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This study utilizes the MIKE 11 hydrodynamic model developed by the Danish Hydraulic Institute to simulate flood behavior downstream of Karot Dam under multi-year in-flow conditions. The key parameters analyzed include breach characteristics, flood duration, water depth, flow velocity, discharge rate, and downstream distance. After dam failure, the peak discharge reaches 33,171 m3/s, exceeding the 10,000-year recurrence peak flow of 32,300 m3/s, with a breach duration of 2 h. The estimated peak discharge after simulation using empirical equations and comparative analyses showed maximum flood discharges of 28,187 m3/s, 28,922 m3/s, and 29,769 m3/s, with breach widths of 181 m, 256 m, and 331 m, respectively. The peak discharge predicted to reach the outlet with travel time ranging from 4 h 25 min to 4 h 40 min. Under multi-year average inflow conditions, Mangla Dam faces no risk of failure, with a maximum outflow of 12,097 m3/s and a spillway capacity of 30,147 m3/s. The model accurately predicted discharge values, with a strong correlation coefficient of R2 = 0.9653, indicating strong agreement between the actual water level data and predicted discharge. These insights are essential for developing effective emergency response strategies to mitigate the risks associated with dam failure. [ABSTRACT FROM AUTHOR]

Based on the results of numerical modelling, characteristic features of distribution of transformed and polluted waters of the Dnieper River in the water area of the north-western part of the Black Sea (NWBS) are determined and analyzed. This pollution of the marine environment resulted from the extremely large man-made flood caused by the destruction of the Kakhovka Reservoir dam by the Russian occupation forces in June 2023. Various types of pollutants, which contained in the Kakhovka Reservoir, in the lower Dnieper River and in the bottom sediments, were carried out into the sea by the flood discharge. A significant amount of pollutants was washed into the sea from the flooded areas of the lower Dnieper basin. Special attention is given to changes in oceanographic conditions in the Dnieper-Bug estuary region (DBR) of the Black Sea, which determine the extent of marine pollution. Sea water salinity was used as an indicator of the degree of infiltration of polluted seawater from the estuary into the sea. It was identified that the least transformed river waters with low salinity correspond to high pollution levels. Delft3D-Flow Flexible Mesh hydrodynamic model, developed by Deltares, was used in this study. The simulation was performed for the time period 01 to 30 June 2023. During the first days after the dam break the desalinated and polluted transitional waters, flowing from the Dnieper-Bug estuary, spread over the entire water column down to 15-20 m depth in the DBR area. In this case, the spreading of transitional waters was atypical, as it usually occurs only within the thin near-surface layer of the sea. By mid-June the flow of transitional water with a salinity of 4-6 ‰ covered the entire water column from surface to bottom near the northern coast of the NWBS and over the Odessa Bank. This was facilitated by the supermassive volumes of transformed Dnieper river waters flowing out over a short period of time due to dam break, as well as by the resulting intense gradient currents and mixing caused by spatial gradients in the velocity of the generated currents. The width of the desalinated water plume and its area in the bottom layer were smaller than in the surface layer. The largest vertical salinity gradients were formed to the south of the Odessa Bank, where salinity was 4-6 ‰ in the surface layer and 14-17 ‰ in the bottom. Dilution of the desalinated water plume in the bottom water layer was much more intensive than in the surface water. The character of water circulation pattern in the northern part of the NWBS in the first days after the inflow of transient waters from the Dnieper-Bug estuary was determined by the runoff gradient currents, which later were replaced by wind-driven currents in the Odessa area and over the Odessa Bank, and by the meandering flow of gradient density currents further south. The findings of this study contribute to a better understanding of the impact of the inflow of transformed river waters from the Dnieper-Bug estuary on the variability of oceanographic characteristics and the ecological state of marine waters in the Dnieper-Bug region of the northwestern Black Sea.

The catastrophic failure of two dams in Libya on 10 and 11 September 2023 resulted in the devastating flooding of the city of Derna, which is located downstream of the dams, causing more than 6000 fatalities and displacing thousands of residents. The failure was attributed to heavy rainfall from Storm Daniel, leading to the dams reaching full capacity and subsequently overflowing and failing. This paper presents an analysis of the dam break, including the modelling of flow discharge and the resulting flooding of Derna. For validation purposes, this study compares the modelled quantities with post-event satellite imagery from UNOSAT and Copernicus, local reports, and data collected from social media using AI detection. The findings provide valuable insights into the dynamics of the dam break and its initial parameters, as well as an assessment of the accuracy of the results. The analysis is performed using a rapid estimation technique developed by JRC to provide the international emergency community with a swift overview of the impact and damage assessment of potential or actual dam break events. The use of all available data shows a satisfactory comparison with the calculated quantities. The rapid modelling of dam break events and combined analysis of multiple data types are proven suitable for promptly assessing the expected dynamic of the event, as well as reconstructing the unknown initial conditions before the break. Incorporating sensitivity analyses provides an estimate of the uncertainties associated with the deduced values of the unknown parameters and their relative importance in the analysis.

