Search

In water conservation projects, reservoirs play a key role in controlling and regulating floods. In recent years, extreme rainfall events have occurred more frequently. Urban reservoirs in danger under extreme rainfall happen occasionally. The breaching of urban reservoirs seriously threatens the lives and property of the population downstream. A lack of clarity regarding the characterization of the flooding response remains owing to urban reservoir overtopping under different rainfall conditions. This study used observed data from the heavy rainfall event in Zhengzhou on July 20, 2021, with Jiangang Reservoir in Zhengzhou as the study site. The study designed a storm-flood process with different rainfall scenarios that combines the long-duration rainstorm formula and Chicago rain pattern method, establishing a response relationship between extreme rainfall and flooding processes. Flood evolution simulation analyses were carried out for different scenarios of rainfall and flooding processes under three working conditions: rainfall only, dam failure only and dam failure coupled with rainfall, to characterize the flood response due to dam failure under different rainfall conditions. The results showed that the peak of the rainfall occurs earlier in the total rainfall calendar time, the faster the dam failure rate of the reservoir. As the rain peak occurs at a time that is later in the total rainfall calendar, and the recurrence period and rainfall duration increase, the flood volume increases and urban inundation becomes more severe. The rainfall type had less of an effect on the difference in the extent of inundation between different working conditions. The extent of flood inundation for the dam failure-coupled rainfall scenario is much greater than that for the dam failure only scenario. The increase in inundation extent in the dam failure coupled rainfall scenario at the higher levels of flood severity is smaller. Study results provide hydraulic element support for flood hazard assessment. [ABSTRACT FROM AUTHOR]

The phenomenon of global climate change has led to an increase in the frequency of extreme precipitation events, an acceleration in the melting of glaciers and snow cover, and an elevation of the risk of flooding. In this study, the DB-IWHR model was employed in conjunction with the MIKE 21 hydrodynamic model to develop a simulation system for the dam failure flow process of an earth and rock dam. The study concentrated on the KET reservoir, and 12 dam failure scenarios were devised based on varying design flood criteria. The impact of reservoir failures on flood-risk areas was subjected to detailed analysis, with consideration given to a range of potential failure scenarios and flood sizes. It was determined that under identical inflow frequency conditions, the higher the water level, the more rapid the breakout process and the corresponding increase in flood peak discharge. Conversely, for a given frequency of incoming water, an elevated water level results in a transient breach process, accompanied by a reduction in flood peak flow. Moreover, for a given water level, an increase in water frequency results in a reduction in breaching time, an extension of flood duration, and an increase in flood peak flow. The observed trend of flood spreading is generally north-south, and this process is highly compatible with the topographic and geomorphological features, demonstrating good adaptability. [ABSTRACT FROM AUTHOR]

The purpose of this research is to analyze the headcut propagation and downstream sediment yield as a result of a low‐head dam failure. While frameworks have been presented elsewhere to track headcut propagation from a dam failure/removal, little research has been conducted to calculate the downstream sediment yield of the resulting headcut. The sediment yield is of particular interest when a reservoir is located downstream of the headcut. This paper estimates the increased sediment yield to Tuttle Creek Lake as a result of a low‐head dam failure on the Big Blue River. From 2018 to 2022, the headcut contributed an estimated 859,000 m3 of sediment to Tuttle Creek Lake. Erosion is unlikely to continue due to the presence of natural grade control provided by boulder riffles and bedrock. [ABSTRACT FROM AUTHOR]

Abstract In water conservation projects, reservoirs play a key role in controlling and regulating floods. In recent years, extreme rainfall events have occurred more frequently. Urban reservoirs in danger under extreme rainfall happen occasionally. The breaching of urban reservoirs seriously threatens the lives and property of the population downstream. A lack of clarity regarding the characterization of the flooding response remains owing to urban reservoir overtopping under different rainfall conditions. This study used observed data from the heavy rainfall event in Zhengzhou on July 20, 2021, with Jiangang Reservoir in Zhengzhou as the study site. The study designed a storm-flood process with different rainfall scenarios that combines the long-duration rainstorm formula and Chicago rain pattern method, establishing a response relationship between extreme rainfall and flooding processes. Flood evolution simulation analyses were carried out for different scenarios of rainfall and flooding processes under three working conditions: rainfall only, dam failure only and dam failure coupled with rainfall, to characterize the flood response due to dam failure under different rainfall conditions. The results showed that the peak of the rainfall occurs earlier in the total rainfall calendar time, the faster the dam failure rate of the reservoir. As the rain peak occurs at a time that is later in the total rainfall calendar, and the recurrence period and rainfall duration increase, the flood volume increases and urban inundation becomes more severe. The rainfall type had less of an effect on the difference in the extent of inundation between different working conditions. The extent of flood inundation for the dam failure-coupled rainfall scenario is much greater than that for the dam failure only scenario. The increase in inundation extent in the dam failure coupled rainfall scenario at the higher levels of flood severity is smaller. Study results provide hydraulic element support for flood hazard assessment.

