About 1% of the total storage capacity in the world’s reservoirs is lost annually due to sedimentation. Sediments can also block intakes in reservoirs and damage tunnels or turbines. One of the most effective techniques to remove these sediments is flushing, whereby water level is lowered sufficiently to re-erode deposits and flush them through the intakes. Outflow sediment discharge may well be related to the parameters such as the sediment characteristics in the reservoir, during flushing and geometry of flushing channel. In this study, laboratory experiments were performed on a 1-D reservoir model in a flume in the hydraulics laboratory of Shiraz University to investigate the flushing operation processes by using polymer particles. The polymer particles were lightweight and non-cohesive with an average grain size of about 2.40 mm and density of 1065.3 (kg/m3). The model was installed in a flume; 30 m long, 1 m wide and 0.75 m height. The length of the test section was 11.5 m, and sediments were placed at a length of 4.8 m long upstream from the dam position. Experimental runs have been performed for two flow conditions; 0.0004678 m3/s and 0.000628 m3/s. The very low inflow discharge helped for better monitoring and measuring of the effective parameters. A sluice gate was placed at the central bottom of the dam (as the bottom outlet) and was opened at a constant rate to make the complete drawdown. Results showed that the rate of sediment flushing is strongly associated with outflow rate, water surface gradient with the dam section and the width of the flushing channel. The results from this study were in agreement with that in the literature. It is considered that the low density of the particles causes them to behave as very fine and non-cohesive sediment particles, like loess sediments.

Sediment flushing of reservoirs is an operational technique, whereby previously accumulated sediments in the reservoirs are hydraulically removed by accelerated flow when the bottom de-silting outlets of the dam are opened. In this research, the process of sediment flushing is simulated by a three dimensional numerical model in which sediment and flow interaction are reflected in the reservoirs. Reynolds Averaged Navier-Stokes (RANS) equations are solved numerically by Finite Volume on a three dimensional grid and a standard k-e turbulence model is used. The resulting flow analysis is used as an input data for the sediment model. The convection diffusion equation for the sediment concentration is solved. The concentration equation derived by Van-Rijn is adopted as a boundary condition, resulting in a calculation of bed material load. The depth integrated mass balance equation is applied to find the bed changes. The results from the numerical model are compared favorably with the data from physical model studies available in the literature.

Control of sedimentation in reservoirs of dams is considered to be one of the most important issues in exploitation of dams and increasing their useful life.Reservoirs act as traps for sediments and prevent transport of sediments to the river. The deposited sediments will decrease the capacity of the reservoirs so that they cannot be in use any more. Various methods are discussed in this study to remove a part of the deposited sediments, but flushing is the method, which has been used extensively in many projects all over the world due to the fact that the flow energy is utilized and there is no need to employ an external source of energy. In this study a one-dimensional model is developed in which continuity equation of sediment is solved by the finite difference method using the Cranck-Nickolson method. The developed model is capable to compute the variation of the reservoir bed with time. Also, the accumulated flushed sediment volume and reservoir water volume are calculated at different time steps. The Fotran language used for programming of the model was based on the results obtained from physical models employed by several investigators.And comparison was done with HEC-6 Model. The verification of the model was done using data from the natural reservoir of Dashidaira dam in Japan. The results were compared with the actual measurements. A good agrement was observed between them but the Hec-6 doesn’t show a good verification.

flushing is a condition with episodic attacks of redness of the skin with a sensation of warmth or burning, this disease causes emotional and functional problems in patients. There is various treatments for this condition; one of them is the use of botulinum toxin A (BTA). In this prospective pilot study we studied the effect of Botulinum toxin A (BTA) effect on DLQI of patients with facial flushing, we compared the DLQI before and after treatment. The number of 24 women with facial flushing admitted to the department of dermatology of Hamadan Farshchian Hospital, with the age range of 18 to 60 was enrolled in the study.Patients completed Dermatology Quality of life Index questionnaire before and one month after treatment. In our study 1 unit of BTA was injected intracutaneously per square cm in both sides of cheeks, to a total dose of 30 units per session. All of 24 patients completed the study. The mean age was 37.79±13.13. In all patients, DLQI decreased, and in two months follow up, the mean of DLQI improved from 8.08±1.17 to 4.5±1.21 (P. value<0.005). Based on this study BTA is an effective and safe treatment for facial flushing.