The economic and environmental benefits of dam flow need to be calculated theoretically using open-source field operation and manipulation (OpenFOAM). The potential consequences of a hypothetical dam failure depend mainly on the kind of collapse and the reservoir's capacity. Riverbed singularities develop during floods and change over time, affecting the dam-break pulse and the shape of hydrographs. Three-dimensional simulators are commonly used to detect incremental variations in dam-break flow. However, physical obstructions or quick changes in the bed channel's characteristics can significantly alter flood propagation and scenarios. To reduce damage to the spillway, flow speed is analyzed, and obstructions in the spillway bed are taken into account. Large eddy simulation is used to explain turbulent flow behavior on the dam spillway. The kinetic energy in a turbulent flow is determined at the input, obstructions, and exit. Using C++ programming and OpenFOAM simulation, velocity and turbulent kinetic energy calculations are shown graphically. The results of the study demonstrate a remarkable alignment with the previously documented findings, which adds to the credibility and validity of our research. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office 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.)

The catastrophic failure of two dams in Libya on 10 and 11 September 2023 resulted in the devastating flooding of the city of Derna, which is located downstream of the dams, causing more than 6000 fatalities and displacing thousands of residents. The failure was attributed to heavy rainfall from Storm Daniel, leading to the dams reaching full capacity and subsequently overflowing and failing. This paper presents an analysis of the dam break, including the modelling of flow discharge and the resulting flooding of Derna. For validation purposes, this study compares the modelled quantities with post-event satellite imagery from UNOSAT and Copernicus, local reports, and data collected from social media using AI detection. The findings provide valuable insights into the dynamics of the dam break and its initial parameters, as well as an assessment of the accuracy of the results. The analysis is performed using a rapid estimation technique developed by JRC to provide the international emergency community with a swift overview of the impact and damage assessment of potential or actual dam break events. The use of all available data shows a satisfactory comparison with the calculated quantities. The rapid modelling of dam break events and combined analysis of multiple data types are proven suitable for promptly assessing the expected dynamic of the event, as well as reconstructing the unknown initial conditions before the break. Incorporating sensitivity analyses provides an estimate of the uncertainties associated with the deduced values of the unknown parameters and their relative importance in the analysis. [ABSTRACT FROM AUTHOR]

Physics-based numerical models often depend on several parameters to close. Some of them can be expressed using established theoretical or empirical closure formulations. However, some others aggregate complex physical processes and are hence left as tuneable parameters, and can only be calibrated by trial and error. Yet, calibration data are not always available to do so, which prevents these models from being applied to wide ranges of laboratory or river flows. We hence propose a machine learning-based methodology to close any group of unclosed and correlated parameters, applied here to a two-phase/two-layer (2P2L) morphodynamical model. The methodology combines a numerical experiment with a known theoretical solution and machine learning. It is applied to the considered model to close two friction parameters for which generalizable and vastly acknowledged closure formulations lack in the literature. The resulting hybrid model, combining the original 2P2L model and the closure models, is tested against two laboratory dam break test cases. Despite excessive smoothness and underestimation of the concentration in sediment, the hybrid model performed similarly to other models from the literature requiring trial and error calibration and showed high stability and accuracy regarding the estimation of the water-sediment mixture's inertia. HIGHLIGHTS A methodology to close tuneable parameters applicable to many morphodynamical models.; Methodology based on machine learning and self-generated data from a numerical experiment with theoretical solution.; Presentation of a two-phase/two-layer model for unsteady flows highly laden with sediment, used as a proof of concept of the methodology.; New model's performance is similar to evenly complex models requiring trial and error to calibrate tuneable parameters.;

This study aimed to comprehensively investigate the influence of substrate level difference and material composition on dam break wave evolution over two different erodible beds. Utilizing the Volume of Fluid (VOF) method, we tracked free surface advection and reproduced wave evolution using experimental data from the literature. For model validation, a comprehensive sensitivity analysis encompassed mesh resolution, turbulence simulation methods, and bed load transport equations. The implementation of Large Eddy Simulation (LES), non-equilibrium sediment flux, and van Rijn’s (1984) bed load formula yielded higher accuracy compared to alternative approaches. The findings emphasize the significant effect of substrate level difference and material composition on dam break morphodynamic characteristics. Decreasing substrate level disparity led to reduced flow velocity, wavefront progression, free surface height, substrate erosion, and other pertinent parameters. Initial air entrapment proved substantial at the wavefront, illustrating pronounced air-water interaction along the bottom interface. The Shields parameter experienced a one-third reduction as substrate level difference quadrupled, with the highest near-bed concentration observed at the wavefront. This research provides fresh insights into the complex interplay of factors governing dam break wave propagation and morphological changes, advancing our comprehension of this intricate phenomenon.

