Dam Failure Research Articles

2D and 3D Numerical Simulation of Dam-Break Flooding: A Case Study of the Tuzluca Dam, Turkey

Unlike river floods, floods caused by dam breaks occur much more abruptly and at higher water velocities. The failure of a dam due to any reason can pose a significant threat to settlements in the downstream area due to the high volume of water in its reservoir. In this case study, 2D and 3D numerical failure simulations of Tuzluca Dam, to be built in the Igdir province of Turkey, was performed using the Flow3D Hydro software. The Shallow Water and Reynolds-Averaged Navier-Stokes (RANS) equations were used to simulate flood propagation. In the numerical models, RNG k-ε was chosen as the turbulence model. In the analyses carried out under different scenarios, it was observed that in both methods (2D and 3D), significant flood depths would occur in two downstream village settlements. Within the scope of the study, the mortality rates in different dam-break scenarios of the Tuzluca Dam were also investigated. It has been observed that the dam failure time and breach geometry have a significant impact on the flood propagation and the loss of life in settlements. Additionally, a dam-break experiment in literature dam-break experiment was numerically solved using the Flow3D Hydro software to validate the numerical model, and a satisfactory harmony was observed between the experimental results and the numerical models. Although the 3D analysis provided a more accurate representation of the experimental results, it took approximately 20 times longer to complete the dam failure simulation in the case study compared to the 2D model. As a result, it has been determined that for comprehensive studies such as those of dam failures, 2D analyses may be more practical, while for smaller-scale scenarios or situations requiring greater precision, 3D modelling is appropriate.

Assessing the risk of check dam failure due to heavy rainfall using machine learning on the Loess Plateau, China

Check dams are widely used throughout the world to tackle soil and water loss. However, the frequency of extreme rainfall events has increased owing to global climate change and the main structure of check dam is gradually aging, which lead to an increase in the failure risk of check dams. Thus, it is necessary to carry out the study on failure risk diagnosis and assessment of check dams. In the study, machine learning algorithms (ML), including random forests (RF), support vector machine (SVM), and logistic regression (LR), were used to integrate the environmental and engineering factors and then assess the risk of check dam failure due to the “7.26” rainstorm on July 26, 2017, in the Chabagou watershed, located in the hilly-gully region of the Loess Plateau, China. To verify the generalizability of the model in this study, these models were used for the Wangmaogou catchment north of the Loess Plateau. The accuracy assessment by the receiver operating characteristic (ROC) curve indicated that the RF model with an area under the ROC curve (AUC) greater than 0.89 was the most precise model and had a higher generalization ability. In addition, the model dataset was relatively small and easy to obtain, which make the risk modeling of check dam failure in the study has the potential for application in other regions. In the RF model, each factor selected was confirmed to be important, and the importance values for engineering factors were generally higher than those for the environmental factors. The risk map of check dam failure in the RF model indicated that 56.34% of check dams in the study area had very high and high risks of dam failure under high-intensity rainfall in 2017. Based on the importance of factors and the risk map of check dam failure, the prevention and control measures for reducing the risk of check dam failure and promoting the construction of check dam are proposed. These proposals provide a scientific basis for the reinforcement of check dams and the future layout of check dams in the Chinese Loess Plateau.

The effect of a mining dam failure on the genetic diversity and population resilience of marine fishes along the eastern Brazilian coast

We used microsatellite DNA markers to examine the impact of the Fundão Dam failure, one of the world’s worst mining-related environmental disasters, on the genetic diversity of four marine and estuarine fishes across the Brazilian east coast's continental shelf and estuarine ecosystems. The strong mud flow along the Doce River and nearby areas resulted in changes in genetic diversity, with all species exhibiting low genetic diversity indices, primarily in estuarine species, and particularly those with a greater association with the substrate. Furthermore, the low M-ratio values in all species tested indicated a recent decrease in the effective population size. Estuarine species, particularly the slipper sole Trinectes paulistanus, were more directly impacted by the mud plume than marine species. The loss of genetic variability due to population decline is concerning because it is ultimately an important component in determining the ability of marine fishes to adapt to environmental changes. Combining genetic data from four fish species with different behaviours, habitats, life histories, and economic values revealed that genetic diversity was a valuable tool for assessing the effects of the Fundão Dam failure.

