mehdi azhdary moghaddam

Considering that dams are one of the most important water storage resources in water projects, therefore, proper construction and operation management of them is one of the most important responsibilities of water resource managers. One of the important parts in the construction of any dam is the design of the dam spillway, which is responsible for discharging excess water from the reservoir to downstream in case of floods. Destruction or inefficiency of spillways causes severe damage to the dam or even causes its complete destruction, that is why the design and construction of this part of the dam is very important. Among different types of spillways, stepped spillways, in addition to passing excess water from the reservoir of dams, are also a structure that consumes flow energy. Until now, in the studies carried out in this field, the optimization of stepped spillways has been considered as a single objective, which usually aims to optimize, minimize construction costs or maximize energy consumption in these spillways, and rarely optimize the dimensions of spillways with Taking into account the two factors of cost and energy consumption has been considered simultaneously. Therefore, in this study, for the first time, a multi-objective optimization model has been developed by benefiting from the capabilities of the improved version of the dragonfly optimization algorithm for the design of stair overflows with the aim of minimizing the volume of concrete used and increasing energy consumption.

In the design of the stepped spillway, the discharge parameters (Q) and the horizontal length of the overflow (L) are among the most important input parameters, which are determined based on the initial studies of topography and hydrology and are considered constant during the design. According to the purpose of the present research, an optimal combination of effective parameters in the design of a stepped spillway, including slope, width, height of the spillway, water pressure on the spillway, and step height, should be determined in a way that leads to the highest energy consumption and the lowest design costs with By-law restrictions should be taken into account. In the current research, the objective function, which consists of decision variables, should simultaneously provide the maximum amount of energy consumption and the minimum volume of consumed concrete, while satisfying the constraints and hydraulic conditions of the design problem. For this purpose, the dragonfly optimization algorithm, which is one of the powerful algorithms of collective intelligence methods, and was first proposed by Mirjalili.This algorithm is inspired by the group and social behavior of dragonflies in nature. Dragonflies usually live alone in the wild and only act in groups for hunting and migration. The basis of the dragonfly optimization algorithm to find the optimal answer is their two crowding behaviors. In this way, based on the static behavior, the members of the algorithm population are divided into smaller groups and search the problem space, then based on their dynamic behavior (exploitation phase), they determine the optimal answer with more members.

The spillway of Sarouq Dam, located in West Azarbaijan province, was selected as a case study in this research to evaluate the developed model. In the first part, the problem of optimal design of the stepped spillway of Sarouk Dam was investigated as a single-objective problem with the aim of maximizing the amount of energy consumption. The purpose of redesigning Sarouk dam spillway was to provide an optimal design for a stepped spillway instead of the existing flat spillway with the aim of maximizing energy consumption downstream of the dam. In all the optimal models provided by IDA, the consumption of water energy has increased significantly. According to the report of Hosseini, 2019, the amount of energy consumption at the foot of the existing spillway of Sarouk Dam is equal to 23.41, which the use of the stepped spillway in the present research increases it for the flow rates of 560.2, 776.9, and 422 cubic meters per second, respectively. 71.32, 65.72 and 74.74 percent. According to the main goal of this article, in this section, the new and improved algorithm based on the dragonfly algorithm has been used to optimize the multi-objective overflow of Sarouk Dam by considering the amount of concrete pouring and the amount of energy consumption as objective functions. The results shown that, using the multi-objective optimization approach for the design of stair overflows leads to the presentation of different types of designs with different implementation costs and energy consumption rates. Therefore, using the multi-objective optimization approach has led to the production of many answers, which allows the employer to design the overflow according to the budget he has.

In this research, using the improvement of a new metaheuristic algorithm called the dragonfly algorithm, a single-objective model was developed with the aim of maximizing energy consumption, and another multi-objective model was developed with the objectives of minimizing the construction costs of the stair overflow. The developed models were used for the optimal design of Sarouk Dam spillway. The use of the improved Dragonfly multi-objective optimization algorithm to minimize construction costs and increase energy consumption showed that the multi-objective optimization approach can provide a set of answers that is a great help to the employer in order to achieve an economic plan based on the budget. available

The Water Column Separation phenomenon is one of the transient flow regimes, which is created under conditions such as the sudden closing of the valve or the shutdown of the pump in the water supply network. Hard pressure fluctuations and damages caused by the mentioned phenomenon require identifying and providing a solution to prevent it. By this purpose, the present article investigates the possibility of Water Column Separation in a Loop Water Supply Network using Computational Fluid Dynamics method. Next, the Effect of the inlet velocity on the pressures created due to the Water Column Separation was investigated. For software validation, the Loop system provided by Wang et al. (2017) was selected. After ensuring the efficiency of the software to model the phenomenon of Water Column Separation, simulation was performed at different speeds. Checking the simulation results indicated the occurrence of Water Column Separation in the Intended Network. Also, the Results indicated that with the increase of the input Velocity, the maximum value of the Pressure in the Network increases and its minimum value decreases. In such a way that with a 12% increase in the input velocity, the maximum pressure value changes by 11.8% and the minimum value by 14.26%. In general, it can be said that by controlling the Velocity as an effective factor on the pressure fluctuations of the Water Column Separation, this phenomenon and the resulting damages are prevented.

