جستجوی مقالات مرتبط با کلیدواژه « پروفیل سطح آب » در نشریات گروه « آب و خاک »

Hydraulic jump is used for dissipation of kinetic energy downstream of hydraulic structures such as spillways, chutes, and gates. In the present study, the experimental measurements and numerical simulation of the free hydraulic jump by applying Flow-3D software in six different conditions of adverse slope, roughness, and positive step were compared. It should be noted that two turbulence models including k-ε and RNG were used for numerical simulation. Based on the results, simulation accuracy using the RNG model was more than the k-ε model. The statistical indices of NRMSE, ME, NS, and R2 for comparing the water surface profile were obtained at 34.3, 0.0052, 0.995, and 983 for the application of the RNG model, respectively. Also, using the RNG model, the values of these indices for the velocity profile were obtained at 14.92, 0.127, 0.9982, and 962, respectively. In general, the error of the simulated water surface and velocity profile were obtained at 5.31 and 12.4 percent, respectively. Moreover, the maximum error of the numerical simulation results of D2/D1, Lj/D2, and Lr/D1 was ±12, ±12, and 16%, respectively. Therefore, the use of Flow-3D software with the application of the RNG turbulence model is recommended for numerical simulation of the hydraulic jump in different situations.

The presence of the in-flow hydraulic structures create gradually varied flow (GVF) profiles which the computation of the hydraulic parameters based on the dynamic equation of flow with high accuracy has significant aspect among researchers. In this study, while doing dimensionless process of flow dynamic equation using yn and yc, Gaussian Hyper-Geometric Function (GHF) has been implemented to solve the equation analytically for five main channel slopes namely Mild (M), Steep (S), Critical (C), Horizontal (H) and Adverse (A). also, a comparison has been done using laboratory data between the accuracy of numerical Rung-Kutta 4th order method and GHF analytical solver based on root mean square error (RMSE), determination coefficient (R2) and mean percent error € for M1, S2 and C3 profiles. While The values of RMSE and R2 indices for M1, S2 and C3 profiles for GHF solver obtained (0.0173,0.9986), (0.0167,0.9984) and (0.0204,0.9988) respectively, corresponds values for Rong-Kutta method were (0.0458,0.9864), (0.0259,0.991) and (0.0327,0.9869). The results showed that using GHF analytical solver to solve the differential equation of GVF is more accurate.

Side weirs are important and practical hydraulic structures in water conveyance systems that are installed on the side wall of the channel to divert excess water from main channels. In this research, the effect of the height of two-side semicircular labyrinth side weir on the discharge coefficient and water surface profile in 3D by using the FLUENT software. side weirs were used in three, four and five cycles with a height of 10,15 and 20 cm and an opening length of 40 cm. The discharge coefficient and water surface profile obtained from this simulation were compared with experimental results for validation. The computed values have a good agreement with the experimental data and the error percentage for the discharge coefficient is between zero and 7% and the relative error was decreased by decreasing of Froude number. Based on the results, as the height of the side weir increases, the rate of water surface fluctuations in the main channel and along the side weir decreases. On average, with every 5 cm reduction in the height of the side weir, the rate of water surface decreases by 3%. Also, the discharge coefficient of the side weir decreases with decreasing congress radius and with increasing the side weir height and upstream Froude number. Therefore, the semicircular labyrinth side weir of three-cycle with height P = 10cm has a higher discharge coefficient than the other side weirs under study.

Water level determination during a flood is always a challenging task for river engineers. During the flood, river channel becomes compound consisting of the main river channel which carries low flows and floodplains that carry overbank flows.  Flow velocity and structures are affected by vegetation, the degree to which depends on vegetation density, flexibility, type, and whether it is in a submerged or emergent condition. Water surface modeling help for the study of flood waves, water level calculation during flood, stage discharge relation, design of water work structures. This work develops a model which can be used to simulate water surface profile in compound channel with vegetated floodplains with various vegetation covers. To predict the water surface, experiments have been conducted in the laboratory for different hydraulic conditions. It can be seen from the results that the trend of stage-discharge relationships is found to be an exponential function giving a high value of R2. A multivariable regression model (MRM) has been developed to predict the water surface profile for such channels. The dependency of water surface profiles on four different non-dimensional parameters such as canopy arrangement, canopy density, relative depth and relative distance are analyzed. Using the relevant experimental data, non-linear regression has been performed. The results obtained from the present water surface profile model shows good agreement with the observed data.