Soil arthropod community responses to restoration in areas impacted by iron mining tailings deposition after Fundão dam failure.

In 2015, the failure of the Fundão dam in Mariana, Brazil released ~43 million m3 of iron mining tailings into the environment. Despite restoration initiatives in the following years, few studies-and most focused on revegetation-have evaluated the effectiveness of the restoration process in areas impacted by the disaster. We aimed to evaluate the responses of the arthropod community in areas impacted by iron mining tailings deposition from the Fundão dam that is in the restoration process. We defined sampling units in the riparian zone of the Gualaxo do Norte River, which is under restoration, and in a native not impacted riparian zone. We collected soil arthropods using pitfall traps and sampled environmental variables in the same sites. We used generalize least squares models (GLS) to test if the restored areas already presented values of arthropod diversity and functional group abundance similar to the reference area and to test which environmental variables are influencing arthropod diversity. We also tested how large the differences of arthropod community composition between the study areas and used the index of indicator species (IndVal) to verify which species could be used as an indicator of reference or restoration areas. The diversity of arthropods and the functional groups of detritivores and omnivores were higher in the native riparian zone. Understory density, soil density, organic matter content, and microbial biomass carbon were the environmental variables that significantly explained the diversity and species composition of arthropods. We show that restoration areas still have different soil arthropod diversity values and community composition when compared to reference areas. Evaluating the response of the arthropod community to the restoration process and long-term monitoring are essential to achieve a satisfactory result in this process and achieve a self-sustaining ecosystem.

Study on the Evolution of Tailings Dam Break Disaster under Complex Environment

In response to the challenges posed by rapid development, the wide-ranging disaster impact, and the untimely warning of debris flow resulting from tailing dam failure, it is of great significance to study the mechanism of dam failure as well as the evolution law and affected area of debris flow for effective disaster prediction and risk assessment. We developed a 1:150 physical model for testing tailing dam failure and combined it with RAMMS (V1.7.0) debris flow software to investigate the mechanisms of tailing dam failure and the evolutionary patterns of rock flows in complex environments. Through the analysis and comparison of experimental data, we comprehensively summarized the consequences of disaster risk resulting from dam failure. The results show that the grain size distribution of the model sand should be moderate; the composition of the particle size distribution has a significant impact on the collapse morphology of the dam after failure. The saturation line is the lifeline for the stability of the wake reservoir, and its level determines the degree of saturation of the wake in the reservoir. The breach was at the midpoint of the crest of the dam. The inflow volume at the time of the breach was 0.313 m3. According to the flow ratio relationship, the inflow volume at breach occurrence was equivalent to 1.78 times the total amount of a 1000-year flood and 1.19 times the total amount of a probable maximum flood (PMF). Analysis of the surface flow field revealed that the region with the highest flow velocity extended from the toe of the dam to Shangdi village; the impact on the village of Shizhou was limited to the backflow of the dam break and the gradual sedimentation of the tailings.

