جستجوی مقالات مرتبط با کلیدواژه « Hydraulic Model » در نشریات گروه « عمران »

Floods are a natural disaster that threatens the lives of millions of people every year. Obtaining the flood zone and consequently obtaining the flood zone map for current with a specific return period for a desired basin is one of the important results obtained from different models. Therefore, extraction of flood zone is one of the basic needs in the design of water structures, a basic step for management and planning to reduce economic and social flood damage, use to determine the amount of insurance for residential areas along the river and also identify high risk areas of the river In terms of flood status and flood control measures. Evaluating the performance of the HAND model, which relies solely on topographic features, is one of the objectives of the present project.

In this study, the flood zone is determined using the HAND model with a calibrated coefficient of roughness. Seymareh River has been selected as a study area to challenge the performance of the model in relation to the observational data obtained from satellite images and also to evaluate it with the HEC-RAS hydraulic model. Also, the HAND model in low and high flows has been evaluated with a 1D and 2D hydraulic model to evaluate the performance of the model in different flow conditions.

In the first part, the HAND model was evaluated using satellite images, which show the very good performance of the model in determining the flood zone. Further sensitivity analysis of Manning roughness coefficient showed that increasing and decreasing it by 25% had no effect on improving the performance of the HAND model and the roughness coefficient was properly calibrated. Finally, the model was evaluated with 1D and 2D hydraulic model in low and high input flow conditions. The results showed that the HAND model still has a good capability in comparison with hydraulic models in different flow conditions.

The most important results can be summarized as follows:• The results obtained from the HAND model based on the calibration coefficient calibrated in Seimareh river indicate the proper performance of the model in obtaining flood zone. According to calculations, the rate of flood zone adaptation is higher than 92% compared to satellite images. Also, the average difference between the HAND model and satellite images for estimating flood zones during the study period of the river was about 8.5%. The occurrence of turbulence and rotational flows due to improper angle of connection between the channel and the freeway bridges in the future will have a significant impact on the hydraulic flow and sediment of the river, especially in the area of the bridges.• The results in Seimareh River show that increasing and decreasing the inlet flow does not change the performance results of the HAND model and also the model has a good capability compared to hydraulic models. According to calculations, the rate of adaptation of the flood zone in comparison with the hydraulic model in different discharges is always higher than 83%. Also, the average difference between the HAND model and hydraulic models for estimating flood zones during the study period of the river will be less than 13%. • Despite the very good performance of the HAND model in estimating the flood zone, in some intervals there are differences between the HAND model with satellite images and the hydraulic model, which can be done by using topographic maps with high resolution and river path inter Extraction of Rating-curves for each substrate greatly enhances the performance of the HAND model.• Hydraulic model has more error in estimating flood zone than HAND model. The main reason for this can be related to important factors such as: distance between cross sections, computational cell dimensions, numerical parameters used in the 2D hydraulic model (such as θ parameter and currant number), boundary conditions used in the hydraulic model Calibrate the time step and determine the Manning roughness coefficient for each cross section. In general, relatively more factors affect the performance of the hydraulic model and affect its output, while the HAND model experiences relatively better conditions in this regard, so that only by considering a coefficient of roughness for the whole The study interval and extraction of the Rating- curve can be used to obtain the flood zone. while the HAND model experiences relatively better conditions in this regard, so that only by considering a coefficient of roughness for the whole The study interval and extraction of the Rating- curve can be used to obtain the flood zone.

Stepped spillways are used to discharge excessing floods entering the reservoirs, through which the energy is exposed to highly dissipation rates. It consists of a series of steps along the spillway to ensure a uniform flow along the spillway. Steps improve the rate of energy dissipation along the spillway, which consequently affect the flow characteristics and energy dissipaters at the downstream. The flow over stepped spillways is divided into three regimes of nappe, transition and skimming flows. So far, limited number of studies have been performed on the basis of analytical and empirical information to check the features and nature of nappe flow. Limitations on physical model studies is also important to mention. As a result, few relationships have been suggested to describe nappe flow characteristics over stepped spillways. In this study, experiments were performed on three large-scales hydraulic spillway models of SiahBishe upper and lower dams and Zhaveh dam, which cover six spillway slopes and 24 flow rates. Measurements of depth, velocity, and static pressure were made at 40 different cross sections along the chutes. Major effective geometrical and hydraulic parameters on energy dissipation in nappe flow regime over spillways were analyzed, based on measurements made in this study. A relationship was then suggested to calculate the rate of energy dissipation in nappe flow regime. This study showed that the ratio of critical depth to height of spillway is the most important parameter in predicting energy dissipation, the increase of which reduces the relative energy dissipation in nappe flow.

Simulating and understanding of abnormal conditions is one of the most important applications of hydraulic models of water distribution networks. Hence, existence of calibrated models is essential to network behavior realization. This process requires field data collection to improve model's performance by comparing predicted and actual data. Sampling from network has different constraints. Therefore the sampling design process is performed in order to optimize it, which includes different aspects of sampling, such as location, number and frequency. This paper focuses on pressure sampling nodes for hydraulic model calibration. To implement sampling design, first by sensitivity analysis, uncertainty of each nodal pressure is divided between model inputs.

