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Embankment dam breach parameters revisited
Abstract
The extent of flooding and travel time of a flood wave that would result from the failure of a dam need to be predicted to establish needed spillway capacities and to prepare emergency action plans that would be used in the event of an actual dam failure. Data generated from 63 embankment dam failures were assembled to evaluate breach formation model parameters. Basing from these data, empirical models of breach formation were evaluated and prediction methods for the height, average width, side slope ratio, and formation time of the ultimate breach were developed. Results of the study are intended to help improve the accuracy of numerical simulations of dam-break flood waves.
... Ongdas et al. (2020) [6] focused on identifying the inundation areas during flooding in a pilot project on the River Yesil by adopting the hydrodynamic model within 2DHEC-RAS. Numerous flood scenarios were implemented with multi-cell sizes (25,50, and 75 m). The outcomes noted indicate that there are no significant changes in model performance. ...
... Figure 5 describes these criteria [24]. Several empirical equations were utilized to estimate these parameters; among them, the Froehlich 2008 equation is stated to be the most suitable for predicting the breach parameters [25]. These equations are: ...
... The resulting top width of the breach was determined to be 477 meters, with a full breach occurring over a duration of 6.27 hours. According to Brunner [25], the side slope of the breach for piping failure is (0.7:1). Figure 11 illustrates the formed breach in the Mosul dam. The simulation revealed a widespread flood flow discharge extending up to 17 km (Aski-Mosul) within a 6-hour period, as described in Figures 13-a to 13-c. ...
In recent years, there has been a serious request for innovative, accurate approaches to be determined and controlled for dam failures. The present study aims to explore and evaluate the flood wave parameters that result from a dam break due to piping failure occurring in the body of the dam and routing the flood waves. Mosul Dam, which lies in the north of Iraq, and a reach of the Tigris River downstream the dam to Samarra Barrage at about 470 km are selected as a case study. A two-dimensional Hydrologic Engineering Center River Analysis System (2D HEC-RAS) and the Geographic Information System (GIS) have been supposed to be suitable for development calculations of the flood wave parameters based on the Digital Elevation Model (DEM) and land cover satellite images that enhance the calculations. The reservoir and two-dimensional flow area are delineated and incorporated with DEM. Manning`s coefficient for the whole area has been extracted according to the Land Cover satellite image, which showed that its value ranges between 0.025 to 0.037 with a correlation coefficient R 2 equal to 0.845 and 0.801 for the calibration and validation processes, respectively. The results of the scenario display a substantial performance of the maps produced from the model that represented the depth, velocity, and water surface elevation. All the maximum values of dam break parameters lie near the dam body and slightly decrease downstream. It is pre-eminent that the 2D HEC-RAS model is appropriate for analyzing and simulating the occurrence of dam breaches by visualizing the distribution of flood wave depth and velocities in two dimensions. Hence, the clear improvement in producing maps, which monitor the spread of hydrodynamic waves, gives an indication of risk areas that are threatened by inundation and aids in the formulation of emergency plans.
... Ongdas et al. (2020) [6] focused on identifying the inundation areas during flooding in a pilot project on the River Yesil by adopting the hydrodynamic model within 2DHEC-RAS. Numerous flood scenarios were implemented with multi-cell sizes (25,50, and 75 m). The outcomes noted indicate that there are no significant changes in model performance. ...
... Figure 5 describes these criteria [24]. Several empirical equations were utilized to estimate these parameters; among them, the Froehlich 2008 equation is stated to be the most suitable for predicting the breach parameters [25]. These equations are: ...
... The resulting top width of the breach was determined to be 477 meters, with a full breach occurring over a duration of 6.27 hours. According to Brunner [25], the side slope of the breach for piping failure is (0.7:1). Figure 11 illustrates the formed breach in the Mosul dam. The simulation revealed a widespread flood flow discharge extending up to 17 km (Aski-Mosul) within a 6-hour period, as described in Figures 13-a to 13-c. ...
