فهرست مطالب افشین اقبال زاده

Climate change has been a crucial environmental issue in recent years, with global warming, water crisis, and ecosystem changes drawing significant attention. Scientists have been developing various scenarios of greenhouse gas emissions to model future climate changes.Prior research has focused on forecasting rainfall using the fifth climate change report, with little attention to the future socioeconomic impacts. This study addresses monthly rainfall prediction for the Kermanshah synoptic station using data from the sixth climate change report, considering various social and economic scenarios.

The Kermanshah province, located in the western part of the country, spans 24.64 square kilometers, in Iran. It stretches between the latitudes of 33° 36' to 35° 15' north and the longitudes of 45° 24' to 48° 30' east. The Kermanshah synoptic station is situated at the coordinates of 34° 21 longitude and 47° 10 latitude.One challenge with using AOGCM model outputs in regional climate change studies is the mismatch in spatial scale between the model's computational cells and the study area. At the same time, regional studies need data at a resolution of 50 kilometers or less to assess the effects of climate change. The current study utilized the Delta Change Factor (DCF) method to reduce the scale of GCM model data. In CMIP6, models typically feature enhanced resolution and improved dynamic processes. The simulation of future climate changes has utilized the Shared Socioeconomic Pathways (SSP) scenarios. These scenarios, employed in CMIP6, forecast global socioeconomic changes until 2100. The study utilizes the SSP5_8.5, SSP2_4.5, and SSP1_2.6 scenarios.To assess model accuracy, RMSE (Root Mean Square Error) and NSH (Nash-Sutcliffe Efficiency)are used as indicators.

In this study, three climate models - CanESM5, MRI-ESM2-0, and MIROC6 - were utilized to forecast monthly rainfall variability in Kermanshah synoptic station for the sixth climate change report across three future periods: 2026-2050, 2051-2075, and 2076-2100 under SSP126, SSP245, and SSP585 scenarios. The comparison of the trend of monthly rainfall changes in the corrected data indicates that the MIROC6 model predicts the median for the Kermanshah region with the least error compared to the other two models.In all scenarios, there is a decreasing trend in monthly precipitation. The lowest amount of precipitation is related to the months (JUNE-JULY-AUGUST-SEPTEMBER), while the highest amount of precipitation occurs in the months (APRIL-MARCH-NOVEMBER) across the near future, mid-term, and far future. The average rainfall in the SSP126 scenario is predicted to be higher for the MIROC6 model than for the other two models shortly (2026-2050). In the mid-term future (2051-2075), the MIROC6 model predicts less rainfall than the other two models, and in the far future (2076-2100), the CanESM5 model predicts the highest average rainfall for April. In the SSP245 scenario, shortly (2026-2050), the MRI-ESM2-0 model predicts the highest amount of rainfall for November, and the rest of the values are similar. In the mid-term future (2051-2075), the predictions of the models are almost similar, and in the far future (2076-2100), the MIROC6 model predicts the highest average rainfall for March, the CanESM5 model predicts the highest average rainfall for April, and the MRI-ESM2-0 model predicts the highest average rainfall for November. In the SSP585 scenario, shortly (2026-2050), the MRI-ESM2-0 model predicts more rainfall than the other two models. In the mid-term future (2051-2075), the CanESM5 model predicts the highest amount of rainfall for November, and in the distant future (2076-2100), the MRI-ESM2-0 model predicts the highest amount of rainfall for November, while the CanESM5 model predicts approximately the highest average predicted rainfall.

The most significant changes in monthly rainfall are expected to occur after bias correction in the first period (2026-2050) in the MRI-ESM2-0 model scenarios. The MIROC6 and CanESM5 models show similar predicted rainfall changes. In the second period (2051-2075), the trend of monthly rainfall changes for all three scenarios is more similar. However, the MIROC6 and CanESM5 models under the SSP126 scenario have predicted greater increases in rainfall compared to the SSP245 and SSP585 scenarios of the MRI-ESM2-0 model during this historical period. The MRI-ESM2-0, MIROC6, and CanESM5 models are suitable for use in the study area after bias correction, based on the validation index values for all three scenarios and models. Nonetheless, there are differences in the accuracy of the models for examining various climate change parameters and different climate regions. For instance, the MIROC6 model exhibits the highest accuracy for predicting monthly rainfall, while the MRI-ESM2-0 model has the lowest accuracy. The accuracy of the MRI-ESM2-0 model for predicting monthly rainfall in this study area is lower, but its accuracy for other climate change parameters and different regions may yield different results. The comparison of observational data and historical scenario model data in the study area for predicting future monthly rainfall shows that the best models for the study area are MIROC6 and CanESM5.

