Breach Hydrograph Research Articles

Glacial lake outburst flood (GLOF) modeling of Tsho Rolpa glacial lake, Nepal

Abstract. In recent decades, the Tsho Rolpa glacial lake has witnessed a significant increase in its surface area. Situated in the Eastern Himalayas at an elevation of 4552 m a.s.l. (meters above sea level), this lake has drawn attention due to the potential risks of glacial lake outburst floods (GLOFs). To comprehensively study and prepare for future GLOF events from Tsho Rolpa, advanced modeling techniques were employed, utilizing the National Weather Service BREACH (NWS-BREACH) and Hydrologic Engineering Center's River Analysis System (HEC-RAS) models. The assessment included the evaluation of dam breach scenarios, especially 20 and 40 m breaches, using the NWS-BREACH model to estimate breach hydrographs. This analysis revealed peak flow rates ranging from 8198 to 26 662 m3 s−1 for the respective breaching scenarios. Additionally, considering a change in the lake area over 20 to 40 years, the peak flow ranged from 8226 to 10 662 m3 s−1 for the 20 m breach scenario. The peak flow estimates obtained from NWS-BREACH were subsequently integrated into the HEC-RAS model to simulate peak discharge and flood heights at varying distances downstream of the lake outlet. To understand the consequences of a GLOF, the impact on downstream areas was assessed through flood inundation maps, and precautionary measures are recommended.

Model tests and numerical simulation of overtopping-induced breach process of the asphalt concrete core dam

Although asphalt concrete core dams have been widely constructed, the mechanism of overtopping-induced dam breaches during catastrophic floods remains unclear, especially concerning the structural failure process of the core wall. This study utilizes a flume model test system to examine the overtopping-induced breach process of an asphalt concrete core dam based on the Sheyuegou Dam breach case in Xinjiang, China. The model tests showed the continuous erosion of dam shell material and structural failures of the core wall during dam breaching, highlighting the significant impact of the erosion-resistant asphalt concrete core wall on the dam breach process. The overtopping breach process of an asphalt concrete core wall dam can be divided into three stages: the asphalt concrete core wall is gradually exposed by backward erosion of the dam shell material until the first structural failure occurs; one or multiple structural failures of the core wall happen due to breach enlargement by continuous erosion of dam shell material until peak breach flow is reached; multiple structural failures of the core wall take place as the breach in the dam shell deepens and widens until breach morphology stabilizes. A numerical model is developed to simulate the overtopping-induced breach process of the asphalt concrete core dam based on the breach model tests. This model utilizes a soil erosion formula to estimate the dam shell material's erosion rate and calculate the exposed length of the asphalt concrete core wall. In addition, the moment balance method is employed to determine the overturning moment and length at each structural failure and the overturning instances of the exposed core wall due to hydrodynamic force and soil pressure. A notable feature of the numerical model is its ability to depict the coupled effects of soil erosion and structural failures of the asphalt concrete core wall during dam breaching. This numerical model is applied to a back analysis of the Sheyuegou dam breach process. The comparison between measured and calculated results indicated that the breach hydrograph and breach evolution process accurately represent the actual breach process of the Sheyuegou dam, with the relative errors of essential dam breaching parameters remaining within ±25 %. Sensitivity analysis showed that the thickness variation of the asphalt concrete core wall significantly influences the dam breach process, with the order of impact on critical breaching parameters being time to peak, final breach size, and peak breach flow. The results provide valuable insights into the simulation of the overtopping failure process of asphalt concrete core dams.

Dam breach analysis of Kibimba Dam in Uganda using HEC-RAS and HEC-GeoRAS

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.

Main channel width effects on overtopping-induced non-cohesive fluvial dike breaching

Laboratory experiments were conducted on the breaching of homogeneous non-cohesive sandy fluvial dikes induced by flow overtopping. Tests were conducted using a main channel, an erodible lateral dike and a floodplain. The main channel width and Froude number prior to overtopping were systematically varied. Breach discharge was deduced from water level measurements and mass conservation. High-resolution 3D reconstructions of the evolving breach geometry were obtained using a non-intrusive laser profilometry technique. The main channel width and Froude number show significant influence on the breach expansion and hydrograph. Breach hydrographs are divided into three types, depending on the Froude number and a non-dimensional main channel width. An adapted fluvial dike breaching model based on the concept of “effective breach width” is proposed. Using the laboratory data, the computed breach discharge is found extremely satisfactory, although the breach downstream expansion is not accurately reproduced by the model.

