Failure and destruction of bridges due to scouring in their foundation, in addition to financial damages and sometimes life damages, disconnects connection to flood points that require help. For this reason, protection of piers and abutments of bridge has great importance. So far a lot of researches have been done on methods of scour control around the piers and abutments of bridge and outer bank in bends. Using immersed vanes is one of the methods that recently have been studied in river engineering to control scour in outer bank in bends. According to source reviewing, it has been observed that no studied have been done on bridge abutment scour control by installing the immersed vanes and there is not many design parameters about this structure. Therefore, the purpose of this study is to investigate the function of immersed vanes with different installing distances (distances = 0.5, 1, 1.5 and 2 times of the effective abutment length) on scour control around bridge abutment. Tests of this study had been done in a flume by 8 meters length, 1 meter width and 60 centimeters height at hydraulic laboratory of shahid chamran university of ahvaz. A sedimentary box filled by a uniform sediment with 0.72 mm average diameter placed at the distance of 4 meters from the beginning point of flume. The abutment used in this study was rectangular with 17 cm effective length and 15 cm width. Immersed vanes had been made from galvanized steel and in the form of rectangle with 2 mm thickness, 75 mm height and 150 mm length. In this study four series of tests were conducted without vanes as base testes and 16 series of tests with vanes. The flow rate for these tests was considered as 28, 32, 36 and 40 liters per second with constant depth of 15 cm (Froude number = 0.15, 0.17, 0.2 and 0.22). tests with presence of immersed vanes were conducted with installing distances of 0.5, 1, 1.5 and 2 times of the effective abutment length and in different flow conditions (Froude number = 0.15, 0.17, 0.2 and 0.22), an the results were compared with base tests. The result showed that increasing the distance between vanes, the variation process of the maximum scour depth was ascending-descending. So that on average, maximum scour depth at installing distances 0.5La, 1La, 1.5La and 2La for Froude number 0.15, 0.17, 0.2 and 0.22 respectively was equal to 0.284, 0.304, 0.254 and 0.218 times of flow depth. Which shows that the most proper distance is two times of abutment effective length. On average, the vanes with installing distances 0.5La, 1La, 1.5La and 2La and for Froude numbers 0.15, 0.17, 0.2 and 0.22 respectively 23%, 17%, 31% and 42% decreased the maximum abutment depth.

  Increasing the world population and lack of drinking water supplies and agriculture, one of the challenges facing humanity will be in the coming years. The growing trend of surface water pollution of the crises facing most countries in the world. In this regard, use of the process of mixing contamination to reuse polluted waters important methods is increased water consumption. One of the characteristics of an open stream in pollution control disturbance coefficients are disturbed. Emotion of contamination in the rivers to several hundred kilometers can water quality Put up Under the influence .So for calculate mass transfer in the great scope that usually in the form one-dimensional model. need to to know the dispersant coefficient is longitudinal. Transversal mixing in rivers and canals also because great effect on rate longitudinal dispersion coefficient it's important. In several designs decrease mixing length one of the goals that different methods, above all increase cross-linking factor, there is to achieve this goal. In order to effect and application submerged pages, rectangular structures mounted in bed of the channel, in increase crossing coefficient and reduce the mixing length in a rectangular Flume been investigated. The channel to the length 15 (m), width 80 (cm) and height 80 (cm) and installing submerged pages with a specific angle and with a number of different rows from the place of injection of the substance detector done. The channel by Pompeii with max dubai 42 (l/s) was fed. It was controlled current in the form uniform and current fixed depth 15(cm), which by sliding valve the end of the flume. Injected after get developed in channel, article tracker contains water solution and salt with specific concentration and Permanganate, in the form pointwise in current center(Transversal mixing) and in the form pointwise in center and the sides current ) Longitudinal mixing) , with speed equal to flow rate that done this work by pumping system and entrance L figure to current center. designed in order to measurement concentration before and after injection article tracker EC meter. Measured Concentrations in 3 to 4 cross section in downstream tracker location and at each level 49 Point simultaneous. It placed the amount of coefficients without presence submerged pages. Shows results of laboratory analysis that with increasing number of rows of submerged pages in all Intensity of currents and compared to non-structured mode cause increase cross-linking factor and decrease the longitudinal mixing coefficient, has been as a result of that reduce the mixing length. Seen best mode this effects in 4 rows of submerged pages.

