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Conventional methods of data collection, like boat-based sonar and hydrographic surveys, are expensive, logistically demanding, and can often be too hazardous to conduct on toxic tailings ponds. Many facilities are surveyed infrequently or not at all, leaving operators with critical gaps in their understanding of storage capacity, sediment deposition, and underwater slope stability.
Drone bathymetric surveying addresses this gap. A UAV equipped with an echo sounder can fly over the water surface, collecting depth measurements without placing personnel on the water. SPH Engineering's technology stack - SkyHub onboard computer with radar altimeter-based true-terrain following, echo sounder, and UgCS flight planning software - provides a complete solution built specifically for this application.
This whitepaper is aimed at drone service providers in the mining and geospatial sectors. It outlines the industry drivers behind growing demand for TSF bathymetric data, explains the technology, and presents the operational and commercial case for adding this capability to an existing service offering.
The Growing Need for Better TSF and Tailings Dam Monitoring
Mining produces vast amounts of waste. To extract metals like copper, gold, or iron, rock must be excavated, crushed, and processed. The useful mineral is only a small part of what comes out of the ground. The rest - a wet mixture of ground rock and processing chemicals - is called tailings.
Tailings are stored in purpose-built containment areas known as tailings storage facilities, or TSFs. These are large engineered structures, typically bounded by tailings dams, that can cover several square kilometers. The scale of the global challenge is significant: current estimates place the total number of TSFs worldwide at between 29,000 and 35,000, including active, inactive, and abandoned facilities, with approximately 223 billion tonnes of tailings in storage [1, 2]. Between 25% and 30% of these facilities are abandoned, raising serious questions about long-term responsibility and monitoring [2]. Every one of these structures requires careful management - not only during a mine's operational life, but even decades after closure.
When TSFs fail, the results can be catastrophic. The 2019 Brumadinho dam collapse in Brazil killed 270 people and released approximately 12 million cubic meters of tailings into the surrounding environment [3, 4]. The Mount Polley breach in British Columbia, Canada in 2014 released roughly 25 million cubic meters of water and tailings into local waterways [5, 6]. The Fundão dam failure at the Samarco mine near Mariana, Brazil in 2015 killed 19 people and polluted 668 kilometers of waterways along the Doce River basin [7, 8]. Investigations into these events pointed to failures in design and oversight, and to critical data that was missing or outdated.
The industry's response has reshaped how TSFs are managed. The Global Industry Standard on Tailings Management (GISTM), published in August 2020 by the International Council on Mining and Metals (ICMM), the United Nations Environment Programme (UNEP), and the Principles for Responsible Investment (PRI), established the first global framework for TSF governance and tailings management [9]. It requires operators to maintain thorough, current knowledge of their facilities - not only embankment integrity, but also how impounded materials are behaving. Where sediment is depositing, how water volumes are changing, whether capacity estimates remain valid. National regulators in Canada, Australia, Chile, and South Africa have followed with tightened requirements of their own.
For drone service providers working in mining or geospatial services, this shift creates a clear market opportunity. Mining companies are moving from infrequent, compliance-driven inspections toward regular tailings dam monitoring programs, creating the need for new tools and service providers to deliver them.
Why Conventional Bathymetric Survey Methods Fail at Tailings Ponds
A tailings storage facility is not static. Throughout its operational life, the underwater landscape of a tailings pond changes constantly. Sediment can settle unevenly, depositing in patterns shaped by discharge points, water currents, and the physical properties of the tailings themselves. Water levels fluctuate with seasonal cycles, rainfall, and operational inputs. Over time, underwater slopes form and shift. Understanding these changes is fundamental to safe TSF management - remaining storage capacity, rate of sediment accumulation, underwater slope stability, and water balance all depend on accurate knowledge of what lies beneath the surface.
Bathymetric surveying - the measurement of underwater depth and terrain - is the only way to obtain this knowledge. Yet for tailings ponds, it has long been one of the most neglected elements of facility monitoring. The reasons are rooted in the nature of the environment itself and the limitations of the methods traditionally used to survey it.
The most common conventional approach is boat-based sonar surveying, carried out either from a crewed boat or from an uncrewed surface vessel (USV). In recent years USVs have become the more common of the two, and at many sites they are now the default choice for pond survey work. A vessel equipped with a single-beam or multibeam echo sounder is deployed onto the pond, and it follows predefined transect lines while the instrument records depth measurements. In natural water bodies - lakes, rivers, harbors - this is a well-established and effective technique. In tailings ponds, however, it becomes problematic on several fronts.