Dam breach analysis of Kibimba Dam in Uganda using HEC-RAS and HEC-GeoRAS

Dam failures have severe consequences on human life and property. In the case of an earth filled Kibimba Dam located in Eastern Uganda, the occurrence of a flood equal to or larger than the probable maximum food (PMF) could result in catastrophic economic losses including loss of human life. This study utilized the USACE Hydrologic Engineering Center's River Analysis System (HEC-RAS) and Hydrologic Engineering Center’s Geographic River Analysis System (HEC-GeoRAS) to analyze the potential dam break of Kibimba Dam, considering overtopping and piping failure scenarios. The results of the analysis revealed that the spillway of Kibimba Dam possesses sufficient capacity to safely discharge a flood resulting from a probable maximum flood peak of 400 m3/s. Therefore, the dam is not susceptible to breach under the overtopping failure mode. However, the dam failed under the piping failure mode. To assess the downstream impact of the dam break, the breach hydrographs resulting from piping failure were examined. Consequently, the study investigated the effects of flood propagation downstream of the dam. This resulted in varying inundation depths of up to 6 m and velocities ranging from 1.2 to 10 m/s. These findings highlight the devastating consequences of Kibimba Dam's failure, particularly affecting rice field plantations, infrastructure, and other economic activities in the downstream area. Therefore, the outcomes of this study are crucial for the development of Emergency Action Plans that incorporate dam breach and flood routing analyses specific to the affected downstream regions.

Storage Earth Dam Failure due to Liquefaction Caused by Earthquakes

Aims: We are researching causes and criteria for the liquefaction dam failure by analyzing the safety of the dam under static and dynamic loads against shear failure using the finite element technique, which is used to simulate stability assessment for selected earth dams under different loading conditions. Background: Storage Massive earth dams are vulnerable to collapse during earthquakes, which can have severe effects ranging from direct human casualties to indirect economic losses. How seismically fragile earth dams are and what issues may arise from a failure depend on how they respond to earthquakes. Slope failure, piping, displacement, and/or settlement are examples of seismic responses that are caused by weak soil and/or the liquefaction of loose sands. Earth dam failure can be caused by a variety of factors, including seepage through the dam body, hydraulic issues, structural instability, and liquefaction failure brought on by earthquakes. Objective: The objective of this study is to find a way to design of earth-fill dams. Methods: The finite element method is a numerical solution. This method is based on a grid pattern (not necessarily rectangular) which divides the flow region into discrete elements and provides N equations with N unknowns. Material properties, such as permeability, are specified for each element, and boundary conditions (heads and flow rates) are set. The finite element method has several advantages over the finite difference method for more complex seepage problems. Results: The Lower San Fernando Dam is dangerous under dynamic loads, and the F.O.S. values for the upstream and downstream directions are 0.264 and 0.183, respectively. 1350 m2 is the Lower San Fernando Dam's liquefaction area. 40.67% of the Lower San Fernando Dam's overall foundation area is represented by that figure. Tapar (India) dam is hazardous due to slope failure under dynamic loads, and the F.O.S. values for the upstream and downstream directions are 0.5 and 0.109, respectively. Tapar Dam in India has a liquefaction area of 457 m2. This amount equals 52.33 percent of the Tapar (India) dam's entire foundation area. The slope failure under dynamic loads and the F.O.S. values of 0.313 and 0.548 for the slopes of the river upstream and downstream of Fatehgadh dam (India), respectively, lead to the conclusion that it is dangerous. 333.5 m2 is the size of the liquefaction area of the Fatehgadh dam in India. The foundation area of the Fatehgadh (India) dam as a whole is represented by that figure at 78.75%. Saluda Dam in Columbia is an unsafe slope failure under dynamic loads, and the F.O.S. values for the upstream and downstream directions are 0.102 and 0.101. Saluda Dam in Columbia has a 32095 m2 liquefaction area. This value represents 32.96% of the Saluda Dam's total foundation area (Columbia). Conclusion: Conclusions state that 32.96% of the minimum liquefaction zone area is what causes liquefaction failure. Under the effect of seismic stresses, a safe design standard for storage earth dams is produced. The evaluation must also take into account the specifications for safety limitations based on global norms, regulations, and codes. examining the dam safety requirements for dynamic loads.

