Journal of Water Resources Engineering
Year:2015 | Volume:7 | Issue:23|Papers Count:8

sedimentation in reservoir addition to reducing the volume of water stored in reservoirs has undesirable effects, including valve and bottom outlet blockage, drinking water distribution and agricultural equipment failure, damage to the equipment of hydroelectric power plants and hydro-mechanical equipment. One of the main causes of sediment transport near to body of dam is turbidity currents. In this paper, using a finite element numerical method to study the effects of control holes with shapes of rectangle, are, trapezoid, isosceles triangle, rectangular triangle on controlling turbidity current entrance in reservoir dam is investigated. The results show that the controlling holes both on subcritical and supercritical flow can control turbidity current. Another advantage of this solution against of obstacle construction is no reduction the useful volume of reservoir. Thus creating a control holes, both in terms of efficiency and cost effectiveness is very good.

Turbulence plays an important role in the transport phenomena in river engineering including mass and momentum transfer. In spite of several researches that have been conducted on this phenomenon, there is no exact method to model turbulence effects. It is due to the fact that the essence of this process has not been completely discovered. In this article, fractal perspective is applied to assess the turbulence behavior. Therefore, an efficient fractal method, entitled detrended fluctuation analysis, was employed to deal with time series of velocity fluctuations. In addition, multi-fractal nature of turbulence was investigated using this method. The results indicated that the fluctuation exponent of stream-wise velocity was larger than those obtained for the both span-wise the vertical. However, the closer the measurement were macle to the channel bed, the lesser differences were occurred between fluctuation exponents, indicating the role of viscosity. Moreover, the results of multi-fractal analysis illustrated that in the turbulence time series, the generalized Hurst exponent (h(q)) depend strictly on q. Finally, the decreasing order of h(q) with respect to q indicates that the small fluctuations are taking place more than the large ones.

Large woody debris (LWD) reduces the flow crass sectional area, deviate the flow and increase the velocity around the bridge piers. therefore, they increase the maximum scour depth and accelerate sediment removal. Accumulated logs and drifts upstream of bridge piers have different shapes. In nature, most of the debris accumulated in front of bridge piers are prismatic. The purpose of this paper is to investigate the effect of the woody debris accumulation in front of square piers on the scour depth. The research was performed in hydraulic lab of Shahrekord University. Rectangular cvboid woody debris with width, length cvncl haight, were placed in front of a square pier with a 9 cm width. Experiments were performed under a clear water condition, and with the flow rate of 15, 20, 30 and 40 litis. The maximum depth of scour hole around square pier in presence of woody debris accumulation was compared with the case that there is no debris accumulation (control sample). The results showed that of accumulation woody debris in front of a pier can increases the scour depth of 2.5 to 3 times compared to the control set-up. Also a new equation for calculating the maximum scour depth of square piers in the presence of woody debris accumulation usingthe has been ceveloped dimensional analysis.

A spur dike may be defined as a structure extending outward from the bank of a stream to protect the outer wall in straight and curved shaped currents. With employing spur dikes, protection of the outer bank and deviation of maximum velocities from the spur dike zone will be possible. Besides the spur dike geometric properties, the geometric properties of the training channel, which influence flow pattern and bed scouring are is studied in this research. We Further investigated scouring in an arched shaped path by changing the ratio of the average radius of curvature to the channel width (Rc/B) from 2 to 5, which range from mild to sharp arc. In this research the SSIIM-l mode which is one of the most power full software in water and scour engineering is used. The results showed that by increasing the ratio radius of curvature to the channel width, the maximum depth of scour hole increases. Flow lines in the longitudinal and transverse profiles have been surveid and Profiles of dimensionless longitudinal and cross sectional bed and dimensionless plans are compared with experimental results. The results showed that there wase good agreement between experimental and numerical SSIIM modeling.

Using stepped spillway due to its low cost and high efficiency is increasingly on the rise. Hence, the studies in this area are associated with the growth and attention from dam engineers but most of these studies were including stepped spillway with uniform step height while the non-uniform step heights can also be considered as an option in some cases. In this study, a physical model of Herat dam for stepped spillway with 1.3 m height and a slope of 19.2o were used for the verification of numerical models then, three types of stepped configurations using computational fluid dynamics in ANSYS CFX software for range of 1.54#dc/h # 16.15 tested. Two-phase flow simulation for each configuration and all of the discharge took place and results in the case of flow pattern, energy dissipation and aeration point were compared. The results showed minimum difference in energy dissipation for nappe regime flow and maximum difference for skimming regime flow.

