Dams In Brazil Research Articles

Multichannel Analysis of Surface Waves based on Common Virtual Source Gathers of Seismic Ambient Noise Cross-Correlations: A Case Study at an Earth Dam in Brazil

The S-wave velocity (Vs) is a valuable parameter for assessing the mechanical properties of subsurface materials for geotechnical purposes. Seismic surface wave methods have become prominent for estimating near-surface Vs models. Researchers have proposed methods based on passive seismic signals as efficient alternatives to enhance depth of investigation, lateral resolution and reduce field effort. This study presents the Multichannel Analysis of Surface Waves (MASW) utilizing Common Virtual Source Gathers (CVSGs) derived from seismic ambient noise cross-correlations, based on Ambient Noise Seismic Interferometry concepts. The method is applied to passive data acquired with an array of receivers at the Paranoá earth dam in Brasília, Brazil, to construct a pseudo-2D Vs image of the massif for interpretation. Our findings showcase the adopted processing flow and combination of methods as an effective approach for near-surface Vs estimation, demonstrating its usability also for large earth dam embankments.

Susceptibility to Liquefaction of Iron Ore Tailings in Upstream Dams Considering Drainage Conditions Based on Seismic Piezocone Tests

One of the critical challenges facing the mining sector is related to the prevention and mitigation of catastrophic incidents associated with its tailing dams. As mining tailings are very heterogeneous and field characterization is expensive and complex, geotechnical properties of these materials are largely unknown. The seismic cone penetration test (SCPTu) provides a field approach to estimate a large array of geotechnical information, including the liquefaction potential of tailing dams. Yet, the exploration of strain softening behaviors in geomaterials under undrained loading, utilizing the state parameter (ψ) inferred from SCPTu tests initially applied to soft soils, has been often used for mining tailings. This study is concerned with the implementation of a tailing classification system which uses the ratio between the small strain shear modulus and the cone tip resistance (G0/qt). A series of laboratory tests was executed, and three different methodologies were adopted to assess the effects of (partial) drainage conditions based on 531.26 m of SCPTu measurements conducted at three different upstream iron ore tailing dams in Brazil. Furthermore, the G0/qt ratio is integrated with ψ to assess the liquefaction tendencies of the investigated materials. The findings reveal the heterogeneous nature of the tailings, wherein indications of partial drainage are discernible across numerous records. Liquefaction analyses demonstrate that the tailings exhibit a contractive behavior in over 94% of the SCPTu data, confirming their susceptibility to flow liquefaction. Our findings are relevant for site characterization within iron ore tailing dams and other mining sites with similar geotechnical attributes.

Increasing flood awareness through dam-break serious games

Dams are one of the most important human-made structures ever conceptualized and allow the development of society by providing multiple uses, such as the development of hydroelectric plants and as a source of water supply. A dam break problem is a catastrophic event that evolves rapidly, causing uncontrollable large floods downstream. In this paper, we develop a simplified modeling approach to assess flood characteristics associated with dam-break problems. The method offers a useful tool to improve the perception of dam safety in terms of the hydrodynamic impacts associated with a dam break. We apply our framework to 20 dams in Brazil, in addition to the Brumadinho dam failure at Córrego do Feijão. This event occurred in Brazil in 2019 leading to almost 300 fatalities. The second case study demonstrates the use of the modeling framework developed in this paper through the simulation of 20 dams in Brazil. The modeling approach uses GIS databases, Google Earth, and National Water Agency (ANA) databases and can be replicated whenever GIS information on dam characteristics, downstream channel, and downstream community is available. The results of this modeling approach indicate that several dams in the northeast of Brazil have relatively large flood hazards. A simplified dam-break hazard index was developed to establish a relative hazard impact that considers only deterministic factors such as the hydrodynamic force, velocity, and depth, as well as the arrival time of the maximum values of these states. These values are determined by a 1-D full momentum solver model (HydroHP-1D).

Socio-environmental tragedies from mine tailings dam failures: Capital prevailing over the state and citizen

Peripheral countries with an abundance of mineral wealth are victims of exploratory capitalism based on neo-extractivism. Production of profit is based on the predatory exploitation of mineral commodities, which corrupts the agents of the State and belittles local populations and their traditional values. This establishes what has been called the coloniality of life, i.e. a process of domination, exploitation, and submission, under the pretext that this will be the path to development. This study aims to show the social cost of this development at any price giving rise to onerous liabilities that trample on human dignity and cause environmental disasters. The consequent alterations to quality of life in populations that have become vulnerable through socio-economic conditioning factors have led to emergencies that must be dealt with, onto which bioethics may throw light, in terms of health, ethics, and the environment. Implications of ethics responsibility and absence of social responsability are discussed based on the tragedy resulting from the failure of two iron ore tailings dams in Brazil.