Any structure that is in the flow path and establishes a simple, specific and definite flow relationship and depth around it is called a flow controller. Weirs are structures that raise the water level behind them and create control sections and are simple means of measuring discharge. Bazin & Schwalt (1898) were the first to conduct experiments on rectangular broad crested weirs. Since then, many researchers have done a great deal of research on a variety of weirs. Among them we can mention: Woodburn (1932), Tracy(1957), Smith(1959), Abou-seida & Quraishi (1976), Hager&Schwalt (1994), Sargison & Percy (2009),….Due to the importance of flow measurement in open channels, the purpose of this study was to investigate the hydraulic performance of inclined weir, to determine the discharge conveyancecoefficient in this kind of structures in free and submerged flow condition, and to provide relationships to predict the discharge conveyancecoefficient.

Based on Equation 1, we can determine the weir discharge. In this equation Q is the discharge (m3 / s), Cd is the discharge coefficient (no dimension), B is the weir length (m), g is the acceleration (m / s2), and H is the height of the water over the weir (m).Also rewrite from the equation 1 to form 2 by defining it   as the discharge conveyancecoefficient (Mohamed, 2010):In this study, the equation 2 is based on the calculation of the discharge throughput on weirs. The following two equations for free and submerged flow are presented using dimensional analysis.The experiments were conducted in a plexiglass flume (Fig. 1) made of the British ArmField Company with a length of 15 m, a width of 30 cm and a height of 50 cm. A total of 60 experiments (30 free-flow and 30 submerged-flow experiments) were performed on the inclined weir.

A) Free flow condition
In this series of experiments, with increasing H/Lw ratio, the discharge conveynce coefficient of all three sloping weirs increased, but the coefficient of conveynce discharge of rectangular broad crested weir decreased (Fig. 1). This figure shows that among inclined weirs are most sensitive to H/Lw changes.Also comparison of the inclined weir with the rectangular broad crested weir indicates that the rectangular broad crested weir later is less sensitive to H/Lw. Equation 5 was derived to calculate the discharge conveyancecoefficient (Cf) in inclined weirs under free-flow conditions. B) Submerged flow conditionMultiple regression was used to investigate the interaction of the extracted dimensionless parameters on the discharge conveyancecoefficient and to provide a mathematical relation to predict these values. Equation 6 was derived to calculate the Cs coefficient in inclined weirs under submerged flow conditions. Figure 2 shows the computational and observational Cf, Cs in free and submerged flow conditions. The scattering of these points relative to the 45 ° line shows that the correlation coefficient of the experimental and computational values for free and submerged flow are equal to 0.9 and 0.91 respectively.

The results show that:- Increasing in H/Lw ratio leads increases in discharge conveyance coefficient of all three sloping weirs and decreases in rectangular broad crested weir. - For a constant value of the H/Lw ratio, the highest discharge coefficient is related to the upstream and downstream slope weir model (SCW-UD-1) and the lowest discharge coefficient is to the upstream slope weir model (SCW-U-1).-The upstream and downstream slope weir are most sensitive to H/Lw changes and rectangular broad crested weir is less sensitive to changes in H/Lw ratio. - As the H/p < /em> ratio increases, the discharge conveyance coefficient of all three sloping weir models increases.

Side weirs are hydraulic structures installing on the side walls of the channels to divert excess water of main channel. Labyrinth weirs are broken in their plans; so, they have more effective length and in some conditions have more discharge coefficient than that of simple ones. In this research, the effects of piles with different arrangements on discharge coefficient of semi-circular labyrinth side weir have been studied. The experiments were carried out in a rectangular channel with subcritical flow with Froude number range equal to 0.1-0.37. Three diameters were considered for semi-circular labyrinth side weirs with constant height. The piles used in the study were cylindrical and the same height of the side weir. The number of piles varied from 1 to 3, and fourteen arrangements were considered for them. First of all, the effects of dimensionless parameters, obtained from the Buckingham method, on side weir discharge coefficient were studied and then a relationship, with acceptable accuracy, between these parameters was obtained to predict the discharge coefficient of semi-circular labyrinth side weir with piles.. The results,  compared with semi-circular labyrinth side weir without piles, showed that semi-circular labyrinth side weir with arrangements of piles have higher discharge coefficient. In fact, piles proved an improvement in the performance of semi-circular side weirs, so that within the range of the studied Froude number, the discharge coefficient faced an increase up to 15% and specific energy changes faced a decrease up to 34%. The most increase in discharge coefficient and the most decrease in specific energy changes occurd when three piles were installed at the downstream end of weirs.

