Alexandria Engineering Journal (11100168)108pp. 897-910
A spillway comprises several sections, primarily the crest and chute, essential for safe water flow from an upstream reservoir to a downstream river. Incorporating a hydrofoil crest and stepped chute features creates an efficient Hydrofoil-Crested Stepped Spillway (HCSS). The hydraulic features of the 60 HCSS models, which were designed through the National Advisory Committee for Aeronautics (NACA) equation, are assessed through laboratory experiments under a skimming flow regime, where the five hydrofoil formation indexes (t), three numbers of steps (Ns), and four chute angles (θ) are of concern. The findings indicate that an escalation in the ratio of upstream depth (yup) to spillway height (P), correlates with a rise in the discharge coefficient (Cd) in HCSSs. Furthermore, augmenting the t effectively boosts the Cd value. On average, the Cd value of the crest at t = 1 surpasses that at t = 0.2 by 20 %. This increase in t accentuates the curvature of the spillway crest, thereby enhancing the curvature of streamlines and reducing the flow distance therein. The Energy Dissipation Ratio (EDR) of HCSS is influenced by factors such as t (positively correlated), Ns (positively correlated), and θ (negatively correlated). Optimal performance of the HCSS is observed at t = 1, where both the Cd and EDR reach their peak values. © 2024 The Authors
Journal of Hydraulic Engineering (07339429)150(3)
Accurate prediction of pressure caused by plunging jets of high spillways is essential for assessing the bed rock scour initiation and expansion. The hydrodynamic pressure characteristics at plunge pools' bottom and inside rock joints are assessed based on the experimental results and the analysis of extensive available library experimental data. A new empirical model of mean dynamic pressure coefficient, the CP, and pressure fluctuation, the CP′, for core and developed jets at stagnation point are presented. The effects of jet break-up ratio (L/Lb), the jet's fall height L to the jet break-up length Lb ratio, on CP and CP′ at the pool bottom and inside the rock joints are assessed. The maximum CP at pool bottom and inside rock joint occurs in L/Lb≤1.2 range while the maximum CP′ occurs within 0.85
Journal of Hydraulic Engineering (07339429)149(11)
Predicting the characteristics of the dynamic pressures at plunge pool bottoms due to the impact of plunging jets is essential in designing and assessing the stability of lined or unlined plunge pool bottoms. In this article, by developing a large-scale physical model, the generated dynamic pressures at plunge pool bottoms are measured in different plunging jet conditions and pool water depths. The validity of the existing empirical formulations in predicting the dynamic pressure mean (CP) and pressure fluctuations (CP′) is assessed based on the experimental data. The comparison of the predicted results through existing empirical models with the observed experimental data indicates that the recently developed models have acceptable accuracy in predicting the CP coefficient, but not the CP′ coefficient. By running a parametric analysis through dimensional analysis, the dimensionless parameter of plunge pool Froude number [FrP=Vj/(gY)0.5, where, Vj = jet velocity at pool surface, g = acceleration due to gravity, and Y = plunge pool water depth] is introduced as an alternative to Y/Dj, (where, Dj is jet diameter at pool surface) to simultaneously consider the effects of pool water depth and jet velocity. The results indicate that at FrP≤2, the CP′ coefficient is negligible and = 0.10. At 2
Agricultural Water Management (18732283)277
Investigating the quantity and quality interaction of the surface and groundwater resources plays an essential role in the integrated management of the surface and groundwater resources. In this study, to estimate the discharge and nitrate concentration of the interaction between the Chadegan aquifer and the Zayandeh-Roud reservoir, a quantitative-qualitative simulation model is developed using MODFLOW and MT3DMS codes. Here, the model is calibrated using the data from the beginning of winter 2011 to the end of winter 2014, and validated for spring 2014 to summer 2020. For the quantitative calibration, in the steady and unsteady conditions, the RMSE values of the water level are 0.74 m and 1.84 m, respectively, and for the qualitative calibration, the measured nitrate concentration values is 1.89 mg/L. In addition, for the validation state of the proposed model, the values of RMSE for the water levels and nitrate concentrations are 3.76 m and 2.85 mg/L, respectively. The results indicate that the aquifer has always been recharged by the reservoir during this time. In addition, the exchange nitrate concentration value is between 39.56 and 48.85 mg/L. The decreasing trend of the water level and the increase in the nitrate concentration, which exceed the permissible limit in some areas, indicate the necessity of adopting the immediate managerial policies. Five managerial scenarios are proposed and the effect on the aquifer conditions in terms of increase in the water level and the decrease of nitrate concentration is investigated. The results indicate that the 20% gradual reduction of the agricultural water consumption and simultaneously a 20% gradual reduction in nitrate fertilizers consumption and completing the urban wastewater treatment systems is the most effective quantitative-qualitative scenario for this region, with a 0.24% increase in the average water level and a 11.36% decrease in the average concentration of the nitrate in the aquifer by the end of the forecasting period. © 2022 The Authors
Iranian Journal Of Science And Technology, Transactions Of Civil Engineering (22286160)46(2)pp. 1359-1374