The various methods have been extensively studied by different researchers to reduce scouring around bridge piers, such as riprap, concrete blocks (CAU), collars, sacrificial piers, creating slot and roughness on the pier, and flow guide vanes, and their results generally relate to determining the size, location, and scope of installation and other geometric characteristics of the devices. Many countermeasures to prevent or reduce local scour around bridge piers, did not have the desired effective, and the concrete armor units (CAUs), which are made to protect shores from erosion caused by waves, have received very little attention in terms of bed armoring around the bridge piers.Therefore, the aim of the present research is to experimentally investigate the hydrodynamics of flow around a new element designed to protect the bed around bridge piers from local scour. The F-jacks, a concrete armor unit (CAU), is introduced and its role on flow characteristics is evaluated for the first time in this study. This concrete element is a new design of the A-jacks concrete model, with one leg and five branches on top, and the angle between the branches surrounding the leg and the central branch is 30 degrees to ensure minimum contact between the legs of the element and the sediment surface. The selection of a 30-degree angle for the branches of the F-jacks element is due to its similarity to the diameter of the bridge pier, to provide complete coverage around the pier.

The experiments of this research were performed in a 7-meter long, 50-centimeter wide, and 0.0001 slope flume with a rigid bed. A wooden cylinder with a diameter of D = 45mm and the same height as the flume was used as a model for a bridge pier and installed at a distance of 4.5 meters from the beginning of the flume (to develop the flow). The water depth (h) in the experiments was constant and equal to 15 centimeters, the flow rate (Q) was 0.021 m3/s, and the flow regime was fully turbulent and subcritical.In order to understand the physics of flow in relation to three-dimensional velocity variations, a Nortek Acoustic Doppler velocimetry (ADV) with a frequency of 25 Hz and a sampling duration of 120 seconds was used. In order to evaluate the hydrodynamics of the flow around the protected pier with F-jacks units, three different placement patterns around the pier were considered: 1) a non-dense arrangement (P1), in which 24 F-jacks elements were placed next to each other around the pier, 2) a dense arrangement (P2), in which 22 F-jacks elements are interlocked around the pier, and 3) an SP arrangement, which refers to a situation where the single pier is placed in the central axis of the flume.In addition to the measurement grid on the vertical XZ plane, a set of measurements was taken on the horizontal XY plane at Z/h=0.47 for each of the three selected patterns. To ensure the development of the flow in the test area, normalized meanvelocity component profiles were shown to follow a similar trend for two 4 and 4.3 meter-long sections from the beginning of the flume, and the velocity data conforms to the logarithmic law of velocity distribution that confirms the validity of velocity data for developed flow conditions. Also, to verify the accuracy and sufficiency of measurements in the developed flow region under investigation, the power spectral density (PSD) of time series for all three velocity components shows that the slope of the power spectrum agrees well with the Kolmogorov -5/3 law in the inertial sub range.

Contour and vector plots of the time-average streamwise velocity component (u ̅) indicated that when the F-jacks elements were placed according to the P2 pattern around the pier, the flow pattern around the pier changes completely. Where, in the upstream of the pier, the average velocity significantly decreased from the water surface to the bottom, indicating the growth of the minimum and weakening of the downflow and horseshoe vortices. In the downstream of the pier, the high-velocity flow region at rear the pier disappeared, and the flow turbulence was significantly reduced, and the region of flow recirculation in the wake of the pier completely disappeared.With the placement of F-jacks units around the pier, a strong upward vertical velocity (w ̅ ) is obvious around the pier compared to the single pier (SP pattern), which is stronger in the dense arrangement of the elements (P2 pattern). This factor refers to the positive effect of the presence of elements in reducing the growth of downflow (negative vertical velocity), reducing bed disturbances, and turbulence transfer away from the bed region in the wake area around the bridge pier.The streamwise and vertical components of flow turbulence intensity (u_rms 〖,w〗_rms ) significantly decreased with the placement of F-jacks units around the pier according to the P2 pattern. Where, in the near-bed region around the pier, the turbulence intensity decreased by an average of about 93% compared to the SP pattern, indicating the high ability of F-jacks elements in controlling and reducing flow fluctuations and turbulence in this region and diverting flow fluctuations towards the water surface and away from the bed.Comparison of Reynolds shear stress on XY plane at Z/h=0.47 for the three mentioned patterns revealed that -ρ(u^' w^' ) ̅ in the SP pattern is approximately 95% higher than P1 and P2 patterns, at the vicinity of the bridge pier. Furthermore, the magnitude of -ρ(u^' w^' ) ̅ has significantly decreased with the placement of F-jacks units as the P2 pattern around the pier.

The laboratory results presented in this paper provide a new understanding of flow behavior details around the bridge pier model with a new design of F-jacks armor units surrounding it on rigid bed conditions. The overall conclusion of this study showed that when F-jacks units are placed densely (P2 pattern) around the pier, the flow turbulence in this area is significantly reduced.