One of the most perilous natural hazards is flooding resulting from dam failure, which can devastate downstream infrastructure and lead to significant human casualties. In recent years, the frequency of flash floods in the northern part of Nicosia, Cyprus, has increased. This area faces increased risk as it lies downstream of the Kanlikoy Dam, an aging earth-fill dam constructed over 70 years ago. In this study, we aim to assess potential flood hazards stemming from three distinct failure scenarios: piping, 100-year rainfall, and probable maximum precipitation (PMP). To achieve this, HEC-HMS hydrologic model findings were integrated into 2D HEC-RAS hydraulic models to simulate flood hydrographs and generate flood inundation and hazard maps. For each scenario, Monte Carlo simulations using McBreach software produced four hydrographs corresponding to exceedance probabilities of 90%, 50%, 10%, and 1%. The results indicate that all dam breach scenarios pose a significant threat to agricultural and residential areas, leading to the destruction of numerous buildings, roads, and infrastructures. Particularly, Scenario 3, which includes PMP, was identified as the most destructive, resulting in prevailing flood hazard levels of H5 and H6 in the inundated areas. The proportion of inundated areas in these high hazard levels varied between 52.8% and 57.4%, with the number of vulnerable structures increasing from 248 to 321 for exceedance probabilities of 90% and 1%, respectively. Additionally, the number of flooded buildings ranged from 842 to 935, and 26 to 34 km of roads were found to be inundated in this scenario. These findings revealed the need for authorities to develop comprehensive evacuation plans and establish an efficient warning system to mitigate the flood risks associated with dam failure. [ABSTRACT FROM AUTHOR]

There has been a frequent occurrence of tailing dam failures in recent years, leading to severe repercussions. Flood overtopping is an important element contributing to these failures. Nevertheless, there is a scarcity of studies about the evolutionary mechanisms of dam breaches resulting from flood overtopping. In order to fill this knowledge vacuum, this study focused on the evolutionary characteristics and triggering mechanisms of overtopping failures, utilizing the Heshangyu tailings pond as a prototype. The process of overtopping breach evolution was revealed by the conduction of small-scale model testing. A scaled-down replica of the tailings pond was constructed at a ratio of 1:150, and a controlled experiment was conducted to simulate a breach in the dam caused by water overflowing. Based on the results, the following conclusions were drawn: (1) The rise in water level in the pond caused the tailings to become saturated, leading to liquefaction flow and local slope sliding at the initial dam. If the sediment-carrying capacity of the overflowing water exceeded the shear strength of the tailings, water erosion would accelerate landslides on the slope, generating a sand-laden water flow. (2) The breach was primarily influenced by water erosion, which subsequently resulted in both laterally widened and longitudinally deepened breach. As the breach expanded, the sand-carrying capacity of the water flow increased, leading to a faster rate of failure. The breach process of overtopping can be categorized into four distinct stages: gully formation stage, lateral broadening stage of gully, cracks and collapse on the slope surface, and stable stage of collapse. (3) The tailings from the outflow spread downstream in a radial pattern, forming an alluvial fan. Additionally, the depth of the deposited mud first increased and subsequently declined as the distance from the breach grew. The findings of this research provide an important basis for the prevention and control of tailings dam breach disasters due to overtopping. [ABSTRACT FROM AUTHOR]

Nowadays, a detailed safety policy is applied for dams. These policies cover structural safety, monitoring, inspection, safe operation, and emergency plans. For high-risk dams, all these policy elements need to be included in dam safety programs. Deficiencies in embankment dams, which suffer the most damage, can be detected by visual inspection and programmed monitoring of dams. In dams, horizontal and vertical deformation, leakage, pressure, stress, loads acting on structural elements, and environmental factors are generally measured. These behaviors can be numerically modeled to determine the dam behavior. Numerical analysis methods are important for monitoring the safety of the dam. Models created with software such as Plaxis provide information about dam behavior. Although numerical analysis is very important for dams, obtaining the material parameters used in the construction of the dam needed for modeling, recording the construction stages of the dam, not taking the water level change in the dam reservoir instantaneously, and not taking the measurement records of the dam measurement instruments correctly for different reasons constitute problems and difficulties for the analyses. Within the scope of this study, İkizdere Dam in Turkey was modeled with the Plaxis finite element program; the survey and piezometer measurement data taken from the dam were evaluated by comparing with the analysis results; the difficulties and problems encountered in the modeling and analysis phase were stated, and recommendations were made on dam safety and numerical analysis. Thus, in addition to other studies, it was emphasized that it is important for dam engineers to monitor the use of numerical analysis models throughout the entire process, not only in the planning phase but also from the planning phase to the life of the dam, and to keep records of all recording intervals that will be needed in digital analysis models. [ABSTRACT FROM AUTHOR]