Threats of dams to the persistence of the world's freshwater fishes

AbstractHabitat fragmentation due to dams is a well‐known threat to freshwater fish. Yet, the global consequences of fragmentation for the viability of freshwater fish populations are unknown. Here, we provide the first global assessment of the threats of dams to the persistence of freshwater fish species. We developed a global macroecological relationship between freshwater fish range size and body size and used this relationship to assess whether isolated range fragments are too small to support a species. Our assessment includes 7369 freshwater fish species and considers the effects of 31,780 dams globally. Furthermore, we performed a more detailed analysis of the threats of dams in Brazil, the greater Mekong region and the United States, using complementary national and regional data sets. Globally, more than half of the species analysed face extirpation in a part of their geographic range, with an average potential range loss of 3.3% (95%‐range: 0%–31.8%) across all species analysed. For 74 fish species, occurring in Brazil, China, India, the Mekong basin, the United States, South‐Africa and the East Adriatic Coast, more than 50% of their range is potentially lost. This includes 18 species threatened with extinction across their whole range. Our complementary regional analysis revealed that the potentially lost range increases by a factor of 2–4 when considering both large and small dams compared with considering only large dams (≥15 m), highlighting the need to establish more comprehensive global dam inventories. Our novel approach and global analysis identifies species at risk of extirpation as well as geographic hotspots of extirpation threat by dams, which can aid in establishing more effective strategies for global hydropower development and barrier removal efforts to optimise the trade‐offs between biodiversity conservation and the socio‐economic benefits of dams.

Estimating environmental and cultural/heritage damages of a tailings dam failure: The case of the Fundão dam in Brazil

We present the results of a contingent valuation study aimed at estimating the monetary value of environmental and cultural/heritage injuries caused by the Fundão (tailings) Dam failure in Brazil in 2015 as perceived by the Brazilian population. While the valuation literature on mining-related externalities is considerable, valuation studies of environmental and cultural/heritage injuries resulting from mining incidents are scarce and most available damage assessments apply market valuation methods, while rarely considering environmental and other nonmarket-valued impacts. The flooding and the release of tailings from the Fundão Dam failure led to injuries to sediments, watercourse opacity, and oxygenation, changes in riparian morphology, damages to cultural/heritage resources, mortality to fish and wildlife, changes in the food chain and more along the 675 km watercourse of the Doce River. This was arguably the greatest environmental and cultural/heritage injury ever caused by a single tailings dam collapse. The study followed state-of-the-art recommendations for the development, administration, and data analysis of stated-preference valuation methods. The survey of a representative sample of 5195 Brazilian urban households revealed that the average lower-bound willingness-to-pay estimate to avoid a similar incident in the near future was 137 USD and the parametric-based estimate was 230 USD per household, which aggregates to 7.96 or 12.91 billion USD, respectively. This corresponds to environmental damages of 176 or 295 USD per m3 of tailings released.

Spatial-temporal variations of metals and arsenic in sediments from the Doce River after the Fundão Dam rupture and their bioaccumulation in Corbicula fluminea.

The rupture of the Fundão dam in Brazil released tons of mining tailings into the Doce River Basin (DRB). This investigation aimed to determine the bioaccumulation of metals in soft tissues of the bivalve Corbicula fluminea exposed to sediments collected in the DRB in four periods (just after, 1, 3, and 3.5 years after the dam rupture). In the exposure bioassays, the concentrations of Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn in sediments and bivalve soft tissues were quantified. The concentration of some elements (As, Cd, Mn, and Al) in sediments exceeded the federal limits or regional backgrounds at some sampling sites, but their concentrations tended to decrease over time. However, higher concentrations of many elements were detected in the winter of 2019. Several elements were detected in C. fluminea soft tissues, but the bioaccumulation factors were generally low or not related to those elements associated with the ore tailings, evidencing that the bioavailability of metals to bivalves, in laboratory conditions, was limited. Integr Environ Assess Manag 2024;20:87-98. © 2023 SETAC.

