mitra javan

Tailing dams are responsible for collecting tailings from mining operations. Tailing dams are built to conserve water for use in mining and protecting the environment. These structures are often constructed using the tailing. This issue, along with factors such as the relatively long construction period and inadequate design and supervision, has resulted in a high number of tailings dam failures. Tailing dam accidents have occurred frequently in recent years. The current rate of failure of large tailings dams is about 2 to 5 cases a year. In the recent failure tailing dam on 2022, Nov. 7, the tailings escaped through an approx. 150 m wide breach of the eastern wall of the impoundment, which caused the release of 12.8 million m3 of water and tailings (World Information Service on Energy 2022. Tailings Dam Safety. https://www.wise-uranium.org/mdaf.html). Some tailings dams have a water pond near the dam crest and the water and tailings liquefy or not contribute to the tailing dam breach. Other tailings dams have no water pond or the pond is far from dam's crest. Water has no or less contribution to the tailings dam failure and the runout of tailings liquefy or not is significant. (Small et al. (2017)).

This research explores a local failure dam near the tailings dam abutment with a water pond in the large-scale experimental setup that consists of a tailings pond by 505 cm(length), 310 cm (width) and 64 cm (height). The uniformity and curvature coefficient of tailings are 2.21 and 1.44 and the tailings are not liquefaction. The longitudinal slope of bed is 2%. A gate with a width of 20 cm as a local dam breach is applied near the left abutment of the dam. An ultrasonic equipment measured the time series of water surface elevation. The experimental tests were carried out at different water surface elevations and repeated three times to ensure the validity of the results. The bed topography is measured by the Kinect before and after the dam breach. These bed elevations were performed to calculate the volume of the eroded tailings by using Civil3D 2019 software. Moreover, some videos are provided to recognize the flow pattern and bed erosion.

In all experiments, after the local failure of the tailing dam, a pit is created inside the tailings dam pond near the breach. At the beginning of the experiment, the scour pit created has no effect on the water surface elevation. After that, the pit effect is recognized on it. Then, there is water at the end of the pond just near the dam body. At the end, there is a small water height inside the pit and a hydraulic jump occurs in the scour hole. The grooves are created on the bed and the eroded sediments do not have any ability to move towards the dam breach downstream.The bed erosion pattern and sediment transfer rate were surveyed in water level variations of the tailings dam reservoir during a local failure near the abutment. The largest scour height has occurred near the local failure. Due to the complex nature of the sediment, the topography bed images of the same experiments are different in detail.

Water and sediment are quickly released from the local tailing dam breach and a scour hole forms in the bed near the local failure. In all experiments, the ratio of the volume of eroded sediment near the local failure to the water volume of the dam pond is about one percent. The variation of the water surface elevation with time is about 0.45. It was observed that the length of the scour hole in the dam body direction is more than the direction perpendicular to the dam body. The ratio of the length to the width of the scour hole is 3 to 3.3, approximately.

Water quality control in terms of solutes, color, taste, odors and existing bacteria is of vital importance from a health point of view. Water quality problems in storage facilities can be classified as microbiological, chemical and physical. Water stagnation in many storage facilities is probably the most important factor associated with declining water quality. Accumulation of sediment in cisterns leads to potential water quality problems and increased demand for disinfectants, microbial growth, water turbidity and chlorine depletion. To investigate the safety of the stored water, further research is needed. Requirements outlined in Issue Sixteen of the Iranian National Building Code emphasize specifications related to water storage tanks. In this research, the field observation method was employed to investigate the requirements of the national building regulations for 105 cisterns of apartments in Kermanshah city in two types of polyethylene and galvanized steel. Additionally, the factors affecting the problems that have been created inside the cisterns of the apartments have been evaluated. The results showed that in 8% of the apartments, the subscribers used direct pumping, which contravenes the established requirements. Furthermore, in 26% of the cisterns, the amount of residual free chlorine is lower than the recommended amount specified in Publication 1053 of the National Standard of Iran. In 7% of the cisterns, the water temperature is higher than the value suggested in the English standard (BS 8558:2015). All cisterns are not equipped with warning pipes, overflow pipes, drain pipes, or vent pipes. Rust was clearly seen inside the galvanized steel cisterns. There is accumulated sediment at the bottom of all cisterns. In 86% of cisterns with a volume of more than 1000 liters, water stagnation occurs due to the inlet and outlet being located on the same side. Therefore, legal follow-ups and periodic visits to the cisterns of buildings are essential.

