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The Teesta basin within the Sikkim Himalaya encapsulates a number of glacial lakes, prominently featuring the expansive and swiftly evolving South Lhonak Lake. The recent South Lhonak Lake Glacial Lake Outburst Flood (GLOF) in Sikkim has triggered a major flash flood in the river. Satellite imagery acquired by the National Remote Sensing Centre revealed that a massive landslide caused a sudden surge in the water levels of the glacial lake, eventually leading to the breach of the moraine dam. The catastrophic GLOF event led to the collapse of the Chungthang Dam, located 65.92 km downstream of the glacier lake, resulting in widespread human casualties and substantial infrastructural devastation. This paper presents a comprehensive analysis, simulation, and reconstruction of the entire GLOF process chain. A key innovation of this study is the consideration of cascading failure effects, including the landslide, South Lhonak Lake breach, and subsequent Chungthang Dam breach. Additionally, this study introduces the application of photogrammetric techniques for the first time to accurately calculate the landslide volume and the corresponding volume of displaced water. The GLOF process chain encompasses the volume of debris falling into the lake, impulse-wave initiation, moraine dam overtopping, moraine dam breaching, and flood propagation. Photogrammetric techniques are applied using pre- and post-event high-resolution stereo-satellite images for estimating the landslide volume and the volume of water displaced due to the reduction in water level. Numerical simulations from the study show the generation of a significant impulse wave, leading to the overtopping of the moraine dam with an exceptionally high overtopping discharge of 15,850 m3/s. The estimated peak discharge due to the moraine dam breach is 12,564 m3/s. The findings indicate that the collapse of the Chungthang Dam generated two distinct peak discharges of 14,673 m3/s and 10,282 m3/s, respectively. The results are illustrated across different sites and validated by comparison with high-resolution satellite imagery and field data. The study demonstrates an integrative scientific methodology that includes photogrammetric techniques, sophisticated numerical modeling, and dam break analysis in simulating the landslide-induced GLOF. [ABSTRACT FROM AUTHOR]

With the extensive construction of pumped storage power stations, understanding the evolution, propagation laws, and factors influencing downstream dam-break floods is essential for effective disaster prevention and mitigation. This paper examines a specific pumped storage power station and develops a numerical model that integrates the dynamics of dam-break floods with the evolution of breach formation. Four dam-break scenarios were created to simulate various situations. The findings indicate that: First, peak flows increase in certain river sections due to changes in river geometry and water diversion/confluence during the evolution of dam-break floods. Second, the analysis shows that damage from a single reservoir's dam break is less severe than that from two reservoirs. Damage varies with distance from the dam: upstream areas experience relatively minor combined dam damage, while instantaneous full dam break damage is greatest; downstream, instantaneous full dam break damage is less harmful than combined dam breaks, which are the most damaging. These variations are attributed to morphological differences and disparities in total water volume under different conditions during the dam-break flood process. This study provides a scientific basis for responding to dam-break floods and conducting flood relief efforts. [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.

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]

Natural hazards are unusual natural phenomena that can cause damage to people, property, the environment, living conditions, and socio-economic activities. Currently, across the country, efforts are being made to prevent and control natural disasters. However, the damage caused by these natural disasters and floods tends to increase, and unusual phenomena become more and more extreme due to the following factors: global climate change, deforestation, and economic development that accelerates urbanization, industrialization, and the conversion of forest land into farmland. Floods and dam safety in river basins have been and are issues of social concern. Practical requirements in disaster reduction toward proactively responding to adverse situations that may occur in cases of flood discharge or dam failure and developing emergency response plans for floods in river basins to minimize the flood risks. [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]

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]

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]

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]