In this study, the roughness at downstream of ogee spillway has been simulated numerically for different flows, and the effects of roughness on the transformation of flow regime, the water surface profiles, and the energy losses also have been investigated. Hence, after solution domain generation, meshing, and specification of boundary conditions, the numerical simulation has been run by using k-e standard turbulence model, and in order to validation of the numerical results of the investigated ogee spillway, the experimental model of ogee spillway proposed by Chatila and Tabara (2004) has been used. Also, the effects of three types of roughness at downstream of this spillway were evaluated. The results indicated that by increasing the heigh of roughness, the energy loss increases up to 80 percent. The roughness types of 3 and 4, imposed the regime transformation and caused 70 to 50 percent, in average, energy losses respectively. Also, we found that increase in flow discharge affected directly the water surface profiles.  Results showed that if the design of stilling basin was considered, the roughness with a height of 0.6Hd had the ability of flow regime transformation and was evaluated as the most successful design.

Flow pattern around the bridge piers includes water surface profile, velocity profile, shear velocity, shear stress distribution, etc. In this research, the effects of the base shape along with scale effects on the flow pattern around the rectangular bridge piers were numerically calculated through "Fluent Software", using Horizontal Velocity Distribution (Vx) and Vertical Velocity Distribution (Vy) criteria. The results showed that in studying the horizontal component of velocity (Vx) for the rectangular bridge piers, the vortices activity radius was 8 times of the length of the pier, and the minimum channel width for vortices activity was 16 times of the length of the Bridge pier; also, the minimum channel length in front of the pier was 4 times of the length of the pier and behind which, it was 25 times more than the bridge pier. Finally, the minimum channel length for the vortexes activity was calculated to be 29 times more than the bridge pier length. Furthermore, for the vertical component of velocity, the flow pattern around the base of the bridge cannot be an appropriate parameter for checking the effects of the length and width of the channel.

A vortex settling basin (VSB) is an efficient continuous flushing structureto remove bed loads and coarse suspended loads. In present study, experiments were conducted in Hydraulics lab of Water Science and Engineeing Departmentat Ferdowsi University of Mashhad on a vortex settling basin model with clear water. The flow rate varied in the range of 8-22 L/s .Velocity was measured in three dimensions within the chamber using ADV. The flow field iscalculated using 3D Reynolds-averaged N–S equations, laminar case (coarse DNS) and turbulent models including standard k-ε, k-ω and Smagorinsky models. The abstraction ratio was determined, water surface counters were depicted and tangential velocity was calculated. The abstraction ratio was in range of 75-87.5%.Flow depth and tangential velocity formula were determined based on dimensional analysis and linear regression. The obtained empirical equations werecompared withother extant empirical equations. Results of turbulent models including abstraction ratio, water surface profile and tangential velocity were compared to the experimental data. Smagorinsky model showed better agreement with the experimental data and the relative error of the model was less than 3%. The free and forced vortex regions in Smagorinsky model was more similar to those in experimental data.

The basic equation of Gradually Varied Flow (GVF) describes the variation of water depth with flow process. Several methods have been developed for numerical solution of the water surface profile in GVF and one of the challenges of numerical integration is determining the appropriate integration spatial step size. In this paper a novel Adaptive Newton-Raphson method is developed for numerical solution of the GVF equation. In this method the spatial steps are determined by using error estimation during calculation, this procedure is smart and increases accuracy and speed of computation the water surface profile in GVF. Several examples were analyzed using the proposed method and compared with the results of previous researches and the accuracy of the proposed method was evaluated. The results indicate good accuracy of the proposed method in comparison with other methods. As shown in one of examples presented in the paper, the obtained results from 10 step of developed Adaptive Newton-Raphson methodapproximately equal with 90 step of standard direct step method.