In response to the escalating challenges posed by climate change, the United Nations (UN) proactively formulated the Sendai Framework for Disaster Risk Reduction (SFDRR-2015- 2030) as a comprehensive strategy for disaster risk management (DRM). This framework delineates four priority action objectives, seven global targets, and a set of guiding principles aimed at mitigating the impact of disasters. Notably, each of the seven SFDRR targets is intricately linked with the Sustainable Development Goals (SDG-2030). Given that natural disasters, such as floods, continue to hinder a country's social and economic progress, achieving long-term development becomes challenging. Both frameworks prioritize initiating and investing in innovation, involving all of society's stakeholders, to build a risk-informed and people-centered disaster-resilient society. However, a research gap exists regarding the relationship between Social Innovation (SI) and disaster risk preparedness. To address this, the present study conducts an in-depth literature review and content analysis focused on SI and flood preparedness. The study also aims to offer strategic recommendations for adopting SI to improve preparedness against dam-related flood risks, aligning with SFDRR targets and SDGs-2030. The study's findings are valuable for academia, policymakers, flood risk management agencies, at-risk communities, and stakeholders. By shedding light on the role of SI in flood risk preparedness, the research contributes to existing knowledge and enhances understanding of SI in the context of disaster risk management. [ABSTRACT FROM AUTHOR]

Dam failures due to changing hydroclimate and ageing infrastructure pose a significant threat to downstream river systems and communities. The detailed geomorphic effects of catastrophic dam failures are not well known because of a lack of high‐resolution topographic data before and after failures. On 19 May 2020, the 17‐m‐tall Edenville and 11‐m‐tall Sanford dams near Midland, Michigan, USA, failed as a result of significant rainfall over the preceding 2 days. We analysed the geomorphic impacts of these failures using a pre‐failure airborne lidar dataset and three uncrewed aerial vehicle (UAV)‐based lidar surveys collected 2 weeks, 3 months and 11 months after failure. Our survey following the dam failure revealed 47 100 ± 11 900 m3 of net floodplain erosion and 17 300 ± 4200 m3 of net deposition downstream of the Edenville and Sanford dam breaches, respectively. Over the year following failure, most geomorphic change was confined to new knickpoints migrating slowly through underlying glacial till substrate, with little change to riverbanks or surrounding floodplains. A lack of impounded reservoir sediment and antecedent downstream topography, including valley width and the location of the breaches relative to the river below the dams, contributed to relatively modest geomorphic changes despite the magnitude of water released. We provide insight into how landscapes are shaped by catastrophic floods, which are likely to become more common with ageing dams and a changing hydroclimate. [ABSTRACT FROM AUTHOR]

Dam failure and unsafe dam reservoirs cause extremely serious flooding and affecting the environment and ecosystem in the downstream area. The study applied numerical modelling (MIKE 11, MIKE 21, MIKE FLOOD) combined with GIS technology to simulate flooding due to the collapse of Dong Be reservoir, Thanh Hoa, Vietnam, with flood scenarios of frequency P=1.5% and P=0.5%. The study calibrated and validated the MIKE FLOOD model for two historic flood events in 2010 and 2017. Assessment results show that they were relatively consistent with flood trace survey data. Inundation results in two scenarios show that the inundation area with the P=0.5% scenario tends to increase compared to the P=1.5% scenario. The evaluation of simulation results for flooding under two scenarios, when overlaid with administrative, population, and construction layers, will help assess the impact of dam failure and establish its consequences.