ABSTRACT The flood map outputs from hydrodynamic models may contain uncertainties due to inaccuracies in the input parameters. On the other hand, the results of dam break models are crucial for performing risk analyses of potential material and social damage. Thus, this study applied a global sensitivity analysis (GSA) to evaluate the effects of the floodplain Manning coefficient on the inundation generated by the hypothetical dam break of a real water dam in HEC-RAS 2D. Three aspects of flood output, the peak discharge, the arrival time and the time of flood damping, were analyzed via variance tests. The Manning coefficient varied from 0.026 to 0.150, resulting in a change of up to 54% in the peak discharge at a distance of 25 km and a delayed arrival time corresponding to 16 minutes in the cross section located 1 km downstream of the dam. However, Manning coefficients between 0.026 and 0.050 show statistically similar results in terms of two aspects (the peak discharge and the arrival time). This study indicated that the GSA and variance tests may contribute to critical analyses of Manning coefficient adoption and help decision-makers develop criteria for planning emergency actions.

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]

The Life Safety Model (LSM) is an agent-based model which assists with emergency planning and risk assessments for floods and dam failures by providing estimates of fatalities and evacuation times. The LSM represents the interactions of agents (i.e. people, vehicles, and buildings) with the floodwater. The LSM helps to increase the accuracy of estimates of loss of life and evacuation times for these events by taking into account a number of parameters which are not described in empirical models, such as the people's characteristics (e.g. age and gender), building construction types, and the road network. The LSM has been applied to three historic flood-related disasters: the 1953 coastal floods, in the UK; the 1959 Malpasset Dam failure, in France; the 2019 Brumadinho tailings dam disaster, in Brazil. These illustrate how the LSM has been verified and improvements to evacuation routes, early warnings, and the refuge locations could have reduced the number of fatalities. The value of using the LSM is not to calculate the ‘exact’ number of flood deaths or evacuation times, but to assess if emergency management interventions can significantly reduce them. The LSM can also be used to assess whether the societal risk posed by dams and flood defences is ‘acceptable’. HIGHLIGHTS Novel agent-based model which allows interactions of people, buildings, and vehicles with the floodwater to be modelled.; Model can be used to assess emergency management interventions for floods and dam failures and provide quantitative estimates of the risks to people.; Summary of the use of the model for three historic events including Malpasset and Brumadinho dam failures, and the 1953 coastal flood in the UK.;

Research on multi-dimensional aspect 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 since 1980. 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. The methodology applied in the study includes related literature review followed by documentation and analysis of reports and data of Queensland Water, Wivenhoe Alliance and Flood Commission. Reviewed literatures 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. In the light of the warnings that the dam operators were given even as far back as December 2010 about the strong La Nina, it would seem that operators made sub-optimal decision about water releases and hence "reasonable discretion" wasn't applied properly. Hence, it can be said that the Brisbane Flood 2011 was a dam release type flood basically related to poor management. [ABSTRACT FROM AUTHOR]

Check dams have been widely used in China's Loess Plateau region due to their effectiveness in erosion and flood control. However, the safety and stability of the check dam decrease with the operation process, which increases the probability of dam failure during flood events and threatens local residents' life and property. Thus, this study simulated flood process of the check dam failure in the Wangmaogou watershed in Yulin City, Shaanxi Province, China, calculated different types of inundation losses based on the flood inundation area within the watershed, and determined the number of key flood protection check dams by classifying the flood risk levels of the check dams. The results showed that 5 dams in the watershed were subject to overtopping during different rainfall return periods, which was related to their flood discharge capacity. Dam failure flood process showed a rapid growth trend followed by slow decrease, and the time of flood peak advanced with increase in the return period. After harmonization of evaluation scales, the magnitude of flood inundation losses can be ranked as: economic losses (212.409 million yuan) > life losses (10.368 million yuan) >ecological losses (6.433 million yuan). The risk value for both individual dams and the whole dam system decreases as the return period increases. The number of key flood protection check dams in the Wangmaogou watershed was 2, 3, 3, 3, 4, and 5 for floods with return periods of 10, 20, 30, 50, 100, and 200 years, respectively. The results provided a theoretical basis for the safe operation and risk evaluation of check dams in the Loess Plateau Hills watershed. [ABSTRACT FROM AUTHOR]