In this study, an incompressible and immiscible two-phase flow solver was employed to assess the accuracy of phase-interface capturing methods in simulating two-phase flows. Three benchmark investigations were conducted involving two dam break flows with deformable free surfaces and the upward motion of a gas bubble through a liquid column. Four phase-interface capturing schemes, namely, MULES, HRIC and CICSAM from the Color Function Volume of Fluid (CF-VoF), and Interface Reconstruction Volume of Fluid (IR-VoF), were utilized. Comparative analysis of the phase interfaces indicated that CICSAM and IsoAdvector consistently provided sharp interfaces across all cases when compared to MULES and HRIC. The mass conservation performance of all schemes excelled in the dam-break case with relatively simple free-surface development and the rising bubble case. An examination of the local pressure distribution over time revealed that methods yielding diffusive interfaces produced inaccurate results. Thus, the importance of employing denser grids or schemes that yield sharper interfaces, such as CICSAM and IsoAdvector, to enhance simulation accuracy was underscored. Overall, the results of this analysis confirm that the IsoAdvector scheme, which provides sharp interfaces, is a reliable option for simulating incompressible immiscible two-phase flows. [ABSTRACT FROM AUTHOR]

Dam-break risk standards are the basis for dam managers to make risk decisions. However, as one of the important contents of dam break risk standard, there is no unified environmental risk standard at present. This paper used the research ideas of ecosystem service value and equivalent factor method in ecological economics for reference, and quantified the environmental value. ALARP criterion and F-N curve were used to effectively link environmental standards with existing standards. Considering the differences of environment and economy in different regions of China, the risk preference matrix was built, and the risk preference of each region was determined, so as to formulate the environmental risk standard in China. Taking Luhun Reservoir in Henan Province as an example, the application of this method was illustrated. [ABSTRACT FROM AUTHOR]

Dam break flows have been a focus of attention for a long in the hydraulic engineering discipline. The interest stems from their high hazard potential to human life and property. This research investigates a laboratory dam break flow using a 3D Reynolds-averaged Navier–Stokes (RANS) and a 2D shallow water Eq. (2D SWE) model. The two numerical models have been compared to measured data regarding flow depth, streamwise surface flow velocity, and point velocity. The results show that as far as a simulation of water depths at gauging stations is concerned, both models are almost at par with an error of about 20% of the mean depth value. Further, the comparison of surface velocity field reveals that though both models are capable of reproducing the salient flow features, e.g., oblique hydraulic jump, wake, etc., the 3D RANS model is more accurate in predicting the jump length and the so-called wet–dry fronts. The important contribution of this research lies in clearly enunciating the tradeoffs between a 2D SWE model and a 3D RANS model. The former model is computationally efficient and accurate as far as flow depth and velocity are concerned while the latter model provides a more complete result output, e.g., vertical flow velocity, turbulent kinetic energy and turbulent dissipation, etc. However, for obtaining significant accuracy with a 3D model a more accurate turbulence model than RANS is required which necessitate usage of very refined mesh (~ mm), thus, raising the cost of the simulation manifold. [ABSTRACT FROM AUTHOR]

The purpose of this work is to develop a hybrid model for predicting the consequences of a mudflow breakthrough of hydraulic structures, such as dams and dams. The presented work is devoted to the automation of the processes of modeling and analysis of the destruction of hydraulic structures, based on modern methods of hydrodynamics and thermophysics. The relevance of this work is due to the increasing frequency and scale of catastrophic floods caused by the destruction of hydraulic structures, which requires effective methods for predicting and preventing such events. The methods and models proposed in the work are of significant practical importance for risk assessment, planning evacuation measures and minimizing damage from emergencies associated with dam and dam breaks. [ABSTRACT FROM AUTHOR]

When settlements are located close to a dam, it is important to accurately predict the breach peak flow and the time to reach the peak. Therefore, the prediction of dam breach properties is essential in dam break studies. Dam breach parameters such as the breach side slope, final bottom width, final bottom elevation, weir coefficient, breach formation time, and initial elevation of reservoirs are the key variables for estimating the peak discharge during a dam break scenario. In this study, these six breach parameters were analyzed to investigate the impact of breach parameters on breach peak flow and the time to reach the peak. Thus, several scenarios were calculated and compared for Atasu Dam. The results revealed that the role of the initial water elevation, final bottom elevation, and breach development time had more of an impact on the breach peak flow and the time to reach the peak. In addition, the study indicated that the final bottom width and breach weir coefficient were less sensitive to both the peak discharge and peak discharge time. Furthermore, the analysis indicated that the breach side slope parameter had no major influence on the time to peak while also having an insignificant impact on the peak discharge. Understanding this breach mechanism provides a basis for relevant research in designating key parameters for dam break analysis. Thus, the results can contribute to decision making toward the design of flood mitigation and dam emergency action planning. [ABSTRACT FROM AUTHOR]

This research focuses on improving the estimations of key dam breach parameters (peak discharge, breach formation time, and average breach width). These parameters are crucial for understanding and mitigating the impact of dam failures. The study acknowledges the difficulty in estimating these parameters due to limited historical data and existing empirical models' uncertainties. To overcome these challenges, the research follows a systematic approach: (1) Data Compilation and Cleaning: multiple datasets of historical dam break events were compiled and cleaned. Missing data were filled in, and anomalous outliers were removed to ascertain the data quality. (2) Data Fusion approach was then considered for (2-a) Identifying the most suitable empirical equations for each breach parameter. (2-b) Developing regression-based models based on the selected empirical equations. (2-c) Conducting uncertainty analyses to assess the reliability and confidence of the models' results. The newly developed data fusion-based models were claimed to outperform existing empirical equations, reducing uncertainty across all breach parameters. (3) The research finally applied the proposed models to four real-world dam cases via a two-dimensional hydraulic model. This application demonstrated how the models can be used in practical engineering scenarios, aiming to enhance our ability to predict and consequently mitigate the impact of dam failures, ultimately contributing to improved dam safety and risk management. [ABSTRACT FROM AUTHOR]