With the entering of materials into channel and rivers and traverse a certain longitudinal distance, which is called the Mixing length, these materials are distributed due to factors such as molecular motion, turbulence and unsteady distribution of velocity throughout the entire flow section. In several designs, the reduction of this length is one of the goals. There are several methods, most importantly, increasing the transverse mixing Coefficient and reducing the longitudinal mixing coefficient, to achieve this goal. In this study, for increasing the transverse mixing and reducing the lengthwise mixing coefficient of submerged vane with variable numbers in flume Width. The experiments are done in four different flows and Tests are carried out at a glass wall rectangular channel with length 0f 15 m, 80 cm wide and 80 cm in Height in 5 different scenarios of without submerged vanes and with vanes in different number (3, 5, 7 and 9 vanes) and constant flow condition. By injecting a sodium chloride solution as a detector material from the center of the canal (with a constant flow rate) using the EC-meter, the EC level was measured at four cross sections downstream of the vanes To calculate the transverse mixing Coefficient and at 3 cross sections downstream of the vanes To calculate the longitudinal mixing coefficient and the results are compared. The results of laboratory analysis showed Which is in all 4 modes The presence of submerged vanes (3, 5, 7, and 9-page) has increased the transverse mixing Coefficient and the lengthwise mixing coefficient has decreased. The 9-page mode also has the most impact on increasing transverse mixing and reducing longitudinal mixing.

In nature, bridges are built on the rivers to facilitate the relocation and movement of people and vehicles. Abutments are weighted structures that are located on both sides of the bridges and the major loads are transported to them. One of the most important factors in bridges΄ destruction before the end of their life is the scouring of the river bed in the bridge range, which includes scouring due to narrowing, scouring of the bridge pier and scouring around the abutment. To control scouring, researchers have proposed and investigated various methods. In this research, the use of immersed vanes in reducing the scouring of the rectangular abutment of bridge was proposed for the control of scour abutment for the first time And was investigated. In this thesis, while reviewing the sources, it was attempted to construct a physical model in Ahwaz Shahid Chamran Hydraulic Laboratory. The experiments were carried out in a flume with a length of 8 m and a width of 1 m and a height of 0.6 m. A rectangular abutment was placed in a sedimentary box with a height of 30 cm that was filled with uniform sediments with an average size of 0.72 mm. Immersed vanes were made with height (Hv) of 7.5 cm and length (Lv) of 15 cm from galvanized sheet with a thickness of 2 mm And 3 numbers. In all experiments, the constant water depth was 15 cm. In this research, an experiment was first performed on a froud number of 0.22 without the presence of immersed vanes in 16 hours And according to the results, it was found that 75% of the total scouring occurred within 4 hours of the start of the test. Since the main purpose of this study was to compare the performance of the vanes at different angles, for other tests, the time was considered to be 4 hours. So, four test experiments were performed at the froud numbers of 0.15, 0.17, 0.2 and 0.22 to evaluate the performance of the immersed vanes. Then the layout of the vanes was tested at different angles and The performance of the vanes was calculated on the scour depth reduction. The results showed that in all experiments, the maximum depth of scour hole occurred in the outer corner of the abutment and The hole was not distanced from the abutment. The most effective function in reducing the depth of scouring, the volume and surface of the erosion hole and The length and width of the hole were related to the installation of vanes with a 65 ° angle to the upstream bank. At the vanes with an angle of 65 degree, the maximum scour depth decreased, on average, by 66% compared to the test without the vane.