Recommendations for the process of classification of dams in Brazil

The Brazilian National Policy on Dam Safety (PNSB) was enacted in 2010 and there are still many actions to be carried out, especially the classification of dams as to associated hazard potential (PHA) and risk category (RC). The analysis conducted based on the Dam Safety Report 2020 informs that there are 21953 dams distributed throughout the Brazilian territory registered in National Dam Information System (SNISB). However, 14849 (67.64%) of the dams were not classified as RC and 13475 (61.38%) of the dams were not classified as PHA. There are 3724 dams classified as high PHA, 2407 (64.64%) of which are considered small in terms of reservoir capacity. Considering this scenario, bibliographic research was conducted on dam classification criteria used in Brazil, Portugal, International Commission on Large (ICOLD) and United States. In addition, bibliographic research was conducted on two studies that used artificial intelligence-based tools to forecast PHA classification. As a result, this study recommends future research with indicated classification criteria and with applications based on artificial intelligence to forecast PHA classification in Brazil.

Dams safety: an analysis of safety management and the difficulties of its supervision

Despite the notable benefits that dams bring to society, they involve immediate and potential risks and impacts, which makes dam safety extremely important. This narrative review paper compares dam safety concepts, including that established in the Brazilian National Dam Safety Policy – PNSB, as well as analyzes the supervision difficulties reported by Brazilian federal and state agencies. Several national and international institutions define dam safety, but considering those presented in this paper, convergency was found out regarding the concept of maintaining structural integrity and operational safety in order to preserve life, health, property and environment. Dams in Brazil are inspected by several public bodies, depending on their priority use and the domain of the body of water in which they are located, each with prerogatives to regulate the matter. In view of the significant increase in the amount of accidents and incidents in 2019 and 2020, it is clear that there is a vulnerability to be corrected in the safety management of Brazilian dams due to their dependence on the treatment of deficient or non-existent technical information and on a lack of specialized staff in dam safety for inspection activities.

CULTIVATION OF XARAÉS GRASS IRRIGATED WITH IRON MINING TAILINGS

The collapse of the Fundão dam in Brazil caused one of the biggest environmental disasters. One of the challenges was how to manage the tailings so that affected areas could be reused. This study aimed to verify whether applying different irrigation depths to Xaraés grass grown with iron mining tailings would affect grass shoot and root dry masses. The experiment was set up in a randomized design with five irrigation depths (40%, 60%, 80%, 100%, and 120% of crop evapotranspiration) and two additional treatments (grass grown in tailings with soil conditioner, and grass grown in natural soil), each with three repetitions. The grass was cut four times, and the shoot dry mass was evaluated after each cut, while the root dry mass was evaluated at the end of the experiment. Our results showed that irrigation depths had a positive linear effect on shoot dry mass and an exponentially increasing effect on root dry mass, with the highest averages in the treatment applying 120% of crop evapotranspiration. This study showed that even in adverse conditions, Xaraés grass was able to grow and develop well.

Characterization of an earth dam in Brazil from seismic refraction tomography and multichannel analysis of surface waves

Effective methodologies to obtain information regarding the internal features in an earth dam are fundamental for rapid and technically correct decision making. Although several geophysical methods have potential applicability for investigations on dams, the contribution of seismic methods is well known, since the P and S-waves velocities can be associated with elastic modules of geotechnical interest. The study area was the Paranoá dam, the largest dam in Brazil's federal capital. We analyzed the internal structure of the dam and identified anomalies that could be associated with water saturation. We used traveltimes tomography to obtain Vp models and the MASW method to obtain Vs models. Four profiles of seismic data were acquired downstream of the dam. Borehole's information was used to corroborate with the geophysical interpretation of the profiles. The dam's abutments and the foundation ground could be identified within most models, and the velocity values obtained were mainly related to the clay material that forms the dam's massif, with higher values associated with the quartzite rocks. The rockfill material was well marked as a low velocity zone. Saturated zones were interpreted as local anomalies of high Vp/Vs ratio. An analysis of the depth range obtained within velocity models suggests that the depth of investigation from both methodologies are likely to be site specific, rather than exclusive matter of source and receiver instrumentation.

Proposal of New Construction Material: Polymer-Stabilized Gold Ore Tailings Composite

Recent events involving the rupture of tailings dams in Brazil have motivated the search for alternatives to incorporate the material into the production chain. At the same time, the consumption of raw materials by the civil construction sector is high, requiring the incorporation of alternative materials to achieve sustainable development. Thus, this paper proposes a new construction material based on the mechanical and microstructural behavior of polymer-stabilized and fiber-reinforced gold ore tailings composites. Unconfined Compressive Strength tests were performed on different polymer contents (6% and 9%), dry unit weights (1.7 g/cm³ and 1.8 g/cm³), and curing periods (7 and 28 days), according to 2K Experimental Design. Microstructural tests were performed using X-ray Diffraction, X-ray Fluorescence Spectrometry, Optical Microscopy, Scanning Electron Microscopy, and X-ray Micro-Computed Tomography. The results demonstrate that adding polymer increased tailings’ mechanical behaviors by forming packages with the lamellar particle, which was observed in microstructural tests. The polymeric composites’ brittle behavior was improved using fiber insertion, leading to an increase of the strain energy absorption capacity. The polymer-stabilized and fiber-reinforced gold ore tailings composites demonstrated its potential as a construction material, especially in landfill structures, tailings stockpiles, and paving base layers. The association of mechanical and microstructural analysis established a new understanding of the effect of the stabilizer and the reinforcement.