A SHANSEP approach to quantifying the behaviour of clayey soils on a constant shear drained stress path

Assessing the risk of slope failures of earth structures comprising loose, saturated soils has seen increased focus recently owing to a series of prominent tailings and water dam failures. The potential for the triggering of slope instability by a rising phreatic surface – commonly referred to as the constant shear drained (CSD) stress path – has been well documented over the past few decades for sands and sandy soils under a wide range of loading modes. Alternatively, there has been limited CSD element testing of more clayey soils, with the available data rather showing a dilative tendency through the CSD stress path and mobilised strengths greater than the critical friction ratio, even for specimens commencing CSD shearing from an initially loose state. The current paper expands on the CSD data of clayey soils by testing an iron ore tailings (IOT) and kaolin clay in both triaxial and direct simple shear (DSS) devices, with an emphasis on the DSS. Owing to the tendency for the CSD stress path to result in an overconsolidated condition (i.e. unloading) the tests in the current study were interpreted in the SHANSEP framework given its frequent use to analyse clay behaviour. The results indicated that the SHANSEP framework can reasonably characterise some aspects of CSD behaviour of clays in DSS loading, with some caveats.

Direct Probability Integral Method for Seismic Performance Assessment of Earth Dam Subjected to Stochastic Mainshock–Aftershock Sequences

Studying the impact of mainshock–aftershock sequences on dam reliability is crucial for effective disaster prevention measures. With this purpose in mind, a new method for stochastic dynamic response analyses and reliability assessments of dams during seismic sequences has been proposed. Firstly, a simulation method of stochastic seismic sequences is described, considering the dependence between mainshock and aftershock based on Copula function. Then, a novel practical framework for stochastic dynamic analysis is established, combined with the improved point selection strategy and the direct probability integration method (DPIM). The DPIM is employed on a nonlinear system with one degree of freedom and compared with Monte Carlo simulation (MCS). The findings reveal that the method boasts exceptional precision and efficiency. Finally, the seismic performance of a practical dam was evaluated based on the above method, which not only accurately estimates the response probability distribution and dynamic reliability of the dam, but also greatly reduces the required calculations. Furthermore, the impact of aftershocks on dam seismic performance is initially evaluated through a probability approach in this research. It is found that seismic sequences will significantly increase the probability of earth dam failure compared with sequences of only mainshocks. In addition, the influence of aftershocks on reliability will further increase when the limit state is more stringent. Specifically, the novel analysis method proposed in this paper provides more abundant and objective evaluation indices, providing a dynamic reliability assessment for dams that is more effective than traditional evaluation methods.

Association between urinary concentrations of toxic metals/metalloids and oxidative stress in Brazilians living in areas affected by the Fundão dam failure

The Fundão Dam failure has been the most significant environmental disaster in Brazil. The catastrophe released large amounts of mining waste into the environment, including toxic metals/metalloids, which are recognized to induce carcinogenic effects. The urinary levels of 8-hydroxy-2′-deoxyguanosine (8OHdG), a widely accepted oxidative stress and carcinogenesis biomarker, provide a potential tool for assessing the disaster's health implications. This study investigated the association between urinary levels of some toxic metals/metalloids and 8OHdG in Brazilian individuals living in areas affected by the Fundão dam failure. Urinary concentrations of arsenic (As), cadmium (Cd), mercury (Hg), nickel (Ni), and lead (Pb) were determined using inductively coupled plasma mass spectrometry, while 8OHdG was analyzed by liquid chromatography-tandem mass spectrometry. Non-parametric bootstrap regression was used to estimate the associations between the urinary levels of toxic elements and 8OHdG. The results showed that except for Hg, urinary concentrations of all metals/metalloids analyzed here exceeded the reference ranges for the Brazilian population. The regression analysis revealed that As (0.337; CI 95%: 0.203; 0.474), Cd (0.268; CI 95%: 0.036; 0.520), and Ni (0.296; CI 950.108; 0.469) were positively associated with creatinine-adjusted urinary 8OHdG levels. Associations were not found for Hg (0.0122; CI 95%: −0.155; 0.183) and Pb (0.201; CI 95%: −0.040; 0.498). The current findings suggest that high exposure to toxic metals/metalloids might increase 8OHdG levels with potential adverse health effects. This study is the first one in which the relationship between toxic metals/metalloids and oxidative stress biomarkers is investigated in populations affected by environmental disasters. Further prospective studies are necessary to monitor exposure levels and explore additional health impacts.