By entering materials into canals and rivers, and at a certain longitudinal distance which is called the length of the mix, these materials are distributed by factors such as molecular motion, turbulence and non-uniform distribution of velocity throughout the entire flow section. In several designs, reducing this length is one of the goals that there are various methods, including increased cross-linking, to achieve this goal. At the beginning of the entry of a pollutant into the water canal, a deep mixing takes place first, due to the small amount of the depth to the width of many canals and rivers, and the low velocity of the deep mixing process, it can be neglect able. After mixing in depth, the mixing takes place across the canal, after mixing in depth, the mixing takes place across the canal. In this study, the effect of the angle of submerged plates installed in the canal bed on the transverse and longitudinal mixing coefficients in a direct rectangular flume was investigated. Tests on four different flow rates and Four Corners 20, 30, 40 and 50 degrees with and without the presence of structures has been done. The salt solution, as the detector material, was fed from the center of the canal with a constant flow rate and the amount of salinity in the transverse mixing experiments was collected at four stations down the track of the location of the detector using EC sensors. Also, in the longitudinal mixing experiments, the tracer material was injected at three points of the flow to complete the first full mixing at the beginning, and then the lengthwise mixing concentration data at three lower levels were removed. Also, electromagnetic speedometer was taken at each section and at different depths of data in three dimensions to calculate shear velocity. The results showed that the submerged panels, at all angles, increase the transverse mixing. The angle of 30 degrees increased the cross-sectional magnitude about 2 times due to the formation of stronger vortices. The plates with increased cross-linking have reduced the mixing length by about 50%. According to Fischer's (1994) relationship, the increase in cross-sectional mixing caused a reduction in the longitudinal mixing coefficient, which in this study, the angle of 30 degrees reduced the coefficient of longitudinal mixing to about 1.4 times

Today, due to advances in science and technology, the use of numerical models is one of the best and fastest way is to learn from the environment. Climate change and shower rainfall additional need for the modeling. To reduce errors, it is necessary to be strong and accurate modeling software. Flood Modeller is a flexible and comprehensive package of tools for deriving flood maps, flood forecasting, designing flood management schemes, developing catchment strategies and many other flood and non-flood applications including modeling low flows, sediment and water quality. The governing equations in this software like any other hydraulic applications, is saint-venant equations, and solving these equations is numerical methods also. This study is based on one and two-dimensional modeling of Dez River was founded. For this purpose, sections of Dez River, raster maps and Dez River information is defined for FLOOD MODELLER software. the cross-sectional study been done For 190 km in length of Dez River which start of Dezful hydrometric stations, and leads in "Bamdej" hydrometric stations. in modeling used 100-year hydrograph of river. the maximum discharge for the dez river is 3009 cubic meters per second and the maximum flow rate for "balarood" branch is 1783 cubic meters per second. After the implementation of model were determined this software is capable the presented the results of modeling with an accuracy of 94% in river discharge. due to high slope, and morphology of the Dez River, was observed a fast river flow changes In one-dimensional modeling and output software hydro graphs. In the two-dimensional model due to the involvement of DEM maps and consideration of coastal areas by software, was observed significant damping in outflow hydrograph. In compared the study software of two-dimensional mode with MIKE software in the storage volume scenario, many similarities can be seen. FLOOD MODELLER software provide the acceptable and usable results in the flood maps. Observations of flood maps indicate in distance between "Dezful" station to "harmale" station, Dez River have the ability to transfer 100-year flood and does not create a lot of problems for surrounding land, but by approaching the "harmale" and "BamdeJ" station, due to the increase in depth of water in the river and the flatness of the land around the river, more land will be flooded. So that 33.2% of the land around the Dez River which mostly near the Karun River will be flooded.

 In this study, the effect of six-leg elements had been investigated experimentally on the ratio of conjoined depths, the length of hydraulic jump and the roller length of hydraulic jump. Six-leg elements were tested through three heights (1.10, 1.12 and 1.14 m) by a rectangular flume with length and width of 7.5 and 0.3 m. All tests were done in hydraulic lab of Shahid Chamran University of Ahvaz.
Six-leg elements were fixed on the bottom of the flume in downstream of the inclined plane, furthermore, lower-level of incoming jet stream was as same level as higher-level of elements. This is because, incoming jet stream in previous studies was as same level as the bottom of the elements and rough elements acted like water-based blocks.
Every element tested in different incoming stream with the range of Froude number between 5.3 and 8.1. In all cases water level profile, roller length and the length of hydraulic jump were measured. The result showed that the presence of six-leg elements could decrease the ratio of conjoined depths, the length of hydraulic jump and the roller length of it and this decrease depends on Froude number and the heights of the elements. Element with 1.10 m height demonstrated the highest decrease of the hydraulic jump. This study also presented some equations to estimate the ratio of conjoined depths, the length of hydraulic jump, the roller length of it and energy depreciation based on Froude number for each height of the six-leg elements.