In this research, the effect of climate change on the groundwater level of Chamchamal Plain in the two 20-year periods was investigated. The GMS groundwater model was used to simulate the aquifer and was calibrated and verified for evaluation and validation of the model for two periods of 18 months, respectively. In order to investigate the effect of climate change on the fluctuations of groundwater level in the region, six AOGCM models were used under three emission scenarios A2, A1B, and B1 in the upcoming period. Then, two methods of weighting and extraction of probabilistic levels were used to consider the uncertainty prediction of climate change models for temperature and precipitation parameters. The predicted climatic variables for scenarios A2, A1B and B1, and two Probability levels 90% and 50%, respectively, show the average temperature changes of +0.57, +0.57, +0.57, -0.04 and +0.6 °C and average precipitation variation of +0.12, -1.8, +2.49, -31.78 and -2.33 during the period 2011-2030. Similarly, for the period 2046-2065, the average temperature changes were +1.92, +2.12, +1.46, +0.98 and +2.3°C, and the average precipitation variation was -20.59, -26.07, -19.55, -47.15 and -15.74 percent. Finally, the effect of climate change on the aquifer level was determined under scenarios. The results showed the groundwater level, under scenarios A2, A1B and B1 and two probabilistic levels of 90 and 50 percent for the periods 2011-2030 and 2046-2065 will drawdown between -9.6 to -17.92 meters, which is Compared to the period 1996-2015, it showed a change in level between -1.06 to -9.38 meters.

Flooding of rivers is accompanied with a threat on the population living on their floodplains and on the neighboring settlements. Accurate modeling of such flows is thus imperative to assess flood risks, perform real-time flood routing, or estimate the impact of a mitigation schema.The converging of the compound channel causing the flow become even more complicated. The flow patterns in converging compound channel and free-surface profile has been simulated by using RSM turbulence model and VOF method, respectively. The comparison of the experimental results including longitudinal free surface profiles, depth-averaged velocity distribution and the ratio between floodplains and total discharge confirmed that the numerical simulation can be used to model the flow pattern in converging compound channel. Furthermore, Absolute Percentage Error (APE) for each of these parameters was amounted to 3.25%, 4.66% and 9.72%, respectively. Respect to the numerical simulation capability in anticipating the flow field parameters, we investigated the effect of relative depth on the flow patterns in a converging compound channel. Moreover, the flow parameters including velocity distribution, depth-average velocity, secondary flows, ratio between floodplain and total discharge, bed sheer stress and energy dissipation were investigated in different relative depths h* (0.1, 0.2, 0.3, 0.4 and 0.5). By evaluating and comparing the flow results in the different relative depths, we came to conclusion that the longitudinal-average velocity in the main channel increased as the cross section was narrowed. However, the longitudinal-average velocity in the floodplains decreased in the relative depths of 0.1 and 0.2 as the cross section was narrowed. In contrast, this parameter increased in the relative depths of 0.3, 0.4 as well as 0.5 the floodplains narrowed. Velocity gradient between the main channel and floodplains in the relative depth of 0.1 was strong and in the relative depth of 0.5 was insignificant. In the smaller shallow depth, this velocity gradient has been resulted in secondary flow in the cross section of converging compound channel. Accordingly, in the relative depth of 0.1 and 0.2 four cells of secondary flows were formed and in the relative depth of 0.3 just two cells of secondary flows were formed. The secondary flows in the relative depths of 0.4 and 0.5 was eliminated. Convergence in the length of main channel get the discharge conveyance capacity of floodplain to decrease. furthermore by decreasing the relative depth the capability of floodplains to conveyance the discharge was significantly decreased. This decrease was evident in the depth of 0.1 in which the ratio between floodplain and total discharge was amounted to 2.52%. Sheer stress in channel bed increased when the relative depth of the main channel increased and the maximum amount of bed shear stress was happened at end of the channel. On the other hand, in the floodplains, this parameter decreased along with the converging in the lower relative depths (0.1, 0.2) and for the other relative depths the bed sheer stress increased along with converging. In channel inlet the maximum and minimum amount of energy dissipation was resulted at the relative depth of 0.1 and 0.5 respectively.