Mining Induced Ground Motions in a Tailings Dam

Mining induced seismicity can expose tailings dams to ground motions with potential to trigger a failure, if the structure reaches a certain level of vibrations that could exceed the seismic coefficient design criteria from pseudostatic analysis. Despite the cited risk, mainly for dams that are closer to open pits, few dams in Brazil are monitored by microseismic systems, and there are no references in the literature about continuous seismic monitoring both in open pit (source) and tailings dam, which represents the motivation of this paper. A microseismic system was commissioned in Cajati Mine, São Paulo, to record seismic events continuously in an array of 16 geophones (14 Hz and 4.5 Hz), installed in boreholes near the open pit (12 sensors) and in the dam (4 sensors), has measured values of PGA (Peak Ground Acceleration) and PGV (Peak Ground Velocity) related to 2,972 induced events from rock removal in the open pit. During the period monitored, the total of 109 events have triggered sensors in both structures, producing 920 seismograms, with the highest values of PGA and PGV of 0.0135 m/s2 (0.1358% of g) and 0.0892 mm/s. The highest PGA value is 36 times lower than the vertical coefficient of 3% of g defined by Brazilian technical standard to dam design criteria, normally used in common pseudostatic analysis from geotechnical engineers. A routine microseismic monitoring brings a new set of valuable actionable data and information to support the management of geotechnical tailings dams’ risks, under the conditions of vibrations induced by mining production.

Enhancements to explicit stochastic reservoir operation optimization method

The Fletcher-Ponnambalam (FP) method is an explicit stochastic optimization method for design and operations management of real-world storage systems including surface water reservoir and groundwater management problems. The FP method faces no curse of dimensionality and no need for scenario generation. The paper introduces a novel implementation for the FP method, named FP-2022 here for clarity, by removing the need for nonlinear constraints and by decreasing the number of decision variables to just one third of its original value, significantly reducing solving time (∼27 times faster than the original formulation). Additionally, new expressions derived for the first and second moments of both reservoir release deficit and surplus variables and the already-derived expression for the second moments of reservoir storages are incorporated into the FP-2022 formulation enabling the method to reach an improved optimality for a nonlinear objective function. The enhanced procedure is applied to solving a reservoir operation optimization problem for a major dam in Brazil. The result comparisons made with other methods along with a thorough analysis of release operation policies prove the optimality of this highly numerically efficient and convenient-to-use FP-2022 method. Finally, a multi-reservoir application of the model is also tested with corrective simulations for improved estimates of some additional variables of interest. A specific constraint-handling approach regarding reservoir release lower and upper bounds is also presented. Satisfactory results are obtained for solving the Parambikulam-Aliyar reservoir system, a real world five-reservoir operation optimization problem from India.

Hydropower in the News: how Journalists do (not) Cover the Environmental and Socioeconomic Costs of Dams in Brazil

ABSTRACT Despite massive environmental impacts and socioeconomic risks, hydropower dams continue to be widely adopted and unquestioned in developing countries. This study analyzes two decades of mainstream media coverage of dams in Brazil, where two-thirds of energy consumption comes from hydropower. Through a content analysis of news articles published by the largest outlets in the country, we found coverage has relied on official and construction companies’ voices and focused on economic progress, bureaucracy, corruption, and partisan politics. News rarely covered the socio-environmental risks and impacts caused by dams or questioned the country’s reliance on hydropower. Overall, newspapers presented dams as highly necessary projects for national progress, conforming to a modernization-oriented mindset prevalent in newsrooms when it comes to coverage about energy. As a result, journalism has contributed to the invisibility of the struggles faced by people and the environment directly impacted by hydropower dams.

A Promising Approach to Mitigate Risks on the Existing Tailings Dams in Brazil.