Hydraulic jump stilling basins are constructed downstream of hydraulic structures such as spillways and gates. The main objective of these structures is to dissipate the excess kinetic energy of the flow. Different types of basins have been introduced over the past years and the main reason for these different types of basins is to have basin with shorter length and higher efficiency. Among these structures are the roughened bed basins which most of the previous works were to attach the rough elements to the rigid (concrete) basin bed. The present study which have been conducted for the first time, the rough elements are placed on the alluvial bed which delete the concrete bed and reduce the uplift pressure. The main purpose is to investigate the hydraulic characteristics of the jump as well as the scour dimensions downstream of the basin. To reach such goal, different tests at Froude number ranged from 5.76 to 9.13 were carried out. The basin length (L_B) in all tests were equal to 126 cm which was equal to the jump length (L_j) for jump over roughened elements. The results show that on average the elements can dissipate 67% of the kinetic energy and the sequent depth, the jump length and the roller length have been decreased by as much as 14.1%, 14% and 51%. The maximum scour depth have occured downstream of the basin having length equal to the jump length and the scour depth decreased by as much as 56% as the sediment particle size increased from 0.95 to 2.23mm. For conditions of L_j/L_B <1 the scour depth is reduced. For prediction of the scour dimensions downstream of the basin, expressions have been developed. The non-dimensional scour bed profiles were plotted and relation was developed.

  Rivers are important components of nature and construction of hydraulic structures such as bridges in a natural balanced system that has evolved over millions of years, changes the flow structure. So far many studies have specially studied on scour around hydraulic structures, especially bridges either at the piers or abutments, and many diagrams and numerous relationships have been developed. Almost relatively complete understanding of the scour mechanisms have been achieved around the bridges abutments, various methods have been implemented to reduce or control scour and stuidies in this issue is still continuing. One of the methods that are used for reduce scour around bridge abutments is using scarifies abutment. The main objective of this study is to investigate the effect of length and distance of wedge-shaped scarified vane attached to the bank on the bed topography around the wedge-shaped bridge abutment. This study was performed in a flume which has a length of 8m, a width of 1m, a height of 0.6m and constant bed slope equal to 0.0003 in the hydraulic laboratory of Shahid Chamran university, Ahvaz. In the distance of 2 m from the beginning of the flume there is a metal box that has a length, width and height of approximately 2, 0.7 and 0.3 meters. This box was filled with a uniform sediment used in this study. This study included 22 experiments in clear water in Froude number of 0.18, 0.21, 0.23, 0.25. Two series of test with and without the presence of a vane attached to the bank made with A-jack were performed. The results show that as the Froude number of the flow increases the maximum depth and spread of the scour increase. By installing the Vane-attached to the beank upstream of the abutment, because of permeability of these overflows in comparison with solid plates, reduce the power of the main vortex at the end of structure and therefore is more efficient in reducing the depth of scour around the bridge abutment. Installation the three angles of 30, 45, 60 degrees were investigated. Applying higher angles increases the risk of scouring caused by constriction. In maximum rate of flow sacrificed structure with a length of 14cm has a better performance in reduction of scouring around the base protection in comparison with a sacrificed structure with a lower length (11.4m) since the flow pattern is formed further apart from the base protection overflow.

 

Erosion of the outer bank of river bend causes lateral migration of river and as a result it causes the destruction of farm lands, roads, river side facilities, aquatic and riparian ecosystems and aquatic habitat of the rivers. In order to decrease and control the bank erosion and to restoring fish and other aquatic organisms’ habitat the environmental friendly structures are suggested. Vanes are among the in-stream structures which are used to control the bank erosion, flow deviation from the banks towards the channel, improve the sediment transport, enhance recreational boating, and in-stream habitat restoration.
Although the application of bank attached vanes have many advantages, there is not precise information relevant to the scouring and deposition, and flow pattern around them under the different hydraulic and geometric conditions and there is not enough study on this matter. Extreme erosion at the toe of the regular structures which are used for bank protection, such as spurs, causes the structure and the neighborhood banks’ failure. Since the new structure is in triangular shape, less scour depth is expected at the structure’s toe.
This research has been conducted in order to investigate the effects of vane spaces on the bed topography of Jungieh bend of Karoon River using experimental model of this certain bend for 4, 5, 6 and 8 times of effective length spaces. Experiments carried out for different hydraulic conditions (Froude numbers of 0.23, 0.26 and 0.29). In this study the angle between the vanes and upstream bank was 30 degree and also all of experiments have been done in clear water condition