Side weir is one of the water diversion structures which is widely used for different purposes such as deviation of the excess water in the urban wastewater collection systems, irrigation networks, control of the floods’ elevation, etc. In some conditions, a spatially varied flow over the side weir might include hydraulic jump which has been less studied yet. In present study the hydraulic jump issue was investigated using a Flow-3D software model. The model was validated with experimental data and the results showed that the numerical model was able to simulate the hydraulic jump with reasonable accuracy. Then, the effect of the downstream water depth on the characteristics of the hydrulic jump was investigated. By decreasing the downstream water depth, the location of the hydraulic jump moved toward the weir downstream end while the hydraulic jump was removed by increasing the downstream water depth. By moving towards the end of the weir, the longitudinal velocity distribution became non-uniform due to formation of the separation zone near the main channel bed flow and the areas with negative velocities were formed.

One of the important purposes of the river engineering is to protect the river banks from erosion phenomenon and to prevent the shifting of the main channel path. Spur dike is a hydraulic structure which has a lot of applications for stabilizing riverbanks and increasing water depth. Owing to the widespread use of thisstructure , it is important to understand the flow patternaround it.Since flow pattern around a spur dike is complex and fully 3D, hence a 3D simulation has been done in this study. FLOW-3D software was employed to simulate the flow around a submerged spur dike. VOF method was used for free surface simulation and RNG k-εmodel was used for turbulence modeling. Based on comparison of the numerical and experimental results for stream wise velocity components and flow depths, it was concluded that the numerical model could simulate the flow passing the submerged spur dike. Then the effect of the spur dike length on the velocity profiles, free surface and flow pattern was studied. Based on the results, the maximum stream wise velocity in the nose of the spur dike increased with increase of spur dike length. This velocity showed about 24% and 59% increase in case of the spur dike with 0.1m and 0.4m length, respectively. Also, the flow depth incr eased with increase of the spur dike length

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.

Scour generation and its development around bridge piers are the main causes of bridges damage and failure. Understanding the scour mechanism is essential to predict the scour and equilibrium scour hole status around bridge piers. In the recent decades, the use of compound bridge piers instead of the simple piers in construction of bridges, has been developed. In this study, using the FLOW-3D software, process of the formation and development of the scour around bridge pier with compound geometry has been investigated. Numerical results obtained from this model were compared with available experimental data. The results showed that this model had the capability to predict the threedimensional flow field and could effectively provide a better understanding of the experimental studies. The results also indicated the complexity of turbulent flow near pile cap so that these flows were deflected in all directions. On contrary to the simple pier, in which the positive maximum velocity occurred in the sides of pier, in the case of piers with compound geometry this velocity occurred in the center of the pier and downstream of the pile cap.

Diversion structures in side wall of open channel are to be used in order to divert flow from main channel. Side weirs, side orifices and side sluice gates are diversion structures which have wide application in dams, irrigation, drainage systems and combined sewer systems. Side weirs are one of the most important and applicable hydraulic structures for water controlling and directing systems that requires careful review and accurate designing due to their critical importance .In this paper, the flow over a sharp-crested rectangular side weir in 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, results related to the distribution of the different components of velocity and angle of the outlet jet adjacent to the crest of the rectangular sharp crest side weir at various heights of the weir crest are validated with experimental data from Bagheri and Heidarpour (2012) research. Then the effects of upstream Froude number on flow pattern and free surface around the side weir were investigated. The results of this study indicated that with decreasing Froude number, maximum and minimum longitudinal velocity along the side weir increases and decreases, respectively. The maximum lateral velocity along the side weir increased with decreasing Froude number. That is why the discharge through the side weir increased with decreasing Froude number. The maximum vertical velocity along the side weir increased with decreasing the upstream Froude numbers because more flow is diverted to the side weir with decreasing the upstream Froude numbers. Distribution of the different components of velocity in the direction of flow height in the middle of the weir crest indicated that by reducing the upstream Froude number, longitudinal velocity distribution in the depth direction became more non uniform, especially near the weir crest. For different Froude numbers, lateral velocity would increased up to a certain elevation from the weir crest and then decreased toward the free surface. By increasing Froude number, the maximum lateral velocity occurs at greater heights above the side weir crest. The maximum vertical velocity for different Froude numbers occurred near the weir crest. Vertical velocity gradually decreased toward the free surface. By reducing the upstream Froude number, the vertical velocity near the free surface of flow is negative due to flow motion to downward. Free surface of the flow experienced extreme changes at the end of the side weir when upstream Froude number was increasing. By increasing the Froude number, the angle of inclination of the outlet jet along the side weir increases. Also by increasing the Froude number, the separation zone around the side weir in near the main channel bed, especially in the channel cross-section decreases.

