نشریه سد و نیروگاه برق آبی ایران
پیاپی 26 (پاییز 1399)

Generally, the design of dams and other hydraulic structures is carried out based on deterministic approaches. However, there are many uncertainties in the estimation of different effective parameters in hydraulic structures design. The inherent uncertainties in these parameters necessitate reliability analysis to ensure the structure stability. In this study, after investigating various uncertainties in design, the height and overtopping failure of Namrood dam as a case study was calculated based on reliability analysis. For this purpose, the Monte Carlo Simulation Technique that is a well-known method for reliability analysis, was used. Results showed that to get 100% safety from design flood, the height of Namrood dam should be considered as 78.7 m. However, in this case the probability of overtopping failure due to control flood was 64%. Moreover, similar analysis was carried out to investigate the effect of spillway type on overtopping probability of failure. Results showed that by increasing the spillway crest length, the probability of failure in the case of Morning glory spillway increased more rapidly than ogee spillway.

Aim of this study is to estimate the optimized volume of reservoir in un-gaged basins and extract the estimation pattern of reservoir capacity for other regions. For this purpose, Ziarat was divided to 9 sub-basins using ArcGIS and the physiographical parameters was determined for each of them. for modelling of volume variation, demand before and after rain and also product before and after spill, were considered as different of Possible scenarios. Time history for amount of volume, was obtained as an equation according to other variables. The optimized volume calculated by mentioned equation as objective function and constrains.i.e. cost, demand and spill for each sub-basin. These volumes vary from 700 to 5000Mm3 and significant relation between volume and curve number index was observed. To extract a relation for prediction of reservoir optimized volume in un-gaged regions, regional parameters and optimized volume was considered and 6 equations was prepared by dimensional analysis and different functions. in this equations, 12 rainfall of 24-h probable maximum event were used for 4 consecutive years (2012-2015). Finally, using R-square and standard deviation error, the more optimized equation was presented.

In the recent years, due to the hydropower plants environmental problems, hydrokinetic turbine usages has been increased. Using such turbines in rivers modify natural flow-field. In previous studies, impacts of turbine on the flow-field just only in rectangular open-channel is studied. In this work, the effects of hydrokinetic turbine in a straight compound channel has been numerically studied using Fluent extension of Ansys 16. To simulate the turbine rotation, Moving Reference Frame (MRF) method has been implemented. Results showed that due to the turbine presence, natural flow structure and pressure distribution has been drastically changed. Indeed, instead of compound channel secondary currents, a strong secondary flow from the right back to left bank (where the turbine installed) is formed. Also results show that a wake region behind the turbine and regions with high velocity around turbine can be notified. In low velocity inlet, the flow field is intact and natural condition is preserved, while high inlet velocity causes drastic changes. Therefore, it can be concluded that in this situation, considering low effects of turbine presence in flow structure the inlet velocity should be low, while in this condition, the efficiency due to the low velocity would be not be impressive.

Iran is one of the pioneers in dam construction, which dam construction considers one of the greatest industry in Iran. In addition, reducing water sources attract the attentions to dam construction. The process of dam construction, supply of materials, and related services need great financial sources, also dam construction is a time consuming process. Therefore, it is important paying attention to supply chain of materials and services along with optimal operation and staff coordination. The purpose of this study is Identification, classification, and evaluation of supply chain risks for concrete dam by using library studies, related literature, and expert opinion.

In this research wavelet coherence measure is implemented for evaluating the relations and effect of rainfall parameters over many years on runoff fluctuations that is for testing proposed linkages between two time series. In this way, monthly Hydro climatological as 3 rainfall stations, one runoff in the outlet of Ardabil plain were used. The results illustrate that 8-12 and 8-16 month modes of variability were seen in most strongly in precipitation. The significance of shared 8-16 month periodicity with 95% confidence in runoff time series was confirmed through continuous wavelet transform and Wavelet Power Spectrum graphs. The results of wavelet coherence and cross wavelet transform showed that 8-16 month had between rainfall and runoff. Also, wavelet transform coherence and cross wavelet transform graphs showed 8-16 month periodicity was conceded as between rainfall and runoff parameters.

Sarroud Dam is located in the north of Khorasan Razavi Province in the city of Kalat. Being located in a fault zone, it is necessary to inject the cut-off wall. Using remote sensing techniques, geographic information system, Landsat satellite imagery and field observations in this research, it was specified that the dam has been located within the range of the Sarroud Fault. According to this, the foundation of axis, overflow shoot and the sides of the dam were evaluated in terms whether or not being affected by fault activities. the zonation of the cut-off wall based which the engineering geology parameters & permeability tests in the Arc GIS was undertaken, was, subsequently, weighed & interpolated through the neighbor method. The outcome was preparation of the zonation maps of the injection/grouting? axis at the cut-off wall. Moreover, the zonation map for the most widely-injected areas was prepared using the Hierarchy Model(AHP).

Due to fossil fuel limitations, the application of small-scale renewable energies has been considered. Recently, the utilization of Archimedes screw turbines, as an emerging turbine, are being increased for converting the potential and kinetic energies of water to a mechanical one. In this research, the performance of Archimedes Screw Turbine (AST) was numerically, using Reynolds-Averaged Navier-Stokes equations, considered in Flow3D to investigate the effect of different blade numbers and rotation speeds. The two equation  model and Volume of Fluid (VOF) method were used to model turbulence and water surface, respectively. The provided model was validated using experimental results. The optimal mesh cells to meshing was determined afterwards. The validation results showed that the numerical model has a good agreement with expetimental one, and a maximum efficiency of 79% was obtained. The results showed that among the investigated options, 2-bladed screw is economically and technically preferable compared to others.