Glacial lake outburst flood risk assessment using remote sensing and hydrodynamic modeling: a case study of Satluj basin, Western Himalayas, India.

Glacier-associated hazards are becoming a common and serious challenge to the high mountainous regions of the world. Glacial lake outburst floods (GLOFs) are one of the most serious unanticipated glacier hazards, with the potential to release a huge amount of water and debris in a short span of time, resulting in the loss of lives, property, and severe damage to downstream valleys. The present study used multi-temporal Landsat and Google earth imageries to analyze the spatio-temporal dynamism of the selected glacial lake (moraine-dammed) in the Satluj basin of Western Himalayas. Furthermore, GLOF susceptibility of the lake was assessed using a multi-criteria decision-based method. The results show that the lake area has increased from 0.11 to 0.26 km2 over the past 28years from 1990 to 2018. The susceptibility index value for the lake was calculated as 0.75, which indicates that the lake is highly susceptible to the GLOF. The depth and volume of the lake were estimated to be 16m and 57 × 105 m3, respectively, using an empirical formula. HEC-RAS, HECGeo-RAS, and Arc-GIS software were utilized in this study to perform unsteady flow analysis and to determine the GLOF impact on the downstream area. The worst-caseGLOF scenario(breach width of 75m) was revealed during an overtopping failure of the moraine dam, resulted in a peak discharge of 4060 m3/s and releasing a total watervolume of 57 × 105 m3. The breach hydrograph has been routed to calculate the spatial and temporal distribution of peak flood, inundation depth, velocity, water surface elevation, and flood peak arrival time along the river channel. The analysis further reveals that the routed flood waves reach the nearest settlement, i.e., Rajpur town, situated at a distance of 102km in the downstream valley of the lake at 6h after the beginning of the lake breach event with a peak discharge/flood of 1757 m3/s and maximum flow velocity of 1.5m/s. With the ongoing climate warming and glacier retreat, moraine-dammed lakes are becoming more hazardous and thus increasing the total threat. Therefore, it is mandatory to monitor and assess such lakes at regular intervals of time to lessen the disastrous impacts of GLOFs on the livelihood and infrastructure in the downstream valleys. The findings of this study will aid in the creation of risk management plans, preparatory tactics, and risk reduction techniques for GLOF hazards in the region.

Numerical Investigation into the Plane Breach Process of Cohesionless Dikes Induced by Overtopping

Dikes made up of erodible geotechnical materials are easily broken by overtopping flow, which poses a serious threat to human lives and properties in protected areas. In this study, the plane breach of cohesionless dikes induced by overtopping was simulated via the discrete-element method coupled with computational fluid dynamics. A method of dynamically setting the permeabilities of fluid computation cells was proposed to implement the variation of the free surface of overtopping flow. The numerical model was validated using published experimental results, and the sidewall effect was also analyzed. The influence of three important factors on the dike breach process was investigated, namely, the inflow discharge per unit width, convergence area length, and particle size. The results suggest that the inflow discharge per unit width has little influence on the breach process within a range, outside which it has a promoting effect. The normalized peak breach discharge increases linearly with the increase in convergence area length. When the relative convergence area length increases to 4, the descent speeds of the convergence water level and the dike height reach a balance for a long time during the peak stage of the breach hydrograph. For the dikes consisting of uniform cohesionless particles, the breach process is linearly related to the particle size without regard to the seepage inside the dike. The findings of this study provide new insights into the mechanism of dike breach.