Predicting the accurate hydrodynamic pressure at plunge pool bottoms due to the impact of plunging high-velocity jets is essential in assessing the stability of the bed rock blocks and concrete slabs. In this context, the subsequent scour depth evaluation is essential. The regression-derived model of multiple nonlinear regression (MNLR) and two intelligent models of artificial neural network and adaptive neuro-fuzzy inference system are developed to predict the hydrodynamic pressure mean and hydrodynamic pressure fluctuations at flat and scoured plunge pool bottom. By running statistical analysis on a wide range of large-scale experimental data, it is revealed that, in general the intelligent models outperform the regression-derived equations of MNLR. The average values of RMSE and R2 in the prediction of hydrodynamic pressure coefficients are improved to 0.054 and 0.87, respectively. Nevertheless, due to its simplicity the empirical equations based on MNLR model are accurate enough for engineering applications. These equations predict both the dynamic pressure mean and root mean square of pressure fluctuations at flat bottoms and scoured bottoms more accurately than the available equations for this purpose, with 70% and 90% of data within 20% range of discrepancy, respectively. An empirical equation of pressure fluctuation at SB is introduced for the first time in this study. © 2021, Shiraz University.
Proceedings of the IAHR World Congress (2521716X)pp. 2744-2750
Predicting the efficiency of plunge pools in dissipating the dynamic energy of impinging high-velocityjets of free spillways is essential for assessing the stability of the bed and subsequent scour depth. In this study, a large-scale physical model is developed to assess the energy dissipation of the plunge pools at the bottom. A wide range of hydraulic conditions including impinging jet velocity and plunge pool water depth is considered, resulting in plunge pool Froude number Frp up to 8 which is in the prototype range (Frp=Vj/(gY)0 5, where, Vj is jet velocity at impact on pool surface, g and Y are acceleration due to gravity and water depth, respectively). The hydrodynamic pressures mean and fluctuation at plunge pool bottom are measured at the impinging jet centerline (stagnation point, SP). Buckingham theorem is applied to introduce non-dimensional parameters, among them is the plunge pool efficient parameter (n) which relates the mean hydrodynamic pressure head at the bottom and the kinetic head due to jet velocity at the plunge pool water surface. Results indicate that n varies between 0.1 and 0.95 depending on the magnitude of Y/Dj (Dj is jet diameter at water surface) and Frp. The multiple nonlinear regression-derived model (MNLR) are developed to predict the efficient parameter of plunge pool (n). Statistical analysis of empirical model indicates that the energy dissipation is accurately predicted by the model, the average values of RMSE and R2 are 0.04 and 0.95, respectively. The model can be applied in practice for the preliminary design purposes. © 2022 IAHR.
Ocean Engineering (00298018)218
The Makran subduction located at the northwest of the Indian ocean, at the Oman Sea mouth has been and is the source of massive tsunamis that threatens the coasts of Iran, Pakistan, India and Oman. The initial tsunami wave produced by the magnitude and focal depth of Makran submarine earthquake in 1945 is determined based on the Okada algorithm. 3D propagation of the generated mega wave in the Indian Ocean and Oman Sea is simulated by adopting OpenFOAM open source CFD software, in its global sense and verified vs. the available data. The wave characteristics are extracted from the global model at the mouth of Chabahar Bay are inserted as the input in a regional model which consist of precise geometry and bathymetry of the bay and finer mesh size. The wave run-up is predicted at the main ports at the Indian Ocean and Oman Sea coastline. The obtained results are implemented to assess the tsunami risk zone of Teess beach town, at Chabahar Bay coastline. The advanced procedure applied in this research consists of the accurate production of the original tsunami and three stages of global and regional 3D and local 2D propagation simulation, that provides reliable results in more accurate estimation of wave run up height and tsunami risk zone, for practical engineering applications. © 2020 Elsevier Ltd
Environmental Fluid Mechanics (15677419)19(6)pp. 1431-1454
Solitary wave theories are frequently adopted to simulate the characteristics of tsunami and to predict the resulting run-up in a numerical and experimental manner. A mesh-free method based on exponential basis functions (EBFs) is implemented to simulate the generation and propagation of solitary waves generated by piston-type wave maker. The pressure form of the Euler equations in a Lagrangian formulation is considered in the method. One of the most significant issues in the numerical simulation of solitary wave is to stabilize the wave height during the propagation. A new stable Lagrangian time marching algorithm is introduced which applies an adaptive parameter based on pressure formulation for tracking free surface and to minimize the discrepancies. In order to evaluate the accuracy of this newly introduced scheme, the results of EBF numerical model is applied to wave propagation according to six solitary wave theories. The results indicate the advantage of the introduced adaptive Lagrangian time marching algorithm and the EBF method in simulating solitary wave propagation with pronounced accuracy, convenient performances and the least run time calculation with implications for predicting solitary wave run-up on the beach. © 2019, Springer Nature B.V.
