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Many of Iraqi's high-hazard dams lack an Emergency Action Plan, which should include a flood inundation map to show which downstream areas would be flooded if the dams were to fail. This article presents the results of the simulation of a hypothetical 2D dam break for the 58 m high Khassa Chai dam in Kirkuk, Iraq, using HEC-RAS 2D 5.0.7 software. The Khassa Chai dam is situated 7.4 km north of Kirkuk. The simulations revealed that the dam-break flood will affect eight major bridges and the majority of Kirkuk city's metropolitan neighborhoods. Within an hour, the floodwaters will reach the city's center. The flood hazard map revealed that if the Khassa Chai dam fails, many people, vehicles, and structures will be at danger. The findings of this paper can be used to identify evacuation routes and refuge sites as well as build suitable warning systems in order to limit the risk for fatalities if the Khassa Chai dam fails. Moreover, as the effect of modeling bridges downstream of failed dams has not been explored yet, to the knowledge of the authors, eight bridges have been modeled. It was concluded that ignoring bridges in such a large dam break model will not affect the results significantly, which saves the time of data collection and model development. [ABSTRACT FROM AUTHOR]

Copyright of Mine Water & the Environment is the property of Springer Nature 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.)

In this paper the authors demonstrate that the simple power function gives a good description of the reservoir morphology. This function proved to be suitable for application on 97 reservoirs taken from three different geographical regions in the world. The power function is suitable to obtain an accurate fitting of the reservoir rating curve using a very limited number of surveyed elevations and volumes or areas. In particular it is shown that two points are enough for a good fitting of the curve, or even only one if volume and surface for an elevation close to normal or maximum pool are both available. The results obtained for dam breach calculations using this equation, have the same quality of those achieved using the elevation-volume table. The paper stresses that the exponent of power equation can be expressed by a formula which has a precise morphological meaning, as it represents the ratio between the volume which the reservoir would have if it were a cylinder with its base area and height equal to the respective maximum values of the actual reservoir, and the real volume of the reservoir. [ABSTRACT FROM AUTHOR]

An Ms 6.5 earthquake shocked the Ludian County, Yunnan Province, China, on 3 August 2014 and triggered the Hongshiyan landslide dam. The dam, with a height of 83 m and a lake capacity of 260 × 10 m, threatened more than 10,000 people. A unique feature of this landslide dam was that it formed between a man-made dam and a hydropower plant. An existing drainage tunnel connecting the lake and the hydropower plant became a natural drainage conduit for the landslide dam, which played an important role in the mitigation of the landslide dam risks. This paper reports a quantitative risk assessment for the Hongshiyan landslide dam considering both engineering and non-engineering risk mitigation measures. The risk assessment is divided into three stages according to the implementation of two engineering measures: construction of a diversion channel and excavation of a branch drainage tunnel. The dam breaching hydrographs, flood zones, population at risk, and likely fatalities in each of the three stages are analysed. The optimum evacuation strategy in each stage is also studied based on the principle of minimum total consequence. It is found that the diversion channel decreases the dam breaching peak discharge and the associated risks significantly. The branch drainage tunnel prevent the landslide dam from overtopping failure in non-flooded period; however, the landslide dam may fail by overtopping in a future flood if the inflow rate is larger than the outflow rate through the drainage tunnels, resulting in serious losses of lives and properties. The dam breaching risks in all the three stages could be largely reduced by the optimal evacuation decision, which shows that timely evacuation is vital to save life and properties. The study provides a scientific basis for decision making in landslide dam risk management. [ABSTRACT FROM AUTHOR]

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

This paper presents two Artificial Neural Network (ANN) based models for the prediction of peak outflow from breached embankment dams using two effective parameters including height and volume of water behind the dam at the time of failure. Estimation of optimal weights and biases in the training phase of the ANN is analysed by two different algorithms including Levenberg-Marquardt (LM) as a standard technique used to solve nonlinear least squares problems and Imperialist Competitive Algorithm (ICA) as a new evolutionary algorithm in the evolutionary computation field. Comparison of the obtained results with those of the conventional approach based on regression analysis shows a better performance of the ANN model trained with ICA. Investigation on the uncertainty band of the models indicated that LM predictions have the least uncertainty band whilst ICA's have the lowest mean prediction error. More analysis on the models' uncertainty is conducted by a Monte Carlo simulation in which 1000 randomly generated sets of input data are sampled from the database of historical dam failures. The result of 1000 ANN models which have been analysed with three statistical measures including p-factor, d-factor, and DDR confirms that LM predictions have more limited uncertainty band. [ABSTRACT FROM AUTHOR]