Identification of phenological stages is the first step to study the plant response to environmental changes, such as climate, temperature, precipitation, fertilization, irrigation and biological control. In order to identify the phenological stages, 100 seedlings were studied at 5-10 days intervals. Stem and leaf length growth were measured by ruler and caliper to draw growth rate curve. Results showed that annual, biennial and 3-years old and older up to productive age of Pinus sylvestris were classified into 10, 10, 9 and 8 groups, respectively. Time of phenological stages was slightly different between biennial and older seedlings. Sigmoidal growth curve of biennial seedlings revealed that the effect of middle part of last year stem on increased seedling height was more than upper part (apical meristem). Hence any parameter that increases middle part of annual seedling will consequently increase the length growth of biennial seedlings. Stem elongation was affected by phenological stage of lammas shoot at the late growth season. Appearance of leaf buds coincides maximum length growth of seedling stem and young trees.

One of the most effective techniques for removing the deposited sediments from reservoirs is pressure flushing which has only much local effects. It is often applied as a clearing process to remove sediment saround the entrance of intakes .In order to make rational design of bottom outlets and other sediment flushing structures, the understanding of the characteristics of a scour funnel in under pressure flushing is significant. The physical model was constructed in the Hydraulic Laboratory at the Water Sciences Engineerin Faculty of Shahid Chamran University of Ahvaz and by performing various experiments on the effect of bottom outlet shape on the volume and dimensions of flushing cone was experimentally investigated. For this purposes, the experiments on 4 bottom outlets with a circular, semicircular, rectangular and square cross-sectional area equal to 18 cm2, five water levels of 30, 45, 55, 65, 78 cm, resulting in five different discharges on the bottom outlet, was performed. The results of this survey revealed that the shape of the lower opening is an important parameter in hydraulic flushing, changing of which results in change of scouring diameter. Results also showed that for a specific water level in the reservoir and for a specific time the scouring dimension for square valves and semicircle valves are more than one of rectangular valves. The scouring dimensions of rectangular valves are more than one of circular valves. The difference is more perceptible in lower water heights (i. e. lower discharge). The length of scouring and the volume of flushing cone increases with incrsing head and is the least for circular valves.

Controlling sedimentation in dam reservoir is one of the most important issues in exploration and increasing useful life of dams. Reservoirs act as traps for sediments and prevent their traveling in the river. The deposited sediments may decrease the capacity of reservoirs and their useful capacity. Even though flushing, due to the fact that the flow of energy is utilized and there is no need to employ an external source of energy, is the method which has been used extensively in many projects around the world, in this study various methods of removing sedimentations have been considered and discussed. In this paper Sefid-Rud data, the morphological changes and volumetric analysis investigated by GSTARS 3 numerical model, is used. flushing process in Sefid-Rud dam reservoir simulated for short and long term. The volume of sediment removed and taken out from reservoir is measured and predicted by applying GSTARS 3 model.

The tanks' useful life will be reduced if their sediments are not discharged with a suitable method. Various hydraulic and mechanical methods can be used in many countries to discharge sediments from reservoirs. Pressure hydraulic sediment flushing is a method of sediment flushing without lowering the water level. In the present study, using the CFD based Flow-3D software, a model has been applied to investigate the pressure hydraulic sediment flushing, and evaluate the effect of blockage phenomenon on sediment flushing efficiency. Results were compared with the available laboratory model. The dimensions of the simulated tank were 2.5 x 1.3 x 1.5 m in length, width and height, respectively, the height of the bed load was 0.4 m, and the diameter of the sediment particles was 0.3 mm according to the laboratory conditions. The average relative error for the sediment flushing cone depth was about 3%. In addition, to investigate the blocking phenomenon, the height of the bed load was considered to be 0.41, 0.45 and 0.5 meters for each simulation. The simulation results showed that when the height of the bed load increases, there is the highest sediment flushing efficiency and more sediment can be removed from the bottom outlet.

The accumulation of sediments in reservoirs of dams has always been one of the problems of reservoir dams. Accordingly, one of the approaches to address this problem can be referred to as the method of pressure flushing. In this method, during the course of flushing, generally the bottom drainage outlets of the dam are opened for a certain period of time and the reservoir water level is kept almost constant. When water discharges through the bottom outlets, and after performing flushing, a hollow or a hole in the form of a funnel or a cone will appear at the front of the outlet gate, that the size of this scour funnel depends on various parameters such as: discharge, depth of water inside the reservoir and the types of sediment deposited inside the reservoir. In this research, a physical model with specific dimensions was used to investigate the effect of cohesive and non-cohesive sediments on the form of flushing funnel. The result of this research shows that in non-cohesive sediment the erosion pattern was retrogressive, and while experiments are done with minimum water depth (40 cm) and maximum discharge (8 lit/s), the flushing funnel will be balanced after 9-11 minutes. of the bottom outlet can be presented in the form of exponential and function of water height and sediment were obtained.