The results indicated that the main amount of scour takes place at the vane toes. Also the triangular vanes divert the flow to the middle part of the model and forms new bank at the outer bend. In different flow conditions the maximum amount of scour depth for the space of 5 times Le is the lowest and for the space of 8 times Le is the highest among all conditions.
 

The main cause of concern about the stability of bridge foundation is the occurrence of scour around the piers. Therefore, there is an interest in finding reliable ways to reduce and control local scour depth. Local scour around a solid pier results from the down flow at the upstream face of the pier and the horseshoe vortex (HSV) at the base of the pier. Separation of the flow at the sides of the pier also creates the so-called wake vortices. These vortices are unstable and shed alternatively from each side of the pier. They act as little tornadoes lifting the sediment from the bed and form a scour hole downstream of the pier.
Countermeasures for local scour at bridge piers can be grouped in two categories: armoring devices and flow-altering devices. Armoring devices include riprap and alternatives to riprap, such as cable-tied blocks, tetrapods, dolos, etc. Flow altering devices that have been used to protect piers against local scour include sacrificial piles placed upstream of the pier, Iowa vanes, and flow deflectors attached to the pier, such as collars. This study The six-legs or A-jack elements have been used in coastal structures and have been recommended as an effective material on river bank erosion too. The purpose of this study is to investigate the applicability of such elements in reduction of scour depth at bridge piers. Therefore, two series of tests were carried out with and without elements. In the second series the elements were placed on the bed around cubic bridge in three different rows. Five different flow conditions, Froude number ranged from 0.16 to 0.24 were run and at the end of each test the bed topography were measured. The results of this study show that generally the six-legs elements can reduce the scour depth. The reduced scour depth for single row was obtained 44%, for two rows elements 83% and 100% for three rows elements in Froude number equal to 0.16. The results show that the increase of Froude number causes the effect of six-legs elements on scour depth reduction are reduced. So for Froude number equal to 0.24, the above mentioned percent scour depth reductions were found to be 44%, 63% and 81%.
 

