Drones have many useful roles to play in the area of environmental hazard detection and remediation.  One of the least known is the growing use of drones for water sampling collection and analysis.  This is potentially a multi-modal intervention; the same work can be conducted by an aerial drone or by an underwater drone (or both), depending, in part, on the setting and depth of the sampling required.  Drone manufacturers in each mode are rapidly expanding their offerings in response to the ever-growing demand for their services.

There are many potential advantages to drone-based water sampling compared to conventional methods using field investigators in boats.  Drones can perform the work faster, and equipped with specialized cameras and sensors offer better visibility into water quality issues. Drones are less likely to disturb environmentally sensitive areas and provide greatly reduced health and safety risks for workers.  There may be upfront cost issues on the front end – the main one being the cost of the drone and its pilot – but increased efficiency and better use of remediation resources can offset that added expense over time

Water sampling by aerial drone is surprisingly simple.  A drone equipped with a plastic bottle or beaker is simply flown to a body of water and allowed to rest on the surface long enough for its container to fill with water.  Once the container is filled, the drone lifts off and flies back to a lab for testing.  The entire operation may take as little as a minute or two.

But that’s just a baseline collection operation.  Over the years, drones have become equipped with more sophisticated on-board sensors that can test the water upon retrieval and then relay the collected data digitally back to a research unit without the need for additional lab testing.  A drone may come equipped with a half a dozen syringes that perform different kinds of tests – one for oxygen or pH levels, another for the presence of microorganisms, for example, one right after the others.  Additional on-board sensors might be used to measure water depth and other surface and underwater characteristics.  With GPS, a drone can return to the exact same coordinates for repeat testing, allowing for consistency in sampling, and improved data reliability.

Underwater drones are becoming increasingly popular with some governments and their research institutes because they can probe and sample at various depths and can also capture video images of harmful algae blooms and other problems invisible at the water’s surface.   Recently, the Netherlands began deploying underwater drones equipped with hyperspectral cameras that can test not only deep water but soil in the seabed to detect its fertility as well as the presence of contaminants.  Underwater drones can be programmed to roam and test continuously, comparing data collected over numerous sites.  The same drones can also probe at the water’s surface, which would eliminate the need for aerial drone sampling.

The Netherlands spends 505 million euro (about $535 million) annually on water sampling, most of it still conducted with conventional field methods at single sites.  Experts say there is a great need for more continuous and comprehensive testing of the kind drones can provide.  In addition, some remote and inaccessible  sites, including alpine lakes, could be reached and tested with aerial drones.

In addition to reservoirs, lakes and rivers, water sampling drones have a special role to play in the case of mines and mining pits.  Pit lakes may form after a mine is closed and the toxicity of the water can threaten nearby communities as well as the crews sent to manage the area.  “Given the value of water in these regions, post-closure pit lake water quality is highly scrutinized by companies, regulators, and the public,” write geochemists in a recent issue of the journal Mine Water and the Environment. “Routine water sample collection at multiple depths in the pit lake water column informs site water management.”

The authors cite the use of an underwater drone to test the water at a closed mineral mine pit lake in Idaho.  In the past, recurring landslides had posed a risk to field inspectors sampling the water in boats.  The authors describe how a lightweight water sampling device affixed to a commercially-available drone allowed the mining company to sample water quality at depths up to 300 feet without risking their field crews’ safety.

Canadian mining companies appear to be in the forefront of developing water sampling drones, some of them custom-built for specific mine-related applications. One popular commercially-available product is Smart Drone, developed by the Swedish firm SGS, together with the University of Linköping, RISE Research Institutes of Sweden and the Swedish Meteorological and Hydrological Institute.  Some companies like Australia-based Nero specialize in the design of water sampling devices that can be affixed to general purpose drones, including the DJI M300 and M600 models.