Mining operations lead to the production of large quantities of mineral waste, such as fluid fine tailings whose disposal is rather challenging. In Brazil, tailings disposal is facing a critical situation due to the large accidents that took place in the last couple of years. As a response to these accidents, the Brazilian Mining Agency became stricter on licensing mining complexes and issued an interruption on activities on 56 tailings dams. In this paper, the authors propose a promising approach to minimize risks on the existing tailings dams hoping that the industry succeeds at mining avoiding social harms and environmental damages. The results presented herein showed that in situ electrical dewatering is a promising technology that offers many benefits. It can significantly increase the solids content of liquefiable tailings stratum within a short time. This leads to tailings masses possessing higher shear strength. As a consequence, this technology might well lead to safe tailing dams in Brazil bringing socio-economic and environmental benefits.

Estimating Environmental Damages of a Tailings Dam Failure the Case of the Fundão Dam in Brazil

Estimating Environmental Damages of a Tailings Dam Failure the Case of the Fundão Dam in Brazil

Rehabilitation of the Doce River Basin after the Fundão dam collapse: What has been done, what can be done and what should be done?

AbstractFive years after the failure of the Fundão Dam in Brazil, no scientific report has been published regarding the rehabilitation interventions performed by the Renova Foundation, which is solely responsible for the rehabilitation of the Doce River Basin. This study aimed to assess the fluvial and riparian rehabilitation efforts performed by Renova, as well as to test and propose alternatives, when appropriate. Before the dam rupture, the fluvial system showed a single‐thread morphology that was sinuous and meandering. After the rupture, changes occurred in the river dynamics with strong sediment deposition in riparian areas, resulting in the loss of several meandering streams, oxbow‐lakes, lagoons, and fluvial islands. There was also a loss of the riparian vegetation, from 61% to 6%, as estimated by the Normalized Difference Vegetation Index (NDVI). Renova subjected nearly 61% of the study area to fluvial rehabilitation techniques, particularly using rip‐rap or larssen sheet piling (37%) and erosion control fibre blankets (17%). However, 50% of these interventions have been unsuccessful because the rip‐rap was poorly positioned and the biodegradable fibre blankets decomposed rapidly. We recommend changing the position of the rip‐rap from convex to concave banks and to avoid using biodegradable fibre blankets. Instead, we encourage the planting of riparian forests with native species to form buffer zone systems. Renova' riparian rehabilitation attempts were found to have low success rates, which was attributed to the unaddressed presence of toxic compounds, such as sodium and ether amine. However, our results proved that riparian rehabilitation using native species is feasible, if physical, chemical, biological, and phyto‐remediation strategies are adopted, to alleviate the ether amine and sodium toxicity.

Embroidering Resistance: Emotional, embodied, everyday struggles of women affected by dams in Brazil

The article analyzes the daily emotional struggles embodied by peasant women affected by a hydropower dam in South Brazil and the use of arpilleras – a popular arts textile technique – as a means of resistance. The article is based on ethnographic research done in collaboration with the Movement of People Affected by Dams (MAB) in a region affected by the Baixo Iguaçu dam, which is the sixth and last dam constructed on the Iguaçu River. I use a Feminist Political Ecology (FPE) approach in order to analyze women’s resistance, highlighting the emotional, embodied, and everyday dimensions of their struggles. Listening to women and paying attention to their narratives embroidered in arpilleras reveals that the implementation of a dam project brings about material impacts as well as complex gendered, emotional, and embodied effects. The article demonstrates that resistance to dams not only takes place in protests and direct action, but also in the everyday, embodied and emotional struggles, women’s networks, and through art. By embroidering arpilleras, women affected by dams in Brazil organized in the MAB are developing a political strategy that uses art as a powerful and gendered tool in their resistance to dams, with transformative effects.

Climate change may impair electricity generation and economic viability of future Amazon hydropower

Numerous hydropower facilities are under construction or planned in tropical and subtropical rivers worldwide. While dams are typically designed considering historic river discharge regimes, climate change is likely to induce large-scale alterations in river hydrology. Here we analyze how future climate change will affect river hydrology, electricity generation, and economic viability of > 350 potential hydropower dams across the Amazon, Earth’s largest river basin and a global hotspot for future hydropower development. Midcentury projections for the RCP 4.5 and 8.5 climate change scenarios show basin-wide reductions of river discharge (means, 13 and 16%, respectively) and hydropower generation (19 and 27%). Declines are sharper for dams in Brazil, which harbors 60% of the proposed projects. Climate change will cause more frequent low-discharge interruption of hydropower generation and less frequent full-capacity operation. Consequently, the minimum electricity sale price for projects to break even more than doubles at many proposed dams, rendering much of future Amazon hydropower less competitive than increasingly lower cost renewable sources such as wind and solar. Climate-smart power systems will be fundamental to support environmentally and financially sustainable energy development in hydropower-dependent regions.