Featured Application: The results of the paper can help to conduct a more scientific dam risk analysis, identify human errors in dam collapse accidents, and improve risk management in a targeted manner. Human factors are introduced into the dam risk analysis method to improve the existing dam risk management theory. This study constructs the path of human factor failure in dam collapse, explores the failure pattern of each node, and obtains the performance shaping factors (PSFs) therein. The resulting model was combined with a Bayesian network, and sensitivity analysis was performed using entropy reduction. The study obtained a human factor failure pathway consisting of four components: monitoring and awareness, state diagnosis, plan formulation and operation execution. Additionally, a PSFs set contains five factors: operator, technology, organization, environment, and task. Operator factors in a BN (Bayesian network) are the most sensitive, while the deeper causes are failures in organizational and managerial factors. The results show that the model can depict the relationship between the factors, explicitly measure the failure probability quantitatively, and identify the causes of high impact for risk control. Governments should improve the significance of the human factor in the dam project, constantly strengthen the safety culture of the organization's communications, and enhance the psychological quality and professional skills of management personnel through training. This study provides valuable guidelines for the human reliability analysis on dam failure, which has implications for the theoretical research and engineering practice of reservoir dam safety and management. [ABSTRACT FROM AUTHOR]

Despite significant improvements in design methodologies, dams and water-retaining structures failures continue to occur. Dams’ failure analysis plays a crucial role in the development of dam safety planning and emergency action. Since the Grand Ethiopian Renaissance Dam (GERD) has been built, there have been many concerns about its safety and its effects on downstream countries in case of its failure. In this paper, the GERD break was modeled by using the USACE Hydrologic Engineering Center’s River Analysis System (HEC-RAS). Two dimensions model under different failure scenarios was suggested. Moreover, outflow hydrographs and flood inundation maps were presented due to dam breach. Finally, it was concluded that, in case of catastrophic failure, flow depths may vary from 3 to 10 m in some residential areas, such as Khartoum. Furthermore, the water surface elevation may reach 184 m above msl (mean sea level) in Lake Nasser in case of dam failure with a fully stored GERD reservoir. Moreover, the maximum flow would reach 325,928 m3/sec which is more than 21.5 times the total capacity of the dam spillway. Finally, the paper’s outcomes may assist decision-makers in developing alternate plans to deal with the dangers of GERD break.

Dam breaks lead to loss of lives plus economic and environmental damages. However, with technological advancements in quantitative research, dam safety management (DSM) can be improved to mitigate mass damage to lives and properties. This study aims to predict the breach outflow hydrograph and prepare downstream flood inundation maps for the flood-prone areas around the Swa Chaung Dam. In this research, the authors emphasized other essential input data such as land use land cover, soil type, curve number, and differences in analytical simulation utilizing 1D and 2D to enhance the body of work. For classifying the dam size, the ICOLD Large Dams Classification and USACE Dams Size Classification Criteria were used because they match Myanmar's condition for hazard potential and inflow design flood. This research's central theme is comparing different flood return periods through analytical simulation methods. Three inflow design floods, 5000 - and 10,000-year return floods, and probable maximum flood (PMF) were applied in rainfall-runoff calculations using the Hydrologic Engineering Center-Hydrological Modeling System (HEC-HMS). The maximum discharge for the flood returns years and PMF were 19,606.51 m3/s, 25,903.53 m3/s, and 36,769.99 m3/s, respectively. 1D and 2D unsteady flow analyses were simulated by applying the Hydrologic Engineering Center-River Analysis System (HEC-RAS). The maximum floodwater depth were 16.13 m and 22.02 m, the affected areas were 45.52 m2 and 58.23 m2, and the affected villages were 16 and 32 for 1D and 2D, respectively. The results from 2D were more detailed and covered more flooded areas than 1D. Therefore, the emergency preparedness plan can be made by using 2D results. Accordingly, floodplain management strategies can easily support downstream areas. Furthermore, mitigation measures can enhance food security, energy, and water sanitation, commonly adversely affected by flood water.