Detailed numerical modeling for breach hydrograph and morphology evolution during landslide dam breaching

Detailed numerical modeling for breach hydrograph and morphology evolution during landslide dam breaching

Investigation of the overtopping-induced breach of tailings dams

Using a 400 g-ton geotechnical centrifuge, a centrifugal model test system was developed to investigate the overtopping-induced breach process of tailings dams. According to abrupt changes in the erosional characteristics and breach morphological evolution, the breach processes of tailings dams could be divided into three stages, namely, the initial, acceleration, and stable stages. The breach mechanisms mainly consisted of backward erosion during the initial stage, followed by rapid downcutting and widening accompanied by intermittent lateral expansion caused by the collapse of breach-side slopes until the rebalancing of the breach channel occurred. Furthermore, a detailed physical hydrodynamic model was used to simulate dam breaching. The Reynolds-averaged Navier–Stokes (RANS) equations combined with the renormalization group (RNG) k-ε turbulence model were adopted to calculate the complex hydrodynamic conditions. In addition, the model considered the sediment transport equations for bedload and suspended load, as well as the breach-side slope sliding. The governing equations of the model were computed using the finite volume method on a rectangular grid. The calculated breach hydrograph and dynamic breach evolution were consistent with the observations made using the centrifugal tests. This study can provide a scientific reference to estimate the failure process of tailings dams.

Dam Break Analysis using HEC-RAS: A Case Study of Karjan Dam

A dam is a structure constructed across river which stores water and supplies water for various purposes. Though the dams have many benefits, there is always a threat of dam break floods which are devastating in nature. Hence it becomes essential to analyze and simulate dam failure scenarios to understand the severity of dam break flood and identify areas under threat which helps in land use planning and developing emergency response plans. This study attempts to carry out dam break/breach analysis for the Karjan dam using a two-dimensional hydraulic model called Hydraulic Engineering Center’s River Analysis System (HEC-RAS). RAS-Mapper tool is used to extract river geometry data from the Cartosat-1 digital elevation model (DEM) and to generate the inundation map to identify the areas affected. The study involves the prediction of breach parameters, breach flood hydrograph, peak flow, flood arrival time, and generation of inundation maps. The dam break model is simulated for unsteady flow conditions using Probable Maximum Flood (PMF) corresponding to different failure scenarios. HEC-RAS tool is utilized to determine the breach outflow hydrograph and hydraulic conditions at critical downstream locations. The outcome will assist the local government in making proper planning and development decisions. Key Words: Arc-GIS, Dam break analysis, Karjan dam, Flood Inundation, HEC-RAS

What Controls the Magnitude and the Shape of Landslide Dam-Breaching Flood Hydrograph? Case Studies of Emergent Forecasts for Outburst Floods of Jiala and Baige Barrier Lakes

Outburst floods released by failing barrier dams are likely to be catastrophic, posing high risk to downstream areas. However, emergent forecasting of the breaching process is still challenging due to the complex mechanisms as well as the lack of adequate data. During October and November 2018, four tremendous barrier lakes formed and breached on the Jinsha River and the Yarlung Zangbo River, China. In this paper, we present numerical simulations for three of these events (October 17 and October 29 at Jiala Village, Yarlung Zangbo; November 3 at Baige Village, Jinsha River), and investigate what factors control the magnitude and shape of the hydrograph of the outburst flood. A physically-based dam-breach model was established for the prediction. We first specified the model parameters based on the aerial images, DEM data and hydrological measurements during the emergency treatment. With these parameters, the model can successfully predict the breaching process of the two barrier dams in the Yarlung Zangpo, but underpredict the peak discharge of the outburst flood in the Jinsha River. The outburst flood in the Jinsha River, however, can be well-reproduced with refined information on dam height and grain size distribution. Moreover, both field data and our numerical simulation showed that the magnitude and shape of the outburst flood hydrograph can be affected by the dam morphology and the composition of dam material. Two patterns of outburst flood hydrographs with different symmetry characteristics were identified using statistical analysis. The approximately symmetrical breach hydrograph of the “November 3” Baige barrier lake could be partly attributed to the relatively fine grain size distribution of the dam material.