First, there is the question of access and safety. Tailings pond water can often be toxic, highly acidic or alkaline, and filled with suspended fine particles and residual chemicals from processing. Placing personnel in a boat on such water creates direct exposure risks. The shorelines of tailings ponds are often unstable - soft, saturated tailings material that may not support the weight of people or equipment needed for boat launching. In many cases, the embankment slopes and pond margins are classified as restricted zones precisely because of these hazards. The safety protocols and risk assessments required to put a crew on a tailings pond can be extensive, and some mine operators simply do not permit it.
Second, there is the logistical and financial burden. Many mining operations are in very remote locations. Mobilizing a boat-based survey crew to these sites means transporting specialized equipment, a suitable vessel, and trained personnel, often over long distances and to locations with limited infrastructure. The cost of a single survey campaign can be substantial, and the lead time required for planning, getting a permit and mobilization means that surveys are rarely conducted more than once or twice a year. For many facilities, the interval between surveys stretches to several years.
Third, coverage and data quality can be limited. A small boat navigating a tailings pond may be unable to access shallow margins, areas near active discharge points, or zones close to the embankment walls - often the very locations where monitoring data is most needed. Wind, currents, and poor visibility in tailings water can further complicate navigation and data acquisition. The result is often a partial dataset with gaps in the areas of greatest interest.
Other conventional methods exist but carry their own limitations. Manual depth measurements using weighted lines or portable depth gauges are slow, sparse, and impractical for covering large areas. Satellite-based remote sensing and aerial photogrammetry can map the surface of a pond and exposed tailings beaches effectively, but these methods are blind to underwater topography. Uncrewed surface vessels (USVs) remove the need to have personnel on the water, which is why they have largely displaced crewed boats for this work, but they still require physical deployment onto the pond and face many of the same access and navigational constraints.
The effect of these limitations is a persistent data gap. Mine operators and engineers often have to make critical decisions about TSF capacity, deposition management, and embankment stability based on bathymetric data that is outdated or incomplete.
This gap is a risk for compliance and safety. But for drone service providers, it also represents an opportunity - one that the next section will address.
Drone Bathymetric Surveying: A Purpose-Built Approach
The core idea behind drone bathymetric surveying is straightforward: instead of placing a boat and crew on a tailings pond, an unmanned aerial vehicle flies over the water surface at low altitude with the echo sounder submerged in the water.
In practice, the implementation requires more than simply attaching a sensor to a drone. Performing a bathymetric survey effectively requires a drone and sensor system that is designed for low altitude bathymetric jobs and a pilot that knows how to plan this type of survey.
The Drone Echo Sounder Payload
The primary sensor is a single-beam or multibeam echo sounder - the same type of acoustic instrument used in conventional hydrographic surveying, but in a compact, lightweight form factor suitable for drone deployment. The echo sounder emits acoustic pulses downward toward the pond bottom, and measures depth based on the return time of the reflected signal. Single-beam systems provide a depth reading along a narrow vertical cone beneath the sensor, while multibeam systems capture a wider swath of the bottom in a single pass, increasing coverage efficiency.
The echo sounder is contained in a small weighted housing that is submerged below the water. This is an important point since the measurements can only be done when the echo sounder is submerged. The flight altitude must be set low enough that the sensor is fully submerged but still leaving enough safe altitude for the drone to fly.
SkyHub: The Onboard Computer
Connecting the echo sounder to the drone's flight system is SPH Engineering's SkyHub onboard computer. SkyHub serves as the integration layer between the UAV autopilot, the echo sounder, GNSS positioning, and the ground control software. It handles several functions that are essential for bathymetric operations.
The most important of these is true-terrain following using a radar altimeter. In a standard drone mapping mission, the aircraft flies at a fixed altitude above its takeoff point or above a reference elevation model. Over a tailings pond, this approach is inadequate. The water surface elevation may differ from the takeoff point, and it may not be uniform across the pond - wind setup, inflow patterns, and pond geometry can all create variation. The radar altimeter constantly measures the drone’s actual height above the water, reports it to SkyHub computer which then controls the drone in real time to adjust the flight height.
SkyHub also manages echo sounder data logging, and synchronizing depth measurements with precise GNSS timestamps and positions. This ensures that every depth reading can be accurately geolocated in post-processing.