China Ocean Engineering (08905487)33(3)pp. 356-364
In this article, the sediment transport processes in the Khuran Strait between the mainland Iran and Qeshm Island at North Central Persian Gulf are studied in regional scale in a comprehensive manner. The objectives of this study include defining the type and origin of the sediment, the influencing factors, and the dominant mode of sediment transport. Four possible scenarios of sediment processes in terms of sediment sources and influential environmental forces are examined. The results of the conceptual and 2D numerical model of MIKE21 applied for this purposes indicate that the sediment sources in the transport processes are mainly provided by the sediments suspended from the central and eastern zones of the strait bed. Other sources including input from rivers do not have direct influence on the processes. The results are applied to the study of morphological changes for engineering applications including the pattern and amount of deposit in the Rajaee port approach channel and harbor basin. The pattern and amount of annual sediment deposits in the approach channel predicted by the model is satisfactory, compatible with annual dredging records. © 2019, Chinese Ocean Engineering Society and Springer-Verlag GmbH Germany, part of Springer Nature.
Environmental Fluid Mechanics (15677419)17(5)pp. 1015-1034
A meshless method based on exponential basis functions (EBFs) is developed to simulate the propagation of solitary waves and run-up on the slope. The presented method is a boundary-type meshless method applying the exponential basis functions with complex exponents. The solution of governing equations is considered as a series of these basis functions. Boundary conditions are satisfied through a point-wise collocation approach. Based on the presented EBF meshless method, a new formula is introduced for the maximum run-up height on different slopes, valuable for engineering applications. The results obtained through the numerical method in the prediction of solitary wave propagation and estimation of run-up are verified through the comparison with experimental data. The comparison with 159 experimental data indicates that this new formula is more accurate than the preceding formulas in predicting the maximum run-up of non-breaking solitary waves. Minimum calculation time and convenient performances are the other advantages of this method. © 2017, Springer Science+Business Media Dordrecht.
Ocean and Coastal Management (09645691)98pp. 140-149
Coastal cells are considered as an appropriate framework in studying coastal processes and shoreline evolution as the basis for both engineering objectives and shoreline management plans. In this article a summary of the identification of cells and sub-cells as part of a multi-level coastal study of Hormozgan coastline and Qeshm Island is presented. The application of this concept for the study area encounters a number of restrictions and requires specific considerations, which stem from complex feature of the coastline and lack of reliable data regarding the available sediment sources and limited evidences for the processes in the past. The scientific value of this study is in its potential application for the lengthy and mostly undeveloped coastline of the Persian Gulf and Oman Sea with the similar characteristics and in association with the objectives of integrated coastal zone management regarding coastal sediment processes. © 2014 Elsevier Ltd.
Coastal Engineering (03783839)71pp. 60-67
Hydrodynamics and sediment transport in the swash zone are unique and very complex phenomena. Acquiring a robust model for predicting sediment motion in the swash zone requires in-depth insight about the behavior of sediment particles in highly asymmetric and turbulent waves that continuingly uprush the beach face and retrieve in backwashes. In order to consider a physical system of the coarse particle motion in the swash zone with a reduced number of external parameters and capture some of the realism of the situation, the experiments are conducted in rather simple conditions to provide some information about the particle responses in terms of jump length against asymmetric waves to be implicated for the swash zone. The results show that despite reduction of many external parameters, jump length is still a highly skewed stochastic parameter. The probability distribution of jump length is quite wide (large variance) and skewed, different from that of saltation length in steady unidirectional flow, in which the distribution is close to normal. Considering integral of excess energy of an arbitrary single wave over its duration as a rational and meaningful representative of flow condition, the average jump length JL incremental trends reduces in the higher energy condition, resulting in a linear trend in logarithmic scale. The JLs due to higher turbulent kinetic energy follow similar trend of less turbulent flow conditions. © 2012 Elsevier B.V.