One of the important purposes of river engineering science is to protect river banks from erosion phenomenon and to prevent shifting of the main channel path. Spur dike is a hydraulic structure which has a lot of applications for stabilizing river banks and increasing water depth. According to widespread use of this structure, it is important to understand the flow pattern around it. Since flow pattern around a spur dike is complex and fully 3D, 3D simulation was done in this study. FLOW-3D software was employed to simulate the flow around a submerged spur dike. VOF method was used for free surface simulation and RNG k-ε model was used for turbulence modeling. Based on comparison of numerical and experimental results for stream wise velocity component and flow depth, it was concluded that numerical model could simulate the flow parameters with relatively high accuracy. In following, the effect of discharge increase on velocity profiles and flow free surface was investigated. According to obtained results, maximum longitudinal velocity Infront of the spur dike nose and flow depth at the upstream of spur dike increased with discharge increase. In lower discharges, the changes rate was more and vice versa. Also, the ratio of the flow depth at the upstream and the flow depth at the downstream increased with discharge increase.

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.

In recent years, newly-developed data mining and machine learning techniques have been applied in various fields to build intelligent information systems. However, few of these approaches offer online support or are flexibleto be adapted to large and complex datasets. Therefore, the present research work adopts Particle Swarm Optimization (PSO) techniques to obtain appropriate parameter settings for membership function and integrates the Adaptive-Network-based Fuzzy Inference System (ANFIS) model to make the model fit for predicting scour depth. A dataset of 188 scour depths for single piers presented by the USGS was used. Results of the model prediction show that the derived model is best fitted to the field data. The proposed one-order momentum method is able to learn quickly through one-pass training and provides high-accuracy short-term predictions. Moreover, this method is suitable for online learning but the two-order momentum method is appropriate for incremental learning. The PSO-ANFIS approach could provide better results in predicting scour depths compared with other models.

Nowadays, due to human progress in computer science, many models have been produced to simulate hydrodynamic and water quality of the water bodies. Among these models, CE-QUAL-W2, a two-dimensional width-averaged model, has been extensively used as a commercial model all around the world. Since this model included a large number of calibration coefficients and there is no standard guideline for calibration, the model calibration is a time-consuming process. In this paper, an appropriate method has been introduced for model calibration. This method reduces the run time and increases the simulation accuracy. In the proposed method, first, the effective coefficients were identified by sensitivity analysis. Then, the calibration performs after classification of the coefficients. For this purpose, the data of 15-Khordad dam reservoir measured at the end of each month of 1997 were used. The results showed that this method was suitable for making accurate predictions of temperature distribution and reducing run time. As the Absolute Mean Error (AME) for water surface elevation and temperature were obtained 2.5 cm and 0.45 °C, respectively. Nowadays, due to human progress in computer science, many models have been produced to simulate hydrodynamic and water quality of the water bodies. Among these models, CE-QUAL-W2, a two-dimensional width-averaged model, has been extensively used as a commercial model all around the world. Since this model included a large number of calibration coefficients and there is no standard guideline for calibration, the model calibration is a time-consuming process. In this paper, an appropriate method has been introduced for model calibration. This method reduces the run time and increases the simulation accuracy. In the proposed method, first, the effective coefficients were identified by sensitivity analysis. Then, the calibration performs after classification of the coefficients. For this purpose, the data of 15-Khordad dam reservoir measured at the end of each month of 1997 were used. The results showed that this method was suitable for making accurate predictions of temperature distribution and reducing run time. As the Absolute Mean Error (AME) for water surface elevation and temperature were obtained 2.5 cm and 0.45 °C, respectively. Nowadays, due to human progress in computer science, many models have been produced to simulate hydrodynamic and water quality of the water bodies. Among these models, CE-QUAL-W2, a two-dimensional width-averaged model, has been extensively used as a commercial model all around the world. Since this model included a large number of calibration coefficients and there is no standard guideline for calibration, the model calibration is a time-consuming process. In this paper, an appropriate method has been introduced for model calibration. This method reduces the run time and increases the simulation accuracy. In the proposed method, first, the effective coefficients were identified by sensitivity analysis. Then, the calibration performs after classification of the coefficients. For this purpose, the data of 15-Khordad dam reservoir measured at the end of each month of 1997 were used. The results showed that this method was suitable for making accurate predictions of temperature distribution and reducing run time. As the Absolute Mean Error (AME) for water surface elevation and temperature were obtained 2.5 cm and 0.45 °C, respectively. Nowadays, due to human progress in computer science, many models have been produced to simulate hydrodynamic and water quality of the water bodies. Among these models, CE-QUAL-W2, a two-dimensional width-averaged model, has been extensively used as a commercial model all around the world. Since this model included a large number of calibration coefficients and there is no standard guideline for calibration, the model calibration is a time-consuming process. In this paper, an appropriate method has been introduced for model calibration. This method reduces the run time and increases the simulation accuracy. In the proposed method, first, the effective coefficients were identified by sensitivity analysis. Then, the calibration performs after classification of the coefficients. For this purpose, the data of 15-Khordad dam reservoir measured at the end of each month of 1997 were used. The results showed that this method was suitable for making accurate predictions of temperature distribution and reducing run time. As the Absolute Mean Error (AME) for water surface elevation and temperature were obtained 2.5 cm and 0.45 °C, respectively. Nowadays, due to human progress in computer science, many models have been produced to simulate hydrodynamic and water quality of the water bodies. Among these models, CE-QUAL-W2, a two-dimensional width-averaged model, has been extensively used as a commercial model all around the world. Since this model included a large number of calibration coefficients and there is no standard guideline for calibration, the model calibration is a time-consuming process. In this paper, an appropriate method has been introduced for model calibration. This method reduces the run time and increases the simulation accuracy. In the proposed method, first, the effective coefficients were identified by sensitivity analysis. Then, the calibration performs after classification of the coefficients. For this purpose, the data of 15-Khordad dam reservoir measured at the end of each month of 1997 were used. The results showed that this method was suitable for making accurate predictions of temperature distribution and reducing run time. As the Absolute Mean Error (AME) for water surface elevation and temperature were obtained 2.5 cm and 0.45 °C, respectively.