Catastrophic failure of dam structures has often led to severe consequences. The colossal wave receding at a higher velocity from the sudden failure of the dams may obliterate the downstream areas causing loss of lives and property damage. Thus, proper mitigation measures and contingency plans must be formulated beforehand to minimize the impact of such disasters. Consequently, there has been a strong tendency to study dam breach flood modeling using different approaches for both hypothetical dam breach scenarios and real incidents. The technology used for dam breach studies is advancing and a comprehensive review of the existing methodologies would help the modelers in their model development. This paper reviews the state-of-the-art methodologies utilized in studies to propagate the dam break flood wave. Furthermore this guides the selection of methods best suited considering the project-specific requirements and the complexity of project to simulate the risk to the vulnerable areas generated from the dam break flood flow. Different terrain datasets, mesh generation techniques and calibration techniques have been adapted and adhered to improve computational accuracy, stability and efficiency in modeling dam break floods. The use of high-resolution global and site-specific datasets, subgrid models, the choice of roughness coefficients and highresolution time steps have to be investigated thoroughly in these models. The paper reviews the existing methodologies with the strengths and limitations facilitating the future dam breach modelers to select the suitable approach in dam break flood wave modeling. This article is categorized under: Engineering Water > Sustainable Engineering of Water Science of Water > Water Extremes Water and Life > Conservation, Management, and Awareness [ABSTRACT FROM AUTHOR]

The potential effects of Grand Ethiopian Renaissance Dam (GERD) failure on the downstream countries were numerically assessed. Flow discharge reaching Lake Nasser and the corresponding water levels were determined, and the inundated areas were defined as a result of GERD failure. High-resolution digital elevation model was developed with 2670-km length starting from GERD till Aswan High Dam. GERD's reservoir, urban, and rural lands downstream of the GERD were presented using a numerical model. The modeled areas included parts of Ethiopia, Sudan, and Egypt, not to mention Toshka Spillway. The model areas were not divided into parts because of calculating the water levels at the existence of intermediate dams as model outputs. In case possible failure of GERD, Roseires and Sennar dams could collapse. Meanwhile, Merowe dam can sustain with the operation of its emergency spillway. Wave height reaches 100-m downstream of the GERD and 64-m and 31-m downstream of the Roseires and Merowe dams, respectively. [ABSTRACT FROM AUTHOR]

This paper analyzes the dam-break flow propagation over a stair using a novel version of the weakly compressible moving particle semi-implicit method, which was improved with the particle shifting technique and the quintic kernel function. The proposed method was validated with the experimental data of dam-break propagation. The simulation was conducted in two scenarios, in the first of which an obstacle-shaped stair was located in the flow direction, and the collision of the water volume with the stair was modeled through the proposed approach. The results were then compared with those obtained from the finite-volume method (FVM) in STAR-CD. In the second scenario, the dam-break flow descended a stair, reaching the bed and propagating in two directions: toward the right wall and backward near the stair wall. The submerged hydraulic jump was created near the stair wall because the flow did not have enough length to make the conjugation depth. The simulation results from both scenarios were consistent with those of the FVM solver. Furthermore, a quantitative analysis was performed by calculating error norms, resulting in values within the 10–4 range. The analysis indicated a high level of accuracy and consistency between the simulated results and the reference data. In addition, the issue of particle clustering was addressed effectively using the particle shifting approach. [ABSTRACT FROM AUTHOR]

Abstract The hyperconcentrated fluid flow occurs as a result of heavy rainfall, during which a large amount of sediments from the upstream basin is washed away and suddenly increases the flow concentration of the alluvial channels. The stresses exerted by this type of fluid on the bed and body of the stream/river and related structures such as dam lead to the failure them and cause many human and financial losses. One of the important topics in the simulation of dam break caused by non-Newtonian fluid flow is the modeling of frictional stresses. In this research, after collecting several relationships to model the coefficient of friction loss of non-Newtonian fluid, a two-dimensional model was developed based on the numerical solution of shallow water equations in curvilinear coordinates to simulate hyperconcentrated flow. The results of the validation of the model were presented by comparing the measurement data of the suddenly complete dam break caused by the non-Newtonian fluid flow in the form of graphs, which all emphasize the accuracy of the developed model. It was also shown that for a suddenly complete dam break, with an increase in fluid volume concentration from 13.8 to 36.4%, the flow depth at the failure site increases by 18.8%. Next, asymmetric two-dimensional partial dam break of non-Newtonian fluid was simulated and compared with the results of Newtonian fluid. The results showed that the maximum flow velocity in the center of the fracture wall for the non-Newtonian fluid with a concentration of 32.2% is less than half of the maximum velocity of the Newtonian fluid.