UgCS: Mission Planning and Flight Control
The flight itself is planned and controlled through UgCS, SPH Engineering's ground control and mission planning software. UgCS allows the operator to plan survey missions based on the specific requirements of bathymetric data collection.
For TSF applications, the ability to define precise, repeatable flight paths is particularly valuable. When a tailings pond is surveyed on a regular schedule - quarterly, biannually, or annually - using the same survey lines each time, the resulting datasets can be directly compared to track changes in bottom topography and sediment volume over time. UgCS stores mission plans and allows them to be reloaded and reused, making repeat surveys efficient and consistent.
UgCS also supports real-time telemetry monitoring and the integration of digital elevation model data, map overlays, and other operational constraints relevant to mine site environments, where airspace may be shared with other operations and ability to plan flights using up-to-date maps and elevation is important.
The Bathymetric Data Pipeline
The output of a drone bathymetric survey is a georeferenced table of depth measurements and locations, analogous to the data produced by a conventional hydrographic survey. From this raw dataset, standard hydrographic processing software such as Hydromagic or BeamworX can generate bathymetric surface models, depth contour maps, volumetric calculations, and change detection analyses when compared against previous surveys.
Moreover, bathymetric data can be combined together with above-the-surface data from LiDAR or a photogrammetry survey, making it possible to get a complete topographic and bathymetric model of the site.
Key Advantages of Drone Bathymetric Surveying over Boat-Based Surveys
There are numerous advantages to using drone-based bathymetric surveys instead of conventional boat-based methods. The advantages fall into several distinct categories.
Safety
The most immediate benefit is the removal of personnel from the water. No one needs to board a boat on a toxic, acidic, or chemically laden tailings pond. No one needs to work on unstable shorelines to launch or retrieve a vessel. The drone operator works from a safe position on solid ground, typically on or near the embankment crest, with full visual line of sight to the aircraft. For mine operators who have restricted or entirely prohibited human access to their tailings ponds, drone surveying may be the only viable method for collecting bathymetric data.
Survey Frequency and Repeatability
Because drone surveys require significantly less mobilization effort than boat-based campaigns, they can be conducted far more frequently. A survey that might have been performed once every two or three years due to cost and logistics can realistically now be done on a quarterly or even monthly basis. This makes it easier to plan regular surveys and build historical datasets to track how the TSF is changing over time, including sediment deposition and volume. It also makes it possible to detect any anomalies early on, in line with GISTM expectations for current facility knowledge.
Reduced Mobilization and Cost
A boat-based bathymetric survey at a remote mine site involves transporting a vessel, sonar equipment, safety gear, and a crew of specialized personnel - often across significant distances. The total cost of a single campaign, including mobilization, field work, and demobilization, can be substantial. An uncrewed surface vessel removes the crew from the water, but it does not remove the logistics. The vessel, its ground control station, power supplies, and a safe launch and recovery point on the shoreline all still have to be brought to site and set up, and safe access to the water’s edge remains a prerequisite.
A drone-based survey, by contrast, requires equipment that fits in a few transport cases. A single operator or a small two-person team can carry everything needed for the survey to site. Setup can be done in less than 10 minutes if flights are preplanned in advance. In mining operations where beyond visual line of sight (BVLOS) flights have become the norm, the equipment often does not need to be transported to the pond at all. The take-off and landing point can sit at a considerable distance from the TSF, for example at an existing operations base, with the drone flying out to the pond and back.
For drone service providers who are already working at or near mining operations - conducting topographic surveys, stockpile measurements, or inspection flights - adding a bathymetric survey to an existing site visit represents a marginal increase in effort with a significant expansion in the scope of deliverables offered to the end-customer.
Access to Difficult Areas
Drone surveys are not constrained by the same physical limitations as boats. A drone can fly transects over shallow margins near embankment walls or confined sections of a pond that a boat might not be able to navigate safely. It can survey ponds with floating debris, vegetation, or surface films that would obstruct boat movement. This extended access often means that drone surveys can achieve more complete spatial coverage than their boat-based equivalents, particularly in the near-shore zones where monitoring data is often most needed for embankment stability assessments.