Longshore sediment transport is considered as one of the most important and influential factors in the functioning of coastal areas. Forecasting and determining the rate of this parameter along the coast and in the vicinity of coastal structures is one the most important for shoreline management during any construction and coastal management mission. This study aims to put different pieces of knowledge together, including field measurements, neural networks, and numerical modelling to obtain a more realistic estimation of the LST rate along the undeveloped Makran Coastline. The focus of this paper is mostly on accurate wave and sediment transport modelling, verified against available field data and morphological evidence. A neural network for the correction of wave data and a numerical model of Mike21 is applied for simulating the transportation process of sediments along the Makran Coastline. Zarabad port on the coast of Makran has selected the case study of this research. The results of this study showed that the observed data are not in good agreement with the output data of the model (except wave height) and need to be modified with the neural network and considering the effective parameters such as the different conditions of the waves in the monsoon and non-monsoon seasons in the Neural network. Neural network can help a lot in improving and correcting data. The results also showed that the sediment transport process occurs in different directions and depending on the wave height at depths more than 4m and at greater depths the sediment transport is insignificant, also, wave force in the region is able to transfer approximately 235000 m3 / year sediment.

Flood risk maps and Flood zoning techniques are useful tools to manage this hazard in the catchment and mitigation of flood impacts. In South Baluchestan and Kahir Basin, due to the existence of winter and summer precipitation regimes, the occurrence of flash floods is inevitable due to the establishment of rural communities and settlements in flood-prone areas, the flooding has caused many damages to the region's vulnerable population. In order to zone flood risk and prepare flood risk maps, climatic data, hydrological, land cover, and topography of the basin were prepared from reliable sources and according to scientific studies, 12 variables affecting flood risk in the form of five main components (Hydrology, vegetation, land cover, climate, and topography) were prepared. According to the regional conditions of the basin, using the opinions of experts based on scientific methods, the weight of each variable and component was determined by Analytical Hierarchy Process(AHP). Using two methods of fuzzy overlay, Weighted Overlay, and the Geographical Information System facilities, a map of variables and components was prepared after reclassification and fuzzy membership function with appropriate operators. The results showed that the fuzzy overlay method concerning its dominant logic has a better distinction of flood-prone areas and can help determine flood hazard micro-zonation in the drainage basins like the Kahir basin. By comparing the results from the real data of the January 2020 flood obtained from satellite images. Due to poor infrastructure and high economic, the risk of flooding may be more harmful and widespread in the future.

Industrial and urban development, Population growth and settlement are common cause of increased pollution. Pollutants are in many instances discharged untreated to rivers due to lack of adequate treatment facilities and high treatment cost. This paper considers assimilative capacity as an important water quality index when the river point source pollution is controllable. The simulation of pollution transport in the river and calculation of assimilation capacity is based on the mathematical equations of pollution propagation with no turbulent flow. The proposed procedure for water quality protection is applied in a hypothetical case study and the obtained results are expressed. The results demonstrate that the river flow variation can modify the assimilation capacity up to 97%.

Precipitation is predicted for different days of the year using fuzzy logic, the Mamdani fuzzy system, and IF-THEN rules. The input variables include five parameters of relative humidity, cloud cover, wind direction, temperature, and surface pressure, each with three membership functions ranging from  0 to 1. The final answer will likely be the amount of rainfall. All input variables are fuzzy, and two types of membership functions are selected. As many as 51 rules are considered for each station. Finally, the best situation of precipitation is chosen, and PMP obtained is applied to Kahir catchment basin, Sistan and Baluchistan. The fuzzy PMP is then calculated and compared with the Hershfield classic method for calculating PMP. Results show that fuzzy PMP estimation is more accurate and reliable for the studied area than the Hershfield method. All implementations are performed with MATLAB.

Lagrangian approaches such as the Moving Particle Semi-Implicit method and Smoothed particle Hydrodynamics are the latest techniques in Computational Fluids Dynamics and have attracted the attention of many researchers. Due to the Lagrangian nature of such practices, they can simulate various problems with large deformations and a variety of boundary conditions which has led to their application in many complex engineering problems. Therefore, the accuracy of the results obtained using these methods is substantial, while various parameters affect the accuracy of the simulation. In this paper, the sensitivity of a dam-break flow simulated by the Weakly Compressible Moving Particle Semi-Implicit method associated with the particle size and Courant number is analyzed. The analysis is performed in two circumstances. First, the Courant number is fixed, and the sensitivity relative to particle size is investigated. Then, sensitivity relative to the Courant number is studied in fixed particle size. In general, it can be concluded that the smaller the particle size and Courant number, the higher accuracy and computational cost.

Precipitation is an important variable in hydrological studies. The high spatial and temporal variability of precipitation makes it difficult to monitor it with observations. The use of satellite data and weather models is a suitable solution for this problem. But, before using these data, their spatial and temporal accuracy should be considered. The aim of this study was to evaluate the accuracy of monthly precipitation data TRMM_3B43_V7, PERSIANN, and ECMWF-ERA5 in comparison with the data of 13 observation stations in the South Baluchestan basin during the period 2000 to 2018. For statistical evaluation of the mentioned data, the coefficient of determination (R2), N-S efficiency factor, the degree of bias (BIAS), index agreement (IA), and ratio root mean square error (RRMSE) were used. The results showed that the best performance was exhibited by TRMM (R2=0.624) and ERA5 (R2=0.562), respectively. PERSIANN data (R2=0.307) did not provide an accurate estimate of precipitation. TRMM data are usually better estimated in areas far from the sea, which usually have higher elevations and receive more precipitation. The TRMM data is overestimated and the ERA5 data is underestimated. Data from both databases performed better in the winter months.