The critical role of the rivers in supplying water for various needs of life has led to engineering identification of the hydraulic regime and flow condition of the rivers. Hydraulic structures such dams have inevitable effects on their downstream that should be well investigated. The reservoir dams are the most important hydraulic structures which are the cause of great changes in river flow conditions.
In this research, an accurate assessment was performed to study the flow regime of Karkheh river at downstream of Karkheh Reservoir Dam as the largest dam in Middle East. Karkheh River is the third waterful river of Iran after Karun and Dez and the third longest river after the Karun and Sefidrud. The Karkheh Dam is a large reservoir dam built in Iran on the Karkheh River in 2000. The Karkheh Reservoir Dam is on the Karkheh River in the Northwestern Khouzestan Province, the closest city being Andimeshk to the east. The part of Karkheh River, which was studied in this research is located at downstream of Karkheh Reservoir Dam. This interval is approximately 94 km, which is located between PayePol and Abdolkhan hydrometric stations. In this research, 138 cross sections were used along Karkheh River. Distance of cross sections from each other was 680m in average. The efficient model of HEC-RAS has been utilized to simulate the Karkheh flow conditions before and after the reservoir dam construction using of hydrometric stations data included annually and monthly mean discharges, instantaneous maximum discharges, water surface profiles and etc. Three defined discharges had been chosen to simulate the Karkheh River flow; maximum defined discharge, mean defined discharge and minimum defined discharge. For each of these discharges values, HEC-RAS model was implemented as a steady flow of the Karkheh River at river reach of study. Water surface profiles of flow, hydraulic parameters and other results of flow regime in HEC-RAS model were obtained for the conditions before and after the construction of the Karkheh Reservoir Dam and then it was reviewed and analyzed.
By exploiting the Karkheh Reservoir Dam, the river flow was changed from the natural condition to the regulatory situation. The results indicate that the river flow was considerably declined because the regulatory effect of the reservoir dam which has contributed to the great alternations at hydraulic parameters of the river. For example, the mean annual discharge of the Karkheh River shows 44pecent reduction during the time period of simulating (after the dam construction in comparison with the natural river flow before construction of reservoir dam) in PayePol hydrometric station. Flow velocity of Karkheh River is influenced by discharge, slope of the river channel and geometry of cross section. By increasing the river flow, the flow velocity has increased and there is a significant difference between pre and post-dam condition at the mean velocity of river flow in different sections. The flow area is directly influenced by river discharge and there is a significant difference in the maximum defined discharge before and after dam construction. The width of water surface is a parameter of the geometric situation of the river cross section that also shows the maximum width of the cross sections, passing discharge through the desired cross section. Since Karkheh River has a relatively large water surface width, it has a high wetted perimeter. For this reason, the Karkheh river hydraulic radius is usually low. The significant reduction of all these quantities is for reduction of flow rate by construction of Karkheh Reservoir Dam. Studying the water surface profiles represents reduction of water level in the longitudinal profile of Karkheh River and water level of hydrometric stations by construction of the Karkheh Reservoir Dam. Also, due to the reduction of the discharge in the downstream of Karkheh Dam, all hydraulic parameters of the river such as flow velocity, flow area, width of surface water, hydraulic depth, shear stress and the hydraulic radius have been changed. In general, it can be concluded that the construction of a large dam such as Karkheh Reservoir Dam has a significant effects on the flow regime conditions at river downstream. Our survey would be helpful for environmental, geological and ecological experiments on effects of dam construction and for engineering next hydraulic structures on such rivers.

The water surface profiles on spillway are important for design of free board and spillway training wall height. The engineers have used physical modeling to design these kinds of structures, Considering that the scale effect in the spillway modeling, leads to the different measured data between model and prototype, in this study, an experimental model based on Garmi-Chay Mianeh dam spillway was designed in three 1:100, 1:75, and 1:50 scales. Next, the water surface profile on spillway crest measured in seven discharges and compared with basic scale of (1:50), the percentage of water level difference on the crest calculated in two physical models with 1:100 and 1:75 scales. Results and observations revealed that in due to the effect of viscosity and surface tension the difference of water level in the scale of 1:100 and 1:75 was 18.4% and 15.6% respectively, relative to the base scale. The larger discharge, water level on spillway increases, leads to decrease viscosity and surface tension effects. For the difference in water level in the scale of 1:100 and 1:75 was 5.8% and 4.8% respectively relative to the base scale. In this study, viscosity and surface tension effects is stated with correction equation (K'), that was functions of Reynolds and Weber numbers. With the ogee spillway modeling the effect of viscosity in Reynolds numbers larger than 3.1*104 and the effect of tension surface in Weber numbers larger than 270 can be neglected and by extrapolation prototype results from model studies can be obtained.