Dynamic stream flow (River Ecosystem) becomes static mound (Lake Ecosystem) after constructing dam on the river. The most important difference between them is of retention time and stratification which induce different qualification to water river prior to reservoir and afterwards. In this study, heat distribution within15-Khordad Reservoir was simulated using 2-D laterally averaged CE-QUAL-W2 model during the year 1997. Then, results which obtained through this model were made comparison by those of 1-D DYRESM model and field data as well. Results showed that both of models are succeeded in simulation of the reservoir temperature profiles in turn over period, hypolimnion and metalimnion forecasting. But DYRESM model was weak in simulation of epilimnion temperature forecasting in stratification period. In the following, two models were used to calculate the heat flux relationships that are aimed at achieving these differences. Since 15Khordad dam is located in an area which evaporation is an important factor, two different equations to calculate the heat flux model is used to evaporate, lead to underestimation of the actual amount of evaporation in the DYRESM model and the difference in temperature epilimnion simulations compared with measured values.

Using slot in bridge piers is one of the reduction methods of scour depth around them. In this study، the flow field around a cylindrical pier located in a smooth bed with and without slot was simulated using FLOW-3D software. The RNG k-ε turbulence model was used for closing the Navier-Stokes equations. The comparison of the numerical results and laboratory measurements for one bridge pier without slot showed that the model could predict velocity and shear stress parameters with reasonable accuracy. The influence of the slot width on the flow field around bridge pier was then investigated. The formed vortex at downstream of the pier became smaller by increasing slot width. In the largest slot case، this vortex was completely disappeared. Also، by increasing slot width، the value of the maximum velocity occurred adjacent the pier decreased، but its location was fairly constant. Finally، because of the lower reduction of the longitudinal velocity of the flow in the vicinity of the upstream face of the pier for the largest slot، shear stress pattern in this area was similar to that of the upstream area.

The assessment of water quality in reservoirs is essential because reservoirs are often one of the main sources of water for human consumption and irrigation. In this paper، a two-dimensional، laterally averaged CE-QUAL-W2 model was used to simulate the water surface elevation، water temperature، and water quality parameters such as dissolved oxygen and nutrients in the Ilam dam reservoir. After simulating the water level، the temperature and dissolved oxygen were respectively simulated with an average absolute error 0. 76°C and 1. 41mg/L during the calibration period and 1. 18°C and 1. 18 mg/l during the verification period. The model results showed relatively good agreement between the measured and simulated data. After model calibration and validation، in order to investigate the hydrological changes on reservoir water quality، two inflow scenarios were simulated based on the dry and normal years. The results of the dry year indicated a six-month stratification period from April to September. Due to increase of water retention time in the dry years، Chlorophyll A concentrations increased in summer so that the reservoir conditions changed from mesotrophic to eutrophic. A similar pattern was observed between the temperature and dissolved oxygen profiles. In the normal year، stratification period included seven months from April to October. Due to decrease of water retention time in reservoir in the normal year، Chlorophyll A concentrations decreased in summer so that the reservoir conditions changed from mesotrophic to oligotrophic condition.

