution. By equipping drones with LiDAR technology, Joel can assess changes that would be otherwise invisible to the naked eye.
In September of 2021, Joel published a paper on drones with LiDAR that can be used to assess the ecohydrology (the relationship between water systems and ecological systems) of forest snow coverage. The objective was to create a management plan for planting a forest to accommodate snowpack distribution that will prove resilient to drought and climate change. Joel compared images collected by ground based LiDAR with drone based LiDAR and found that the drones were able to record snow depths with a 92-97% accuracy. “Our results,” Joel states in the paper, “demonstrate that 3-dimensional datasets are critical in rapidly characterizing changing snowpack to better understand the impacts of forest structure and topography to inform forest restoration treatment designs. The relationships observed in our study can inform currently ongoing regional-scale forest restoration in the southwest to improve forest health and resiliency.”
The following month, Joel published a paper titled Carbon and ecohydrological priorities in managing woody encroachment: UAV perspective 63 years after a control treatment. Woody encroachment, or otherwise natural vegetation overgrowth, can be harmful to more fragile ecosystems. A common practice is to use chemical treatments to prevent such encroachments. According to Joel, there is plenty of documentation on the short term effects of such practices, but not much on the long term effects of using these chemical interventions. “Using a controlled herbicide treatment from 1954 in the Sierra Ancha Experimental Forest in central Arizona, USA, we quantify woody encroachment and associated aboveground carbon accumulation in treated and untreated watersheds,” Joel explains. “Woody encroachment and aboveground carbon are estimated using high resolution multispectral images and photogrammetric data from a fixed-wing unmanned aerial vehicle (UAV). We then combine the contemporary UAV image-derived estimates with historical records from immediately before and after the treatment to consider long-term trends in woody vegetation cover, aboveground carbon, water yield, and sedimentation.”
The study showed that the chemical treatments have had a long lasting impact. The encroachment sites were noticeably less campared to those not treated, even though regrowth had occurred. These are just two studies done by one USGS researcher in a short time utilizing drone technology. Drones are providing USGS with the tools needed to carry out government appointed studies. These studies will help protect the landscape of the United States, giving decision makers the right information to set management plans in action.