Simulation of dam break and flood flows resulting from it has always been one of the important and interesting problems for researchers. This issue has been underlying many laboratory, analytical and numerical studies. Most of the numerical studies that are based on solving shallow water equation (SWE) are developing to find the better methods to increase accuracy and convergence of solution of governing equation. Also, in this research, in order to simulation of dam break flows, a numerical model is developed based on solving SWE on curvilinear grid. To increase the number of involved points in discretization scheme in order to smoothing the sharp geometric and hydraulic gradients and reducing the probability of oscillation and divergence the present model uses Lax and Leap-Frog schemes on staggered mesh simultaneously. Experimental and numerical literature data in simulation of hydraulic jump, full dam break over wet bed, partial dam break and dam-break in a convergent-diverging channel are compared to present results. In all the performed test cases, the overall agreement between the result of the present model and experimental and numerical literature data is acceptable.

Introduction In dam failure studies, prediction of its hydraulic components, including depth and velocity, has always been important for hydraulic engineers due to its impact on the severity of the disaster. There are various hydraulic, hydrological, geotechnical and geometric factors that affect the characteristics of the flow through the failure of the dam. In order to investigate the effect of the factors, research has been carried out especially in the field of laboratory, but little numerical research has been done. Resource surveys show that although the walls of concrete reservoir dams are not perpendicular to the lateral support, but so far, the effect of wall deflection on the hydraulic properties of the flood due to the dam failure has not been considered. Therefore, in this research, the effect of quarries of 2.5 to 10 percent of the wall of the dam was examined from the perpendicular to the base. Since the wall deviation of the dam from the normal state removes physical space from a rectangular state, the use of orthogonal coordinate system is not possible. Therefore, in this study, using the curvilinear coordinate system of the physical non- rectangular space studied, It is very accurately converted to computational space and the governing equations are solved. Materials and Methods In this research, the governing equations for shallow water were discritized in curvilinear coordinates by explicit finite difference method. For more stability Lax and Leap-Frog schemes on staggered mesh are utilized, too. For areas studied, in order to determine the coordinates of points in the physical space, by presenting a computer program, the computational mesh is created in Cartesian coordinates. Then, by converting the coordinates in the Cartesian system (x, y) to the curvilinear coordinates (ξ, η). Results and Discussion In order to validate the present model, its results were compared with experimental investigation by previous researchers. 1- Failure of the dam in the convergent-divergent channel without sloping and sloping: The water level profile of the laboratory model is presented for different times (zero, 4, 20, 60) seconds. The mean error in the results of the present numerical model is 4.02% for the results of the measurements for the non-slope channel and for the channel with a 0.01 slope, 1.65%. 2- Dam Failure in canal with dry bed with trapezoidal reservoir: The results of the model follow a similar trend to the experimental results, and the magnitude of the error in the peak areas that is more important is not significant. 3- The effect of the wall angle of the partial symmetric dam-break in the dry bed: It was observed that with the diversion of the wall angle of the dam from the perpendicular position in the failure site, depth and rate of flow decreased more. A closer examination shows that for diversion of 2.5, 5, 7.5 and 10 percent, peak discharge values were decreased  3.5, 6.1, 9.2, 11 percent, and the maximum water level was 2, 6, 9 and 12 percent.   Conclusions In simulating the ideal failure of the deformed reservoir on a dry bed, the results of this numerical model are adapted with the results obtained from the physical model. In another study, the results of the model were compared in the simulation of the dam failure phenomenon in the convergent-divergent channel without sloping and sloping with the results of the measurements. It was determined that a numerical model with an average error of less than 5% estimated the depth of the flow in the failure location.In order to achieve the main objective of the research, the results of the present numerical model in simulating the partial symmetric dam failure on dry bed have been investigated. It was observed that the diversion of the angle of the dam wall at the failer site affects the depth and discharge peak flow. The variations in “q” from the upstream of the reservoir to the failer site increase sharply and reach the maximum at the fracture site, then slowly decrease to the end of the reservoir wall. Similarly, changes in the water level with the distance from the upstream wall and moving towards the failer site are higher.  Keywords Dam-Break, Leap-frag and Lax schem, Curvilinear grid, Angel of Dam Wall  with Support.