2D-HEC-RAS Modeling of Flood Wave Propagation in a Semi-Arid Area Due to Dam Overtopping Failure

Dam overtopping failure and the resulting floods are hazardous events that highly impact the inundated areas and are less predictable. The simulation of the dam breach failure and the flood wave propagation is necessary for assessing flood hazards to provide precautions. In the present study, a two-dimensional HEC-RAS model was used to simulate the flood wave resulting from the hypothetical failure of Al-Udhaim Dam on Al-Udhaim River, Iraq, and the propagation of the resulting dam-break wave along 100 km downstream the dam site for the overtopping scenario. The main objective is to analyze the propagation of the flood wave so that the failure risk on dam downstream areas can be assessed and emergency plans may be provided. The methodology consisted of two sub-models: the first is the dam breach failure model for deriving the breach hydrograph, and the second is the hydrodynamic model for propagating the flood wave downstream of the dam. The breach hydrograph is used as an upstream boundary condition to derive the flood impact in the downstream reach of Al- Udhaim River. The flood inundation maps were visualized in RAS-Mapper in terms of water surface elevation, water depth, flow velocity, and flood arrival time. The maximum recorded values were: 105 m (a.m.s.l.), 18 m, 5.5 m/s, and, respectively. The flow velocity decreased from upstream to downstream of the terrain, which means less risk of erosion in the far reaches downstream of the study area. The inundation maps indicated that the water depth and flow velocity were categorized as Catastrophic limits on the terrain's area. The results offer a way to predict flood extent and showed that the impact of a potential dam break at Al-Udhiam Dam will be serious, therefore, suitable management is needed to overcome this risk. Moreover, the maps produced by this study are useful for developing plans for sustainable flood management. Doi: 10.28991/cej-2021-03091739 Full Text: PDF

Overtopping‐Induced Failure of Non–Cohesive Homogeneous Fluvial Dikes: Effect of Dike Geometry on Breach Discharge and Widening

AbstractLaboratory experiments were conducted to assess the influence of dike geometry on the breaching of non‐cohesive homogeneous fluvial dikes. Both the channel‐side and floodplain‐side dike slopes and the crest length were varied systematically. The time‐evolution of the breach discharge and breach width was monitored. Dikes having a larger volume per unit width lead to a more gradual increase in breach discharge and in breach width during the first stage of breach expansion (i.e., phase of rapid erosion). In contrast, the later stage of gradual breach widening is less influenced by the dike geometry. The breach hydrographs were observed to follow three distinct patterns, which are explained based on the relative magnitude of two characteristic time scales and of a normalized form of the dike unit volume.

Effect of vertical velocity profile approximations on estimates of dam breach discharge using surface velocities

AbstractIn order to investigate the relationship between water surface velocity and breach hydrograph, a series of dam breach experiments with a generalised landslide dam were conducted in an open channel of 50 m × 4 m × 2 m. The large‐scale particle image velocimetry (LSPIV) technique was applied to measure the time history of water surface velocity during the dam breach process, and the hydrography was obtained by integrating the surface velocity along the water depth. The influence of different vertical velocity profile approximation and suspended sediment concentration on the peak breach discharge were analysed and discussed. The results showed that the water depth over the breach crest can be described as a function of water surface velocity using . A simple formula based on surface velocity and breach width for the estimation of breach discharge was further proposed and verified.

Effects of Grain Size Distribution on Landslide Dam Breaching—Insights From Recent Cases in China

Landslide dams are common geological features in mountainous areas, which may have serious consequences due to sudden breaching of the dam. An effective emergency response requires rapid and accurate forecasts regarding the landslide dam breach process. However, most existing models use physical, mechanical, and erosion properties of the mean or characteristic grain sizes to represent the landslide deposits. The grain size distribution and variations in soil erodibility with the depth in the landslide dam are not considered, resulting in an incorrect estimation of the breach flow hydrograph. In this paper, a simplified landslide dam classification is presented based on the formation mechanism and grain size distribution of landslide dams. Additionally, the influences of grain size distribution on the residual dam height and breach process of landslide dams are analyzed. This paper proposes a numerical method to rapidly obtain the breach hydrographs and breach morphology evolution of landslide dams. The new method can quickly classify landslide dams according to geological survey data and predict the landslide dam breach process. Three types of representative landslide dams in China are simulated to validate the proposed method. The breach flow discharge is significantly affected by spillway excavation. This contribution can provide rapid prediction of the landslide dam breach process and can be used for the emergency response planning before dam breaching.