Hydropower requirement and agricultural development at upstream points of Hirmand River has significantly reduced the water discharge to Sistan region and the has been led to decreasing right of water and drying of Hamoon International Wetland. This, has been considered as the main reason of Hamoons of Sistan water volume reduce and increasing drought periods. Due to the 120-day winds and the location of Sabouri Wetland, one of the three wetlands in this region, some researchers introduced this wetland as the main source of dust in Sistan region. In this study, decreasing the effects of dust propagation due to water cover area using satellite images is investigated. For precise analyzing and estimating water demand for dust propagation decrease, water cover area in Sabouri Wetland and NDWI index in 113 satellite images from 2009 to 2013 are extracted. By calculating this index and water cover area no correlation between the above parameters is observed and specified that Sabouri is not the main source of the dust propagation. Also results indicated that between 2014 and 2018 the lowest water cover area equal to 150 million square meters was available in the region.

This article presents a case study of numerical simulation of effluent in Konarak plant. by collecting data related to the case study which includes data such as output water characteristics of desalination (water concentration, discharge, temperature, outlet geometry), environmental conditions including wind speed in the region, the velocity of water flow, tidal velocity, tidal depth, and sea surface profile, to launch a numerical distribution model pollution at the seashore have been investigated using Cormix11 software at different depths and the effect of important parameters of effluent distribution on distribution and considering environmental conditions have been studied.Numerical results show that increasing the discharge of effluent leads to more salinity in the sea. but in some cases, it can be managed with flow velocity and tidal time so that increasing discharge has less effect on water distribution in the sea.

Due to the strategic nature of water supply, dam construction projects are very important and at the same time costly projects. Various project-related risks are important factors affecting the economic viability of construction projects. Dam construction projects have a high risk among construction projects due to the need to spend a lot of time and money, as well as the appropriate quality and sometimes complex spatial conditions of the construction site. This research identifies and determines the importance of risks and their ranking in dam construction projects, using PROMETHEE multi-criteria decision-making method and GAIA analysis. To evaluate project risk, firstly, it is necessary to identify the types of risks in projects. Risks have been extracted using data from earlier researches as well as interviews with experts in the field of dam construction. The final selection of risks has been done by screening through fuzzy Delphi method. Then the ranking of risks and their impact on the project is determined using the PROMETHEE method and GAIA analysis. The results represented that exchange rate change, sanctions, geotechnical conditions, overpass and dam failure are the most important risks in dam construction projects. The results also indicated that the use of the PROMETHEE method and GAIA analysis can accurately rank the risk of dam projects and other construction projects.

This study investigates the effects of climate change on the water requirement of saffron in 13 regions of South Khorasan and Khorasan Razavi for three periods of 2030-2050, 2055-2075 and 2080-2100 using the Hybrid algorithms ANN-NSGA-II and ANN-ICA. For the first time, this research has obtained the water requirement of saffron based on climate change using the CMIP6 models and the scenarios of SSP245 and SSP585. In addition, for the first time, the main parameters of CMIP6 models have been calculated for the prediction of climatic variables. Statistical downscaling method and inverse distance weighting technique were used for downscaling and spatial interpolation of CMIP6 data, respectively. The ANN-NSGA-II model was used to select suitable parameters and the ANN-ICA model was used to predict the future of climatic variables and finally the Cropwat model was used to calculate the water requirement of saffron. The results of parameter selection showed that Hfls and Hfss parameters were selected for future prediction in 90% of cases. The mean percentage of precipitation decrease and increase of temperature of maximum and minimum were calculated for GFDL-CM4, MIROC6, and NorESM2-LM models (8.6, -1, 10), (10, 5.7, 8.7), and (6.6, 0.6, 9.1) in SSP245 scenario and (5.7, 5.6, 13), (12, 2.4, 11.6), and (8.2, 4.7, 3/17) in SSP585 scenario, respectively. The Water demand increased in 90% of stations, GCMs, and scenarios compared to the base period. The highest increase in water requirement was obtained in Golmakan for the MIROC6 model and the period of 2055-2075 with the amount of 87.1.

The application of dynamic and continuous time series has drawn attention due to the complexities of the rainfall-runoff process and the simplification of multiple regression and static methods. On the other hand, forecasting river flow is one of the main topics in flood control. This paper reports the results of applying the SWAT hydrological model to analyze the rainfall-runoff relationship for a 6-year period in the Kahir catchment basin, Sistan and Baluchistan province. The model output was calibrated by the SUF12 optimizer algorithm, and the data entered the model again. Then, the model output was used to forecast future periods using Support Vector Regression (SVR) and essential codes in MATLAB. The acceptable results of the SVR model regarding data prediction can be used as another method to estimate parameters and inputs.