Dam failures occur worldwide and can be economically and ecologically devastating. Communicating the scale of these risks to the general public and decision-makers is imperative. Two-dimensional (2D) dam failure hydraulic models inform owners and floodplain managers of flood regimes but have limitations when shared with non-specialists. This study addresses these limitations by constructing a 3D Virtual Reality (VR) environment to display the 1976 Teton Dam disaster case study using a pipeline composed of (1) 2D hydraulic model data (extrapolated into 3D), (2) a 3D reconstructed dam, and (3) a terrain model processed from UAS (Uncrewed Airborne System) imagery using Structure from Motion photogrammetry. This study validates the VR environment pipeline on the Oculus Quest 2 VR Headset with the criteria: immersion fidelity, movement, immersive soundscape, and agreement with historical observations and terrain. Through this VR environment, we develop an effective method to share historical events and, with future work, improve hazard awareness; applications of this method could improve citizen engagement with Early Warning Systems. This paper establishes a pipeline to produce a visualization tool for merging UAS imagery, Virtual Reality, digital scene creation, and sophisticated 2D hydraulic models to communicate catastrophic flooding events from natural or human-made levees or dams. Abbreviations: ASDSO: Association of State Dam Safety Officials; DEM: digitalelevation model; EWS: Early Warning System; HEC-RAS: Hydrologic EngineeringCenter-River Analysis System; HMD: Head-Mounted Display; NOAA: NationalOceanic and Atmospheric Administration; Reclamation: Bureau of Reclamation; United States Agency; SfM: Structure from Motion; 1D: one-dimensional; 2D:two-dimensional; 3D: three-dimensional; UAS: Uncrewed Aerial System (drone); US:United States; USACE: United States Army Corps of Engineers; VR: VirtualReality

Dam failure risk standards are the foundation of risk decision-making for dam managers. However, as an important component of dam failure risk standards, there are currently no unified environmental risk standards. Drawing on research ideas of ecological economics on ecosystem service values and equivalent factor methods, this study quantified environmental values and effectively connected environmental standards with existing standards using the ALARP principle and the F-N curve. Considering the differences in environmental and economic conditions in different regions, a risk preference matrix was constructed to determine the risk preference of each region and formulate the dam failure environmental risk standards for China. This study presents a preliminary exploration of the formulation of dam failure environmental risk standards, providing new methods and ideas for subsequent research.

One of the most important indirect economic consequences of dam failure (DF) is decrease the employment of agricultural sector (EOAS) downstream of the dam, its accurate estimation is difficult due to multi-layer effects of (DF). The main purpose of this study is to predict rate of employment by considering qualitative and quantitative impacts of DF by using dummy variable (DV) regression models technique in estimating income functions (IF) and production of crops functions (PFs) in the AS and using the functions in linear programming model (LPM) for optimal allocation of labour. The results of model showed that with 36% decrease in accessible water resource after DF, proportionate with the decreasing trend, the level of labour employment has decreased about 23% in downstream area of the dam. The results of this research have good conformity with former findings such as simulation method for failure embankment which is equal to 25%. So, combination of LPM with DV regression for predicting unemployment rate originated from DF and managing social and economic crisis in line with sustainable development is a realistic and accurate method. [ABSTRACT FROM AUTHOR]