Side weir is a hydraulic control structure that is widely used in irrigation, drainage and urban sewage purification. In this research, 220 tests were carried out to study discharge coefficient and water surface profile of one-side semi-circular labyrinth side weir under subcritical flow condition. The effects of upstream Froude number, the ratio of length to width of the channel, weir height to upstream water depth, number of cycles and the radius of the Labyrinth on the discharge coefficient of the weir were investigated. The results showed that discharge coefficient of the semi-circular labyrinth side weir was 21 percent higher than rectangular side weir. Using SPSS software, a general equation based on the dimensionless parameters was presented for calculating the discharge coefficient of the semi-circular labyrinth side weir. The determination coefficient and NRMSE of this equation were obtained, 0.93 and 0.28 respectively. The water surface profile along the central axis of the main channel was almost horizontal.

Side or lateral weir is a flow measurement structure that is extensively used in irrigation and drainage networks and sewer systems. The main channel cross-section and side weir shape completely modify the flow conditions. Up to now, many studies have been conducted on side weirs. Most of the previous theoretical analysis and experimental research works are related to the flow over rectangular side weirs. This study focuses on a circular sharp-crested side weir located in a rectangular main channel in subcritical flow regime. This kind of side weir has some advantages, in comparison to other general weir types. Since the height of this side weir varies along its length, it can control flood better than other side weirs in flood conditions. In addition, because of its circular shape, it has a greater discharge coefficient.
The governing equation of the circular sharp-crested side weir has no analytical solution and thus should be solved by numerical methods. In order to simplify the solution, the equation of inline circular weir with discharge coefficient as a calibration parameter is used. The reference flow depth which should be used in this equation is an important point. In this study, three reference depths were considered (average depth 0.5(y1), center depth and initial depth y1).
In this research, the equation of conventional circular weir presented by Vatankhah (2010) is used for circular sharp-crested side weir:where Qa=actual discharge; Cd = discharge coefficient; g = gravitational acceleration; and η=H/D, with H being flow depth above the circular sharp-crested weir of diameter D.
For circular sharp-crested side weir, effective non-dimensional parameters were determined using dimensional analysis and Buckingham's Pi-Theorem. Finally, the following non-dimensional parameters were considered as the most effective ones on the discharge coefficient:where Fr= Froude number and B= main channel width.
The experiments were performed in a rectangular open channel having provisions for a side weir at one side of the channel. The main channel was horizontal with 12 m length, 0.25 m width, and 0.5 m height which was installed on a frame. The lateral channel has a length of 6 m, width of 0.25 m, and height of 1 m that was set up parallel to the main channel; the walls and its bed were made up of Plexiglas plates. The side weir was positioned at a distance of 6 m from the channel’s entrance. A total of 123 experiments on circular sharp-crested side weirs were carried out.
Different depths were considered as the reference depth. According to the experimental analysis, the discharge coefficient is a function of the upstream Froude number and the dimensionless ratio of its diameter to the main channel width.
The proposed empirical equations for discharge are as: (Average depth 0.5(y1) as the reference depth)
(Center depth as the reference depth)
(Initial depth y1 as the reference depth)
The average errors of the proposed equations are less than 2.4%, and only 5.5% of the experimental data have error more than 5% if the averaged and center depths are considered as the reference depth. However, 8.1% of the experimental data have error more than 5% if the initial depth is used as the reference depth.
In this research, the characteristics of the circular sharp-crested side weir overflows in subcritical flow regime are discussed. For this purpose, experimental data related to the water surface profile of the side weir and discharge coefficient were collected and carefully analyzed to develop accurate and simple discharge equation. The results showed that the most efficient section for measuring the water surface profile is located on the center line of the approaching channel. It was also found that for the circular sharp-crested side weir, the discharge coefficient depends on the Froude number and the ratio of weir diameter to the main channel width. In this study, the conventional circular sharp-crested weir theory has been used in order to evaluate the discharge coefficient and provide a side weir discharge equation. For this purpose, three reference flow depths were considered for conventional weir (average depth 0.5(y1), center depth and initial depth y1), and for each flow depth an equation was developed for the discharge coefficient. Comparison between predicted values and experimental data showed that the average and center flow depths result in accurate outcomes for estimating the discharge coefficient. The average value of error for discharge coefficient estimation by the proposed equations is less than 2.4%. Thus, these equations are proposed for practical use.