 Rivers are regarded as vital arteries of any country. Many facilities including bridges, pumping stations, roads, residential buildings and other structures are constructed next to the river. On the other hand, rivers contain alluvial materials which may be eroded due to the flow of water. Erosion may be occurred in the riverbed that culminates in deepening the river, and finally causing the coasts to be unstable. Erosion in the body of rivers may cause the instability of the coast. The bed particles may start moving under the specific conditions of the flow regime in a particular place which is called Scour. Scouring is a natural phenomenon that arises from the erosive action of flow field in the alluvial streams. Bridge failure caused by fully scouring of the foundation makes completely clear the necessity of investigating in the case of scour prediction and ways to protect against it. Calculation and construction of the bridge piers in the crossing a river are of the most important and sensitive stages of a bridge-building project. Owing to the significance of dealing with scour at the location of bridges, various researchers and institutions have attempted to the preparation of procedures and guidelines in order to protect the bridge (piers and abutments) against the scour. The structural methods are the most important of them. One of the ways to reduce scour is utilizing the six-based elements (A-JACKS) around the abutment. In this study, the impact of the structure known as six-based elements on the control of the maximum scour depth of the bridge abutment was investigated as well as the scope of locating the six-based elements in order to safeguard the bridge abutment in front of the scour has been studied. In this investigation, experiments were carried out in a flume with a length of 10m, 1m width, 0.6m height and the constant slope of 0.0003 in the hydraulic laboratory of Shahid Chamran University, Ahwaz. The trapezoidal abutment (wall-wing) was used. Input discharge was adjusted using the entrance valve and measured by a V-shaped spillway. The flow depth was also adjustable with the use of the outlet gate. The water conditions were taken into account clear. In order to prevent the unwanted scour, flume was initially filled with low rate. A type of uniform sedimentary particle was also used in the experiments that their D50 was 0.66 mm; and the tests were performed with Froude numbers of 0.18, 0.208, 0.235, and 0.25 and in 4 placement scopes (W) of 4, 6.5, 8.5 and 10.6cm. According to the results obtained with the structure of six-based element in the most critical mode investigated in this research, that means the maximum Froude number and minimum scope, was able to reduce more than 50% scour of the abutment head. As well as in 75% of the studied cases, the structure of the six-based element has decreased more than 80% of the scour which this would represent that the use of the six-based elements around the abutment is of the techniques appropriate to reduce the scour in the abutment head. The scour was decreased one hundred percent in the Froude numbers of 0.18 and 0.208, and scopes of two-row (W2), three-row (W3) and four-row (W4). Froude number of 0.235 and scopes of three-row (W3) and four-row (W4) reduced fully the scour and the Froude number of 0.25 and scope range of four-row (W4) controlled 98.55 % of the scour. In comparison with the performance of two scopes, the maximum six-based elements namely W3 and W4 were observed in the maximum Froude number that only have 7.47% difference in the reduction rate of the scour and have completely the same performance in the two Froude numbers of 0.18 and 0.208. In conclusion, it can be stated that the use of W3 range is most optimal mode of replacing elements around the abutment, because it has approximate performance to W4, but the cost and time of its construction is low.

 In this study, the effect of six legs elements on the sequent depth ratio of hydraulic jump, length of hydraulic jump and roller length of hydraulic jump has been investigated experimentally. For the purpose of this study, six legs elements with different density percent (36%, 63% and 100%) have been tested in a rectangular flume with 7.5 m long and o.3 m wide. Experiments are conducted in the hydraulic laboratory of Shahid Chamran University of Ahvaz. The six legs elements are glued on the bed of flume downstream of chute in such a way that the incoming water jet is just above the element surface. It should be noted that in previous studies the rough elements have been tested such that the incoming jet was at the same level of the element bottom so the elements act as baffle blocks. Each density percent of six legs elements was tested under different flow conditions. The incoming Froude Number was in range of 5.3 to 8.1. During each tests the water surface profile, the roller length and the jump length were measured. The results indicate that the presence of six legs elements can reduce the sequent depth ratio, the length of jump and the length of roller. The amount of reduction depends on the Froude Number and the density percent. Six legs elements when density percent is equal to 36 can produce maximum of reduction of characteristics of hydraulic jump. Relations have been presented in this study for prediction of the sequent depth ratio, the roller length, the length of hydraulic jump and the amount of energy dissipation as a function of the Froude Number for each density percent of six legs elements.

 Stilling basins the type of hydraulic jump in irrigation and drainage networks are frequently used and the introduction of more efficient structures can help to increase efficiency and reduce costs of the project. One of the ways to optimize the geometric characteristics of hydraulic jump created a rough bed at the site of the jump so that the rough surface to create severe turbulence during stream increasing tension Reynolds and friction bed. The hydraulic jump need for formation to lower downstream depth and in result significantly reduced length of the jump. Also, if to build the stilling basin bed from permeable materials assuredly needless will be to provide high thickness of the slab floor Because of greatly reduced uplift pressure and will cause Thrift a lot of the cost. In order to create a stilling basin with rough and permeable bed, in this study bed basin are covered with six basic elements. With regard to that till now no study has been done on the application of effect of the six basic elements on the characteristics hydraulic jump in the bed basin, several questions about the effect of arrangement on reducing the conjugate depth and or length jump and finally optimal design of the stilling basin that main objective of this study is answer these questions. In this study, 40 test were conducted in the range of 5.32 to 8.09 Froude numbers and selected elements were investigated under 6 different arrangement. The result show that reducing of secondary depth and increasing shear stress and energy loss in rough bed than smooth bed independent from arrangement of roughness at bottom of the basin. Also the average value of bed shear stress coefficient values, in current rough and permeable beds is maximum 15.93 times the smooth bed. On the other hand triangular arrangement of six basic elements have the greatest impact on length jump and averagely have decreased it to 29.91 present than smooth bed.
In the end proposed relationship for relative conjugate depth, loss energy and bed shear stress than the initial Froude number for composed jump on the covered beds of six basic elements of the A-jacks.