Despite significant improvements in design methodologies, dams and water-retaining structures failures continue to occur. Dams' failure analysis plays a crucial role in the development of dam safety planning and emergency action. Since the Grand Ethiopian Renaissance Dam (GERD) has been built, there have been many concerns about its safety and its effects on downstream countries in case of its failure. In this paper, the GERD break was modeled by using the USACE Hydrologic Engineering Center's River Analysis System (HEC-RAS). Two dimensions model under different failure scenarios was suggested. Moreover, outflow hydrographs and flood inundation maps were presented due to dam breach. Finally, it was concluded that, in case of catastrophic failure, flow depths may vary from 3 to 10 m in some residential areas, such as Khartoum. Furthermore, the water surface elevation may reach 184 m above msl (mean sea level) in Lake Nasser in case of dam failure with a fully stored GERD reservoir. Moreover, the maximum flow would reach 325,928 m3/sec which is more than 21.5 times the total capacity of the dam spillway. Finally, the paper's outcomes may assist decision-makers in developing alternate plans to deal with the dangers of GERD break. [ABSTRACT FROM AUTHOR]

Common analytical assessment methods for concrete dams are unlikely to predict material fracture in the dam body because of the assumption of rigid body behavior and uniform- or linear stress distribution along a predetermined failure surface. Hence, probabilistic non-linear finite element analysis, calibrated from scale model tests, was implemented in this study to investigate the impact of concrete material parameters (modulus of elasticity, tensile strength, compressive strength, fracture energy) on the ultimate capacity of scaled model dams. The investigated dam section has two types of large asperities, located near the downstream and/or upstream end of the rock–concrete interface. These large-scale asperities significantly increased the interface roughness. Post-processing of the numerical simulations showed interlocking between the buttress and the downstream asperity leading to fracture of the buttress with the capacity being determined mainly by the tensile strength of the buttress material. The capacity of a model with an asperity near the upstream side, with lower inclination, was less dependent on the material parameters of the buttress as failure occurred by sliding along the interface, even with inferior material parameters. Results of this study show that material parameters of the concrete in a dam body can govern the load capacity of the dam granted that significant geometrical variations in the rock–concrete interface exists. The material parameters of the dam body and their impact on the capacity with respect to the failure mechanism that developed for some of the studied models are not commonly considered to be decisive for the load capacity. Also, no analytical assessment method for this type of failure exists. This implies that common assessment methods may misjudge the capacity and important parameters for certain failure types that may develop in dams. [ABSTRACT FROM AUTHOR]

Sermo Dam is located in the Special Region of Yogyakarta and serves multiple purposes including providing drinking water, supplementing irrigation systems in the Kalibawang area, and flood control. According to data published by the World Commission, 60% of mitigation measures taken to overcome the impact of dam structure failures are unsuccessful. The simulation of dam failure serves as a crucial aspect of flood mitigation plans and strategies because it is more destructive than natural flood waves. This research used HEC-RAS 5.0.7 to examine the flood inundation mapping and simulate dam failure in two dimensions. However, Dam Break Analysis was adopted to provide a Dam Emergency Action Plan Guide to guide managers and the community. The overtopping scenario was adapted to model the failure of the Sermo Dam based on the frequent occurrence of heavy and extreme precipitation in the affected area. Data were analyzed using unsteady flow and PMF discharge with peak inflow discharge of 1276.6 m³ s-1, which result in an inundation area of 9394 hectares and a maximum flood height of 17 m. Dam failure-induced floods tend to potentially affect eight sub-districts including Kokap, Pengasih, Sentolo, Wates, Panjatan, Galur, Lendah, and Temon. The piping scenario is also considered based on the potential damage that tends to occur. In the piping scenario, the biggest flooding area was 5112 hectares with a maximum flood height of 13 m. About six sub-districts are potentially affected by dam failure-induced floods with Kokap and Sentolo being excluded from the list. Therefore, it is crucial to establish early warning systems and infrastructure to mitigate disaster risks. The results of this research can also inform evacuation planning, damage estimation, and post-flood rehabilitation efforts in the affected areas. [ABSTRACT FROM AUTHOR]