Flow pattern in river bends is very complicated and fully three dimensional in nature with high turbulence intensity. This type of flow has a great influence on the river morphology by eroding the outer bank which results in deposits of sediment at the inner bank. Owing to the importance of the study of such flow، in this study flow in bend was simulated using FLOW-3D software. FLOW-3D utilizes a volume of fluid (VOF) method for free surface simulation. RNG turbulence model was used for closing the 3-D Reynolds-averaged Navier-Stokes equations. Experimental data from a laboratory study of flow in a rigid bed channel with a 90 degree bend were used to verify the results from the numerical model. The central radius of the bend and ratio of radius of the bend to width were 2. 4 m and 4، respectively. Numerical results showed good agreement with the experimental results. Then four ratios of radius to width of the bend: R/B=2، 3 4 and 5 were simulated to study the effect of ratio of radius to width on flow pattern. Based on the results of the longitudinal velocity component، at the start of the bend the cross-section maximum velocity occurred adjacent to the inner bank for all ratios of radius to width. Toward the end of the bend، in the sharpest bend (R/B=2)، maximum velocity occurred adjacent to the inner bank، but it shifted to the area close to the outer bank for other ratios of radius to width. The transverse slope of the free surface increases as the ratio of radius to width decreases.

Prediction and control flood is essential in water resource management. Studying and analysis on this problem is done using flood routing methods in hydraulic science. The Muskingum model is one of the best methods in the hydrologic flood routing rivers. In order to estimate of the Muskingum parameters have been used experiential methods as trial and error method، least squares. Genetic algorithm is one of the estimation methods of the parameters. Comparison between experiential methods results and genetic algorithm show that Genetic algorithm method is benefit and easy method for estimated the Muskingum parameters. The determining of objective function is most important in this method (GA). In this paper، different objective functions have been selected for linear and non-linear Muskingum models and are optimized using genetic algorithm then the effects of objective function are investigated on prediction of Muskingum parameters and computational output discharge. Comparison between computational hydrograph of output discharge and experimental result show that the effects of objective function on result prediction predominate in the linear Muskingum model whereas these are virtually negligible in non-linear Muskingum model.

Because stepped spillways can significantly reduce the depth and size needed for a stilling basin at the toe of a dam and lead to great economic benefit, these spillways are increasingly attractive in hydraulic engineering. It is commonly acknowledged that free-surface aeration is significant in stepped spillways. In this paper, for investigation of Mixture and VOF method's ability, air-entrainment in skimming flow over the stepped spillways is simulated by using Fluent software. The numerical simulation results of free surface, velocity components and air concentration in water and circumstance of air entry into the water have been compared with the experimental results. It was found, downstream of the inception point of free-surface aeration which rapid free-surface aeration is observed, free surface is simulated better by Mixture method. On the steps downstream of the inception point of free-surface aeration, the results of Mixture and VOF methods about velocity distribution are closer together (RMSE is equal to 0.25 and 0.23 for Mixture and VOF Methods, respectively). But on the steps located further downstream by a strong air entrainment, Mixture method gives relatively better results (RMSE is equal to 0.23 and 0.33 for Mixture and VOF Methods, respectively). Also in the Mixture method, convergence time is much less than VOF method. This time reduces about four to five times.

Broad-crested weirs are common engineering structures in irrigation systems and hydroelectric schemes. Varying the upstream and downstream face slopes are of the important factors affecting flow conditions and discharge efficiency of structure. In this paper, the Hydraulic Grade Line, free surface profile over the broad crested weir and separation zone at the upstream corner of it have been simulated by using Fluent software. The turbulence models considered are the standard and renormalization group (RNG). The simulation results are found in good agreement with measured data. The numerical simulations show that sloping the upstream face slope increases the discharge coefficient and decreases separation zone at the upstream corner and varying the downstream face slope does not affect the separation zone and discharge coefficient. Water depth before the critical depth in the weir with the steep upstream face slope however, is greater than the weir with the mild upstream face slope. The position of critical depth does not change by varying the downstream face slope. By using mild downstream face slope, negative pressure value decreases due to the decrease in curvature of streamlines, separation zone in downstream corner and the possibility of cavitations.