This study utilizes the MIKE 11 hydrodynamic model developed by the Danish Hydraulic Institute to simulate flood behavior downstream of Karot Dam under multi-year in-flow conditions. The key parameters analyzed include breach characteristics, flood duration, water depth, flow velocity, discharge rate, and downstream distance. After dam failure, the peak discharge reaches 33,171 m3/s, exceeding the 10,000-year recurrence peak flow of 32,300 m3/s, with a breach duration of 2 h. The estimated peak discharge after simulation using empirical equations and comparative analyses showed maximum flood discharges of 28,187 m3/s, 28,922 m3/s, and 29,769 m3/s, with breach widths of 181 m, 256 m, and 331 m, respectively. The peak discharge predicted to reach the outlet with travel time ranging from 4 h 25 min to 4 h 40 min. Under multi-year average inflow conditions, Mangla Dam faces no risk of failure, with a maximum outflow of 12,097 m3/s and a spillway capacity of 30,147 m3/s. The model accurately predicted discharge values, with a strong correlation coefficient of R2 = 0.9653, indicating strong agreement between the actual water level data and predicted discharge. These insights are essential for developing effective emergency response strategies to mitigate the risks associated with dam failure.

This study focuses on the flood disaster and risk that can potentially occur in the event of a dam break in the Gurara watershed, Nigeria. The aim is to evaluate the effects of land use and land cover (LULC) and hydroclimatic variability on the aforementioned dam. This is done through integration of Hydrological Simulation Fortran Program (HSPF), hydro-dynamic models and field observations. The simulation result presents the extent of the flood downstream, which inundates 274.6 Km2 (27,460 ha) of the watershed, that includes a peri-urban Jere town with a total population of 9912 and 6000 ha of irrigation area that has the potential to produce 100,000 metric tons of food in four circles per year. Further analysis of the result shows that the flood hazard map of the flooded area produced a varied index for each scenario, but it shows that the hazards increase with an increase in the literal inflow into the dam from the upstream runoffs. The hazard maps identify risks in vulnerable areas. The downstream area experiences diverse exposure based on the proximity of LULC class to the prone zones. This research presents details about the possible disaster associated with dam collapse in nearby communities. [ABSTRACT FROM AUTHOR]

The hyperconcentrated fluid flow occurs as a result of heavy rainfall, during which a large amount of sediments from the upstream basin is washed away and suddenly increases the flow concentration of the alluvial channels. The stresses exerted by this type of fluid on the bed and body of the stream/river and related structures such as dam lead to the failure them and cause many human and financial losses. One of the important topics in the simulation of dam break caused by non-Newtonian fluid flow is the modeling of frictional stresses. In this research, after collecting several relationships to model the coefficient of friction loss of non-Newtonian fluid, a two-dimensional model was developed based on the numerical solution of shallow water equations in curvilinear coordinates to simulate hyperconcentrated flow. The results of the validation of the model were presented by comparing the measurement data of the suddenly complete dam break caused by the non-Newtonian fluid flow in the form of graphs, which all emphasize the accuracy of the developed model. It was also shown that for a suddenly complete dam break, with an increase in fluid volume concentration from 13.8 to 36.4%, the flow depth at the failure site increases by 18.8%. Next, asymmetric two-dimensional partial dam break of non-Newtonian fluid was simulated and compared with the results of Newtonian fluid. The results showed that the maximum flow velocity in the center of the fracture wall for the non-Newtonian fluid with a concentration of 32.2% is less than half of the maximum velocity of the Newtonian fluid. [ABSTRACT FROM AUTHOR]

Landslides often occur in V-shaped valleys exhibiting strong river incisions and large elevation differences between the riverbed and surrounding mountains. This study expounded upon the topographical and flow conditions of typical landslide dam sites through field investigations and data collection and established a small-scale physical model for experimental research. The formation conditions of landslide dams, an important part of the long-term management of such events, were studied. Simultaneously, the experiments verified a series of engineering measures proposed based on calculus theory and implementation principles according to their experimental disposal effects to mitigate short-term flood risks. Results showed that the dam formation is mainly related to topographic characteristics, upstream flow, and dam compositions. Specifically, steep V-shaped valleys should be considered when establishing physical models as they provide great conditions for landslide mass blocking the river completely. In addition, for earth dams, the effects of the position and direction of excavated diversion channels were compared; it showed that when there are multiple passes on the dam crest, priority should be given to lateral excavation of channels from the pass to restrict the lateral development process. The dam-break flow direction should better be orthogonal rather than be parallel to the river bend, which can reduce peak flow discharge by natural energy dissipation. For earth and rockfill dams with wide particle distributions, piles and flexible nets were instead utilized to coarsen the dam breach and reduce peak flow discharge. Finally, applicable values and research significance were summarized based on the obtained results. This research enriches studies of mountain disaster management and provides guidance for on-site emergency response. [ABSTRACT FROM AUTHOR]