Tailings Dam Breach Analysis: A Review of Methods, Practices, and Uncertainties

Recent catastrophic failures of tailings storage facilities have highlighted the critical roles that dam engineers can play in ensuring public safety, and have motivated the mine waste industry to assess and improve the practice of tailings dam breach analysis (TDBAs). As industry moves towards a standard of no catastrophic failures, it is critical that practitioners, owners, and operators have a unified understanding when conducting TDBA, in order to provide a high level of confidence within communities and environments surrounding operational or closed facilities. Currently, uncertainties exist surrounding the industry’s standard practice in conducting appropriate TDBA. This paper provides a summary of the currently available approaches and models for TDBA and when it is appropriate to use a particular method. A critical review of key challenges of TDBA (release volume estimate, hydrograph development, and routing the breach hydrograph downstream) is also provided. This paper aims to be a thorough summary of what is known about TDBA and a reference source for engineers and researchers.

Prediction of the overtopping-induced breach process of the landslide dam

Timely prediction of a landslide dam breach is particularly important for assessments of expected disaster consequences and to plan emergency responses. However, due to the complex composition and specific geotechnical properties of the landslide dam material, such a prediction is challenging. In this study, geological survey results and landslide dam breach mechanisms were used to develop a numerical model for overtopping-induced landslide dam breaches, considering variation of soil erodibility with depth. The model included a hydrodynamic process module, a soil erosion module, and a breach evolution module. Moreover, a time step iteration algorithm was adopted to simulate the soil and water coupling process during dam breach. A comparison of calculated and measured breach hydrographs, variations of dammed lake water level, breach sizes, as well as two other typical models were used to validate the rationality of the numerical model, by considering the Baige landslide breach case of November 3, 2018 with detailed measured data. Parameter sensitivity analysis showed that the soil erodibility coefficient exerted an important influence on the breach process, while soil critical shear stress had a relatively small influence (which remained within ±15% for output parameters when it was multiplied by 0.5, 1.0, and 2.0). Furthermore, spillway excavation was found to significantly reduce the peak breach flow if the dammed lake has a large storage capacity, thus identifying it as an effective measure for disaster mitigation.

Dam Break Analysis of Temenggor Dam Using HEC-RAS

Embankment dam is commonly built in Malaysia as it provides benefits to the local population, mainly agricultural activity and flood control measures. However, its massive potential energy reservoir would impose risk of sudden containment breach leading to loss of life and property at inhabited downstream area. This paper deemed to provide a dam break analysis of Temenggor Dam to generate breach hydrograph and inundation map as a result of dam break event under piping and overtopping failure. The Hydrologic Engineering Center’s River Analysis System (HEC-RAS) is capable to model 1-dimensional (1-D) and 2-dimensional (2-D) dam failure event by utilizing hydrological and terrain information generating unsteady-state flow simulation of the dam breach. The process for gathering and preparing data, estimating breach parameters, creating one dimensional and two-dimensional unsteady-flow model in HEC-RAS, performing a dam failure analysis for two dam failure scenarios and mapping the flood propagation are outlined in this paper. From 1-D analysis, it is found that the breach flow of Temenggor Dam failure can achieve 281,588 m3/s for piping failure and 331,030 m3/s for overtopping failure. 2-D analysis’ breach flow attained 268,341 m3/s and 328,869 m3/s for piping and overtopping failure, respectively. Furthermore, the expected arrival time of flood wave at selected locations also presented in this paper. 1-D model produced comparable breach hydrograph result of Temenggor Dam against 2-D model with the advantage of significantly shorter simulation time requirement. However, 2-D model able to generate inundation map due to dam failure in wider area which can provide insight of flood hazard risk level and contribution for emergency action plan development.