In recent years, there has been a serious request for innovative, accurate approaches to be determined and controlled for dam failures. The present study aims to explore and evaluate the flood wave parameters that result from a dam break due to piping failure occurring in the body of the dam and routing the flood waves. Mosul Dam, which lies in the north of Iraq, and a reach of the Tigris River downstream the dam to Samarra Barrage at about 470 km are selected as a case study. A two-dimensional Hydrologic Engineering Center River Analysis System (2D HEC-RAS) and the Geographic Information System (GIS) have been supposed to be suitable for development calculations of the flood wave parameters based on the Digital Elevation Model (DEM) and land cover satellite images that enhance the calculations. The reservoir and two-dimensional flow area are delineated and incorporated with DEM. Manning`s coefficient for the whole area has been extracted according to the Land Cover satellite image, which showed that its value ranges between 0.025 to 0.037 with a correlation coefficient R 2 equal to 0.845 and 0.801 for the calibration and validation processes, respectively. The results of the scenario display a substantial performance of the maps produced from the model that represented the depth, velocity, and water surface elevation. All the maximum values of dam break parameters lie near the dam body and slightly decrease downstream. It is pre-eminent that the 2D HEC-RAS model is appropriate for analyzing and simulating the occurrence of dam breaches by visualizing the distribution of flood wave depth and velocities in two dimensions. Hence, the clear improvement in producing maps, which monitor the spread of hydrodynamic waves, gives an indication of risk areas that are threatened by inundation and aids in the formulation of emergency plans.
... Similarly, the dam breaks parameters like breach formation time (T f ), width (B w ), and side slopes (H: V)were calculated using the empirical relationship (Equations 2 and 3) developed by Froehlich (1995) as illustrated below: ...
... Therefore, we used an empirical relationship to determine volume on the same scale. Similarly, the breach parameters in our study were computed from the relationship given by Froehlich (1995). Hence, the peak discharge estimated for different breach cases depends on parameters like width, height, side slopes, and formation time. ...
Due 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 km 2 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.
... Unfortunately, the breach width could not be characterized for the protected models since the whole width of the materials were washed away downstream, indicating that the breach width exceeds the flume width. However, for the unprotected model (U4), except for the equation from Froehlich (1995a), all the parametric equations provide results quite close to the reality of the obtained breach (Table 6). Still, none of them managed to predict the exact breach width. ...
... Dimensions of a final trapezoidal dam breach, modified fromFroehlich (1995a). ...
Overtopping of the crest is the main cause of embankment dam failure and because of the potentially catastrophic effects of a dam breakage, dam safety must be carefully considered. Especially, the demands from dam safety regulations and guidelines are increasing to upgrade the resistance of rockfill dams against overtopping and leakages. Indeed, rockfill dams are made from over 50% of coarse-grained material and account for 13% of the entire world’s existing dams. The breaching of embankments must be assessed in the risk evaluation of hazard studies. Usually, that assessment is carried out with statistically derived parametric equations, based on historical dam failure cases, which are known as breach models. However, important parameters such as material properties are not taken into consideration so meaningful uncertainties are associated with the results from these breach models. In this research work, carried out at the hydraulic laboratory of the Norwegian University of Science and Technology, rockfill dam experimental models (1:10 scale models) are exposed to overtopping events with increasing discharge levels until complete failure. Three different configurations of dams are considered: i) unprotected dam with compacted rockfill shell material, ii) protected dam with filter and placed riprap layer, iii) protected dam with filter and dumped riprap layer. Using dynamic photogrammetric methods to produce 3D models from these experimental dams, an extensive dataset on breach development is obtained to quantify the accuracy of breach parameters predicted by different breach models available in the literature. Also, the benefits of using placed and dumped riprap protective layers instead of simple unprotected dam shells are discussed and put into perspective with the observed failure mechanisms.
... The compilation of dam failure databases prior to 1998 (e.g. MacDonald andLangridge-Monopolis, 1984;Costa, 1985;Froehlich, 1987Froehlich, , 1995aFroehlich, , 1995bSingh and Scarlatos, 1988) are not explicitly listed in the database file provided because the most recent dam failure databases have been built on and added to these earlier databases (e.g. Wahl (1998)). ...