Tailings dams are structures that store both tailings and water, so almost all tailings dam accidents are water related. This paper investigates a tailings dam's failure pattern and damage development under flood conditions by conducting a 1:100 large-scale tailings dam failure model test. It also simulates the tailings dam breach discharge process based on the breach mode using FLOW-3D software, and the extent of the impact of the dam failure debris flow downstream was derived. Dam failure tests show that the form of dam failure under flood conditions is seepage failure. The damage manifests itself in the form of flowing soil, which is broadly divided into two processes: the seepage stabilization phase and the flowing soil development damage phase. The dam failure test shows that the rate of rise in the height of the dam saturation line is faster and then slower. The order of the saturation line at the dam face is second-level sub-dam, third-level sub-dam, first-level sub-dam, and fourth-level sub-dam. The final failure of the tailings dam is the production of a breach at the top of the dam due to the development of the dam's fluid damage zone to the dam top. The simulated dam breach release results show that by the time the dam breach fluid is released at 300 s, the area of over mud has reached 95,250 square meters. Local farmland and roads were submerged, and other facilities and buildings would be damaged to varying degrees. Based on the data from these studies, targeted measures for rectifying hidden dangers and preventing dam breaks from both technical and management aspects can be proposed for tailings dams. [ABSTRACT FROM AUTHOR]

Copyright of Jurnal Teknologi dan Rekayasa Sumber Daya Air is the property of Brawijaya 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.)

Copyright of Jurnal Teknologi dan Rekayasa Sumber Daya Air is the property of Brawijaya 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.)

Copyright of Jurnal Teknologi dan Rekayasa Sumber Daya Air is the property of Brawijaya 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.)

Copyright of Jurnal Teknologi dan Rekayasa Sumber Daya Air is the property of Brawijaya 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.)

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco 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.)

A dam break event can cause heavy loss in the affected area due to the lack of a mitigation system. Therefore, modeling the possibility of a dam break occurrence requires a risk analysis. The Saguling Dam, Cirata Dam, and Jatiluhur Dam make a cascade dam and is one of the country's most valuable assets. This study simulates a flood induced by the failure of this cascade dam. The dam break is simulated using HEC-HMS 4.6 with several dam-break scenarios due to overtopping and piping. The scenario with the highest peak discharge is then used to simulate the overland flow using HEC-RAS 5.0.7, representing the most extreme condition when the dam break occurs. The generated flood induced by the dam break hit seven regencies with a total affected area of 1,596.59 km². Moreover, an economic analysis is conducted. The result states that the most affected regency by economic losses is Karawang Regency, and the least affected is Subang Regency. The financial analysis, conducted using the ECLAC method, shows that the extent of inundation influences economic losses due to flooding, the distribution of depth, and the land cover of the affected area. This study hopes to assist in developing a mitigation plan for future possible dam breaks and provide a recommendation for decision-makers for developing land use areas. [ABSTRACT FROM AUTHOR]

The results of numerical modeling are presented for a complex cascade hydrodynamic breakdown (not based on an actual threat) caused by a dam break in the body of the Verkhneural'sk embankment dam. The studies were carried out by the methods of numerical hydrodynamic modeling using the Russian software package STREAM 2D CUDA. [ABSTRACT FROM AUTHOR]

Natural and man‐made factors can cause dam failure, which constantly threatens downstream assets. Flood risk assessment is typically developed according to the hydraulic and geographic characteristics of floodplain regions. However, previous approaches have not considered asset values and the impacts of flooding on them, including threat probability and consequences. This report presents a new integrated hybrid model based on security vulnerability assessment and hydraulic analysis of floods and uses the source‐pathway‐receptor‐consequences (SPRC) approach to comprehensively examine all factors. A questionnaire survey was used for performing threat analysis and attractiveness analysis and determining the asset values and consequences. A geographical information system was applied to superimpose layers based on the SPRC approach in five different scenarios based on piping discharge and downstream flow in the case of a dam break. These scenarios were developed considering the basin water level. The results illustrate that residential areas have the highest vulnerability, and farmlands exhibit the lowest exposure to flooding caused by dam failure. Based on the attraction to terrorism, criticality due to consequences, and flooding characteristics, high‐risk zones were identified for implementing mitigation or protection countermeasures. [ABSTRACT FROM AUTHOR]

Potential risk identification due to off-stream reservoir failure typically requires the use of two-dimensional hydraulic models, which demands considerable effort in terms of expertise, time and financial resources. Unfortunately, not all reservoir owners have access to these resources, and the process of assessing hazard classifications for administrations can be burdensome. ACROPOLIS was developed to address this challenge, employing a Machine Learning model to provide a preliminary risk classification according to Spanish regulations for off-stream reservoirs without the necessity of building a hydraulic model. This approach has been integrated into a user-friendly interface, simplifying the process for users.

Estimation of the potential consequences from events occurring downstream of a dam is part of the risk assessment needed during the installation phase of a new dam. In the case of specific natural or man-made ongoing or prospected events, it may also be important to carry out fast computations that can provide information on the areas at risk either because the original design analyses are not available or because the parameters needed are different. This study aimed to develop a procedure that strongly facilitates the preparation of the input deck and the derivation of the output quantities to allow a fast analysis of a dam break event using a shallow water model, NAMI DANCE, as the analysis tool. The analysis shows that in a few minutes, it is possible to obtain the input deck for a new case. This makes it possible to include the prospected methods into automatic routines in analytical tools such as the Global Disasters Alerts and Coordination System (GDACS) to have a quick overview of the expected flood due to a dam break event.