Combined Topographic and Bathymetric Campaigns
One of the most compelling operational advantages for service providers is the ability to deliver both above-water and below-water datasets from a single site visit. A standard photogrammetric or LiDAR drone survey can map the embankment walls, dry tailings beaches, and surrounding terrain. The bathymetric drone survey maps the underwater portion of the pond. Together, these datasets provide a complete three-dimensional model of the entire TSF - a deliverable that is extremely difficult and expensive to produce using conventional methods, which would require two entirely separate survey operations with different equipment and crews. For the mining company this combined dataset allows to do comprehensive volumetric analysis of the full facility.
Limitations of Drone Bathymetry and Practical Considerations
No survey method is without trade-offs, and drone bathymetric surveying is no exception. Service providers considering this technology should be aware of its current boundaries.
Flight endurance is the most obvious constraint. Multirotor UAVs carrying an echo sounder payload have limited battery life - typically between 20 and 40 minutes per flight, depending on the platform, payload weight, and conditions. For large tailings ponds, this means a survey must be broken into multiple flights with battery swaps or battery changes in between. While this is manageable, it does extend total survey time and requires careful mission planning to ensure efficient coverage.
Depth range is another factor. The maximum depth a drone-deployed echo sounder can measure is governed by the same physics as any sonar system - acoustic frequency, water clarity, and bottom composition all play a role. Most single-beam systems used in drone applications are effective to depths of 50 to 100 meters, which is sufficient for the majority of tailings ponds. However, very deep facilities or ponds with exceptionally high suspended solids concentrations can reduce effective range and data quality.
Weather sensitivity is inherently greater for a drone than for a boat. Strong winds, heavy rain, and low visibility can ground a drone survey entirely, whereas a boat crew might still be able to operate in moderate conditions. In exposed, high-altitude, or high-latitude mine sites where weather windows can be short and unpredictable, this is a practical planning consideration.
Multibeam coverage from a drone remains more limited than from a vessel. A boat-mounted multibeam system can achieve very wide swath widths due to its stable, water-level mounting position. The more fundamental reason is payload capacity. A vessel, crewed or uncrewed, can carry a far heavier multibeam unit than a drone is able to lift, and heavier systems offer considerably better parameters, including a greater number of beams and longer range. A drone-deployed system typically achieves narrower swaths, requiring more transect lines to cover the same area. For applications where full-bottom, high-resolution multibeam coverage is the primary requirement, a conventional vessel survey may still offer advantages in raw data density per pass.
Finally, regulatory frameworks for drone operations vary by jurisdiction and are still evolving. Flight permissions, visual line of sight requirements, and restrictions on operations near active mine infrastructure can all affect where and how drone surveys can be conducted. Service providers must factor local aviation regulations into their operational planning. Remote mine sites are often easier in this respect than they first appear. Large operations frequently manage their own airspace, since they run their own helipads or airstrips, and can close that airspace to other traffic when a BVLOS flight is required.
However, for the majority of TSF applications - where the alternative is either an expensive and infrequent boat survey or no bathymetric data at all - drone-based surveying offers a practical, cost-effective, and safer solution. The question for most facilities is not whether drone surveys match every capability of a fully equipped survey vessel, but whether they deliver the data that is actually needed, at a frequency and cost that makes regular monitoring feasible. In most cases, the answer is yes.
Latest Drone Bathymetry Case Studies
Oyu Tolgoi Mine, Mongolia: recurring TSF pond monitoring
Best Survey Mongolia, working with SPH Engineering, surveys a water pond of approximately 15,000 square metres inside the tailings storage facility at the Oyu Tolgoi copper and gold operation. The pond offers no safe deployment point for a vessel of any size, so boat-based survey was ruled out before the programme began. The team flies a DJI M350 RTK carrying the SPH Engineering bathymetry kit with an ECT D052S echo sounder, with SkyHub handling onboard integration and UgCS providing the pre-planned survey lines, while the crew remains on the bank for the full mission. The surveys have been running since 2025 on a repeat cycle and produce georeferenced bathymetric maps of depth variation across the pond that feed directly into the site's monitoring records. Because each return visit reuses the same kit and the same mission file, the datasets are directly comparable from one cycle to the next.
Konawe, Southeast Sulawesi, Indonesia: an otherwise inaccessible mining water body
Oseanland Survei Indonesia, in partnership with SPH Engineering, ran a field demonstration at PT Sulawesi Cahaya Mineral in Konawe, Southeast Sulawesi. The target was a swampy mining water body with shallow water, dense vegetation, and soft ground, terrain that ruled out launching a crewed boat or a USV. The survey used a DJI Matrice 350 RTK with an Echologger ECT D052S echo sounder, a SkyHub onboard computer with a radar altimeter for true-terrain following, and UgCS for mission planning, flying planned lines while SkyHub held the altitude needed to keep the sensor submerged. The result was a bathymetric depth map of the surveyed area, collected without any personnel or equipment entering the water, and it confirmed that the method works in swampy mining environments where conventional access is not available.
