Uncrewed Aerial Systems in Alaska’s Parks: Safer Surveys, Mapping and Monitoring

Wildlife surveys from crewed aircraft are typically flown low and slow, often over water or ice, which carries substantial risks for biologists and pilots. Since 2016, parks and National Park Service (NPS) programs in Alaska have used uncrewed aerial systems (UAS), unoccupied aircraft controlled through a radio-linked interface and an onboard autopilot, to inform science and resource monitoring, and the authors expect the shift from crewed aircraft to raise safety substantially. A 2021 Alaska Park Science article by Jamie N. Womble, Parker Martyn and Britta Schroeder of the NPS describes what the aircraft can do, what parks have used them for, and what holds them back.

A 3DR Solo carrying a Micasense multispectral camera over the intertidal zone in Katmai National Park and Preserve. Image from NPS's page.

Why use them

A UAS can stand in for a crewed aircraft to collect natural resource data, increase safety, reduce costs, and provide an aviation resource where a crewed aircraft is not appropriate, available or able to fly. In June 2014 the NPS Director issued Policy Memorandum 14-05, which outlined UAS use for administrative or research purposes. The authors see the most promise in inventory and monitoring, natural and cultural resource management, law enforcement, and search and rescue.

Crewed aircraft have traditionally been used for relatively high-resolution surveys over large areas, but those surveys can pose significant safety risks, may be costly, and may be hard to get in many regions of Alaska. For projects limited in geographic scope, a UAS may be more cost-effective. It may also show aspects of animal behavior that crewed aircraft cannot, and potentially disturb wildlife less. It can fly beneath the clouds, can be pre-programmed for systematic surveys and, in most cases, runs on batteries rather than fossil fuels.

Platforms and sensors

An uncrewed aircraft is a platform plus a sensor. Platforms are multi-rotor, fixed-wing, or transitional aircraft that take off and land vertically (VTOL). Multi-rotors can hover; fixed-wing aircraft use lift from the airfoil rather than thrust, so they can stay aloft longer; VTOL aircraft can launch and land in small areas and hover over a spot. They can carry inexpensive commercial off-the-shelf payloads without modification: mapping cameras, real-time high-definition video, thermal-infrared sensors, multispectral cameras, Lidar and other sensors such as aerosol monitors. Resolution depends on the lens, the rate of data capture and the flight altitude, and the products include orthomosaics, digital surface models and time-series data.

What Alaska's parks have done

In Denali National Park and Preserve, multi-rotor aircraft have mapped streams affected by mining for restoration and trail planning, produced elevation models to monitor volume changes at mass-wasting sites, and built 3D models of historic districts to assess land instability from melting permafrost, with thermal imaging to find ground temperatures. Multispectral and thermal sensors have mapped permafrost and fire ecology sites to assess plant growth in burned areas and patterns of permafrost thaw. With the University of Alaska Fairbanks, UAS have mapped paleontological specimens in Denali and glaciers in Kenai Fjords National Park.

The NPS Inventory & Monitoring Program has surveyed the intertidal zone in Katmai and Lake Clark national parks and preserves with Gulf Watch Alaska and the U.S. Geological Survey Alaska Science Center. The data are being evaluated for the distribution and abundance of intertidal species and for multispectral orthomosaics for land cover and topographic change along the coast. A pilot project in Denali collected real-time video of nesting Canada jays to quantify chick health.

A classified image of the intertidal zone at Takli Island, Katmai National Park and Preserve, made from imagery collected with a 3DR Solo. Image from NPS's page.

What is planned

UAS are expected to give information on the condition and long-term trends of vegetation and other natural resources, to show how well management practices sustain park ecosystems. Under a partnership agreement with the U.S. Forest Service, NPS fleet operations within the Alaska Inventory & Monitoring Program will provide high-resolution baseline imagery to check the accuracy of vegetation maps of forested areas. Denali plans to map thermal refugia with infrared sensors, stream turbidity with multispectral sensors, and the presence of fish with optical sensors.

Counting wildlife populations with small aircraft is harder, because the areas are large and remote, but platforms with longer battery endurance will be able to transform wildlife population assessment over large areas. A planned project will evaluate UAS for population assessments of harbor seals and sea otters and their habitats, aiming to make future data collection safer and more efficient. Dall's sheep surveys require flights in narrow box canyons in turbulent conditions close to terrain, and a UAS with thermal and optical sensors may serve as an alternative platform and reduce people's exposure to aviation hazards.

Limits to solve

• Batteries. Endurance can be limiting. Department of the Interior call-when-needed contracted UAS are available with 16-hour flight times, and engineers are designing a quad-biplane for the National Oceanic and Atmospheric Administration with multi-day endurance and a heavy payload.
• Weather and weight. Exposed mechanical parts make UAS more susceptible to rain, snow, cold and wind, and smaller aircraft can carry only small sensors, which limits resolution. Weatherized, ruggedized bodies and longer radio range are in development and approval.
• Data. Like satellite and crewed surveys, UAS surveys produce large amounts of imagery, and post-processing can be time-consuming, technical and costly. Automated methods such as machine learning will be essential, and NOAA Fisheries is leading an initiative with industry and academic partners on open-source software for automated analysis of optical data from vessels, crewed aircraft and UAS.
• Rules and concerns. Federal regulations have evolved to allow more flights beyond line of sight, but there are concerns about wildlife, soundscapes, visitor experience and privacy. Using UAS to study protected species such as marine mammals requires federal research permits, and the Interior Department's Office of Aviation Services plans to evaluate "Blue" UAS for stronger cybersecurity.

The authors conclude that using UAS in parks has helped define best practices and procedures for operating in Alaska national parks and built relationships with other Interior bureaus and with local, state, federal and academic partners.

Sources

• National Park Service, Alaska Park Science 20(1), Uncrewed Aerial Systems as a Tool for Natural Resource Applications, by Jamie N. Womble, Parker Martyn and Britta Schroeder (2021); two photographs that name staff are left out; rewritten in hubnx's own words.