Hydroelectric dams are critical assets in the global transition to renewable energy[1], however, their safety and structural integrity are under increasing scrutiny. Aging infrastructure, climate-related stressors, and changing load demands all contribute to heightened risk profiles. For operators, regulators, and engineers, early detection of structural deformation is critical to maintain safe and reliable electricity generation[2].
In this post, we examine the evolving challenges of dam safety, draw insights from notable case studies, and review how EarthDaily’s Iris solution brings enhanced visibility to dam monitoring. By leveraging satellite-based observations with millimeter-scale measurement sensitivity, Iris enables proactive risk management at scale.
During the 2010s, more than 3,700 dams were planned or under construction worldwide,[3] reflecting a surge in hydropower development. But this rapid growth has often outpaced safety and oversight.[4]
According to the International Commission on Large Dams (ICOLD), over 90% of recorded dam failures have occurred in small dams,[5] structures often excluded from stringent monitoring and regulatory frameworks. In the past five years alone, most collapse events have involved small-to-medium-sized dams, typically 30 meters or less in height[6] and in this category of dam, traditional in situ monitoring is limited due to cost and resource intensity. Aging dams with heights of >30 m still pose a risk, however significant effort has been placed in monitoring these dams, particularly concrete arch and high gravity dams (typically at least 100 m in height).
Dam failures can result from a range of mechanisms, including overtopping, internal erosion, slope instability, structural sliding or overturning, and excessive deformation. Amongst these, deformation is a critical early indicator that, if detected in time, can help prevent catastrophic outcomes.
Deformation may be triggered by a combination of external forces such as thermal expansion, hydrostatic pressure, seismic activity, and changes in geotechnical properties of the substrate and internal factors, including alterations in the strain-stress characteristics of materials, localized sinking or sliding, and water seepage.
Given the range of potential failure drivers, precise deformation monitoring of the dams and their surroundings is essential. Tracking early deformation signals enables identification of instability trends before they escalate to visible damage or failure.
Interferometric Synthetic Aperture Radar (InSAR) is a satellite-based remote sensing technique that detects ground deformation with exceptional precision. By sending microwave radar pulses to the Earth’s surface and recording the reflections, InSAR detects subtle ground movement with millimetric precision.
A key advantage of InSAR is that it operates day or night, and in any weather. It covers vast areas, without the need for on-site equipment. This is especially valuable in remote or hard-to-access dam locations, where traditional in situ monitoring can be logistically challenging or cost-prohibitive.
InSAR produces detailed deformation maps over thousands of square kilometers, delivering consistent, repeatable measurements. Rather than replacing in situ monitoring and inspections, InSAR complements these localized monitoring solutions by filling gaps with continuous, scalable, system-level, wide-area surveillance. In the case of small-medium sized dams where in situ monitoring is limited, or in the case of aging dams, InSAR offers a cost effective and scalable option for detecting and monitoring precursors of dam deformation.
EarthDaily Iris is engineered to meet these challenges by transforming InSAR data into actionable insights. Designed by leading InSAR experts, Iris stands out for its cost-effectiveness, robust analytics, and ease of integration with existing monitoring systems.
Completed in 2017, the Saradoba Dam was designed to store 922 million cubic meters of water for agricultural irrigation across surrounding provinces[7]. In April 2020, construction began on an associated hydroelectric power station (HPS), with a plan to generate 10.7 MW across two hydro turbines, producing over 41 million kwh annually.[8]
On May 1, 2020, a section of the 29-meter-high concrete structure failed catastrophically. Approximately 500 million cubic meters of water was discharged from the reservoir, resulting in tragic loss of life, the evacuation of over 100,000 people, and widespread flooding across 35,000 hectares of land.[9]
EarthDaily Iris was applied retroactively to assess if deformation signals could have been detected prior to the failure event.
Figure 1: East-West-Vertical (EWZ) InSAR based on Sentinel-1 SAR visualized over the western embankment of the Saradoba Reservoir, Uzbekistan. Cumulative deformation is calculated over the period May 17, 2019, to April 17, 2020.