AbstractNatural and man‐made factors can cause dam failure, which constantly threatens downstream assets. Flood risk assessment is typically developed according to the hydraulic and geographic characteristics of floodplain regions. However, previous approaches have not considered asset values and the impacts of flooding on them, including threat probability and consequences. This report presents a new integrated hybrid model based on security vulnerability assessment and hydraulic analysis of floods and uses the source‐pathway‐receptor‐consequences (SPRC) approach to comprehensively examine all factors. A questionnaire survey was used for performing threat analysis and attractiveness analysis and determining the asset values and consequences. A geographical information system was applied to superimpose layers based on the SPRC approach in five different scenarios based on piping discharge and downstream flow in the case of a dam break. These scenarios were developed considering the basin water level. The results illustrate that residential areas have the highest vulnerability, and farmlands exhibit the lowest exposure to flooding caused by dam failure. Based on the attraction to terrorism, criticality due to consequences, and flooding characteristics, high‐risk zones were identified for implementing mitigation or protection countermeasures.

AbstractDue to climate change, the future Glacial Lake Outburst Flood (GLOF) risk is more likely in the Himalayas. Despite several GLOF studies, little attention has been given to the combined surge that can result from a pair of upstream-downstream glacial lakes. We chose Upper and Lower Barun glacial lakes as a pilot study due to the region’s increasing population and hydropower investments and the possible outbursts of upper-lower glacial lakes. This study mainly considered four scenarios (100 and 50% breach combination of upper-lower lakes), using a two-dimensional dam break model and inundation propagation. Based on our observations, the glaciers in the study area shrank by 33 km2, and the two glacial lakes expanded by 2.06 km2 between 1976 and 2020. The modeling result suggests that the single flood triggered by Upper Barun cannot travel beyond 50 km; however, the combined flow from the lakes could reach over 85 km. Our results illustrate that at least 60 buildings, motorable bridges, and infrastructures of Arun hydropower along the river course have high damage potential. The study insights can be helpful for effectively planning and formulating various disaster risk reduction initiatives to mitigate the likely effects of glacial lake(s) outbursts.

This research aims to examine the capability of the Computational Fluid Dynamics (CFD) method in simulating the behavior of dam break waves. It begins by building a 2D numerical simulation using OpenFOAM. To overcome the influence of turbulence, we employed the Large Eddy Simulation (LES) turbulent model, specifically the k-Equation and Smagorinsky model. The simulation was developed by applying the Navier-Stokes equations using the finite volume method in OpenFOAM. The analysis focuses on the free surface of a dam break. The results are in good accordance with both analytical and experimental results. The simulation has followed the trend of experimental and analytical free surface profiles at the dam break's early and late conditions. The low mesh number on the computational domain caused significant differences in the wavefront of the dam break. It reduced the accuracy of the calculation between the water and air interface. This study highlights the importance of understanding dam break wave behavior as part of risk mitigation for dam leakage. The behavior of dam break waves can be observed by determining observation positions at different locations, with the water gate of a dam serving as the reference point. These highly accurate numerical results indicate that the CFD approach employing OpenFOAM can be relatively cost-effective yet accurate in analyzing multiphase problems, such as dam breaks. This CFD approach is expected to contribute to developing mitigation and disaster prevention in the future. [ABSTRACT FROM AUTHOR]

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

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To accurately predict dam break peak outflow (Qp), two standalone [random tree (RT), instance-based k-nearest neighbors learning (IBK)] and four new ensemble machine learning algorithms, that couple the standalone models with two ensemble methods [bootstrap aggregating (BA), disjoint aggregating (DA)], are proposed. The machine learning methods (RT, IBK, BA-RT, BA-IBK, DA-RT, and DA-IBK) and several popular empirical equations are applied to predict Qp using dam reservoir volume above the breach invert (Vw) and height of water in the dam reservoir above the breach invert (Hw) collected from 122 historical dam break events. Three different input scenarios (Vw, Hw, Vw and Hw) are considered to find the most effective combination of input variables. The proposed models are evaluated visually (using scatter and violin plots as well as Taylor diagrams) and quantitatively (using Nash–Sutcliffe Efficiency (NSE), Willmott's index of agreement (WI), and Legates and McCabe coefficient of efficiency (LM) metrics). It is found that DA-IBK provides the best performance (NSE = 0.866, WI = 0.960 and LM = 0.687), leading to a ~ 28% improvement in NSE compared to the best empirical equation. However, all machine learning models (particularly, the ensemble models), provide substantially better performance than the empirical equations, especially at the highest outflows. [ABSTRACT FROM AUTHOR]

Estimation of the potential consequences from events occurring downstream of a dam is part of the risk assessment needed during the installation phase of a new dam. In the case of specific natural or man-made ongoing or prospected events, it may also be important to carry out fast computations that can provide information on the areas at risk either because the original design analyses are not available or because the parameters needed are different. This study aimed to develop a procedure that strongly facilitates the preparation of the input deck and the derivation of the output quantities to allow a fast analysis of a dam break event using a shallow water model, NAMI DANCE, as the analysis tool. The analysis shows that in a few minutes, it is possible to obtain the input deck for a new case. This makes it possible to include the prospected methods into automatic routines in analytical tools such as the Global Disasters Alerts and Coordination System (GDACS) to have a quick overview of the expected flood due to a dam break event. [ABSTRACT FROM AUTHOR]