of the effect of reservior shape coefficient on dam-break waves using Leap-Frog and Lax methods in curvilinear coordinates Background and objectives The prediction of hydraulic components of depth and speed has always been important for hydraulic engineers because of its impact on the severity of the disaster dam break. In the past, many studies have been carried out to investigate and predict the hydraulic properties of dam-break waves using numerical methods. The necessity of this research is the need to expand the scope of research in numerical solution of factors influencing the dam failure phenomenon. In this research, a comprehensive computer model has been developed in which using the explicit finite difference method and simultaneous use of Leap-Frog and Lax algorithms on the staggered mesh shallow water equations are solved to simulation dam break problem. This will increase the number of involved points in the computation and sharpen hydraulic gradients become smooth and the probability of oscillation and divergence will decrease without the use of artificial viscosity. In this study, the equations of interest are the governing shallow water equations. Due to the inability of the Cartesian coordinate system to reflect the irregular boundaries of the physical domain, in the curvilinear coordinate system on the staggered mesh are discretized. The method of discretization is a explicit method that simultaneously utilizes Leap-Frog and Lax algorithms. In order to validate the present model, comparing its results with laboratory measures or with the results of other numerical models has been proposed by several researchers. One of these cases is the ideal failure in the canal with tail water, in which case the results of the discharge and the depth of water were simulated for the failure of the dam in a 100 meters horizontal channel with a high accuracy. The simulation of the dam failure with a trapezoidal reservoir with a maximum of 2.04 meters, a small 0.05 m, and a height of 2.02 meters in a canal with a dry bed was carried out, and the results of the model for the discharge and depth with the consistency well presented with laboratory results. The partial asymmetric dam failure in the wet bed is another case investigated in this study, which simulated an asymmetric failure in a reservoir with a length and width of one meter for three different shape coefficients of 1, 1.25, and 1.5. The flow and discharge hydrographs have been simulated for different situations, with the increase of the shape coefficient, discharge values and the level of the water surface increase due to increased reservoir volume. In this research, a computer model in the curvilinear coordinate system with the consideration of shallow-water equations and the use of Lax and Leap frog methods are presented simultaneously for the dam failure phenomenon. In the simulation of the ideal failure with tail water, the present model ability to approximate the analytical solution is highly accurate. In the simulation of failure in trapezoidal reservoirs on the dry bed, the results of the present numerical model are in agreement with experimental results, also in studying the main objective of the research, the results of the present numerical model for simulating partial asymmetric dam failure with different shape coefficients of reservoir in dry bed have been investigated. It was observed that water level increased with the change of shape coefficients following the deformation of the reservoir walls, compared with the simple reservoir. Also, the amount of discharge per unit width for a reservoir with a larger coefficient of shape than a reservoir with a lower coefficient is greater.

The water demand is rapidly increasing due to economic and social development and population growth. In keeping with the freshwater restrictions, the allocation of water needs to take a comprehensive view and integrated management approaches are vital in different sectors. This study was implemented in the Gamasyab Watershed, which is the main sub-watershed of the Karkheh River. Much of the watershed is located in the Province of Kermanshah, while its headwaters are in the Province of Hamadan. In this study, the WEAP Software was used as a powerful tool to assess an integrated water resources management for investigating an applied management in the Gamasyab Watershed, and evaluating the effect of upstream dams on the performance of the Bistoon reservoir. Long term hydrological data were used to model the water resources and demands in the watershed. The water demands were obtained using the data of population, agriculture, and industries, and the environmental flow requirements determined using the Montana Method. Different management scenarios were defined in accordance with the current conditions and watershed development perspective. The results indicated that the demands maybe fully met under the present conditions; however, the demands will exceed the available water in the Bistoon Reservoir if the planned dams come in to operation. Its regards to the importance of considering the principles of integrated water resources management, the results of this study may be used with certainty by the researchers and decision-makers in the water sector in Iran.

An important consideration in water resources management is the total cost of the water supplied to customers. The factors involved in water supply costs are divided into the four main components of water distribution; purchase, supply, and harvest; treatment and disinfection; and facility running and maintenance costs, each of which comprises individual parameters. In this study, the parameters in the four components are investigated and prioritized using the factor analysis method. Results show that the parameters in each componet may be coalesced into two main factors. In the water distribution component, transportation, machinary rental, building depreciation, and machinery and equipment depreciation costs may be considered as one factor while vehicle depreciation and maintenance costs as well as the costs of fixed assets account for the second factor. The treatment component involves facility depreciation, labor, materials (disinfectants), equipment depreciaion, and building depreciation costs as the first factor while machinary rental cost forms its second factor. In the purchase component, machinery and equipment depreciation, water purchase, transportation, machinary rental, and vehicle depreciation costs form one factor while building depreciation costs form the second factor. The water facility component comprises one factor that includes machinery and production equipment depreciation, vehicle depreciation, building depreciation, and labor costs and its second factor includes asset depreciation, machinary rental, and labor costs.