A large amount of loose deposit between the sides of a landslide lake may slide into a reservoir at any time because of influences such as earthquakes, heavy rainfall or other triggering factors. These factors can cause the formation of a huge surge and result in the instantaneous failure of a landslide dam. The failure of a landslide dam can threaten people's lives and property downstream. This paper analyzes the destruction mechanism of landslide dams because of a surge and the impact of the contact area, the landslide height, and the distance between the entry point and the dam site for a dam break through physical experiment and compares the experimental results with the calculated values. Experimental results show that the contact area and the landslide height have a significant impact on the dam-break surge. A measure based on the previously mentioned factors can be made to reduce the dam failure risk caused by a landslide surge. Two empirical methods (Pan's method and Miller's method) are used to predict the landslide surge wave and compared with the experimental results; the simulated results show that the Miller's method used for predicting the landslide surge wave is more reasonable. [ABSTRACT FROM AUTHOR]

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

The benefits of dams are unquestionable, with the water impoundment upstream and flood-control downstream usually being sufficient to increase investments and promote growth. However, their presence brings risks to the downstream population and the environment. This paper employs a fuzzy approximate reasoning for dam safety risk assessment, initially using a FAHP to weight the importance of the indicators suggested by a dam expert and then adopts linguistic variables in a two-stage risk assessment. In the first stage, we compute the risk of dam collapse, hereinafter called dam break, through indicators such as design premises and safety procedures. In the second stage, we evaluate the combined effect between the risk of a dam collapse and the socioeconomic and environmental impact on the surrounding area, hereinafter called potential risk. The danger scale of dam break and the hazard scale of potential risk were constructed. The risk assessment of the Simplicio Hydroelectric plant, located in Brazil's Southern region, showed that the risk classification of the proposed method attached great importance to the downstream consequences. The accuracy of the evaluation results was proved through a study of the Oroville Dam, whose spillway faced a failure event. These findings indicate the importance of extracting the knowledge of experts and incorporating it in the model specification through fuzzification of variables and the rule-based construction. [ABSTRACT FROM AUTHOR]

The historical records show that the Northwestern Algeria has experienced more than 130 floods, which were sometimes catastrophic. They caused more than 1000 deaths and significant damage. In this work, we try to reconstruct the most devastating and deadly historical flood that occurred on November 26 and 27, 1927. This event is interesting to discuss disaster scenario because of its extent and impacts and the availability of data. For this purpose, we used historical press reports, scientific papers, and archival reports. This work allowed the reconstruction of the hydroclimatic situation during the flood and the regional scale impacts. It presents also the catastrophic flooding of the Ain Sefra river at Mostaganem and that of El Hammam river, as well as the Fergoug dam breaking at Mohammadia. The main factor triggering these floods was the heavy rainfall. Other factors have increased the damage such as the occupation of high-risk areas and the human failure. This event caused 430 killed persons, more than 1200 disaster victims, and around one billion francs losses. These effects evidence the high vulnerability of the Northwestern Algeria to the occurrence of floods. For that, if a similar event occurs in the future, it can be extremely negative. [ABSTRACT FROM AUTHOR]

There are different methods to identify dispersive soil and several studies have attempted to produce a reliable method for this goal. Some studies have shown incompatibility between field observations and laboratory test results, especially for a chemical criterion. In this study, the dispersivity potential of 328 soil samples having a broad distribution in Iran was evaluated using pinhole and chemical tests in saturated soil extract. The compatibility of the Sherard chemical criterion and pinhole test results was first evaluated. Then, a modified criterion in the general form of the Sherard chemical criterion was suggested based on the pinhole test results to evaluate the dispersivity potential of the clay soil. The results show 44% compatibility between the Sherard chemical criterion and pinhole tests results for the studied samples while the proposed criterion shows 67% of compatibility. [ABSTRACT FROM AUTHOR]

Tailings impoundments are the important structures for the normal mine production, which are also the potential major hazard sources of mine safety. On the basis of the previous tailings dam break model experiment and numerical simulation results, the important characteristic parameters were selected to develop a hazard degree evaluation index system for the disasters induced by the discharged tailings flow from dam failure. The evaluation model was established further by using the uncertainty measurement theory. The results show that the hazard degrees of three characteristic regions (village locations) in the downstream of tailings impoundment were evaluated; it was determined that, the regional safety level of village I was "dangerous", while those for villages II and III were "relatively safe". Moreover, the evolution process of discharged tailings flow was divided into three characteristic stages on the whole, and a greater sand burst amount was associated with a greater risk to the downstream of the tailings impoundment. The results were highly consistent with the results of the laboratory dam break model experiments and numerical simulations. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature 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.)