Probabilistic designation is a powerful tool in hydraulic engineering. The uncertainty caused by random phenomenon in hydraulic design may be important. Uncertainty can be expressed in terms of probability density function, confidence interval, or statistical torques such as standard deviation or coefficient of variation of random parameters. Controlling cavitation occurrence is one of the most important factors in chute spillways designing due to the flow’s high velocity and the negative pressure (Azhdary Moghaddam & Hasanalipour Shahrabadi, 2020). By increasing dam’s height, overflow velocity increases on the weir and threats the structure and it may cause structural failure due to cavitation (Chanson, 2013). Cavitation occurs when the fluid pressure reaches its vapor pressure. Since high velocity and low pressure can cause cavitation, aeration has been recognized as one of the best ways to deal with cavitation (Pettersson, 2012). This study, considering the extracted results from the Flow-3D numerical model of the chute spillway of Darian dam, investigates the probability of cavitation occurrence and examines its reliability. Hydraulic uncertainty in the design of this hydraulic structure can be attributed to the uncertainty of the hydraulic performance analysis. Therefore, knowing about the uncertainty characteristics of hydraulic engineering systems for assessing their reliability seems necessary (Yen et al., 1993). Hence, designation and operation of hydraulic engineering systems are always subject to uncertainties and probable failures. The reliability, ps, of a hydraulic engineering system is defined as the probability of safety in which the resistance, R, of the system exceeds the load, L, as follows (Chen, 2015): p_s=P(L≤R) (1) Where P(0) is probability. The failure probability, p_f, is a reliability complement and is expressed as follows: p_f=P[(L>R)]=1- p_s (2) Reliability development based on analytical methods of engineering applications has come in many references (Tung & Mays, 1980 and Yen & Tung, 1993). Therefore, based on reliability, in a control method, the probability of cavitation occurrence in the chute spillway can be investigated. In reliability analysis, the probabilistic calculations must be expressed in terms of a limited conditional function, W(X)=W(X_L ,X_R)as follows: p_s=P[W(X_L ,X_R)≥0]= P[W(X)≥0] (3) Where X is the vector of basic random variables in load and resistance functions. In the reliability analysis, if W(X)> 0, the system will be secure and in the W(X) <0 system will fail. Accordingly, the eliability index, β, is used, which is defined as the ratio of the mean value, μ_W, to standard deviation, σ_W, the limited conditional function W(X) is defined as follows (Cornell, 1969): β=μ_W/σ_W (4) The present study was carried out using the obtained results from the model developed by 1:50 scale plexiglass at the Water Research Institute of Iran. In this laboratory model, which consists of an inlet channel and a convergent thrower chute spillway, two aerators in the form of deflector were used at the intervals of 211 and 270 at the beginning of chute, in order to cope with cavitation phenomenon during the chute. An air duct was also used for air inlet on the left and right walls of the spillway. To measure the effective parameters in cavitation, seven discharges have been passed through spillway. As the pressure and average velocity are determined, the values of the cavitation index are calculated and compared with the values of the critical cavitation index, σ_cr. At any point when σ≤σ_cr, there is a danger of corrosion in that range (Chanson, 1993). In order to obtain uncertainty and calculate the reliability index of cavitation occurrence during a chute, it is needed to extract the limited conditional function. Therefore, for a constant flow between two points of flow, there would be the Bernoulli (energy) relation as follows (Falvey, 1990): σ= ( P_atm/γ- P_V/γ+h cos⁡θ )/(〖V_0〗^2/2g) (5) Where P_atm is the atmospheric pressure, γ is the unit weight of the water volume, θ is the angle of the ramp to the horizon, r is the curvature radius of the vertical arc, and h cos⁡θ is the flow depth perpendicular to the floor. Therefore, the limited conditional function can be written as follows: W(X)=(P_atm/γ- P_V/γ+h cos⁡θ )/(〖V_0〗^2/2g) -σ_cr (6) Flow-3D is a powerful software in fluid dynamics. One of the major capabilities of this software is to model free-surface flows using finite volume method for hydraulic analysis. The spillway was modeled in three modes, without using aerator, ramp aerator, and ramp combination with aeration duct as detailed in Flow-3D software. For each of the mentioned modes, seven discharges were tested. According to Equation (6), velocity and pressure play a decisive and important role in the cavitation occurrence phenomenon. Therefore, the reliability should be evaluated with FORM (First Order Reliable Method) based on the probability distribution functions For this purpose, the most suitable probability distribution function of random variables of velocity and pressure on a laboratory model was extracted in different sections using Easy fit software. Probability distribution function is also considered normal for the other variables in the limited conditional function. These values are estimated for the constant gravity at altitudes of 500 to 7000 m above the sea level for the unit weight, and vapor pressure at 5 to 35° C. For the critical cavitation index variable, the standard deviation is considered as 0.01. According to the conducted tests, for the velocity random variable, GEV (Generalized Extreme Value) distribution function, and for the pressure random variable, Burr (4P) distribution function were presented as the best distribution function. The important point is to not follow the normal distribution above the random variables. Therefore, in order to evaluate the reliability with the FORM method, according to the above distributions, they should be converted into normal variables based on the existing methods. To this end, the non-normal distributions are transformed into the normal distribution by the method of Rackwitz and Fiiessler so that the value of the cumulative distribution function is equivalent to the original abnormal distribution at the design point of x_(i*). This point has the least distance from the origin in the standardized space of the boundary plane or the same limited conditional function. The reliability index will be equal to 0.4204 before installing the aerator. As a result, reliability, p_s, and failure probability, p_f, are 0.6629 and 0.3371, respectively. This number indicates a high percentage for cavitation occurrence. Therefore, the use of aerator is inevitable to prevent imminent damage from cavitation. To deal with cavitation as planned in the laboratory, two aerators with listed specifications are embedded in a location where the cavitation index is critical. In order to analyze the reliability of cavitation occurrence after the aerator installation, the steps of the Hasofer-Lind algorithm are repeated. The modeling of ramps was performed separately in Flow-3D software in order to compare the performance of aeration ducts as well as the probability of failure between aeration by ramp and the combination of ramps and aeration ducts. Installing an aerator in combination with a ramp and aerator duct greatly reduces the probability of cavitation occurrence. By installing aerator, the probability of cavitation occurrence will decrease in to about 4 %. However, in the case of aeration only through the ramp, the risk of failure is equal to 10%.

