Accelerating Displacement Detected 2 Months Before Dam Failure
Bokeo Province, Laos
Water Management
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Dams are a vital part of the global infrastructure network. There are more than 15,000 dams classified as high-risk in the United States alone. These are defined as dams with a high consequence of failure, including loss of life. Furthermore, the average age of dams in the US is 57 years, and by 2030, nearly three quarters of all dams will be more than 50 years old.
Construction costs for dam rehabilitation can be in the millions, representing a substantial investment from private stakeholders and taxpayers alike. Dam monitoring for slope stability should cover all related components including reservoirs, upstream slopes, spillways, saddle dams, turbine halls, and primary dams. Regular inspection and monitoring of dam slope stability protects the integrity of this critical infrastructure.
Dams and reservoirs present a unique geotechnical challenge. Effective dam monitoring with in-situ ground instrumentation poses a lot of challenges—large slopes, remote geographic locations, and difficult access for staff and personnel.
Reducing the risk of dam failure should be a top priority for stakeholders at all levels. This combined responsibility provides proper protection for workers, the environment, and the surrounding communities. Monitoring displacement using InSAR provides an early warning of safety concerns regarding dam slope stability.
Effective instrumentation for dam monitoring can be prohibitively expensive. To start, engineers and consultants need historic site data to identify the areas of potential hazards to monitor with instrumentation.
Then, adequate coverage of upstream slopes, saddle dams, embankments, and spillways needs proper sensor density. Finally, monitoring plans may require costly in-person site visits to manually download and record data.
InSAR is a satellite-based and fully remote technology. Its large image footprint can cover the entire reservoir, dam walls, spillways, and access roads, while maintaining high displacement precision. InSAR results can also complement existing ground-based sensors and aid in choosing appropriate installation locations.
Another drawback to localized monitoring instrumentation is that measurements are only taken when and where the instrumentation has been installed. 3vG’s monitoring projects can include archival satellite imagery to provide baseline analysis on historical data that goes back several years or decades, depending on the area of interest. This data provides insight to reveal cyclical displacement patterns which help identify anomalies in dam behaviour. The frequency of InSAR monitoring data can be adapted to dam raises and other ongoing construction. InSAR monitoring doesn’t require input from on-site staff.
Using 3vGeomatics’ satellite InSAR, clients can remotely monitor hundreds of thousands or even millions of data points around the entire reservoir for slope stability, with measurements for each data point being updated as frequently as every few days.
3vG’s InSAR monitoring is satellite-agnostic, which means clients are served with the best data for the application. The slopes surrounding dams are often densely vegetated and our experience in monitoring vegetated areas using longer wavelength L-band data is unparalleled in the industry.
In addition, InSAR analysis can simultaneously include the dam wall to supplement existing instrumentation. Measurements are updated in near-real-time through our web-based delivery tool, called Motionary. Operators and dam safety officers can simultaneously access results with Motionary without the need to manage disparate data sources or to visit instrument locations.
InSAR provides proactive monitoring of watersheds, perimeter embankments, dikes, spillways, upstream slopes, dam walls, outlet facilities, and all access roads and neighboring infrastructure. Often, all of these components are monitored within the same satellite footprint, offering budget efficiencies for monitoring dam safety.
3vG’s Displacement DataStream can provide satellite InSAR results to Motionary in near-real-time or adjusted to the timetable within the operational maintenance and surveillance manual designed by the local regulating body and Dam Safety Officials.
3vG’s dam monitoring solution includes increased protection against overtopping caused by upstream slope failures. This is done by selecting appropriate satellite parameters during project design such that reservoir slopes are adequately covered and measured. As a result, new slope instabilities can be identified through 3vG’s Acceleration and Detection Polygons and continuously tracked using Displacement Detection Contours. Acceleration and Detection Contours are automatically generated using robust statistical algorithms before being quality checked by trained InSAR Analysts—a process which outperforms alternative remote sensing techniques for displacement monitoring.
Monitoring programs can also include an Emergency InSAR Response Plan which, when activated, will pull alternative InSAR satellite data into the Displacement DataStream. Within hours of image download to the 3vG data processing farm, additional results are published to Motionary to provide actionable intelligence, enabling the dam operator to immediately remediate the problem, or issue evacuation notices.
Interferometric synthetic aperture radar (InSAR) is a satellite remote sensing technology used for mapping ground displacement across a number of sectors.
Discover the benefits of using InSAR and learn more about this fascinating technology and how it can be applied to your next project by clicking the button below.
Learn MoreWe are very impressed with this data. We realized that we have problems right now in several areas caused by rain. We saw them shown in red on the map.”