Numerical models have been developed over the years to simulate the variety of dam failures, evaluate the flows and flood, estimate and quantify downstream consequences. However, as a result of the current determinist available models (especially for embankment dam failures, i.e. which only "mimic" the characteristics of the breach development), standard frameworks have been formulated using semi-empirical approaches. Indeed, most standard specifications thus remain intimately dependent on the published number of failure parameters (e.g. final breach dimensions, peak discharge, etc.). This technical paper expands the current available data collection of "detailed" dam failure cases. This data acquisition process has led to record a total of 3,861 cases of historical dam failures around the world. Technical description of the recorded data collection, and the lessons and learning concerning their compilation are also presented. This database and dataset description are provided in open access, at: https://doi.org/10.5683/SP2/E7Z09B. This Dataverse, hosted by Research Portal Dataverse and posted by Polytechnique Montreal, also facilitates future data acquisition and identification of dam incidents. Overall, this cutting-edge and evolutive database coupled with this technical paper allow to frame and to pave the way for data acquisition in the field of dam safety in the actual era of "Big Data".
Bernard-Garcia, M. Mahdi, T.-F. (2022) A WORLDWIDE DATABASE OF DAM FAILURE CASE STUDIES / UNE BASE DE DONNÉES MONDIALE DE CAS DE RUPTURES DE BARRAGE. 27th CONGRÈS DES GRANDS BARRAGES À MARSEILLE 2022. 2022 ICOLD/CIBG, Paris, France. Q105-R.46. p.99-100. DOI : 10.1201/9781003211808-92
Numerical models are used for detailed and site-specific tailings dam breach analyses (TDBAs) to estimate the downstream inundation and deposition resulting from a potential breach at a tailings dam. The results of TDBAs are key inputs into risk assessments, consequence classification, and emergency planning. This paper describes the research and development of a database of 12 tailings dam breach events with a specific focus on observations that are needed for numerical modelling, in conjunction with an assessment of existing dam breach conventions to improve consistency in reporting. The characteristics relevant to modelling include outflow volumes, breach processes, breach geometries, and runout observations local to the downstream area. This study and the new database shed light on the diversity of outflow materials, facility arrangements, breach processes, and downstream environments that affect the breach development and tailings runout. Familiarity with case studies is a crucial element of expert judgement for forward-analysis TDBAs, which this database supports. The database can also be used to define model inputs for back-analysis of additional tailings dam breach events, and simultaneously provides calibration or validation constraints with the runout observations. Continued review and critical assessments are needed to reduce uncertainties and to enhance case history data availability and quality in this database.
This study was, therefore, taken up to dam breach modeling and downstream flood inundation mapping. To achieve this objective, the software ArcGIS Version 10.4 extension program of HEC-GeoRAS Version 10 tool was used for HEC-RAS model development, to generate modeling reach and floodplain cross-sectional geometric data and for downstream inundation mapping and HEC-RAS Version 6.3.1 tool was used for subject dam break simulation and unsteady flood routing at downstream regions. Von Thun and Gillette regression equation was selected to estimate the breach parameter and the result shows that breach bottom width is 113 m, side slope 0.5H : 1V and breach development time is 0.85 hr for overtopping and bottom width is 111 m, and side slope 0.5H : 1V and breach development time is 0.83 hr for pipping. During analysis of flood routing the peak discharge at the dam site is 19,753.68 m3/s occurred at 4 hr for overtopping and 25,128.1 m3/s at time to peak 4 hr for pipping.
Unlike river floods, floods caused by dam breaks occur much more abruptly and at higher water velocities. The failure of a dam due to any reason can pose a significant threat to settlements in the downstream area due to the high volume of water in its reservoir. In this case study, 2D and 3D numerical failure simulations of Tuzluca Dam, to be built in the Igdir province of Turkey, was performed using the Flow3D Hydro software. The Shallow Water and Reynolds-Averaged Navier-Stokes (RANS) equations were used to simulate flood propagation. In the numerical models, RNG k-ε was chosen as the turbulence model. In the analyses carried out under different scenarios, it was observed that in both methods (2D and 3D), significant flood depths would occur in two downstream village settlements. Within the scope of the study, the mortality rates in different dam-break scenarios of the Tuzluca Dam were also investigated. It has been observed that the dam failure time and breach geometry have a significant impact on the flood propagation and the loss of life in settlements. Additionally, a dam-break experiment in literature dam-break experiment was numerically solved using the Flow3D Hydro software to validate the numerical model, and a satisfactory harmony was observed between the experimental results and the numerical models. Although the 3D analysis provided a more accurate representation of the experimental results, it took approximately 20 times longer to complete the dam failure simulation in the case study compared to the 2D model. As a result, it has been determined that for comprehensive studies such as those of dam failures, 2D analyses may be more practical, while for smaller-scale scenarios or situations requiring greater precision, 3D modelling is appropriate.