The Iris analysis in Figure 1 reveals localized vertical deformation along the section of the dam that ultimately failed. A transect along the wall (blue polyline) shows over 30mm of vertical subsidence, with minimal movement detected in adjacent areas. When compared to stable reference points just beyond the structure, the total differential displacement exceeded 70 mm in the year leading up to failure.
Figure 2: Deformation anomaly detection algorithms deployed in Iris, shows persistent anomaly detection over the point of failure at the western embankment of the Saradoba Reservoir, Uzbekistan.
Figure 2 shows anomaly detection algorithms in Iris highlighting persistent deformation within the middle and edges of the failure location. These anomalies were detected approximately 7 months prior to the failure event.
An article in the International Journal of Applied Earth Observation and Geoinformation titled New insights into the 2020 Saradoba dam failure in Uzbekistan from Earth Observation indicates that the differential settlement of ~60mm indicated by InSAR at the point of failure was a sign of internal erosion through the embankment which was a key physical factor contributing to the failure. This aligns with the deformation signals visualized within Iris.
The Xiaolangdi Dam impounds the Yellow River in China and plays a critical role in flood control and safety, ice management, and agricultural and industrial water supply, and hydropower. It has a total installed capacity of 1,836 MW and generates up to 5.1 TWh annually across six 306 MW turbines[10]. As a rock-fill embankment dam, it experiences changes in deformation due to the change in water level. InSAR can be used to measure deformation along the dam wall to ensure that it is within its safe operating levels.
EarthDaily Iris was applied to evaluate deformation signals to examine seasonal and long-term trends.
Figure 3: Line of Site (LOS) - Ascending InSAR based on Sentinel-1 SAR visualized over the Xiaolangdi Dam, Jiyuan, Henan Province, China. Cumulative deformation is calculated over the period September 11, 2020, to July 15, 2022.
Results in Iris show both a long-term subsidence trend near the crest of the dam, as well as a seasonal off-loading trend which anticorrelates with water levels within the reservoir. The 22 month-long analysis shows a consistent long-term linear deformation trend with greater subsidence near the top center of the dam, and lower magnitudes toward the edges and the base.
The seasonal offloading aligns with fluctuations in water load and is typical of embankment dam behavior. These results are consistent with those found in Dam Surface Deformation Monitoring and Analysis Based on PS-InSAR Technology: A Case Study of Xiaolangdi Reservoir Dam in China, which compares InSAR to seasonal water levels and determines that this type of motion is expected and does not indicate safety or stability issues at the Xiaolangdi dam.
In a world where dam failure can have devastating consequences, transforming risk management practices is imperative. InSAR provides continuous, scalable, system-level, wide-area surveillance and when combined with in situ monitoring can provide a holistic and proactive risk management strategy that can help to reduce deformation-based failure risk to the lowest reasonable achievable level.
Whether you are a hydroelectric dam operator, a regulatory body, or an engineering firm, EarthDaily Iris provides the intelligence needed to safeguard assets, protect communities, and support long-term structural resilience.
[1] International Energy Agency (IEA). (2021). Hydropower Special Market Report.
[2] Aging dams, political instability, poor human decisions and climate change: recipe for human disaster
[3] Zarfl, C., Lumsdon, A.E., Berlekamp, J., Tydecks, L., & Tockner, K. (2015). A global boom in hydropower dam construction. Aquatic Sciences, 77(1), 161-170.
[4] UNEP-DHI & IHA (2019). Hydropower Sector Climate Resilience Guide.
[6] Precursory Motion and Deformation Mechanism of the 2018 Xe Pian-Xe Namnoy Dam Collapse, Laos: Insights from Satellite Radar Interferometry
[7]Saradoba Dam Bursts in Uzbekistan
[9] Dialogue Earth: Uzbekistan Dam Collapse Was a Disaster Waiting to Happen