In this paper, a global sensitivity analysis method, Sobol, is used which divides the variance of model into model inputs and their interactions. Then, two criteria for selecting sampling points are defined. The first criterion maximizes the entropy and magnitude of sensitivity values of each parameter for the set of sampling design points. The second criterion, by replacing number of points with sampling costs, follows minimization of sampling costs. To solve the integer multi-objective optimization problem, the multi-objective integer genetic algorithm called MI-NSGA-II is employed.

Investigating different scenarios demonstrates effect of parameter type on the position of selected points. In the meantime, similarity between the results of combinatorial and individual scenarios decreases from cases including roughness to cases involving demand. This indicates effective role of roughness in selecting points in combinatorial scenarios. Also, analysis of combinatorial scenarios suggests that parameter interactions are effective in selecting points.

The results showed that the developed approach offers good performance in selecting sampling points with different scenarios. The MI-NSGA-II algorithm has a good ability to find the solutions of the integer multi-objective optimization problem. The use of pressure driven simulation method is effective on the results of sensitivity analysis and sampling design.

Labyrinth weirs are among the hydraulic structures that are constructed to regulate the water level and control the flow in canals, rivers and reservoirs of dams. This structure is designed to transmit large currents in low heads by increasing the effective length of the overflow crown. The crest axis of this type of weirs is indirect and in showing the horizontal surface, the overflow is composed of interconnected walls. Labyrinth weirs are repeated with triangular, trapezoidal, rectangular and arc geometries alternating in flow width. The main criterion in the labyrinth design of the weirs was to increase the flow transmission capacity on the overflow with a fixed canopy and for a certain height of the water level upstream of the weir. In this study, 145 laboratory data were used, including four types of arc labyrinth weirs with different arc radius and tangent lengths. The discharge efficiency was introduced as a dimensionless parameter  using dimensional analysis. The relationships between  and the critical depth of flow (y_C/P) were obtained using graphs for two different types, R2 = 0.983 and R2 = 0.998. Then a graph to y_(C_Lt )/P and H_t/P a relation to calculate the critical depth were presented. The results showed that the calculated flow rate obtained using yc is consistent with laboratory values so that the relationship between them is R2 = 0.982.Labyrinth weirs are among the hydraulic structures that are constructed to regulate the water level and control the flow in canals, rivers and reservoirs of dams. This structure is designed to transmit large currents in low heads by increasing the effective length of the overflow crown. The crest axis of this type of weirs is indirect and in showing the horizontal surface, the overflow is composed of interconnected walls. Labyrinth weirs are repeated with triangular, trapezoidal, rectangular and arc geometries alternating in flow width. The main criterion in the labyrinth design of the weirs was to increase the flow transmission capacity on the overflow with a fixed canopy and for a certain height of the water level upstream of the weir. In this study, 145 laboratory data were used, including four types of arc labyrinth weirs with different arc radius and tangent lengths. The discharge efficiency was introduced as a dimensionless parameter  using dimensional analysis. The relationships between  and the critical depth of flow (y_C/P) were obtained using graphs for two different types, R2 = 0.983 and R2 = 0.998. Then a graph to y_(C_Lt )/P and H_t/P a relation to calculate the critical depth were presented. The results showed that the calculated flow rate obtained using yc is consistent with laboratory values so that the relationship between them is R2 = 0.982.Labyrinth weirs are among the hydraulic structures that are constructed to regulate the water level and control the flow in canals, rivers and reservoirs of dams. This structure is designed to transmit large currents in low heads by increasing the effective length of the overflow crown. The crest axis of this type of weirs is indirect and in showing the horizontal surface, the overflow is composed of interconnected walls. Labyrinth weirs are repeated with triangular, trapezoidal, rectangular and arc geometries alternating in flow width. The main criterion in the labyrinth design of the weirs was to increase the flow transmission capacity on the overflow with a fixed canopy and for a certain height of the water level upstream of the weir. In this study, 145 laboratory data were used, including four types of arc labyrinth weirs with different arc radius and tangent lengths. The discharge efficiency was introduced as a dimensionless parameter  using dimensional analysis. The relationships between  and the critical depth of flow (y_C/P) were obtained using graphs for two different types, R2 = 0.983 and R2 = 0.998. Then a graph to y_(C_Lt )/P and H_t/P a relation to calculate the critical depth were presented. The results showed that the calculated flow rate obtained using yc is consistent with laboratory values so that the relationship between them is R2 = 0.982.Labyrinth weirs are among the hydraulic structures that are constructed to regulate the water level and control the flow in canals, rivers and reservoirs of dams. This structure is designed to transmit large currents in low heads by increasing the effective length of the overflow crown. The crest axis of this type of weirs is indirect and in showing the horizontal surface, the overflow is composed of interconnected walls. Labyrinth weirs are repeated with triangular, trapezoidal, rectangular and arc geometries alternating in flow width. The main criterion in the labyrinth design of the weirs was to increase the flow transmission capacity on the overflow with a fixed canopy and for a certain height of the water level upstream of the weir. In this study, 145 laboratory data were used, including four types of arc labyrinth weirs with different arc radius and tangent lengths. The discharge efficiency was introduced as a dimensionless parameter  using dimensional analysis. The relationships between  and the critical depth of flow (y_C/P) were obtained using graphs for two different types, R2 = 0.983 and R2 = 0.998. Then a graph to y_(C_Lt )/P and H_t/P a relation to calculate the critical depth were presented. The results showed that the calculated flow rate obtained using yc is consistent with laboratory values so that the relationship between them is R2 = 0.982.