During the application of semi-theoretical models to predict peak discharges for breached embankment dams, it is often encountered to be lack of necessary model parameters such as breach height. In order to solve this deficiency and improve the application of the semi-theoretical models for estimating the peak discharge, a mathematical relation is proposed to predict the breach height (Hb) using the water depth above breach bottom (Hw) based on a subset of a composite database (72 historical dam failures). The breach height relation has a high coefficient of determination (R2) when it is applied in the composite database. Using the prediction by the breach height relation as a substitute for the observation, these semi-theoretical models used here produce similar results in terms of both prediction accuracy and uncertainty. Moreover, the dispersion of the flood peak discharge predicted by forecasting models is weakened and the skewness is improved by adopting the breach height relation. Therefore, the application of semi-theoretical models to predict peak discharges can be improved obviously. So, it is found that the breach height using the proposed relation can be a satisfactory substitute when the observed value of Hb is unavailable in a dam failure. Besides, the prediction accuracy will decrease slightly with the increase of database, but the decrease is limited. It should be noted that the proposed breach height relation is only suitable for predicting the height of embankment dam breach in principle. [ABSTRACT FROM AUTHOR]

Failure modes for earth dams are extensively reviewed and analysed using a three-pronged approach including a literature review, physical observations of a representative earth dam site and finite element structural analysis of the dam wall. Several failure scenarios are used for predicting consequences in terms of downstream inundation and damage. The fluid flow component is performed using the mesh-free smoothed particle hydrodynamics method. For a representative earthen dam, piping and landslip are identified as key failure modes based on a combination of finite element analysis, theory and physical observations. Inundation behaviour is very different for the two failure modes. The landslip failure is the most critical one for the dam studied with flood water breaking the river bank and affecting surrounding property and farmland. For the piping failures, water flow from the initial pipes formed for significant periods before they collapse, but the flow rates are small compared with that of the much larger landslip mode. After failure, fragments of the collapsing wall block the breach and can considerably restrict the flood discharge. In some cases, the water pressure is able to push the obstructing material downstream and some minor flooding occurs, but in others cases the breach can remain blocked with little flooding occurring. A prototype risk framework is developed using the small database of the pre-computed flooding scenarios and key variables that affect inundation such as water level in the reservoir. This can be used to estimate inundation maps for as yet non-computed scenarios through interpolation and superposition techniques. The implementation of the risk framework is demonstrated by the estimation of inundation maps for two in-between non-computed reservoir levels. Inundation due to multiple breaches is also estimated by superposition of three single-breach scenarios. Results are compared against the simulated multiple breach. A preliminary implementation of this risk framework into a geographic information system is also described. [ABSTRACT FROM AUTHOR]

This study proposes an automatic identification approach for landslide dam formation using a real-time abnormal hydrology record and artificial neural network (ANN). In Taiwan, natural dams occur frequently and have the potential to cause significant disasters, especially in the presence of fragile geological conditions such as steep mountains, earthquakes, intense typhoon, and storm events. During a river blockage event, obtaining immediate real-time information can be difficult or even impossible due to extreme weather conditions, remote locations, and the mountainous terrain of the area. As a result of these issues, there is a strong need for a practical tool that can not only detect the occurrence of this type of natural dam but also estimate the potential real-time risk of dam failure. In order to develop the appropriate safety response, a rapid preliminary assessment of the failure type must be identified, followed by a thorough investigation into the failure process after the event has occurred. In this study, a new method is developed that applies an ANN model (1) to evaluate, in real time, the occurrence of a natural dam and the storage changes behind that dam; (2) to rapidly assess the natural dam failure type and failure process; and (3) to reconstruct the dam height variation during the dam failure process after the event. The proposed methodology is applied to Chi-Shan River Basin located in Kaohsiung, Taiwan, during Typhoon Morakot in 2009. In 3 days, Typhoon Morakot produced 1,911 mm of precipitation. The typhoon event produced a landslide dam and a debris flow that inundated Hsiaolin Village, causing 398 deaths. The tragic results of this case study demonstrate the need for an applicable, accurate, and efficient method to evaluate dam formation and its failure rate. [ABSTRACT FROM AUTHOR]