Ocean and Coastal Management (09645691)84pp. 163-173
An overview of a comprehensive multi-level approach on coastal processes and shoreline evolution is introduced in this article. Different scales of the work in terms of coverage, tools, applications and required accuracy of the outcomes is considered, for both managerial supports and engineering applications. The study is part of a multidisciplinary project of data gathering and modeling met-ocean parameters and coastal processes at Hormozgan province and Qeshm Island which cover more than a thousand kilometers of Iranian coastline bordering the Persian Gulf and Oman Sea. The main part of the study is devoted to understanding coastal processes, possible accretion/erosion areas and resulting coastline changes thereof in order to form a knowledge foundation for addressing broad coastal management objectives. The study is initiated with compartmentalization of the entire coastline to cells and sub-cells. Three levels of study are then introduced. The coverage and procedure of study for each level are chosen based on the availability and accuracy of the data and expected outcomes. It appears that a well-organized multi-level approach of study is essential when a lengthy coastline is the subject and where a variety of outcomes are expected, especially when basic information is scarce and unevenly distributed. © 2013 Elsevier Ltd.
Proceedings of the Coastal Engineering Conference (01613782)
Erosion and accretion of the beach face and consequently the movement of the coastline are the direct result of net sediment transport in the swash zone. Different models have been introduced in order to predict hydrodynamic parameters and, thereafter, movement of particles. However, the capability and comprehensiveness of the models in different conditions are still questionable. In reviewing models established for sediment transport in the swash zone, one can easily conclude that in the most cases the transport of bed load has been predicted traditionally by the application of quasi-steady formula. Scientists have identified many of the important physical processes driving sediment transport throughout the swash zone, but a detailed description of the small-scale sediment dynamics is still far from complete. In this paper the behaviour of coarse sediment particles in the bed load mode of transport in response to the flow regime experienced in the swash zone are investigated. Accordingly, a model called event-based model is introduced for prediction of the beach profile change, and the results of the model are compared with some laboratory data. The comparison between the results of the model and measured beach profile in the laboratory reveals that the results of the model developed in the present study on the basis of the event-based concept are very promising, particularly in the range of flow for which the behaviour of sediment particles is more accurately understood.
In this paper, framework of a decision support system (DSS) for sustainable water resources management in basin-scale is presented. In development of this DSS, focus is on connecting hydrologic, environmental, and economic analysis tools and decision support methods by combining the DPSIR (Driving force, Pressure, State, Impact and Response) approach with multi-criteria analysis methods. The proposed framework can help in involving decision makers and stakeholders in the decision making process using a conceptual framework and procedure. Specific challenges of economic, technical, and political uncertainties in water resources management in developing countries have been discussed in the paper and are also considered in the development of the DSS framework. Different modules of the DSS including the "Database Management", "Model-Base Management", and "Multi-Criteria Analysis Module" have been also presented and their relations with the DPSIR approach are discussed in details. ELECTRE III method has been used in the Multi-Criteria Analysis Module and results of a case study are also presented in the paper. © 2008 ASCE.
Coastal Engineering (03783839)54(11)pp. 835-855
For the study of the cross-shore wave-induced hydrodynamics in the swash zone, a numerical model is developed based on the one-dimensional non-linear shallow water (NSW) equations for prediction of hydrodynamic parameters in the swash zone. In order to evaluate the accuracy of the outputs of the numerical model, the model's predictions in terms of water surface elevations and cross-shore velocities, are compared to field data from full-scale experiments conducted on three sites with different beach slope; mild and steep, several bed particle sizes and under various incident wave conditions. The quantitative and qualitative comparison of the results of the numerical model and the full-scale data reveals that the model can generally predict many aspects of the flow in the surf and swash zone on both types of beach. The accuracy is adequate for application in a sediment transport study. Considering the time-history and probability distribution of water surface elevation, the model is generally more accurate on steep beaches than on the mild beach. The model can adequately simulate the dominant frequency across the beach and saturation of higher frequencies on both mild and steep beaches for various incident wave energy characteristics. With regard to the horizontal (cross-shore) velocity, the sawtooth shape of time-history and negative acceleration of water are well predicted by the model for both mild and steep beaches. Due to the uncertainties in maximum and minimum values of velocity data, clear judgement about the accuracy of the numerical model in this matter was not possible. However, the comparison of the minimum velocities (offshore direction) revealed that the application of friction factors below the range which is suggested by literature best match the data. © 2007 Elsevier B.V. All rights reserved.
