فهرست مطالب saeid reza khodashenas

Nowadays water scarcity has become one of the most important problems in many communities. Construction of dams and water storage to provide part of the required water and flood control is one of the ways to coexist with problems caused by Water scarcity, flood or drought. Evaporation of lakes, reservoirs and ponds surfaces in the optimal utilization of water resources is highly effective. The evaporation of surface waters, usually in dry areas, especially in areas where heat transfer horizontal flow there is significantly will be greater than the wet areas. On the other hand, over time, the rate of sedimentation in the reservoir will increase. One of the problems of sedimentation is changes in the geometry of the reservoir and dam lake level rise to different amounts per storage volume. This in turn leads to increased evaporation due to rising levels of Lake dam. So the main purpose of this research is estimate the rate of evaporation from the lake and choose the most appropriate method for estimating evaporation from the surface of the lake and also determine the effect of sedimentation on evaporating from the surface of the lake of dam. In order to estimate the rate of evaporation from the Kardeh lake, first by using 6 thermal evaporation method such as Jensen-Haise, Hamon, Estefen- Stewart, Papadakis, Abtew and Turc evaporation rate was estimated in monthly, quarterly and annual scale. Then these values were compared with data from pan evaporation, using nine indicators evaluate errors. Also to determine the impact of sedimentation on the evaporation of the lake of this dam, According to the Hydrographs that was conducted in the years 1375-1376, 1382-1383 and 1387-1388, reservoir levels per amount of storage volume (5 scenario includes volumes 5, 10, 15, 20 and 25 million cubic meters) was determined. The results show that Jensen-Haise method, is the best thermal method of estimating evaporation in terms of lack of pan evaporation measured data. . It should be noted that in order to estimate the evaporation in monthly or seasonally scale, Papadakis method for winter and Turc method for the summer season will be appropriate methods. Also by reducing profitable volume due to sedimentation, reservoir lake level (per amount of stored stream) increased. So that this increased level by increasing the storage volume from 5 million cubic meters to 25 million cubic meters, Evaporation rate increase to three times the first case. In other words, it can be stated that with 5 times the volume stored in the reservoir (storage volume change from 5 to 25 million cubic meters) and also increase sedimentation the volume of surface evaporation 3 times increases. . Studies show that all methods whether overestimated or underestimated, show Increased evaporation process by changing the storage volume during the mentioned years due to increase the level of the lake of Kardeh reservoir. Jensen-Haise due to the closest data with pan evaporation data and earn the most points from the total score of 9 evaluation index error in estimating evaporation from between 6 ways, were selected as the best thermal method for estimating evaporation in terms of the lack of pan evaporation measured data in the region. Hamon estimation of evaporation method is the most underestimated and Etefen - Stewart method is the most overestimated method. Increasing sedimentation in the reservoir improve the water level to higher level in the reservoir, due to the openness geometry of the Kardeh reservoir, increasing the level of the lake will follow and ultimately increase the rate of evaporation from the surface of the reservoir.

Protection of water pipelines - wastewater or fuel materials - on the bed of erosion of the sea and rivers against such factors as bending, slipping and even fracture are important and costly issues in ocean engineering. In order to protect the potential destruction and fracture of these pipelines due to hydrodynamic forces of flow-waves or human activities. It is necessary to be covered with a concrete-coat or buried at an appropriate depth of bed with trenching.Objective observations showed that the pipelines that are located on the erosion bed of the sea and the rivers have the potential to produce a natural burial (self-burial pipe) in a bed of sediment, due to localized scouring.But in natural conditions, the burial process takes place with little speed. Therefore, by installing the spoiler on the pipelines, it is attempting to increase the Perpendicular cross-section of the flow (making changes in the pattern of flow around the pipeline) and, finally, the occurrence of erosion and self-burial inlower environmental velocities, but more intense. Therefore, it is necessary to first investigate the factors affecting for erosion sediment bed and estimate the dimensions of scour hole under pipelines, to study the accelerating factors and its effects on ocean engineering.
Themost of researchers considered the local scouring around the pipelines relatede to be rapid, the depth of the flow, the pipe diameter and the particle size of the bed. Moncada-M and Aguirre-Pe (1999) describe that, the scour depth below the pipeline as a function of the flow loss number and the dimensionless distance between the pipe and the intact bed. Cheng and Chew (2003) and Zhao and Wang (2009), by simulating the flow area around the pipeline with the mounted fin on it, found that the lifting force and shear stress in the bed and the scour depth increased with the fin. (2012), by using laboratory results, showed that the flow loss number and the height of the fin had a significant effect on the depth of scouring under the horizontal pipelines. Shan et al. (2015) with numerical evaluation of self-burial of tube with the fin mounted on it, and in displacement mode, with Fluent software, found that increasing the flow loss number in near of the bed would help to increase the burial speed of the tube.
recently studies showed that the mounting of the fins on the pipeline lead to increasing the amount of erosion around the tube. The application of mounted Piggyback line with cross sectional and different angles on the main pipelines can be a major difference with previous research

Using some additive materials to gypsum soil can increase its compressive strength and erosion and make it fit for civil projects in irrigation networks. In this study, (Journal No. 268., 2003) five levels of cement (5, 8, 10, 12 and 15 % to dry soil) and three levels of micro silica (0, 5 and 10 % cement) were added to the local soil. The processing of soil samples were conducted in two temperature (27 and 400C) and their compressive strength was studied and analyzed via SAS statistical software. In the present research, the best combination, with the minimum addition and a high compressive strength, was reached by adding 10% cement and 10% micro silica to the soil. In order to evaluate the sample’s erosion potential, it was exposed to water jet plane in four angles (Ө = 0,30,60, 90), five speeds (V = 2, 4, 6, 8 and 8.64 m/s) and three times (T =4,8 and 12 hr) and the highest weight loss erosion (dw) was observed between the speed of 4 to 8 m/s and the time of 8 hours later in a horizontal state (0 Ө =). .

using of concrete lining for erosion control water conveyance channels in mountainous and impassable ways in many areas due to high cost of providing and transportation materials is not economical. This Parameter in gypsum soils due to the higher solubility and erosion is Very important. Previous studies show that additives cement and the other materials to Location soils, can increase compressive strength soils .The application of micro silica for stabilization gypsum soil and Evaluation of erosion and compressive strength could have major differences with previous research. In the present study, the erosion and compressive strength due to jet flow plane with samples analyzed. Results indicate that, the incipient erosion in samples dependent with speeds, angles and times of erosion. For samples with 10% micro silica, velocity 4 m/s and impact angle vertical (Ө=00) the mixture of 10% cement at 6 hours and the mixture of 12% cement at all of time (8 hours) and velocity 6 m/s and impact horizontal (Ө=900) both of mixture (10% and 12% cement) all of time (8 hours) of experiment were resistance to erosion.

Rivers have a significant impact on human life as its pollution and harming leads to the degradation of the aquatic ecosystem and eventually will cause irreparable and irreversible damage. In order to protect the stability of ecosystems in the rivers, a criterion named “environmental stream” or “environmental water requirement” is defined for the rivers which actually expresses how much current is required to maintain an aquatic ecosystem. Several methods are available for estimating this flow, however, the International Institute of Water Management Resources has classified these methods into five groups. These consist of Hydrological Methods, Hydraulic Methods, Habitat Simulation Methods, Comprehensive Methods and Combinational Methods. The purpose of this study is introduction and comparison of these methods and choosing the best methods for different regions of Iran and application of the most appropriate ones in each area.