Dams are built for different purposes, but failure of a dam could result in extreme disasters such as floods. The Grand Ethiopian Renaissance Dam (GERD) was mainly built for power generation, but concerns about its safety, location and site conditions have led the downstream countries to investigate the GERD's stability. This paper aims to investigate the impact of the failure of the dam on the downstream countries using the Hydrologic Engineering Center River Analysis System (HEC-RAS). Outflow hydrographs and flood inundation maps were provided through a hypothetical dam break scenario. An unsteady flow hydrodynamic routing with a 2D model was used to simulate the failure of the dam. A sensitivity analysis study of the output's findings against breach parameters was also performed. The breach outflow discharge increases as the breach dimension increases. However, the peak discharge decreases with increasing breach formation time. Moreover, to prepare emergency action plans, it is important to predict the inundation depth, levels, arrival of flood waves, flood coverage area and water velocity. Furthermore, the results showed that Khartoum would turn into lakes within about 10 days and flood water depth would exceed 11 m at some locations in residential areas. Moreover, the flood waves overtopped the Roseires, Sennar and Merowe dams by 11, 7 and 20 m, respectively. In addition, the level of Lake Nasser would reach 188 m above sea level and the Aswan High Dam might be in great danger. [ABSTRACT FROM AUTHOR]

A dam breaking is a major flood catastrophe. The shape, depth, and wave Doppler effect of initial water flow are all modified as a result of the interaction of the water body with downstream structures after a dam breach, forming a diffraction and reflection flow field. This study investigates the dam breaking problem of a single liquid, by creating a two-dimensional simplified numerical model using the VOF approach, analysing the interaction and effect between barriers of various forms and the dam failure flow, and explains the problem of a complex flow mechanism involving significant deformation of the free surface of a medium. According to the findings, obstacles of varying forms could obstruct the dam break's water flow to various degrees, and the viscous dissipation characteristic of the water body at the edge of the obstacle is closely related to the slope of the site. The numerical simulation presented in this study is validated, demonstrating its accuracy for both the gate-pulling and downstream wet-bed scenarios. [ABSTRACT FROM AUTHOR]

Sermo Dam is located in the Special Region of Yogyakarta and serves multiple purposes including providing drinking water, supplementing irrigation systems in the Kalibawang area, and flood control. According to data published by the World Commission, 60% of mitigation measures taken to overcome the impact of dam structure failures are unsuccessful. The simulation of dam failure serves as a crucial aspect of flood mitigation plans and strategies because it is more destructive than natural flood waves. This research used HEC-RAS 5.0.7 to examine the flood inundation mapping and simulate dam failure in two dimensions. However, Dam Break Analysis was adopted to provide a Dam Emergency Action Plan Guide to guide managers and the community. The overtopping scenario was adapted to model the failure of the Sermo Dam based on the frequent occurrence of heavy and extreme precipitation in the affected area. Data were analyzed using unsteady flow and PMF discharge with peak inflow discharge of 1276.6 m³/s, which result in an inundation area of 9394 hectares and a maximum flood height of 17 m. Dam failure-induced floods tend to potentially affect eight sub-districts including Kokap, Pengasih, Sentolo, Wates, Panjatan, Galur, Lendah, and Temon. The piping scenario is also considered based on the potential damage that tends to occur. In the piping scenario, the biggest flooding area was 5112 hectares with a maximum flood height of 13 m. About six sub-districts are potentially affected by dam failure-induced floods with Kokap and Sentolo being excluded from the list. Therefore, it is crucial to establish early warning systems and infrastructure to mitigate disaster risks. The results of this research can also inform evacuation planning, damage estimation, and post-flood rehabilitation efforts in the affected areas.

