فصلنامه علوم و مهندسی آبیاری
سال چهل و ششم شماره 1 (بهار 1402)

In recent years, the accumulation of heavy metals in the environment mostly due to its adverse impact on human health and wildlife has become a main concern (Al-Yemni et al., 2011). Meanwhile, sediments are the main storing heavy metals accumulations and serve as tools for assessing the status of river pollution (Taghinia Hejabi et al., 2010). At the same time, to using geographic information systems and Geostatistic methods is desirable. Many studies have been conducted by researchers such as Mortazavi and Saberi nasab (2017) in Meiqan, and Islam et al. (2015) in the water and sediments of the Korotoa River in Bangladesh. The purpose of this study was to investigate the concentration of lead, zinc, copper and chrome metals in surface sediments of GharehSo River and zoning of sediments of the region with Potential Ecological Risk Index and Muller's Geo-accumulation Index.

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

The entry of sediments in to the lake of dams over many years and the sedimentation within the reservoirs is on inevitable phenomenon and it is expected that with the reduction of reservoir volume of dams, planning for exploitation of dam and water allocation for various issues such as agriculture, industry and drinking became difficult (Ashrafi vaghefi et al., 2008). Reducing the volume of the reservoir will shorten the useful life of the dams and any neglect of this issue, especially in arid and semi-arid countries of the world, can be a serious threat (Emamgholi Zadeh 2008). One of the effective methods for sediments removal from reservoirs of dams is the hydro suction method, in this method, the difference between water level in reservoir and downstream is used as suction force for sediment transfer. In this method, using the minimum volume of water, the maximum amount of sediment are discharged and saved costs (Chin et al., 2010). Also, other advantages of this method can be environmental compatibility due to controllable amount of outlet sediments, low muddy and ability to concentrate dredging to one area and also the ability to transfer siphon dredging, the low cost of constructing and installing, ability to perform even in low water seasons, waste of less water and non-interrupted operation. It seems that combining hydrosuction and water jet methods in addition to having the mentioned advantages, increases the sediment removal efficiency, which is received less attention of researchers. Therefore, in this research, the effect of jet arrangement and hydraulic jet distance relative to sediment surface on improving sediment removal in jet- hydrosuction method has been studied.

The Severe shortage of surface and groundwater resources is the most important constraint on sustainable agricultural development in arid and semi-arid regions. Frequent droughts in recent decades have also led to a significant drop in groundwater levels due to uncontrolled abstraction. In the present study, different irrigation scenarios are provided to reduce the withdrawal of water from the aquifer of Kavar plain in Fars province. The results of various studies show that due to climate change, water resources are reduced and irrigation requirements of plants will be increased during the growing season (Goodarzi et al., 2015; Zeinoddini et al., 2019). In this study, to simulate future climate parameters, the outputs of AOGCMs models and emission scenarios RCP2.6, RCP4.5, and RCP8.5 of the Fifth Climate Change Report were used (IPCC,2014). Then irrigation requirements of the study area were calculated by Cropwat software considering the cultivation pattern for the future period. Finally, by defining irrigation scenarios, the simultaneous effects of climate change and cultivation pattern change in the development of irrigation systems (surface and pressurized) on groundwater resources were evaluated.

Net-Stone water structures, in particular gabion stepped weirs, have become more prevalent due to their significant impact on reducing energy dissipation, proper stability, cost-effectiveness, ease of construction, and increasing the level of oxygen in the mixed water. Furthermore, due to air entrainment, the flow rate passing through the structure can prevent a considerable amount of cavitation, which is one of the problems in the design of hydraulic structures such as weirs (Shamsayi and Paknahal, 2005). One of the important characteristics of this structure is the internal flow through the permeable body of the weir, which creates complexities in the flow behavior. The energy dissipation of gabion stepped weirs is a function of the upstream and downstream slope of the weir, the number of steps, porosity, and the Froude number. Changing the porosity leads to a change in the ratio of the internal flow to the overtopping flow, and consequently, the amount of energy dissipation changes.Wüthrich and Chanson (2014) and Pallavi and Harshith (2018) conducted experiments to investigate the flow characteristics of the overtopping and internal flow of gabion weirs and compared the hydraulic characteristics of this type of weir with a solid weir. The results showed that the energy dissipation in the gabion weir is higher than the solid weir due to the division of the overtopping and internal flow.The aim of this study is to investigate the effect of the number of steps in gabion stepped weirs with a fixed slope on the energy dissipation of the structure. It should be noted that in the case of a small number of steps, the flow conditions on the steps are often in a cascading form, which leads to more energy loss. Certainly, increasing the energy loss of the structure is affected by the downstream hydraulic jump conditions and the length of the calm pool.