In the dark of a July night in 2018, a 5-billion-cubic-metre torrent of muddy water crashed through rooftops and ripped through the downstream villages of southeast Lao People's Democratic Republic (Lao PDR). An auxiliary "saddle" dam had collapsed in the US$1.02 billion Xe Pian-Xe Namnoy (XPXN) Hydropower Project that was still under construction and had just reached financial contractual close five years prior, in 2013. In the aftermath of the collapse, official state narratives pointed to extreme weather conditions and "unforeseen" construction and engineering miscalculations, viewing soil conditions as the primary culprit. This paper examines the financial dimensions of dam failure and introduces the term "fast finance": financier-driven timelines that have drastically expedited and shortened the legal, social, and pre-construction processes involved in hydropower dam projects to the detriment of dam safety, due diligence, and local participatory input. Extreme weather and anthropogenic climate change are not sole explanatory factors in the XPXN dam disaster. This paper highlights the also significant role of financial and political interests as contributing factors in dam safety and failure alongside extreme weather. The paper challenges conventional "natural disaster" framing of dam collapse by bringing into focus ex-ante political decision-making, financial engineering, and construction planning prior to dam construction to highlight the ways in which the XPXN catastrophe also had anthropogenic and "unnatural" contributing factors. Fast finance encompasses the role of temporality and the responsibility of state-business actors in ex-ante financial and infrastructure decisions that conclude with catastrophic outcomes. The article examines the re-engineering of contemporary dam finance through a case study of Lao PDR and argues that issues of financial engineering should be examined alongside other forms of civil, mechanical, structural, and hydrological engineering in the analysis of dam disasters. The temporal logics of financial actors-particularly the financialized logic of fast finance-has displaced the public-good-producing logic of patient capital. Financial logics shape and condition other forms of engineering and construction and are central to considerations of dam safety and accountability. Naturalizing discourses around extreme weather and aging dams deflect from the financial decisions and policy action, or inaction, of state-business actors to prevent dam collapse. [ABSTRACT FROM AUTHOR]

Future global sustainability depends heavily on the development of renewable energy. The object of this study is a system of two plants (Kaunas hydropower plant (HP) and Kruonis pumped-storage hydropower plant) and upper and lower reservoirs. A possible dam failure accident in such an important system can endanger the population of Kaunas City. The methodology for estimating dam-failure-induced flood wave uncertainty included scenarios of the upper reservoir embankment failure hydrographs, modeling flood wave spreading (MIKE 21 hydrodynamic model), and estimating wave heights. The GRS methodology was selected to assess the uncertainty of flood wave modeling results and the sensitivity of hydrodynamic model parameters. The findings revealed that the discharge values of the Nemunas inflow and outflow through the HP outlets are the most important parameters determining the greatest height of the flood wave. Therefore, by correctly managing the amount of water in the upper reservoir, it would be possible to prevent the lower reservoir dam from breaking. [ABSTRACT FROM AUTHOR]

The occurrence of dam failures and the consequent floods pose substantial risks to submerged regions, and their unpredictability increases the hazard of their impact. This research simulates the flood event scenario due to the dam failure of the Hemrem dam in Diyala Governorate, Iraq. HEC-RAC model jas been used to modeling the Hemren dam failure. The generated flood waves are routed downstream until the confluence of the Diyala and Tigris rivers, covering a large study area of 5,378.5 km². The configuration of the model's geometry is formulated using the Digital Elevation Model (DEM) that encompasses the geographical extent of the Diyala River study area, from Hemren Dam to the confluence with the Tigris River south of Baghdad. The length of this reach is approximately 210 km. Based on the inundation maps, the region's geography is classified as having catastrophic constraints due to the water depth and flow rate. The results demonstrate how to predict the magnitude of floods and highlight the severity if Hemren Dam were to fail. This underscores the need for effective risk management. Furthermore, the maps created by this study can be utilized to develop long-term flood control plans.

The integrated hydrodynamic modeling study conducted in the Kathmandu valley, Nepal, utilizing the MIKE Hydro River Model and incorporating diverse datasets, including satellite imageries, ALOS PALSAR RTC DEM data, topographical map at 1:25,000 scale and hydraulic data. Various scenarios, including a probable maximum flood (PMF) routing simulation, were examined, with a focus on assessing impacts on infrastructure, particularly two bridges located at different chainages. The analysis uncovered that the invert level at bridge-1 measured 1384.19 meters, while at bridge-2, it was recorded at 1343.98 meters. Historical records show significant floods in various years, including 1988, 1991, 1995, 1996, 1999, 2018, 2019, 2021, 2022, and 2023. During the flood inundation modeling, it was observed that the water level of the river near Gokarneshwar Mahadev and its adjacent areas experienced an elevation increase to 13 meters. Furthermore, the water level near both modeled bridges was noted to rise to 8 meters. Conversely, in other segments of the modeled river, the water level ranged between 5 to 6 meters. Hydrodynamic modeling emerged as a critical tool for flood risk assessment, providing accurate simulations of water flow behavior and facilitating informed decision-making for flood risk management and infrastructure resilience.