ABSTRACT Objective: To describe the patterns of overall mortality and mortality from external causes and the temporal evolution in the municipalities of the Paraopeba River Basin, before the socio-environmental disaster of the Brumadinho dam and, additionally, to investigate the correlation between mortality and socioeconomic deprivation in these municipalities. Methods: Global Burden of Disease Study mortality estimates for 26 municipalities in the state of Minas Gerais, Brazil, were analyzed. Rates of overall mortality and mortality from external causes were estimated in the triennia (T) T1 (2000 to 2002), T2 (2009 to 2011), and T3 (2016 to 2018). Pearson’s correlation coefficient measured the association between mortality rates and socioeconomic deprivation, according to the Brazilian Deprivation Index (IBP). Results: There was a decrease in overall mortality in the Paraopeba River Basin from 717.7/100 thousand to 572.6/100 thousand inhabitants, and in most municipalities between T1-T3. Mortality from external causes increased from 73.3/100 thousand to 82.1/100 thousand, and it was higher in these municipalities compared with the mean for Brazil and Minas Gerais. Deaths from suicide and interpersonal violence increased from 29.6/100 thousand to 43.2/100 thousand in most of the 26 municipalities. Death rates due to unintentional injuries decreased during the period, and those due to transport injuries, increased. There was a positive correlation between socioeconomic deprivation and the percent change in mortality rates. Conclusion: Despite the strong presence of mining activity in the region, such did not reflect in the improvement of the sanitary situation. Death rates due to external causes increased in the period, associated with inequalities, which must be considered in the planning for the recovery of the disaster areas.

Dam failure can cause extraordinary flooding. Water and wastewater treatment plants, electricity generation facilities, bridges, highways, population centers, and other dams often lie downstream of a dam. If poorly maintained, aging dams can be overtopped by extreme rainfall events, and long-term loss of critical infrastructure services for many communities and regions may result. Such events are now more likely as the climate changes. How should we prioritize dams that need immediate attention and retrofit or remove them? Losses from a dam failure could exceed the infrastructure's replacement costs, through cascading effects in multiple sectors such as electricity, transportation, water supply, and environmental services. The existing dam hazard classification frameworks in the US and many other countries do not formally characterize "hazard hotspots" considering these impacts. Given that there are over 90,000 dams at different stages of repair, maintenance, and budgetary constraints, a systematic approach is needed to rank their potential failure hazard and allocate resources for risk mitigation. In this paper, we synthesize an approach for preliminary ranking of the priority areas of concern. The approach is scalable over many regions for rapid assessment of magnitude and exposure of a dam failure. The estimation of the consequences of a dam failure, including its financial losses, as well as affected critical infrastructures and population, is explored using publicly available dam break and consequence tools as well as national infrastructure data sets. [ABSTRACT FROM AUTHOR]