The main cause of concern about the stability of bridge foundation is the occurrence of scour around the piers. Every year a large number of bridges in the river just when they are needed mostly, are destroyed by flood occurring. One of the most effective factors in the destruction is scouring around the piers. Two major factors causing of scour around bridges piers are the down flow occurred in upstream part of the piers and separation of streamlines from piers called horseshoe vortex. . Covering methods such as using riprap is among techniques which are widely applied for the existing bridges. For those places where the stones of adequate size are not available use of A-jack elements is good choice. . In this study, a cubic base side of 7 cm was used. the tests carried out in condition of clear water with Froude Number of 0.16, 0,17, 0.19, 0.22 and 0.24 in an laboratory flume with mean measure of bed deposit of 0.7 mm. Changes of scour hole around the piers were investigated by placing the a-jack in three different cases of above, mid and below the bed. the results showed that decreasing of scouring was seen in total experiments rather than experiments without using A-jack and scour reduced by reducing the froude number. In the Froude number of 0.24 a-jack on the bed with a decrease 44% and the Froude number 0.16, a-jack mid of bed with a decrease 57% of best efficiency have in reducing scour. a-jack under the bed down all the Froude numbers have been modest performance.

<p>&nbsp;River banks erosion is a phenomenon which we are faced with its destructive affect nowadays. River bank erosion causes sediment production, river migration and casues a lot of damage to the surrounding area, agricultural land and facilities of the river bank. Spurs are structures that can be used as one of the effective methods to stabilize river banks. Construction of structures such as spurs create a new vortex flow around its toe which will lead to the removal of bed material around the nose of spurs which a scour hole is developed at the tip of the spur and possibility would cause the failure of the structure. One of the methods which can reduce the scour hole depth is to use the triangular shape of spurs. In connection to the this structures, not much studies have been conducted so far.<br /> Thus, according to the explanations provided, the aim of this study is to investigate the effect of angle of triangular plate on bed topography, using the physical model. By this study it is hope to go step forward to develop design criteria for the triangular spur type at bank of river. Therefore, in this study the erosion and deposition process around bed of triangular spurs will be investigated experimentally.<br /> Experimental tests are conducted in clear water condition. Four different angles of triangle plates 45, 30,20 and 60 &deg; are used. The flume length of 7.3 m, height of 0.6 meters and a width of 0.56 m were used in this study. Four different Froude numbers and constant depth of 0.16 m were studiued. For bed sediment, natural sand of uniform size 0.7mm was used. Dimensionless parameters extracted using dimensional analysis. Results showed that during experiments with triangular and rectangular plates maximum scour observed in the nose of structure. During experiments with triangular plates with increasing Froude number flow at angles of 45.30, 20 and 60 degrees scour depth around of first plate 51.5%, 60.2%, 47.6% or 63% was occurred respectively. The length of scour 51.8%, 51.6%, 48.5% 55.3% and width scour the 31%, 50%, 36.5% and 30% increase. Also in constant Froude number of the flow increases angle triangular plates from 20 to 45 degree show that the scour depth increases. Increasing the vane angle from 45 to 60 degrees, it was found that the scour hole dimensions is decreased. Comparison of scour dimension at the tip of both triangular and rectangular spurs were compared and it was found that for the same conditions, the scour hole dimensions in the triangular spurs are less than in rectangular plates.</p>