Introduction. In the current process of climate change, the phenomenon of unusual rainfall and flooding is causing widespread flooding and causing great loss of life and property. In addition, the most vulnerable structures are dams and reservoirs. A dam failure causes a disaster that can threaten human lives and entire socio-economic activities. There are many causes of dam failure, of which hydraulic fracturing is considered one of the most likely causes as it causes concentrated seepage leading to the risk of dam failure. Hydraulic fracturing is a process in which cracks form in soil or rock and then propagate under water pressure. Hydraulic fracturing is not a new topic, nor is it an old one, receiving a lot of attention from scientists, but it is still a controversial issue. Many opinions are given. This paper aims to summarize the mechanism of hydraulic fracturing based on previous studies and at the same time proposes some methods to prevent hydraulic fracturing in an earthen dam.Materials and methods. Literature analysis of sources related to the phenomenon of hydraulic fracturing.Results. Hydraulic fracturing is closely related to the phenomena of differential settlement of dam soils and building structures. In earth-fill dams, the phenomenon of differential settlement often occurs in the areas between the fill soil of the dam and the side masses of the dam site, fill soil and concrete structures such as culverts and spillways, foundation structural elements, the impermeable core of the dam and adjacent soil zones. Based on an analysis of the causes of hydraulic fracturing, a number of measures were proposed to reduce the risk of hydraulic fracturing.Conclusions. Hydraulic fracturing, that is, the formation of cracks and cavities in the soil mass, which contribute to the formation of concentrated seepage paths. The occurrence of hydraulic fracturing increases the likelihood of seepage instability in the dam, which affects the safety of the dam and can lead to serious damage. Implementing hydraulic fracturing prevention techniques is critical to ensuring safe dam operating conditions.

Introduction. In the current climate change conditions, the protection of irrigation structures, especially dams, is a very important task. Seepage is one of the main causes of dam failure, so it is very important to investigate the seepage regimes and find solutions to prevent dam failures as a result of the seepage processes in earth dams. In this paper, the analysis of the seepage regimes in the body of earth dams is performed by means of mathematical modelling using numerical finite element models. A homogeneous earth dam with an imperfect diaphragm on an impermeable foundation is taken as the object of study. The purpose of the study is to determine the influence of relative parameters: diaphragm height, diaphragm location in the dam body, their number. In addition, the influence of diaphragm parameters on the seepage flow through the dam body and its velocity is analyzed.Materials and methods. The study was carried out with the help of numerical modelling using PLAXIS 2D software. The model of the dam is based on typical design solutions used in practice.Results. The results of the study show that the placement of the diaphragm in the dam body reduces the seepage flow through the dam and the height of the diaphragm is inversely proportional to the seepage rate. The maximum seepage rate was recorded at the upper end of the diaphragm and its magnitude is directly proportional to the height of the diaphragm. When the diaphragm is displaced towards the downstream side, the filtration rate slightly decreases. The value of maximum velocity increases when the diaphragm is displaced towards the downstream end.Conclusions. Dam failure due to seepage can result in serious property damage and loss of life. Implementing methods that reduce seepage discharge and seepage velocities is important to ensure safe dam operating conditions

Research on multi-dimensional aspects of dam engineering is gaining momentum because of massive flood destructions in lives, ecosystem and development including Wivenhoe dam flood in 2011, Oroville dam’s spillway incident 2017 and the Europe’s widespread flooding in 2021. The aim of this study is to capture and review research activities in dam science. A case study of the Wivenhoe dam Brisbane Australia, focusing on its design, catchment, water storage and flood mitigation capacity, management procedure, climate change and historical rainfall pattern has been carried out to conclude why such a catastrophic flood event happened in Brisbane in January 2011. Reviewed literatures throughout the world indicated that dam failures are primarily associated with improper design, inadequate monitoring in construction period and poor management (operational) practices. In the case of the Wivenhoe dam flood, the report of the Flood Commission of Inquiry Australia was that the dam was operated so that its flood mitigation was near optimal. Whilst the operators were found to be at fault for not following the Operation Manual, it was found that the manual was confusing and difficult to follow, and therefore, they were cleared of all liability. Hence, it is difficult to conclude what would have actually happened if the Wivenhoe dam operators had released more water earlier, author’s reasoned outlook about the flood mitigation measures used at the time is to ask the question “was reasonable discretion” used during the flood.