Back analysis of the breach flood of the “11.03” Baige barrier lake at the Upper Jinsha River

<p indent="0mm">A second landslide took place in China on 3 November 2018 at the provincial boundary between Sichuan and Tibet. This landslide blocked the reach of the Jinsha River and created a barrier lake with a <sc>5.79×10⁸ m³</sc> storage reservoir and a <sc>31000 m³/s</sc> peak breach flood. To reveal the beach formation process of the barrier lake, this paper gathers the lake’s geography and hydrology information and conducts material property tests including gradation, soil erosion, and shear strength experiments. Back analyzes on the dam breach hydrograph were conducted in tandem with the parametric sensitivity studies based on the tested knowledge using the DB-IWHR and DB-NHRI respectively. The measured results show that the theory, methods, and tools currently available for dam beach analysis can accurately predict the flood of a dam breach. Among the feedback regarding the hydraulic and geotechnical parameters, only those related to the relationship between the rate of erosion and shear stress are more important to the measured peak flow. The results from this study may provide a reference in the event of an emergency to other barrier lakes.

Glacial Lakes Outburst Floods (GLOFs) modelling of Thulagi and Lower Barun Glacial Lakes of Nepalese Himalaya

Melting of glaciers is one of the major effects of recent atmospheric warming in the Himalayas which results in the development of supraglacial lakes that coalesce to form proglacial lakes. Large volumes of water in these lakes are considered dangerous due to its unstable surrounding geomorphology. Most of the proglacial lakes are moraine-dammed and breaching of such moraine due to some triggering events may give rise to rapid release of water and sediment, often termed as Glacial Lake Outburst Floods (GLOFs). GLOFs represent catastrophic phenomenon of the Himalaya and pose a risk to downstream communities and infrastructure. Several GLOF events have been recorded in Nepal in the past few years. Since 1990s, the lake area of Thulagi has increased from 0.72 to 0.94 km2 while that of Lower Barun has increased from 0.64 to 2 km2 and both glacial lakes rank No. I in the Potentially Dangerous Glacial Lakes (PDGLs) in Nepal. In this study, NWS-BREACH and HEC-RAS model are used to access the impact of GLOF on downstream areas. Different dam breach scenarios of 5, 10, 15 and 20 m is evaluated by NWS-BREACH model to estimate the breach hydrograph. The peak flow at the time of breach ranges from 1400 to 5400 m3/s for Thulagi and 2600 to 7900 m3/s for Lower Barun in low and high breach scenarios respectively. The peak flow estimated from NWS-BREACH is used for the flood routing in HEC-RAS to simulate peak discharge and flood height at different distances in the downstream from the lake outlet. The impact on downstream regions of the two glacial lakes is then evaluated by flood inundation map to access the land exposed to GLOF. Nepal consists of large number of glacial lakes and only a few have been studied. Furthermore, detail field survey of the lakes and downstream areas need to be incorporated for better prediction of GLOF events.

Breaches of the Baige Barrier Lake: Emergency response and dam breach flood

This paper documents the emergency response to the breaches of the Baige Barrier Lake. The lake was successively formed by landslides that occurred on October 10th and November 3rd, 2018 at the provincial border between Sichuan and Tibet in China. The barrier lake created by the “10.10” landslide breached on October 12th and triggered a flood with a peak discharge around 10000 m3/s. The residual landslide barrier was enhanced by a second landslide on November 3rd, resulting in a higher barrier with larger flood potential. An overflow channel was excavated in the crest of the barrier to prompt the breach to be triggered at a lower water level. The second breach happened on November 12th with a measured peak discharge of 31000 m3/s. Nearly 75000 people were evacuated before the two breaches. In order to prevent the downstream dams from possible over-topping, nearly 3.27 × 108 m3 of the stored volume was released from the Liyuan reservoir 688 km downstream of Baige Barrier Lake. This paper presents the measured hydrographs and the back-analysis results for the “11.03” barrier lake. It is shown that the modern models of dam breach hydraulics can reasonably reproduce the barrier breach hydrographs; however, further studies are needed to define the key parameters which highly influence the calculated results. Knowledge acquired during the emergency response to the case can be shared with experts working on breaches of embankment dams and can be referenced to promote both the theory study and the engineering practice to mitigate the potential risks caused by this type of catastrophic events.