The most common practice of flow-altering measure for river bank protection is to construct series of spurs. The spur is a rectangular shape structure usually perpendicular to the bank toward the river center to redirect the flow velocity from the bank. The view of the structure perpendicular to the flow velocity is rectangular in shape. The most common problem with this structure is developing a deep scour hole which usually occurs at the toe of the structure and can damage the structure itself. Any structure which can reduce such scour depth is the interest of engineers. In recent years the triangular shape of spur has been experimentally investigated in sinuous or 90 degree flume bend which the results has proved the effectiveness of this structure on river restoration in addition the scour at the vane tip is reduced. Since no study has been conducted in straight flume, the aim of the present study is to see the effect of a triangular spur shape (TSS) on bed topography of river in a straight flume. This structure has a sloping crest that extends from the riverbank and forms a low angle with the bank. Series of TSS were attached to the bank with space of 4Le between spurs and was tested under four different flow conditions (Froude number equal to 0.2, 0.22, 0.24 and 0.26). For comparison the same tests carried out using regular rectangular spur shape (RSS). Bed topography was measured after each test. The results show that in general the river bed deeper part for both spur shape is shifted toward the center of river. However the scour at the toe of TSS is considerable less than the RSS. Accumulation of sediments in between spurs has been observed with more deposition for TSS.

One of new measures to control river outer bank against erosion is to use the triangular shape vane. These vanes are attached to the outer bank with a low angle of 20 to 30 degree to the upstream. These structures reduce the strength of secondary flow within the bend and the flows which spill over the vanes are deflected normal to the vane position. Therefore the general flow pattern within the bend is modified in such a way that the flow velocity closed to the outer bank is reduced thus the river bed at outer bed is reduced and the river thalwege is shifted from outer bank toe to the middle of river. So far little study have been conducted on vane attached bank therefore the aim of this study to experimentally investigate the bed erosion and sedimentation patterns in a 90 degree river bend due to triangular vane attached vanes. Tests are conducted in a 90 degrees mild bend with R/B ratio of 4 and width of 7ocm. Two types of vanes were used in this study. The triangular vane with length of 142cm and height of 33.5cm and the rectangular shape vanes with 53 cm in length and height of 45cm are attached to the bank with effective length (L) of 14cm which is 1/5of the flume width with a angle of 20 degrees to the upstream. The Froude numbers in this study were 0.24, 0.26, 0.29 and 0.32. The vanes are installed at different vane spaces of 5L, 6L, 7L and 8L. All tests are carried out at clear water conditions. The results show that in general the vanes are causing the main flow is shifted from the outer bank to the middle of flume which causes shear stress is reduced and the maximum scour depth at bank toe is reduced. It was found that at any vane spaces, the thalwege is deeper as the Froude number is increased. It was also found that the maximum scour depth at the tip of rectangular vane is greater than the scour at the tip of triangular vane by as much as 80%.

In hydraulic engineering application of hydraulic jump type energy dissipater structures is one of the common techniques for reducing scour downstream of gates and spillways. Type I of stilling basin with horizontal and smooth apron with the length equal to the classical jump length is among these structures. At the downstream of this basin, threed dimensional flow patterns is developed which its vertical flow component impinges the bed, pick up the sediment and flashed a way to the downstream. Such process is continued and a scoure hole is developed just downstream of the basin which may cause failure of the structure itself. The ultimate scour dimensions are related to many parameters including the flow conditions such as Froude number and tailwater depth. Increase in flow depth can change the type of the jump and the B-jump is formed which start at the chute and ended at the basin. The main goal of this study is experimentally investigate variation of scour dimensions due to change of jump type from A to B jump. To reach such goal total of 20 tests were conducted at the hydraulic laboratory of Shahid Chamran university. The Froude number ranged from 4.5 to 12, the ratio of sequent depth was in the range of 9.3-28.2 and the jump start at different location on chute. At the end of each test bed topography was measured by a laser meter and plotted using SURFER software. The analysis of results show that in general the scour dimensions decrease as the tailwater depth increases. The results show that by moving the start of jump from level of 14% of the chute height to the level of 28% and 41%, the normalized scour depth increase from 6 to 17 and 24 respectively. The normalized scour length also is increased from 15 to 30 and 36 respectively. The non dimensional scour bed profile of due A-jump is differ than the B-jump. In B-jump the scour length is longer and in A-jump the height of point bar downstream of scour is larger. In general at B-jump the scour is longer than the scour at A-jump. From the dimensional analysis and applying the two parameters of M and N, general relation for predicting the scour depth at both A and B jumps were developed. By applying the experimental data with the help of SPSS software expressions were developed which was found to be in good agreement with data.