Monitoring heat transfer for seepage in earth-rock dams with clay cores considering damaged areas: Laboratory experiments and numerical modeling

This study conducted a laboratory test and two-dimensional numerical simulation on seepage heat monitoring of a core rockfill dam. A fully automatic laboratory test system for dam seepage monitoring has been developed, which can achieve automatic control of water flow and temperature, as well as automatic data collection. A flow-heat coupling model based on [Johansen, O., (1975). Thermal conductivity of soils. P. D. thesis. University of Trondheim, Norway, Trondheim] empirical thermal conductivity model was established through secondary development using COMSOL Multiphysics finite element software, and its accuracy was verified. The influence of the location of damaged leakage in the core wall of the dam on flow and heat migration was analyzed. Among the investigated conditions, a damaged channel with a curved cross-section causes the formation of the prominent arc in the saturation line of the dam body downstream, induces the largest increase in the average seepage discharge, and makes the dam body most unstable. The effects of damage on the temperature and seepage fields are positively correlated for different damage types. The presence of a damaged area induces sudden changes in the pressure, velocity, and temperature at each monitoring point. The pressure, velocity and temperature are correlated, and there is a lag in temperature transfer. This study provides a reference for the application of distributed fiber optic temperature measurement technology in core rockfill dam engineering, especially in terms of fiber optic placement position. The established numerical model can provide an accurate and effective reference method for identifying abnormal temperature data and locating dam leakage. Our next step will be to study the flow and heat transfer characteristics throughout the entire process from undamaged to dam failure.

Polycyclic aromatic hydrocarbons in estuarine sediments as a consequence of the mine tailings remobilization and transport in the Rio Doce basin.

The Fundão dam failure in 2015 severely impaired the economy, the lives of riverine communities, and the aquatic ecosystems of the Rio Doce basin in southeast Brazil. Several contaminants, including polycyclic aromatic hydrocarbons (PAHs), were transported downstream, deposited in the estuary, and released into the Atlantic Ocean. The high concentration of PAHs in estuarine sediments may pose ecological risks and deleterious effects to benthic organisms, so here we aimed at determining the source and fate of these compounds before and after the tailings' arrival. The mean concentration of the analyzed Σ16PAHs increased from 34.05 µg kg-1 in the prefailure period to 751.77 µg kg-1 one year after the arrival of the tailing. The classification of the sediment quality changed from low to moderate contamination. Our results suggest that there was PAHs remobilization by mine tailings along the Rio Doce basin. The target analytes exhibited mostly a pyrolytic profile from fossil fuel and biomass burning. In addition to other contaminants deposited in the estuary after the arrival of the tailings, this study revealed that the profile change of PAHs in the estuary region is a consequence of the mud's erosive power. Integr Environ Assess Manag 2024;20:169-178. © 2023 SETAC.

Numerical three-dimensional modeling of earthen dam piping failure

A physically-based numerical three-dimensional earthen dam piping failure model is developed for homogeneous and zoned soil dams. This model is an erosion model, coupled with force/moment equilibrium analyses. Orifice flow and two-dimensional (2D) shallow water equations (SWE) are solved to simulate dam break flows at different breaching stages. Erosion rates of different soils with different construction compaction efforts are calculated using corresponding erosion formulae. The dam's real shape, soil properties, and surrounding area are programmed. Large outer 2D-SWE grids are used to control upstream and downstream hydraulic conditions and control the boundary conditions of orifice flow, and inner 2D-SWE flow is used to scour soil and perform force/moment equilibrium analyses. This model is validated using the European Commission IMPACT (Investigation of Extreme Flood Processes and Uncertainty) Test #5 in Norway, Teton Dam failure in Idaho, USA, and Quail Creek Dike failure in Utah, USA. All calculated peak outflows are within 10% errors of observed values. Simulation results show that, for a V-shaped dam like Teton Dam, a piping breach location at the abutment tends to result in a smaller peak breach outflow than the piping breach location at the dam's center; and if Teton Dam had broken from its center for internal erosion, a peak outflow of 117 851 m3/s, which is 81% larger than the peak outflow of 65 120 m3/s released from its right abutment, would have been released from Teton Dam. A lower piping inlet elevation tends to cause a faster/earlier piping breach than a higher piping inlet elevation.