Modelling of water waves within a sewer network is a contemporary research area where the main goal is developing an accurate sewer design and planning tools. The prediction models should ideally be able to simulate the unsteady flow regime within the sewer network as well as the flow field created inside the manholes which link the surface flows to the sewer system. Manhole is one of the sewer network components which conveys surface flow to underground network. Inspection of the flow behavior when propagates and enters the sewer network is therefore momentous.

In general, modelling of such flows is only possible by means of Navier-Stokes equations with free surface capability. However, for a large domain and three-dimensional problem, the computational demands are rather high and prohibitive. The shallow water equations (SWEs), on the other hand, are a well-known system of conservation laws that generally require less computational resources in particular for areas of the flow where the fluid depth is assumed small compared to the entire width. Herein, the shallow water equations (SWEs) with the assumption of hydrostatic pressure is used as a proper substitution for Navier-Stokes equations to predict the wave movement. In order to solve the SWEs, a modified wave propagation algorithm with complex wave interaction capability over a dry-state is utilized. Moreover, an ODE system of equations is utilized to anticipate the flow action through the manhole. Then these equations are coupled with each other to unify the approaches. STAR-CD software is utilized to validate the results of abovementioned approach. The STAR-CD is the commercial Navier-Stokes solver based on the VOF (volume of fluid) approach which models free-surface motion quite generally, although at considerable computational expense. To calculate the error between SWEs results and STAR-CD solution, Root Mean Square Error (RMSE) method is used. RMSE is the standard deviation of the residuals (prediction errors). Residuals are a measure of how far from the regression line data points are; RMSE is a measure of how spread out these residuals are. In other words, it shows how concentrated the data is around the line of best fit.

First, to test the ability of the proposed approach, the interaction of dam break flow with two surcharged flows released on a dry bed is studied. This test case is important as it shows the ability of the proposed method in modelling multiple wave interactions over the dry-state. Then a 1D sewer network consisting of one manhole and an underground channel is considered and flowing water inside the system is modelled. For all test cases, the achieved numerical results were compared with those of the 3D Navier-Stokes solver, STAR-CD, which was setup to use the two-phase VOF solver for capturing free-surface. In addition, a dimensionless number named Manhole Number (MN) is defined based on the height of manhole and underground channel, manhole width and the velocity of the water entering the manhole. Moreover, many experiments are performed by changing the mentioned effective parameters to create a range for the manhole number. This range shows that the defined numerical solver gives accurate predictions if the MN is satisfied. Results are shown that if MN ≤ 0.98, the error obtained using RMSE method will be less than one percent and tends to zero. The simulation results show that in all investigated cases, a good agreement is observed between the solutions of the proposed method and the Navier-Stokes solver. This is despite observing some inherent drawbacks such as inability to capture cavities and model free-fall problems in the SWEs solutions.

inter-basin water transfer is the transfer of water from one basin to another. The basin which water is transferred to that is called the destination basin and the basin which water is transferred from that is called the origin basin. Inter-basin water transfer despite the supply of water in the destination basin, could possibly be the cause of changes in the origin and destination basins that need to be evaluated. The purpose of this study is to predict the possible effects of Beheshtabad River water transfer to the central plateau of Iran on the surface and volume of one of the aquifers in the origin basin called Shalamzar and also to provide different strategies during 30 years. For this purpose, WEAP software was used. According to the results, inter-basin water transfer can have a negative impact on the surface and volume of aquifers in the origin basin and cause a decrease in groundwater level. in order to prevent the reduction of the volume of aquifer, the maximum water transfer in normal water conditions and drought was estimated at 450 and 160 MCM per year, respectively. Also, the maximum amount of transferable water according to the environmental needs in normal water conditions, was estimated about 350 MCM per year. The results of the model indicate that the rate of decrease in the volume of study aquifer in the conditions of water transfer and in case of implementation of water resources development projects during 30 years will be about 5 times.

Scouring control in the downstream of the ski jump spillway is one of the most important issues faced by hydraulic engineers. In this study, an experimental investigation was done to evaluate the reduction of the maximum scour volume due to the combination of six-legged concrete elements (A-Jacks) in different hydraulic conditions. These elements were placed in the downstream of the ski jump spillway. The experiments included a single size of concrete element and two sizes of riprap with five discharges and three different tail-water depths. The change in depth of tail-water resulted in the spillway having free, semi-submerged and submerged states. The results showed that as the scour depth increased, the scour rate is reduced significantly. The simultaneous presence of concrete elements and riprap amid different hydraulic conditions caused a 100% decrease to the maximum scour volume when compared to the control tests. The use of A-Jacks when equated to riprap covered structures in a 100 m2 area indicated a 10% reduction in bed protection costs ( By use of Price list ).