Limited water resources in many arid and semiarid regions of the world pose a serious threat to land reclamation and sustainable development. Therefore, it is necessary to review past policies and formulate new policies in this area. In Iran, with mostly arid and semiarid climatic conditions, water scarcity has become a great concern affecting not only the agricultural sector but also the industrial sector and even the drinking water supply in some parts of the country. In recent years, due to climate change, population growth and increasing water requirements, it is expected that the method of water distribution will change and the optimal redistribution of resources will be seriously considered (Mazandarani Zadeh and Hosseini, 2021; Misaghi et. al., 2020; Hosseiniasl et al., 2018).A review of past research shows that although many studies have been conducted on how to redistribute water optimally among retailers, each has sought to provide and optimize water resources by defining a specific objective function. Since most objective functions do not show the ability to describe mathematics accurately, it is better to use linguistic descriptions to model them.In this research, the objective function has been defined using fuzzy capabilities to describe peripheral phenomena. The irrigation network of Qazvin plain was equal to 255 million cubic meters per year in the past, but in recent years due to various reasons such as climate change and increased harvest for drinking water supply in Tehran, the allocated amount has decreased to about 120 million cubic meters per year. The network consists of 11 subnets, each of which acts as an operator. Due to the reduction of allocated water in the irrigation network of Qazvin plain and the lack of reform of the irrigation program to this plain, in this study, an attempt has been made to reallocate water to maximize utility, including increasing the total network revenue and observing justice using fuzzy inference system.

Flow-induced vibrations (FIVs) are a type of vibration that is caused by the interaction of a structure with a fluid flow. FIVs can occur in a variety of structures, including bridges, buildings, and offshore structures. In the case of tandem cylinders, FIVs can be caused by the interaction of the two cylinders with the fluid flow.FIVs are suppressed because of their destructive nature. MRElab managed to convert the kinetic energy of water flows into electricity by enhancing FIV (Bernitsas, 2016; Bernitsas et al., 2008). In MRElab, Flow Induced Vibrations (FIV) are studied to convert marine hydrokinetic energy, from oceans, tidal and rivers to electricity using the VIVACE energy harvester. Vortex Induced Vibrations for Aquatic Clean Energy Converter is probably the closest to commercialization because it has suffered extensive laboratory testing and many field deployments since its introduction in 2006. The objective of the Marine Renewable Energy Lab (MRELab) is to investigate FIV of single and multiple cylinders and find different ways to enhance FIV to design VIVACE Converters and optimize the power output for various flow velocities. Vortex-induced vibration (VIV) to a cylinder has been studied experimentally (Alam et al., 2003; Park, 2012) and numerically  (Ding et al., 2013; Kim et al., 2021) by researchers in order to eliminate or at least regulate this unsteady fluid-structure interaction phenomenon since it has been identified as the cause for many structural failures. But it is challenging, and it is still being debated due to the complexity of the interaction between body dynamics and fluid dynamics. The two cylinders arrangement has been studied in many types of research as the simplest arrangement. In this research, both cylinders can oscillate which has not been done very often in previous papers up to now. Moreover, most of the previous experiments on VIV were conducted in TrSL2 regime which fluctuating lift coefficient rises as the Re increases. But in this research, experiments placed in TrSL3 that shear layer becomes fully turbulent, and the fluctuating lift coefficient of a smooth cylinder reaches its maximum value.

The accurate determination of the amount of runoff resulting from precipitation on the surface of the watersheds is accompanied by errors due to the effect of various components, such as soil moisture, evaporation and transpiration, infiltration, and the impossibility of accurately measuring them. Therefore, the simulation of the precipitation-runoff process is associated with uncertainty. Uncertainty in calibrating models is caused by input information, model structure, and used parameters. Quantifying uncertainty is necessary for making decisions in water resource plans. One of the methods of calculating the uncertainty in the simulation process is to use Bayes's theory as the basis of calculations. In this research, an innovative method, which is a combination of Bayes analysis and the Monte Carlo method, taking into account the goodness of fit criteria, under the title of generalized similarity function, was used to calculate uncertainty. To determine the uncertainty of the parameters used in the calibration of the HBV rainfall-runoff model, the equation of daily flow entering the Shahid Rajaei dam in the Tajen catchment was used. The results showed that the mentioned method can detect uncertainty in the model. So the Nash index was obtained in the range of 0.4 to 0.68. The mentioned method is effective in identifying and introducing the co-termination theory, using a set of different parameters in the calibration of the model. So that by using the set of parameters, the same value of the goodness of fit index is obtained.