Seepage safety evaluation of high earth-rockfill dams considering spatial variability of hydraulic parameters via subset simulation

Seepage failure of high earth-rockfill dams have devastating consequences, and its safety analysis is of great importance in the design phase. However, the highest safety standards in high dams pose a challenge to the calculated efficiency of safety assessment. To address this problem, a random seepage safety assessment method which can consider the spatial variability of hydraulic parameters is proposed. Firstly, the spatial variability of the hydraulic parameters in the impervious materials is simulated using the covariance matrix decomposition under the framework of the non-intrusive finite element method. Then, according to the safety index of critical hydraulic gradient, the seepage stability formula is established to evaluate the safety state. Finally, considering that the highest safety standards in high dams make the probability of seepage hazard small (low failure probability event), it may require more than 10,000 deterministic calculations to complete the assessment process. Therefore, an efficient method based on subset simulation is proposed to optimize the computational efficiency. After the seepage safety evaluation of a 315 m high dam, the results show that the hydraulic conductivity of the core wall has the greatest influence on the seepage safety of the dam, and even under the influence of strong parameter spatial variability, its seepage failure probability is lower than 10-3. Compared with Monte Carlo simulation, the proposed method requires only 1/11 of the computation time at the 10-3 failure level. In addition, the results of grey relational analysis show that the coefficient of variation and correlation distance have obvious effects on seepage safety, and the autocorrelation distance has a greater effect.

Optimization of Reservoir Level Scheduling Based on InSAR-LSTM Deformation Prediction Model for Rockfill Dams

The Xiaolangdi reservoir has a storage capacity of more than 10 billion cubic meters, and the dam has significant seasonal deformation. Predicting the deformation of the dam during different periods is important for the safe operation of the dam. In this study, a long short-term memory (LSTM) model based on interferometric synthetic aperture radar (InSAR) deformation data is introduced to predict dam deformation. First, a time series deformation model of the Xiaolangdi Dam for 2017–2023 was established using Sentinel-1A data with small baseline subset InSAR (SBAS-InSAR), and a cumulative deformation accuracy of 95% was compared with the on-site measurement data at the typical point P. The correlation between reservoir level and dam deformation was found to be 0.81. Then, a model of reservoir level and dam deformation predicted by neural LSTM was established. The overall deformation error of the dam was predicted to be within 10 percent. Finally, we used the optimized reservoir level to simulate the deformation at the measured point P of the dam, which was reduced by about 36% compared to the real deformation. The results showed that the combination of InSAR and LSTM could predict dam failure and prevent potential failure risks by adjusting the reservoir levels.

Analysis of flood warning and evacuation efficiency by comparing damage and life-loss estimates with real consequences related to the São Francisco tailings dam failure in Brazil

Abstract. Economic damage and life-loss estimates provide important insights for the elaboration of more robust alerts and effective emergency planning. On the one hand, accurate damage analysis supports decision-making processes. On the other hand, the comparison of different flood alert scenarios through modeling techniques is crucial for improving the efficiency of alert and evacuation systems design. This work evaluates the use of flood damage and life-loss models in floods caused by tailings dams through the application of these models in the real case of the São Francisco dam failure, which occurred in January 2007 in the city of Miraí in Brazil. The model results showed great agreement with observed damage and loss of life. Furthermore, different simulations were done in order to measure the impact of increasing and decreasing alert system efficiency on life-loss reduction. The simulated scenarios exploring the inefficiency of flood alert and evacuation revealed that life loss could have reached the maximum rate of 8.7 % of the directly exposed population when considering the more pessimistic and uncertain scenario instead of the actual null life loss achieved. The results of this work indicate that the models could represent both the observed accident and different alert and evacuation efficiency impacts. It highlights the importance of developing and implementing robust alert and evacuation systems and regulations in order to reduce flood impacts.

