Overview
Tailings dams, which store waste materials from mining operations, pose significant safety and environmental risks when they fail. Brazil has experienced several catastrophic tailings dam failures in recent years, including the 2015 Mariana and 2019 Brumadinho disasters, which resulted in hundreds of fatalities and severe environmental damage. These events highlighted the critical need for improved monitoring systems to detect early warning signs of potential dam instability.
Satellite Used
Sentinel-1
Time Period
2020-2023
Challenge
A major mining company operating in Brazil's Iron Quadrangle region faced several challenges in monitoring their tailings dam infrastructure:
- Managing a large portfolio of tailings dams across multiple mining sites
- Detecting millimeter-scale deformations that could indicate potential instability
- Ensuring continuous monitoring regardless of weather conditions or site accessibility
- Complementing ground-based monitoring systems with broader spatial coverage
- Meeting increasingly stringent regulatory requirements following recent disasters
- Providing early warning of potential issues to protect communities and the environment
Traditional monitoring approaches relied heavily on ground-based instruments and visual inspections, which provided limited spatial coverage and were sometimes hindered by site access issues. A more comprehensive and systematic monitoring approach was needed to enhance safety and reduce risk.
Solution
We implemented a comprehensive tailings dam monitoring system using Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR), which offers:
- Millimeter-scale deformation detection capability
- All-weather monitoring unaffected by cloud cover
- Regular 6-12 day revisit frequency
- Wide-area coverage of entire mining complexes
- Historical data archive for baseline establishment
Key Components of the Solution:
1. Advanced InSAR Processing
We implemented a specialized InSAR processing workflow that:
- Applied Persistent Scatterer Interferometry (PSI) to detect stable measurement points
- Utilized Small Baseline Subset (SBAS) techniques for areas with lower coherence
- Incorporated atmospheric phase correction to improve measurement accuracy
- Applied terrain correction using high-resolution DEMs
- Achieved sub-millimeter precision in deformation measurements
2. Integrated Monitoring System
The satellite-based monitoring was integrated with other data sources:
- Ground-based monitoring instruments (piezometers, inclinometers, etc.)
- Weather data to account for seasonal effects
- Dam design specifications and construction history
- Historical deformation patterns and baseline behavior
3. Automated Alert System
We developed an automated alert system that:
- Processed new Sentinel-1 acquisitions within hours of availability
- Applied machine learning algorithms to detect anomalous deformation patterns
- Classified alerts based on deformation rate, acceleration, and spatial pattern
- Generated notifications for different alert levels
- Provided visualization tools for engineers to investigate detected anomalies
InSAR deformation map showing millimeter-scale movement on a tailings dam
Results
Deformation detection threshold
Critical issues detected
Monitoring coverage
The implementation of the Sentinel-1 InSAR monitoring system delivered significant benefits:
- Early Warning: The system detected three instances of anomalous deformation that were not identified by conventional monitoring methods. In one case, this led to the early identification of internal erosion (piping) that could have progressed to a serious failure.
- Comprehensive Coverage: The satellite-based approach provided 100% coverage of all tailings facilities, including areas that were difficult to access with ground-based instruments.
- High Precision: The system consistently achieved a deformation detection threshold of 2 mm, enabling the identification of subtle movements that could indicate developing problems.
- Continuous Monitoring: Regular Sentinel-1 acquisitions ensured continuous monitoring regardless of weather conditions or site access limitations.
- Historical Analysis: Processing of the Sentinel-1 archive allowed for retrospective analysis of dam behavior, establishing baseline deformation patterns and identifying long-term trends.
"The Sentinel-1 InSAR monitoring system has transformed our approach to tailings dam safety. It provides us with a level of insight and early warning capability that was simply not possible with conventional monitoring alone. In one case, it detected subtle deformation patterns that led us to identify and address a developing issue before it could progress to a serious problem."
Conclusion
This case study demonstrates the powerful capabilities of Sentinel-1 InSAR for monitoring critical infrastructure such as tailings dams. By leveraging the millimeter-scale deformation detection capability and regular revisit frequency of Sentinel-1, we were able to develop a monitoring system that significantly enhances safety and reduces the risk of catastrophic failures.
The success of this project highlights the value of satellite-based monitoring as a complement to traditional ground-based approaches. The system has now been expanded to cover all of the company's tailings facilities in Brazil and is being considered for global implementation across their mining operations.
This approach can be applied to monitor other types of critical infrastructure, including dams, bridges, pipelines, and landslide-prone areas, providing a cost-effective way to enhance safety and reduce risk.