In this research, a multi-layer perceptron neural network (MLP-NN) model was used to simulate dissolved oxygen and total phosphorus in the Ilam Dam catchment. The NN model was developed using experimental data from three sub- catchments of Ilam Dam during the 2009-2010 period. Input variables of NN model including water PH, electricital conductivity, total suspended solids, temperature, total phosphorus, sulfate, ammonia, iron and total nitrogen were employed for the dissolved oxygen modeling. Input variables for total phosphorus modeling were temperature and phosphate, which have been measured at one station on the reservoir vicinity at different depths. The performance of the models was assessed by the coefficient of determination, relative error, and sum of squared errors (SSE) indices. The neural network results indicated that all the input variables affected modeling of the dissolved oxygen concentration, while the most effective parameter was the total suspended solids. Phosphate presented the highest impact on the total phosphorus modeling than the temperature. The cofficient of determination values for modeling dissolved oxygen and total phosphorus were 0.813 and 0.940, respectively. The results of NN models were then compared with the two-dimensional, laterally averaged CE-QUAL-W2 model. Based on the results, the multi-layer perceptron model showed more accurate responses than the numerical model in predicting water quality variables. Results also showed that the NN was able to predict the eutrophication process with acceptable accuracy and could be used as a valuable tool for qualitative management of reservoir water.

The U-shaped channels are applied as transition cross-section from rectangular to circular in manholes. Also the U-shaped channels along the side weirs are used in the sewage networks, irrigation-drainage systems, flood protection and etc. The flow in the main channel along the side weir can be the supercritical conditions. In this study, the free surface flow in the supercritical regime has been simulated by FLOW-3D software, RNG model and volume of fluid (VOF) scheme in a U-shaped channel along the side weir. The comparison between the numerical and experimental results showed that the numerical simulation predicted the free surface flow with the reasonable accuracy. Generally, the flow depth decreases with distance from the upstream end of the side weir towards the downstream end in the U-shaped channel. The APE and RMSE of the water surface profile along the side weir have been computed 1.7% and 0.213%, respectively. Also, the APE and RMSE were respectively 3.8% and 0.0177% for the discharges over the side weir. In continue, the effects of the upstream Froude number on the flow pattern in the main channel were investigated. For all Froude numbers, because of entrance effects, a free surface drop occurred at the upstream end of the side weir and the water depth gradually reduced toward the downstream end. Then, a surface jump happened at the last fourth of the side weir length in vicinity of the inner bank. Unlike the potential energy, the kinetic energy increases along the surface jump. Also, a stagnation point is created at the end of the surface jump. The height of this stagnation point increases with increasing the Froude numbers. In addition, the dividing stream surface and stagnation zone were respectively produced near the inner and outer bank in the main channel along a side weir. The dividing stream surface reduces from channel bottom toward the side weir crest then increases to the flow surface. Also, the dimensions of the dividing stream surface and stagnation zone increased with increasing Froude number. The maximum lateral flow in the U-shaped channel occurs almost at the downstream end of the side weir. The transverse velocity increases at each cross-section of the main channel with increasing Froude number. The angle of the spilling jet was close to 90° at the upstream and downstream of the side weir crest and the pattern of spilling jet angle is similar for all Froude numbers. The minimum angle of the spilling happens approximately at the downstream of the side weir crest however, the minimum decreases with increasing Froude number. The pattern of the bed shear stress can be used to prediction of the areas of the scour and sedimentation in the alluvial channels. In the U-shaped channel along a side weir, the bed shear stress increases along the main channel axis form the beginning of the side weir toward the middle then decreases toward the downstream end. Generally, with increasing Froude number, the bed shear stress increases in the main channel along the side weir.