Stepped spillways are technically and economically regarded as one of the most efficient options for energy dissipation of spillway flows. A remarkable amount of the flow energy is dissipated due to the hydraulic resistance of rough elements or those steps. Therefore, the energy dissipation obviates the need to build an energy dissipation system at the end of the downstream and reduces its size to a large extent. Considering the mentioned point and the required technology to use RCC in building such spillways, it is indispensable to thoroughly examine the hydraulic processes and the flows passing through them. The flows passing through the stepped spillways are divided into three types of nappe, transition, and skimming. Most studies concerned with stepped spillways have focused on nappe and skimming flows, while transition flows have not been fully addressed. Moreover, most of the stepped spillways’ designs have been based on nappe and skimming flows types. Therefore, the present study employed laboratory methods to examine the flow formation in transition mode in order to determine the upper and lower limit of the transition flow regime, and finally, provides more space for studying its characteristics. The flow regimes’ type depends on the step discharge and geometrical shape. Due to variations in the depth and velocity of flow, air concentration and energy dissipation in the three different regimes, it is essential to evaluate the flow in the regimes. Thus, the flow regimes’ onset has been the subject of many laboratory studies. The previous experiments and studies have shown that the nappe flow onset is a function of the height and length of step and also, the critical depth. This research was conducted in Water Research Center of Power Administration in order to determine the range of transition flow regime and hydraulic parameters of various flow regimes, including dynamic pressure at the steps’ bottom and the depth of flow passing over the steps as a flow profile. To do so, spillways’ models of Siahbisheh dams were used, which were constructed with the scale of 1:15 and 1:20. The flow will be fully developed, after passing through the spillway crest and the aeration inception point. The upper and lower limits of the transition flow regime were determined by letting different discharges pass over the spillways. To detect the nappe flows’ entrance into the transition flows, i.e. the lower limit of transition flow regime, the inception of water spray can be used. The water spray level will be higher in sloped spillways. Moreover, the flow jet has more fluctuations in the transition flow regimes of pool; in other words, it will be in immersion mode. In addition, some flow rotation works can be noticed. The criterion for determining the threshold for the onset of skimming flow, i.e. the upper limit of transition flow, is the flow slipping from the edge of one step onto the next. It is worth mentioning that existence or lack of air holes does not play any role in proving this. This is in contrast to Chanson’s theory; however, it is in line with Chamani and Rajaratnam’s view. The onset of flow rotation in the pool below the step was also taken into account; these rotations are not still complete enough to enter the skimming flow section. After determining the flow regimes, the dynamic pressure and profile of passing flow were measured in transition regimes. In order to measure the pressure exerted on the steps’ bottom, 3 piezometers at (y/l), which are equal to 0.14, 0.45, and 0.71, were installed on four spillways. Transducer system adapters, computer systems and an information processing software were used in order to measure the dynamic pressure moment-by-moment. The pressure sensors used in the experiment were 0.150 kg/〖Cm〗^2 (150 mbar). The pressure fluctuations in each piezometer were recorded during 30 seconds with the frequency of 100 hertz. To measure the flow profile, without accounting for water spray, a point gauge was used. The results of the study revealed that the increase in the spillway slope reduces the area for occurrence of transition flow regime. Moreover, as the ratio of h/l increase the ratio of y_c/h decreases, which shows faster formation of a skimming flow. In the nappe flow regime, it is noticed that pressure increases from the step bottom to the edge, where it moves with a slight slope to the middle of the step and then, continues with a steep slope. In the nappe flow regime, increasing the spillway slope, increases the pressure from the step bottom toward the edge. Moreover, the maximum and minimum pressures occur near the step edge. With respect to the transition flow regime, the pressure remains almost constant from the step bottom up to y/l=0.4 and then continues with a steep slope toward the step edge. In addition, in the transition flow regime, the maximum and minimum pressures occur on the step edge. In the skimming flow regime, the mean pressure increases from the step bottom toward theedge. This increasing trend has a direct influence on the spillway slope. The maximum pressure occurs in the middle of the step and then decreases with a slight slope. Similarly, the minimum pressure occurs in the middle of the step and then, increases toward the step edge. Finally, in the skimming flow regime, increasing the spillway slope is followed by a decrease in the maximum pressure.

The rainfall Intensity–Duration–Frequency (IDF) relationships are among the most important requirements in the field of planning, design and operation of hydraulic structures and water resources different projects. Mainly the creation of IDF curves requires statistical analysis of precipitation data at different durations and so when the study basin is no data or has limited statistics, the survey is difficult. However, in most basins, availability to daily precipitation data is easily possible. Therefore, aim of present study is an evaluation and comparison of IDF curves derived from the integrating fractal theory and generalized extreme value distribution relationship for ungaged site on the basis concept of fractal properties of precipitation with the empirically common relationships and determination of the error rate and calculation accuracy and reliability of this relationship into other relationships.
In this research, by using of data of maximum depth of annual rainfall at daily duration, construction of IDF curves with the method based on the approach of an integrated of fractal nature of rainfall data and generalized extreme value distribution was done. Then, IDF curves was created by applying Ghahraman method of the empirical relationship was given for this method and at the conventional method of statistical analysis of extreme annual rainfall data at different durations for study station. Ultimately, evaluation and quantitative and qualitative comparison of results of fractal theory method with Ghahraman empirical relationship was done. This research was applied for the Chenaran rain gauge station at latitude 〖36〗^° 〖 38〗^' 〖 38〗^" and longitude 〖59〗^° 〖07〗^' 〖53.1〗^".
Investigation of Fractal behavior in precipitation data at the Chenaran rain gauge station showed precipitation properties at time range from 1 to 7 days, follows from the simple scaling hypothesis (Monofractal) and the estimated design storm by fractal theory has a good agreement with the precipitation observed data. The results at Chenaran rain gauge station shows the accuracy superiority of an integrated of fractal theory and generalized extreme value distribution relationship with an error average 9.34 than the Ghahraman empirical relationship with an error average 16.43. In addition, estimation error of quantities IDF by the fractal theory relationship to the conventional method that is based on the real data at 24 hours duration was calculated zero. So far as the construction of IDF curves by an integrated of fractal theory and generalized extreme value distribution relationship, only is done by using the 24-hour maximum rainfall intensity data; it can be concluded; the mentioned method has the suitable accuracy and acceptable results.
The present research is an attempt to increase the use of IDF scaling relationship than to using of compiled empirical relationships that conducted without regard to geographical and hydrological conditions; for using in regions that are faced with deficiency or the lack of rainfall data. The important characteristics of this relationship is the foundation of it based on the fractal properties of rainfall and in contrast, prepared of IDF curves in both experimental and conventional method is only depends on the statistical and mathematical analysis without attention to physical principles of precipitation process, and thus will follow increase the uncertainty of the results.