Simulation of dam breach scenarios can help in the preparation of emergency action plans for real dam breaks or flash flooding events. The purpose of this study was to identify flood-prone areas in the Al Wala Valley in the governorate of Madaba in Jordan through analysis of the Al Wala Dam. Modelling of dam breaches was conducted under two scenarios: a Clear Day scenario and a Probable Maximum Flood (PMF) scenario. The former scenario does not address the various dam failure modes; rather, it addresses the formation and development of a breach as a result of structural failures like the sliding of dam blocks in the case of a concrete dam or piping failures in the case of embankment dams. The PMF scenarios, however, simulate unsteady flow in pipes and overtopping failure via consideration of runoff hydrography. In the PMF scenario, flood-prone areas can be identified by in-depth analysis of data from previous extreme rainfall events. The related hydrologic and hydraulic data can then be modelled using intensity-duration-frequency curves applied to an hour-by-hour simulation to discover the areas most at risk of flooding in the future. In the present study, data were collected from inlet of flow to Al Wala Valley on 10 January 2013. The collected data, which included rainfall and discharge data, were fed to the HEC-HMS software in order to calibrate the hydrological parameters of the watershed of the Al Wala Dam. Additionally, the HEC-RAS tool was employed to determine the breach outflow hydrography and hydraulic conditions across various critical downstream locations, which were determined by use of dynamic flood wave-routing models. The simulations revealed that, in the case of the Clear Day scenario, downstream inundation would cover an area of 5.262 km2 in the event of a pipe failure. However, in the event of a six-hour storm, a twelve-hour storm, and a twenty-four-hour storm, the flooded area would rise to 6.837 km2, 8.518 km2, and 9.390 km2, respectively. In the event of an overtopping failure, 13.171 km2 would be inundated, according to the Clear Day scenario. On the other hand, in the event of a six-hour storm, a twelve-hour storm, and a twenty four-hour storm, the flooded area would rise to 13.302 km2, 14.249 km2, and 14.594 km2, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT Objective: To describe, within the Human Rights to Water and Sanitation (HRWS) framework, the access to water supply services and the incidence of waterborne diseases in the communities affected by the dam disaster in Brumadinho (MG), Brazil. Methods: A quantitative and qualitative methodology was used, having as variables information on access to water supply services and waterborne diseases. The primary data were extracted from the “Brumadinho Health Project”, using a sample stratum with 981 people interviewed, totaling 92.5% of the eligible population in the affected communities of Córrego do Feijão and Parque da Cachoeira. The secondary data from Brumadinho was extracted from the project “Sanitation conditions and the River Basin of the B1 River Basin of Mineradora Vale between 2017 and 2020”, available in public databases between 2017 and 2020, and qualitative data was collected in 2022 through individual interviews with health professional also live in the communities. Results: With regard to access to water supply services, the results of this combined data analysis indicate that the HRWS is being neglected, especially with regard to availability, accessibility, acceptability and quality of water. The study also shows a significant increase in the incidence of waterborne diseases in the region after the disaster. Conclusion: It is necessary to use the HRWS as the basis to the implementation of public policies aiming to reduce vulnerability in access to water supply services.

Human factors are introduced into the dam risk analysis method to improve the existing dam risk management theory. This study constructs the path of human factor failure in dam collapse, explores the failure pattern of each node, and obtains the performance shaping factors (PSFs) therein. The resulting model was combined with a Bayesian network, and sensitivity analysis was performed using entropy reduction. The study obtained a human factor failure pathway consisting of four components: monitoring and awareness, state diagnosis, plan formulation and operation execution. Additionally, a PSFs set contains five factors: operator, technology, organization, environment, and task. Operator factors in a BN (Bayesian network) are the most sensitive, while the deeper causes are failures in organizational and managerial factors. The results show that the model can depict the relationship between the factors, explicitly measure the failure probability quantitatively, and identify the causes of high impact for risk control. Governments should improve the significance of the human factor in the dam project, constantly strengthen the safety culture of the organization’s communications, and enhance the psychological quality and professional skills of management personnel through training. This study provides valuable guidelines for the human reliability analysis on dam failure, which has implications for the theoretical research and engineering practice of reservoir dam safety and management.

This article presents experimental research focusing on the structural failure of the central core of a rockfill dam using sand-bentonite mixtures. It comprised an extensive geotechnical characterization of soil materials and mixtures, including compaction and strength tests, as well as the construction of 1 m high and 1.5 m wide physical models. The displacements of the cohesive cores were recorded using a tailored measuring system, based on a laser pointer and a mirror, designed to amplify the real displacements. The cohesive cores were extremely sensitive to small oscillations and behaved as rigid bodies, similar to concrete slabs with three fixed sides and another free. The shape and dimensions of the breach formed on the cohesive cores had roughly the same shape and dimensions as the unprotected area. This experimental research has the potential to be used as validation tool for several models available in the literature to predict the failure of embankment dams. [ABSTRACT FROM AUTHOR]

This article examines the results of experimental studies of the travel time by a breakthrough wave front from a dam to a downstream site in experiments with instantaneous, partial-width, and full-height failure of the dam for the case of the presence of water in the downstream. [ABSTRACT FROM AUTHOR]