Conclusions and the Path Forward
The core ideas in the mining industry around tailings management are changing. Driven by catastrophic failures, tightened regulations, and the comprehensive requirements of the Global Industry Standard on Tailings Management (GISTM), operators are under increasing pressure to know more about their facilities - and to know it more often.
Bathymetric data, once an afterthought in TSF monitoring programs, is now recognized as essential to understanding storage capacity, sediment behavior, and underwater slope stability.
For most of the industry's history, collecting this data was difficult enough to justify not collecting it at all. Boat-based surveys were expensive, logistically demanding, and in many cases too hazardous to conduct on toxic tailings ponds. This caused decisions about facility safety and capacity to be made based on incomplete or outdated information.
While drone bathymetric surveying does not eliminate every limitation of underwater data collection, it does remove personnel from the water, offer reduced mobilization costs, and enable frequent repeatable surveys.
These factors combined make regular bathymetric monitoring more practical and affordable. The combination of a reliable UAV platform, an integrated echo sounder payload, SkyHub onboard computing with true-terrain following, and UgCS mission planning provides a complete, field-proven technology stack purpose-built for this application.
For drone service providers, the opportunity is both technical and commercial. TSF bathymetric surveying is a specialized service with strong and growing demand, driven by regulatory requirements that are not going away. It builds naturally on existing capabilities in aerial surveying and mine site operations, and it offers the ability to deliver high-value combined topographic and bathymetric datasets. Providers who develop this capability now are positioning themselves in a market that is still in its early stages but expanding steadily as the mining industry's monitoring obligations increase.
The facilities exist - tens of thousands of them around the world. The regulatory mandate is clear. The technology is ready. The question for drone service providers is not whether this market will develop, but whether they will be part of it when it does.
References
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[2] Responsible Mining Foundation. (2021, January 25). Responsible Mining Foundation concerned about thousands of abandoned, at-risk tailings facilities worldwide. As cited in MINING.COM. https://www.mining.com/responsible-mining-foundation-worried-about-thousands-of-abandoned-at-risk-tailings-facilities-worldwide/
[3] Zhu, F., Zhang, W., & Puzrin, A. M. (2024). The slip surface mechanism of delayed failure of the Brumadinho tailings dam in 2019. Communications Earth & Environment, 5(1). https://doi.org/10.1038/s43247-023-01086-9
[4] Silva Rotta, L. H., Alcântara, E., Park, E., Negri, R. G., Lin, Y. N., Bernardo, N., Mendes, T. S. G., & Souza Filho, C. R. (2020). The 2019 Brumadinho tailings dam collapse: Possible cause and impacts of the worst human and environmental disaster in Brazil. International Journal of Applied Earth Observation and Geoinformation, 90, 102119. https://doi.org/10.1016/j.jag.2020.102119
[5] Province of British Columbia. (n.d.). Mount Polley Mine tailings dam breach. https://www2.gov.bc.ca/gov/content/environment/air-land-water/spills-environmental-emergencies/spill-incidents/past-spill-incidents/mt-polley
[6] Independent Expert Engineering Investigation and Review Panel. (2015). Report on Mount Polley Tailings Storage Facility Breach. Government of British Columbia. https://www.mountpolleyreviewpanel.ca/final-report
[7] Fernandes, G. W., et al. (2016). Fundão tailings dam failures: The environment tragedy of the largest technological disaster of Brazilian mining in the global context. Perspectives in Ecology and Conservation, 14(2), 35–45. https://doi.org/10.1016/j.ncon.2016.10.003
[8] Samarco Mineração S.A. (n.d.). About the failure of the Fundão dam. https://www.samarco.com/relatoriobienal20152016/en/about-the-failure-of-the-fundao-dam.html
[9] International Council on Mining and Metals, United Nations Environment Programme, & Principles for Responsible Investment. (2020). Global Industry Standard on Tailings Management. https://globaltailingsreview.org/wp-content/uploads/2020/08/global-industry-standard-on-tailings-management.pdf