Dams are engineering structures that are of great importance in regularly meeting the drinking and utility water that we need, providing electrical energy needs, protecting residential areas against floods, and creating recreation areas. Although dams have many benefits, it is known that the damages in these structures poses serious disaster risk for the settlement areas located downstream. In addition, our existing dams, which are aging, and in addition to these, our dams that are increasing day by day, increase the disaster risk even more, especially in areas with increasing residential areas downstream. In this study, Darlık Dam, which is located in Istanbul and has a dense residential area on its downstream, was selected as the study area. Dam failure simulation was developed at the downstream of Darlık Dam and the areas that would be affected by the flood wave were observed. In this context, it is aimed to contribute to the determination of the areas where measures should be taken by the authorized institutions and to the prevention or reduction of the disasters that will occur due to dam failure. Failure analyzes of Darlık dam were generated by using HEC-RAS program. In accordance with the dam breach scenario, the breach parameters were defined into the HEC-RAS program and the dam failure flood analysis was modelled in two dimensions. Within the scope of the study, flood flow, water velocity and water depth were calculated in case of possible dam failure. Flood inundation, depth and velocity maps were obtained. Flood hazard areas was created and possible flood wave’s hazard ratio was determined by observing flood inundation areas. Finally, damage of buildings in flood wave areas was calculated and damage ratio and risk maps were obtained. According to the result of damage calculation, it was observed that approximately 3043 buildings were damaged. The damage ratio was shown on the flood inundation areas. It was concluded that %80.05 of all buildings affected by the flood are in the very high risk class. In the next stage, each building in the flood inundation areas was marked according to its risk class, shown in risk maps and presented within the scope of the study.

The failure of a 144‐m‐high lava‐dam waterfall on the Río Coca, Ecuador, in February 2020 initiated a catastrophic watershed reset—regressive erosion upstream and a massive sediment pulse downstream—as the river evolves towards a new equilibrium grade. The evolution of this river corridor after a sudden base‐level fall embodies the "complex response" concepts long understood through laboratory experiments, numerical modelling and smaller‐scale field studies, but that have not been observed in the field before on this scale. This paper presents geomorphic and geotechnical data to characterize the evolution of the Río Coca since 2020. In the three years after the lava‐dam failure, the erosion front migrated almost 13 km upstream along the mainstem river and triggered secondary headcuts that began migrating up tributaries. Erosion of the mainstem and tributary valleys generated a sediment pulse estimated to be 277 million m3 and ~500 million tonnes (Mt) over three years, depositing sediment tens of meters thick over tens of kilometres downstream from the former waterfall. This sediment pulse is one of the largest in modern times, comparable to the annual sediment load of a major continent‐draining river but with orders‐of‐magnitude greater sediment yield. Geomorphic adjustment of the Río Coca represents a highly unusual natural disaster threatening life, property, water quality, the regional economy, major infrastructure and energy security. However, this event also provides a rare opportunity to learn how a large autogenic watershed disturbance and recovery evolve, with important lessons for interpreting the sedimentary record of volcanic landscapes. [ABSTRACT FROM AUTHOR]

Secondary sediment disasters caused by the failure of landslide-dammed lakes are often more severe than the primary landslide events, resulting in catastrophic damage to surrounding infrastructure and the environment. The lifespan of landslide-dammed lakes is a crucial factor in determining the success of disaster prevention and response measures. However, the locations of landslide-dammed lakes are often inaccessible due to disrupted transportation or damaged access roads, making it difficult to obtain real-time information. Being able to estimate the time of dam failure is essential for assessing disaster response and making informed decisions. In this study, we analyzed 30 cases of landslide-dammed lakes in Taiwan, classifying them based on the actual time of dam failure and extracting geomorphic factors from the dam's catchment area. Using discriminant analysis, we quantitatively described the lifespan of the lakes. The results indicate that geomorphic factors in the dam's catchment area can effectively predict the lifespan of landslide-dammed lakes, with a classification accuracy of 93.3%. Through this research model, it is possible to predict the time of dam failure for landslide-dammed lakes, serving as a reference for establishing disaster warning, landslide-dammed lake monitoring, and disaster prevention notification systems. [ABSTRACT FROM AUTHOR]

The integrated hydrodynamic modeling study conducted in the Kathmandu valley, Nepal, utilizing the MIKE Hydro River Model and incorporating diverse datasets, including satellite imageries, ALOS PALSAR RTC DEM data, topographical map at 1:25,000 scale and hydraulic data. Various scenarios, including a probable maximum flood (PMF) routing simulation, were examined, with a focus on assessing impacts on infrastructure, particularly two bridges located at different chainages. The analysis uncovered that the invert level at bridge-1 measured 1384.19 meters, while at bridge-2, it was recorded at 1343.98 meters. Historical records show significant floods in various years, including 1988, 1991, 1995, 1996, 1999, 2018, 2019, 2021, 2022, and 2023. During the flood inundation modeling, it was observed that the water level of the river near Gokarneshwar Mahadev and its adjacent areas experienced an elevation increase to 13 meters. Furthermore, the water level near both modeled bridges was noted to rise to 8 meters. Conversely, in other segments of the modeled river, the water level ranged between 5 to 6 meters. Hydrodynamic modeling emerged as a critical tool for flood risk assessment, providing accurate simulations of water flow behavior and facilitating informed decision-making for flood risk management and infrastructure resilience. [ABSTRACT FROM AUTHOR]