Quantity and water quality is an essential factor in the distribution of plant are species on the Earth's surface. water potential of the country represent a severe limitation of water resources, on the other hand increased production mainly depends on the development of the irrigated land is, resulting in a lower quality of water should be considered as a source of irrigation water and irrigated land in future development plans managerial approach to correct for the continuation of agricultural sustainability and achieving reasonable performance, should be seriously considered. The experimental design was a split-split plot randomized complete block in which at least four different levels of salinity (at levels 0.5, 5, 8 and 11 dS/m) as the main plots, four irrigation as sub (supply 125, 100, 80 and 50% water requirement) and two cultivars of canola (Hyola401 and RGS003) as the sub-sub plots in three replications. The results showed that at all levels of the different treatments, WUE for Hayola, is higher than the RGS, that The results generally show that under limited water conditions and water salinity by using management in irrigation for cultivar of Canola, Hayola due to higher WUE for cultivation in the study area has a higher priority. The overall increase in salinity for the two varieties of rapeseed decreased water use efficiency is relative. With the increase in water consumption compared to about 40 cm Hayola relatively sharp gradient increased the WUE rate as 5.4 (mm-1. Kg.ha-1) it increased the amount of water consumed by em 40 nor more than WUE will not increase but only a gentle slope- Terry will start to decrease. The salinity of water depth increases but should maintain yield in this segment reached the conclusion that the increase in water depth of irrigation water use efficiency is slightly increased and then economical cost-effective It was not. However, too much salt causes a slight increase in irrigation water use efficiency is. It is observed that the optimal manner of salty groundwater can be used for land use and the amount of salt water savings in other areas used. Dynamics of learning and recall the specific climatic conditions similar to the study area is.

Beshar River is one of the most valuable water sources in the Kohgilooye and Boyerahmad province, which has special economical and ecological values and conditions, but it is encountered with danger of discharges from Yasuj wastewater treatment plant, wastewater of sugar, glucose, and starch factories, agricultural drainage, municipal garbage, and the surface water collecting network of Yasuj town.In the current research, QUAL2K software was used to identify and understand changes and to predict water quality of Beshar river for its future urban, agricultural, and industrial plans. For this reason, at first, the statistical data and information were collected and their accuracy and their qualities were studied; including weather data such as temperature, dew point temperature, wind velocity, cloud coverage, the percentage of the river which is in shadow, and date related to sunshine, water measurement including discharge data and water quality, river hydraulic including data of the beginning point to the ending point of each river profile with equal hydraulic specifications such as their distances, their longitudes and latitudes, their digital elevation at the beginning and at the end points, the form of their cross sections, and the hydraulic coefficients, contaminant sources including the place they were entered the river and their qualities, and the synthetic coefficient. Then by field studies, 4 appropriate points between Tang-e Sorkh to Mokhtar Bridge were determined for sampling.Water temperature, electrical conductivity, dissolved oxygen, biochemical oxygen demand (BOD), nitrate nitrogen, organic phosphorus, and acidity parameters were measured by collecting and analyzing samples, in September and March months which have the lowest and the highest water amounts in the year, The data measured at field and the analyzed results of samples in the lab, were used for calibrating the model.Model simulation of biochemical oxygen demand parameters showed that the values in September were more frequent than in March, because of the entered urban wastewater, agricultural drainage, and the aquacultures wastewater in that month. The minimum and the maximum BOD simulated by the model in September were 4.6 and 8.4 mg/l, respectively; however, the simulated values in March were I to 7 mg/l.Real and simulated results showed relatively high dissolved oxygen concentrations in Beshar River, which indicated its high assimilative capacity. Also pH of the river was generally basic, and almost equal. The river interval from Dehno village to Mokhtar bridge showed the highest contamination, and the quality after Mokhtar bridge had the worst condition in September month, but appropriate assimilative capacity of the river caused the quality of the river current to be improved in 10 km. Finally comparing values simulated by QUAL2K model to real data showed that it can be used for qualitative investigations and management of Beshar River.

Due to limited water resources, in the very near future Iran will face a serious water crisis. So planning and management of resources in order to achieve the integrated management and sustainable development of water resources in the catchment basins is of utmost importance. For solving this problem, optimal operation of water resource systems and a duty to preserve, protect and predict the future demands of a system for the next generations cause a great emphasis on water allocation in recent years. Water allocation is determined by the amount of water that the resources (surface and groundwater) should allocate in order to meet the different needs of the catchment basins. But this allocation is not an easy work because there are too many stakeholders (such as farmers, citizens, industries, ...), that there needs have interactions and conflicts sometimes. In this respect, modeling and simulation of water resources systems that can incorporate all factors and interactions which act effectively in the allocation of water resources, is very important. System dynamic is one of the new management tools that can simulate and analyze a wide variety of policy and decision making in complex systems of water resources. In this research, modeling, design, operation and optimal allocation of Alavian dam in Uremia lake basin is studied by using system dynamics. For this purpose after collecting data and analyzing them, the conceptual model is made in VENSTM DSS. By using that model, we can predict the behavior of dam and shortage of agricultural, industrial, environmental and municipal demands due to various scenarios. For analyzing, we use monthly data during the period of 1339 - 1389. Several statiscal analyzes was performed on data to have a trustable information for modelling. Based on findings of this study, it was shown that beside simplicity and good accuracy, this model has a very good adaptability with various conditions of dam's water allocations. Great shortage in ecological and agricultural needs was shown after simulation and it is necessary to propose new plans to defeat these shortages. In order to study the behavior of the model from different angles, two possible scenarios were simulated in the catchment area of the dam to meet the needs of agriculture, environmental, industrial and municipal. After simulation, we can predict the behavior of dam in respect to growing demands. Results show that due to increasing population that causes increase in municipal, agricultural and industrial demands, Alavian dam can not reply to all this growing demands and we should think about some new resources or use some plans to decrease the demands.