Numerical modelling is a valuable and effective tool for predicting the dynamics of the inundation caused by the failure of a dam or dyke, thereby assisting in mapping the areas potentially subject to flooding and evaluating the associated flood hazard. This paper systematically reviews literature studies adopting three-dimensional hydrodynamic models for the simulation of large-scale dam-break flooding on irregular real-world topography. Governing equations and numerical methods are analysed, as well as recent advances in numerical techniques, modelling accuracy, and computational efficiency. The dam-break case studies used for model validation are highlighted. The advantages and limitations of the three-dimensional dam-break models are compared with those of the commonly used two-dimensional depth-averaged ones. This review mainly aims at informing researchers and modellers interested in numerical modelling of dam-break flow over real-world topography on recent advances and developments in three-dimensional hydrodynamic models so that they can better direct their future research. Practitioners can find in this review an overview of available three-dimensional codes (research, commercial, freeware, and open-source) and indications for choosing the most suitable numerical method for the application of interest. [ABSTRACT FROM AUTHOR]

This study aims to develop a robust sediment transport model focusing on the vertical two-dimensional water–sediment two-phase flow in which sediments are constantly interacting, hitting each other, gradually becoming smoother and smaller, and accumulating when velocities decrease. The grid-based models currently available can be cumbersome when dealing with phenomena that require replication of this water–sediment interface. Therefore, a two-dimensional water–sediment two-phase flow model based on Smoothed Particle Hydrodynamics (SPH) is established in the macroscopic scale to simulate a large amount of sediment accumulation and propagation typical of a landslide caused by a dam break. In this study, water and sediments are treated as two kinds of fluids with different densities and viscosities to accurately simulate the flow structure, the sediment transport, and the water–sediment interaction process. The interaction model developed treats the interface of the two phases within a unified framework. The model developed was then tested against three applications, and the results obtained confirmed its accuracy in correctly replicating the movement of the sediment phase. The preliminary results obtained can be helpful in providing further insights into the mixing of water and sediments and their propagation following a dam break and the consequent wave profile generated. [ABSTRACT FROM AUTHOR]

The main goal of this study is to identify the probability distribution of earthfill dam breach parameters using a dam failures database (3861 observations). This work looks to fill the lack of studies observed, using an extensive database instead of empirical models, plausible values, or small databases. It is, expected that this will contribute to the development of probabilistic dam breach inundation maps instead of deterministic mapping. Four parameters were selected: (i) side slope, (ii) height, (iii) width, and (iv) formation time. To identify the best‐fit distributions, a correlation analysis was performed and a comparative analysis was undertaken by groups related to dam and failure properties such as dam type, material erodibility, magnitude, failure mode, and others. These steps defined samples with 33–311 observations. The results demonstrate that dam breach parameters might be considered independent of each other and are affected by factors such as side slope by failure mode and bottom width by dam shape. The probabilistic case study indicated that deterministic dam breach models predominantly produce conservative results of breach peak outflow. [ABSTRACT FROM AUTHOR]

Abstract The main goal of this study is to identify the probability distribution of earthfill dam breach parameters using a dam failures database (3861 observations). This work looks to fill the lack of studies observed, using an extensive database instead of empirical models, plausible values, or small databases. It is, expected that this will contribute to the development of probabilistic dam breach inundation maps instead of deterministic mapping. Four parameters were selected: (i) side slope, (ii) height, (iii) width, and (iv) formation time. To identify the best‐fit distributions, a correlation analysis was performed and a comparative analysis was undertaken by groups related to dam and failure properties such as dam type, material erodibility, magnitude, failure mode, and others. These steps defined samples with 33–311 observations. The results demonstrate that dam breach parameters might be considered independent of each other and are affected by factors such as side slope by failure mode and bottom width by dam shape. The probabilistic case study indicated that deterministic dam breach models predominantly produce conservative results of breach peak outflow.

The first part of the research reported here consists of an experimental campaign to study the scouring of a granular bed (glass beads, sand) induced by a dam break in an open channel. Two configurations are considered: with and without cylinders. In the second part of this study, the volume of fluid method coupled with the shear stress transport turbulent model and the lagrangian particle tracking method is used to simulate the local scour processes. The four-way coupling is realized by considering the drag force and collisions between particles. Using a vortex map and velocity profiles, the flow dynamics and scour pattern can be studied. The current research also focuses on the profiles of the erodible particle bed and the sediment transport rate to study the effects of a cylinder on local scour. The presence of the cylinder increases the experimental erosion depth by up to 42%. It was found that for relatively close particle diameters (2 and 3 mm), a granular bed with larger porosity (larger diameter) erodes the most. Experimentally and numerically it was found that the center of the granular bed experiences more erosion compared to the channel sides. In the last part of the research, comparisons between the numerical results and the experimental data allowed risk areas to be identified and the roles of porosity, sediment density, and flow dynamics on erosion to be identified. [ABSTRACT FROM AUTHOR]