A remotely operated underwater vehicle (ROV) is a tethered underwater mobile device that can conduct a bathymetric survey cost‐efficiently. Assessment of the utility of ROV‐based bathymetric surveys in flood inundation mapping remains limited. This study aims to examine the utility of ROV‐based bathymetric surveys in high‐resolution flood inundation mapping for a hypothetical case study of the Lake Tuscaloosa Dam breach in the state of Alabama, USA. This study conducted the sensitivity test of flood inundation mapping to the river channel depth (ROV‐based vs. digital elevation model [DEM]‐based) and initial flow condition (e.g., wet vs. dry), via six different simulations of the parallelized diffusion hydrodynamic model (pDHM). This study found that the ROV‐based pDHM runs had higher maximum water depths over the flood‐inundated areas, ranging from +73% to +166% of the simulated depths of the DEM‐based pDHM runs. However, the impact of initial streamflow condition on the maximum depths was limited. This study also found that the pDHM runs with a dry initial flow condition delayed the time to reach the maximum depth after the dam breach by 2 h relative to the pDHM runs with a wet initial streamflow condition. This study suggests that ROV‐based bathymetry surveys improve flood inundation mapping by emphasizing the influence of river channel depth, initial streamflow conditions, and bathymetry, thereby bolstering community resilience to a potential human‐made hazard such as dam failure. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Natural Hazards & Environment (JNHE) / Doğal Afetler ve Çevre Dergisi (DACD) is the property of Artvin Coruh University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Arsenic (As) and antimony (Sb), two toxic metal(loid)s, behave similarly and commonly occur in mine tailings. Yet, responses of microbes to As and Sb co-contamination in tailings dam failure-affected area remain limited. Herein, soil microbiomes (archaea, bacteria and fungi) across two contrasting sites (tailing-contaminated farmland and nearby undisturbed forestland) at a Sb-Au mining district in Chizhou, China were investigated by high-throughput sequencing. Results showed that As and Sb occurred mainly in the residual form, accounting for 55.82 % and 52.04 %, respectively. The bioavailable form was 12.77 % and 10.39 % in contaminated farmland compared to 13.31 % and 11.66 % in undisturbed forestland, respectively. Contrary to archaea and fungi, bacterial alpha-diversity significantly increased in contaminated farmland. The taxa-taxa interactions in archaea were most robust, followed by bacteria; and fungi were the weakest, which was corresponding to the habitat niche breadth. Microbial communities were affected by the deterministic processes with a modified stochasticity ratio (MST) value of 36.36 %, whereas more stochasticity (MST = 49.71 %) was raised in contaminated farmland than in undisturbed forestland (MST = 36.98 %). The microbial function based on taxonomy-based inference indicated that nitrogen and carbon metabolisms associated with archaea and bacteria increased in contaminated farmland, as well as plant pathogen, wood saprotroph and endophyte related with fungi. The turnover of soil microbiomes was tightly correlated with As and Sb speciation. Collectively, this study reveals that the soil microbial survival strategies to As-Sb co-contamination after dam failure, providing guidance for the development of bioremediation and tailings management strategies. [Display omitted] • As and Sb co-contamination increased bacterial α-diversity, not archaea and fungi. • Most complex interactions occurred in archaea, followed by bacteria and fungi. • Determinism shaped microbial assembly, farming practices increased stochasticity. [ABSTRACT FROM AUTHOR]

Tailings storage facility (TSF) failures in China have historically resulted in downstream consequences, including fatalities, economic harm, and environmental contamination. However, the nation-wide documentation on existing TSFs is incomplete, and the magnitude-frequency statistics of the failures are poorly quantified. These gaps have impeded ongoing efforts of risk assessment and mitigation. This study collates and analyzes new databases on historical TSF failures and existing TSFs in China. We report 143 TSF failures in China over the period 1957–2023, which exceeds the number (∼20) reported in previous studies. Magnitude-frequency statistics indicate that the mean return period for TSF failures in China with at least 10 fatalities is ∼5 years, while for those with released volumes >1 million m3 is ∼16 years. Our review confirms that there are at least 14,217 existing TSFs in China; therefore, the cumulative failure rate of TSFs in China is estimated to be ∼1 %. We supply a database of 1853 TSFs that lists the statistics such as storage volume and dam height. Using these datasets along with downstream demographic statistics, we undertake a regional risk assessment for Jilin Province, which identifies 11 TSFs with intolerable risks. Among these, the most critical TSF poses a potential loss of 175 lives. Our findings provide the most comprehensive picture of TSFs in China to date. We anticipate that this study will advance tailings disclosure practices in China and support screening-level risk assessments by provincial regulators to help prioritize community engagement and risk mitigation efforts. [ABSTRACT FROM AUTHOR]