Formation and Hazard Analysis of Landslide Damming Based on Multi-Source Remote Sensing Data

Remote sensing plays an increasingly important role in the investigation of natural hazards, not only by obtaining specific data related to hazards, but also by realizing targeted research by combining with other data and/or technologies. Small-scale landslide hazard chain events occur frequently in mountainous areas with fragile geological environments and have strong destructive effects, yet have been somewhat understudied. This paper analyzes the Zhoujiaba (ZJB) landslide hazard chain that occurred in Longnan City on 18 August 2020. On the basis of the comprehensive application of multi-source remote sensing data, combined with time-series InSAR technology, electrical resistivity tomography (ERT), and numerical simulations, we studied the formation mechanism, damming characteristics, and potential outburst scenarios of this event. Our research suggests that geological structure and strong natural weathering are the preconditions for landslide development, which is eventually induced by extreme rainfall. Specific topographic conditions determine the rapid sliding and accumulation of landslide materials, and ultimately result in river damming. Our simulation results showed that a flood, rather than a debris flow, will be the result of dam outburst. When the simulated upstream inflow is 1.5 times that when the landslide occurred, 68% of the downstream village area will be flooded. The artificial spillway can effectively reduce the scale of the potential outburst flood, but there remains a risk of dam failure owing to the shallow depth. Our study of the hazard chain of a small-scale landslide using a combination of methods will provide a valuable reference for the analysis and treatment of similar hazard chains.

A Bayesian method for dam failure risk analysis using causal loop diagrams and word frequency analysis

A Bayesian method for dam failure risk analysis using causal loop diagrams and word frequency analysis

Analysis of Storage Capacity Change and Dam Failure Risk for Tailings Ponds Using WebGIS-Based UAV 3D Image

Tailings ponds, essential components of mining operations worldwide, present considerable potential hazards downstream in the event of tailings dam failures. In recent years, instances of tailings dam failures, carrying potential environmental safety hazards, have occasionally occurred on a global scale due to the limited technical approaches available for safety supervision of tailings ponds. In this study, an innovative WebGIS-based unmanned aerial vehicle oblique photography (UAVOP) method was developed to analyze the storage capacity change and dam failure risk of tailings ponds. Its applicability was then validated by deploying it at a tailings pond in Yunfu City, Guangdong Province, China. The results showed that the outcomes of two phases of real-scene 3D images met the specified accuracy requirements with an RSME of 0.147–0.188 m in the plane and 0.198–0.201 m along the elevation. The storage capacities of phase I and phase II tailings ponds were measured at 204,798.63 m3 and 148,291.27 m3, respectively, with a storage capacity change of 56,031.51 m3. Moreover, the minimum flood control dam widths, minimum free heights, and dam slope ratios of the tailings pond were determined to comply with the flood control requirements, indicating a low risk of dam failure of the tailings pond. This pilot case study demonstrated the performance of the UAVOP in evaluating storage capacity change and dam failure risk for tailings ponds. It not only enhanced the efficiency of dynamic safety supervision of tailings ponds but also offered valuable references for globally analogous research endeavors.

Impacts of metal mining on river systems: a global assessment.

An estimated 23 million people live on floodplains affected by potentially dangerous concentrations of toxic waste derived from past and present metal mining activity. We analyzed the global dimensions of this hazard, particularly in regard to lead, zinc, copper, and arsenic, using a georeferenced global database detailing all known metal mining sites and intact and failed tailings storage facilities. We then used process-based and empirically tested modeling to produce a global assessment of metal mining contamination in river systems and the numbers of human populations and livestock exposed. Worldwide, metal mines affect 479,200 kilometers of river channels and 164,000 square kilometers of floodplains. The number of people exposed to contamination sourced from long-term discharge of mining waste into rivers is almost 50 times greater than the number directly affected by tailings dam failures.