Structures such as side orifices, side weirs, and side sluice gates are known as flow diversion structures. Side orifices are flow diversion structures which have wide application in hydraulic and environmental Engineering. This flow diversion structure has been extensively used in irrigation and drainage networks, wastewater treatment plants, sedimentation tanks, etc. Therefore, Study of the characteristics and flow pattern such as flow velocity components and free surface adjacent to the side orifice is important. In this paper, the flow over a sharp-crested rectangular side orifice in an open channel was simulated by FLOW-3D software. RNG turbulence model was used to apply the Navier-Stokes equations and the VOF method was used to model the free surface profile changes. In the present study, at first, the results related to the side orifice discharge and flow patterns obtained from numerical simulation were compared with experimental data. In this study, some experimental data of Hussian et al (2011) were used for model verification. In this study, the discharges through the orifice resulted from the present numerical simulation and the experimental research, along with the relative errors are reported. All relative error quantities were about 8-9%, thus there was relatively good agreement between numerical and experimental results. Therefore, the numerical model can be employed as a powerful tool for studying flow through side orifices in open channels. Then the effects of height of the side orifice crest on the flow velocity components and free surface adjacent to the side orifice was investigated. The results indicated that the discharge ratio, ratio of the discharge through the side orifice to the inlet discharge of the main channel increases with decreasing heights of the side orifice crest. Maximum and minimum longitudinal velocity for all heights of the side orifice crest was occurred at the beginning and end of the side orifice, respectively. By decreasing the height of the side orifice crest, maximum and minimum longitudinal velocity increases and decreases, respectively. By decreasing the height of the side orifice crest, the longitudinal velocity in the vicinity of the side orifice is negative because of the reverse flow formed in this area. Examining the lateral velocity component variation showed that this component increased with decreasing height of the orifice crest. That is why the discharge through the side orifice increased with decreasing height of the orifice crest. At height 2.2 cm of the orifice crest, the flow direction is upward then in all cases vertical velocities in the orifice length are positive. In the other hand, at height 6.7 cm of the orifice crest, the flow direction is downward then in all cases vertical velocities in the orifice length are negative. Also, the absolute value of the vertical velocity increases with by decreasing the height of the side orifice crest because more flow is diverted to the side orifice with decreasing the height of the side orifice crest. Also, increasing height of the orifice crest caused significant changes in the free surface profiles especially in the vicinity of the side orifice.

In this research, a 2D laterally averaged model of hydrodynamics and water quality, CE-QUAL-W2, was applied to simulate water quality parameters in the Ilam reservoir. The water quality of Ilam reservoir was obtained between mesotrophic and eutrophic based on the measured data including chlorophyll a, total phosphorus and subsurface oxygen saturation. The CE-QUAL-W2 model was calibrated and verified by using the data of the year 2009 and 2010, respectively. Nutrients, chlorophyll a and dissolved oxygen were the water quality constituents simulated by the CE-QUAL-W2 model. The comparison of the simulated water surface elevation with the measurement records indicated that the flow was fully balanced in the numerical model. There was a good agreement between the simulated and measured results of the hydrodynamics and water quality constituents in the calibration and verification periods. Some scenarios have been made base on decreasing in water quantity and nutrient inputs of reservoir inflows. The results have shown that the water quality improvements of the Ilam reservoir will not be achieved by reducing a portion of the reservoir inflow. The retention time of water in reservoir would be changed by decreasing of inflows and it made of the negative effects on the chlorophyll-a concentration by reduction of nutrient inputs and keeping constant of discharge inflow to reservoir, the concentration of total phosphorus would be significantly changed and also the concentration of chlorophyll-a was constant approximately. Thus, the effects of control in nutrient inputs are much more than control in discharge inflows in the Ilam reservoir.

Spur dikes are one of the many kinds of hydraulic structures, and they are employed in stabilizing rivers’ outer walls and redirecting the flow. Considering the importance of understanding flow pattern around the spur dikes, the present work firstly simulated the flow pattern around a T-shaped spur dike located in a 90 degree bend channel. The rigid-bed channel’s curvature radius and radius to width ratio were respectively 2.4 and 4. FLOW-3D was used in order to simulate the flow pattern, and the effect of section constriction on the flow pattern was studied afterwards. VOF was used for distinguishing the water surface profile from the open surface model, and RNG k-ɛturbulence model was employed to model the turbulent flow around the spur dike. The piece of research indicated an acceptable correspondence between numerical and experimental results. The results obtained through various simulations per 10, 20 and 25% constrictions of the section indicated that increase in section constriction would increase the water surface fluctuations, and the maximum height upstream and the minimum height downstream were observed in the case of the large spur dike. In addition, the vortices appear over a longer area of the bend, downstream the spur dike.

Numerical solution of flows with a freely moving boundary is of great importance in practical application such as ship hydrodynamics. Details are given of the development of a two-dimensional vertical numerical model for simulating unsteady and steady free-surface flows on a non-staggered grid in curvilinear coordinates, using a non-hydrostatic pressure distribution. In this model, Reynolds equation and the kinematic free-surface boundary condition are solved simultaneously, so that the water surface elevation can be integrated into the solution and solved for, together with the velocity and pressure field. In the computational space, the Cartesian velocity components and the pressure are defined at the center of a control volume, while the volume fluxes are defined at the mid-point on their corresponding cell faces. Detailed numerical results are presented for the wave generation above an obstacle and small amplitude Stokes waves. The results show that the numerical algorithm described is able to produce accurate predictions and is also easy to apply.