• The dam-breach wave propagation is studied through a dimensionless formulation. • The dimensionless hydrographs shape depends mainly on the reservoir morphology. • The wave downstream attenuation is governed by a key dimensionless parameter. • A quick assessment of the attenuation can be performed using the graphs presented. In the past, several authors have proposed methods to study the routing behaviour of a flood caused by a sudden dam failure (dam-break). As regards, instead, the progressive failure of earthen dams, defined as "dam-breach" in the literature, very few studies have been proposed in this scope. Furthermore, existing studies have limited validity, as they are often based on weighty simplifications and/or limited to a specific range of cases. Therefore, there is a need to study the dam-breach wave propagation phenomenon with a more comprehensive approach, in order to identify the essential key aspects related to the wave routing. In light of the above, in this work the generation and propagation of the dam-breach flood waves have been studied by means of an appropriate dimensional analysis that allowed for the identification of the parameters that have the major influence on the breach outflow hydrograph and the downstream attenuation of the flood wave. As for the generation, a parameter describing the morphology of the reservoir has been shown to control the shape of the dimensionless discharge hydrographs outflowing from the breach. As for the propagation, all the involved parameters (i.e., flood volume, peak discharge at the dam site, downstream longitudinal slope, and cross-sectional flow area and depth) have been collected in two dimensionless parameters that characterize the 1D full-momentum Shallow Water Equations in dimensionless form. One of them has been shown to be predominant in controlling the downstream attenuation of the flood wave. So just three graphs have been enough to cover much of the possible real-world variability. These graphs can also be used for the purposes of a quick assessment of the downstream attenuation of a flood generated by the hypothetical breaching of a real earthen dam. The proposed method has been shown to give satisfactory results through application to different case studies: the hypothetical failure of three real earthen dams, in which the results of the proposed method have been compared with the results of 2D full-momentum hydrodynamic simulations, and the Baige landslide dam-breach flood that occurred along the Jinsha River (China) in November 2018. [ABSTRACT FROM AUTHOR]

This study provides a sociohistorical account of decisions made over a 150-year period about the Jagersfontein mine in South Africa's Free State and the catastrophic failure of its tailings dam that occurred in the early morning of September 11, 2022. The failure resulted in the sudden and uncontrolled release of more than 6 million m3 of liquid sludge, smothering nearly 200 nearby houses and approximately 1600 ha of agricultural and grazing land. Two people died, and one remains missing. Our account of this disaster shows the analytic force of examining the history of the mine's development, the issues decision-makers faced at various points in time, the choices made and the cumulative influence of these conditions on human vulnerability. We present a disaster timeline over four historical periods, linking sources and literature to each significant point in the timeline. It is one of the only available tailings dam failure timelines linked to the social context through historical analysis. • Historical analysis is critical to characterizing conditions and causes of disaster. • Novel application of disaster constructs to the examination of tailings dam failure. • Our timeline presents distinct inflection points relevant to the disaster. [ABSTRACT FROM AUTHOR]

• An innovative method was proposed for controlling discharge from landslide dam failure using a flexible protecting net (FPN). • The FPN on the landslide dam notably controlled outburst flood hydrographs. • Inflow, FPN length, and dam grain-size had significant impact on discharge control. • The mechanism by which the FPN controls discharge during instances of landslide dam failure was revealed. The outburst flood resulting from a landslide dam failure, commonly known as landslide dam outburst flood (LDOF), can lead to severe downstream impacts. Effective methods to prevent such catastrophic outburst floods are crucial for disaster risk reduction. This study proposes an innovative approach of using flexible protecting net (FPN) to control the outburst discharge of the landslide dam based on failure machnism. Flume experiments were conducted to investigate the effects of inflow discharges, FPN length, and the grain-size distribution of the dam on discharge control. The findings elucidated the discharge control mechanisms of the FPN and showed that: 1) the application of the FPN to the landslide dam resulted in a considerable reduction in the outburst flood hydrograph, along with a substantial decrease in peak discharge, a notable extension in the dam-break duration, and a significant increase in the residual dam height; 2) Generally, the discharge control effectiveness of the FPN improved as the inflow discharge decreased, the FPN length increased, and the mass proportion of grains exceeding the FPN aperture increased; and 3) The FPN functions by covering and obstructing dam particles, thereby, dissipating the energy of the outburst flood, finally accounting for the decrease in outburst flow. This study provides an effective method to reduce the impact of LDOF and facilitates measures for emergency disposal. [ABSTRACT FROM AUTHOR]