In this paper the effect of different coating types of rebar on bars corrosion and durability of self-compacting concrete structures in Oman Sea (Chabahar port) are investigated. Self-compact concrete samples with three types of coating include 40 and 60 micron of zinc, epoxy and uncoated with 3,5 and 7 cm thickness of concrete cover were made and cured according to the related standards in tidal, submerged and atmospheric conditions for 14 months. Compressive strength test according to Standard BS 1881 part 116, water absorption according to Standard BS 1881 part 122, permeability test under water pressure according to Standard DIN 1048, permeability of chloride ion according to Standard ASTM C1152, electric resistance Cabera and corrosion potential according to ASTM G876 and bar weight loss were performed at different ages of samples. The results of weight loss and corrosion experiments indicate better performance of concrete with epoxy and zinc coated bar comparing to uncoated samples at different conditions. Also, 40 micron zinc coating decreased the weight loss of bars about 10 percent comparing with uncoated bars. The epoxy coating was decreased the weight loss about 4-8% on different samples. It should be noted that the increase of concrete cover from 3 to 5 and 7 cm decreased the weight loss from 34 to 27 and 21%.

Accurate investigation of physical phenomena is one of the important challenges in engineering fields. The present study is about a wet tank which entrance of water is investigated in three cases. When the water wave moves into a tank, complex flow regimes are created. This complexity is mainly associated with different flow mechanisms during the entrance of water and propagation of waves at the bottom bed that should be modelled by means of Navier-Stokes equations with free-surface capability and in 3D phase. Due to complexity and time consuming of Navier-Stokes equations modelling, Shallow water equations are used with the assumption of hydrostatic pressure. First case is about efflux over a wet bed. Second, water influx from the middle top is investigated and then influx from top edges is modelled. A dimensionless number is introduced for each case based on water velocity, gap length and drop height which shows acceptable domain for appropriate compatibility between results. Finally, results of numerical modelling are compared with Navier-Stokes solutions which are obtained from STAR-CD software. Results show admissible compatibility with each other based on observations and inspections.

A dam spillway is a hydraulic structure that appropriately and safely diverts the outflow to downstream, so that the dam stability and passing of flood flows can be guaranteed. Compared to straight crest spillway, an Ogee spillway with curvature in plan in a fixed-width can pass more flow. Therefore under the low hydraulic heads and the need for a smaller place in plane, they are considered as an economical structure so that their application from several aspects are under developed. An experimental model of the Garmi-Chay Miane dam spillway was made in 1:50 scale. The water head over spillway crest was measured in the eight discharges values and consequently the efficiency of spillway were determined. For Q/Qd ranging from 0.63-1.13, discharge coefficient had ascendant trend with acceptable agreement against the diagram of USBR, while for Q/Qd between 1.13-1.51, due to the submergence of spillway, the discharge coefficient decreased.

Dam spillways are the structures that lead rightly and safely the outflow downstream, so that the dam integrity can be guaranteed. Many accidents with dams have been caused by an inadequate spillway design or insufficient capacity. To accurately respond the hydraulic spillways, designers use physical modeling for designing this kind of structures. The scale effect in the spillway modeling, as a result, leads to the difference between the measured data and the prototype. In this study, an experimental model of Germi-Chay Mianeh dam spillway was made in three 1:100, 1:75, and 1:50 scales. Then, the water level in upstream of the spillway crest was measured in seven discharges and compared to 1:50 scale (basic scale), the percentage of water level difference on the crest was calculated in two physical models with 1:100 and 1:75 scales. Results revealed that as the scales of ogee spillway with an arc in plan and converging training walls decrease using Froude simulation, the effect of viscosity and surface tension increase in turn resulting in decreasing discharge coefficient. In this study, the scale effect in discharge coefficient ogee spillway was stated with K' equation. Using model family approved that the minimum Reynolds and Weber numbers which are 3.1×104 and 270, respectively indicated the minimum scale effect and thus, it is possible to avoid the effect of viscosity and surface tension in ogee spillway with an arc in plan and with converging training walls. Moreover, results obtained from the small scale which has been simulated using Froude simulation could be extrapolated to the prototype.