Dam failures have severe consequences on human life and property. In the case of an earth filled Kibimba Dam located in Eastern Uganda, the occurrence of a flood equal to or larger than the probable maximum food (PMF) could result in catastrophic economic losses including loss of human life. This study utilized the USACE Hydrologic Engineering Center's River Analysis System (HEC-RAS) and Hydrologic Engineering Center’s Geographic River Analysis System (HEC-GeoRAS) to analyze the potential dam break of Kibimba Dam, considering overtopping and piping failure scenarios. The results of the analysis revealed that the spillway of Kibimba Dam possesses sufficient capacity to safely discharge a flood resulting from a probable maximum flood peak of 400 m³/s. Therefore, the dam is not susceptible to breach under the overtopping failure mode. However, the dam failed under the piping failure mode. To assess the downstream impact of the dam break, the breach hydrographs resulting from piping failure were examined. Consequently, the study investigated the effects of flood propagation downstream of the dam. This resulted in varying inundation depths of up to 6 m and velocities ranging from 1.2 to 10 m/s. These findings highlight the devastating consequences of Kibimba Dam's failure, particularly affecting rice field plantations, infrastructure, and other economic activities in the downstream area. Therefore, the outcomes of this study are crucial for the development of Emergency Action Plans that incorporate dam breach and flood routing analyses specific to the affected downstream regions.
Giving the current growing international interest in hydroelectricity, this paper aims to put back in context the limits that still marred most of the actual standards related to the field of dam hydraulics safety and the challenges needed to be properly considered in this ever-changing world. As a result of the limits of knowledge in various fields (e.g. sediment transport, etc.) and the actual computational capacities (e.g. computer time calculation, etc.), most current standard frameworks (i.e. legislative or normative) have been formulated using empirical or semi-empirical approaches instead of physical approaches. Indeed, the "precision"/"accuracy" of these current standard specifications remains statistically intimately linked to the amount of historical dam failure case studies recording failure parameters (e.g. final breach dimensions (breach depth, top width, bottom width, etc.), breach formation time, etc.). Regarding the small number of historical dam failure case studies used to define most of the current standard specifications, it is not only necessary to expand the current small data collection of "detailed" historical dam failure cases available in the literature but, moreover, to provide methods to facilitate their record, publication and sharing. To provide "useful" and "efficient" results for the dam industry (i.e. dam owners, etc.), the authors have strived to obtain new knowledge to improve dam hydraulics safety frameworks. In this paper is thus presented (1) an overview of 75 historical dam failure compilations, which have also led the authors to provide (2) a method to access the believed largest dam failure database recorded to date. In summary, in this paper is briefly described, in chronological order, a technical review of 75 historical dam failure compilations, which put back in context the evolution of the previous 88 years of historical dam failure records, publications and compilations encountered by various authors around the world. Leading to the believed largest worldwide dam failure compilation recorded to date (Bernard-Garcia and Mahdi, 2020), a method to access this database is provided for open access, under a CC0 License, at this following link : https://doi.org/10.5683/SP2/E7Z09B. This DOI is linked to a Dataverse hosted by Scholars Portal Dataverse and deposit by Polytechnique Montreal, which ensures access to any readers exempted from the authors' consent and, moreover, over the authors' lifetime. In practical terms, notice that this Dataverse allows any users to download the current (V1) database file available (i.e. including past and/or future "updated" versions over the years) and provides a method to deposit sets of "new" data and/or "revised" data. This "sharing platform" encourages a "more" collaborative and efficient method to record and access dam failure case studies, which is necessary to reach an international consensus on the reliability of the data recorded. As described in the technical track presented in this paper, notice that this database records a total of 3,861 historical dam failures around the world and has been assembled from a total of 196 references. The 75 compilations listed in this paper thus "only" represent a subset of the references obtained by authors during the investigation and compilation process encountered. Overall, this database records man-made dam failures (e.g. embankment dams, concrete dams, etc.), landslide dam failures, tailings dam failures and
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