Reduction of water resources and low efficiency of irrigation networks makes it necessary to pay attention to the management methods and the proper operation of the irrigation canals. In each irrigation network, there is a large number of offtake and cross-regulators that any change in their operating situation affects the behavior of other structures and lead to decrease in the hydraulic performance of canals. The structural perturbation is formed under partial changes in the setting of offtake and cross-regulator, which causes variations of the design depth and water surface profile. Partial changes in the inflow of a canal discharge lead to hydraulic perturbation and variation in water surface profile. In this research, in order to investigate the influence of structural and hydraulic perturbation on the flow depth, the governing Gradually Varied Flow (GVF) equation was linearized by Taylor's expansion and an analytical equation was developed to calculate the water depth changes. Then, for various hydraulic conditions, the results of the numerical solution of the governing GVF equation and the developed analytical formula were compared. The results showed that the errors of the presented formula to calculate the water surface profile changes under structural and hydraulic disturbances were less than 4% and 3.8%, respectively.

Determination the hydraulic performance of an irrigation network requires adequate knowledge about the sensitivities of the network structures. Hydraulic sensitivity concept of structures and channel reaches aid network operators in identifying structures with higher sensitivities which will attract more attention both during network operation and maintenance program. Sluice gates are frequently used as regulator and delivery structures in irrigation networks. Usually discharge coefficient of sluice gate is considered constant in the design and operation stage. Investigation of sensitivity of offtakes and cross-regulators has carried out by various researchers and some hydraulic sensitivity indicators have been developed. In the previous researches, these indexes were developed based on constant coefficient of discharge for free flow sluice gates. However, the coefficient of discharge for free flow sluice gates depend on gate opening and the upstream water depth. So, in this research, some hydraulic sensitivity indicators at structure based on variable coefficient of discharge for free flow sluice gates were developed and they were validated by using observed data. An experimental setup was constructed to analyses the performance of the some hydraulic sensitivity. The flume was provided with storage reservoir, pumps, electromagnetic flowmeter, entrance tank, feeder canal, delivery canals, offtakes, cross-regulators, collector reservoir, piezometric boards. The flume is 60.5 m long and the depth of that is 0.25 m, of which only a small part close to offtake and Cross-regulators was needed for these tests. Offtakes and Cross-regulators are free-flowing sluice gates type. Offtakes were located at distances 20 m and 42.5 m downstream from the entrance tank, respectively. and, Cross-regulators were located 2 m downstream from each offtakes. The offtakes are 0.21 m and Cross-regulators are 0.29 m wide. The upstream and downstream water levels at gates were measured with piezometer taps. There is a collector reservoir downstream of each delivery canal that was equipped with a 135 V-notch weir as a measuring device. The flow was provided by a pump having maximum capacity 35 lit/s, and was measured by an electromagnetic flowmeter of 0.5% accuracy. The suction pipe of the upstream pump was connected to the storage reservoir and its discharge pipe delivered the water to an entrance tank located at the upstream side of the flume. The entrance take was equipped with a turbulence reduction system. Measured water entered to feeder canal and, after adjusting water depth by Cross-regulators, it moved to offtakes and the brink of the feeder canal. Underneath the downstream end of the feeder canal and delivery canals, a tank was installed to collect the water. Water accumulated at the collector tanks was pumped to the storage reservoir by using a pump to complete the water circulation cycle. Discharge coefficient is the most important parameter that is effect on hydraulic indicators sensitivity. Therefore, coefficient of discharge for free flow sluice gates determined based on experimental data. Sluice-gate discharge coefficient is a function of geometric and hydraulic parameters. For free flow, it is related to upstream depth and gate opening. In this study, analytical relationships for various sensitivity indices for channel reach were developed, and the performance of the proposed relationships was verified with experimental data compiled during this research. It was shown that using constant discharge coefficient yields average error in the calculated sensitivity of the water depth upstream regulator to the inlet flow, and average error of calculated reach sensitivity indicator, as 16.6% and 5.8%, respectively. While those values for variable coefficient was 5.7% and 1.9%, respectively. Also, for 20% variation in reach inflow, the variable coefficient improved the calculated mean flow depth error upstream of a regulator drastically, i.e. the mentioned error using constant coefficient was 17% while that of variable one was 4.3% In this research, Analytical relationships based on using variable discharge coefficient for Three sensitivity indicators for a canal reach, i.e. reach sensitivity indicator of water depth, reach sensitivity indicator for conveyance and delivery developed. Comparing reach canal sensitivity indicators and the structural sensitivities, i.e. sensitivity of delivery of offtake to absolute water depth deviation and water depth sensitivity to the discharge for regulator with experimental data, showed good agreement. Hence, the technique proved to be reliable in providing what is necessary for practical canal.

One of the important parts of the urban and agriculture water conveyance systems are channel junctions. In this research، the effects of different factors such as inlet discharge ratio، bed elevation of lateral channels and height of weirs at the end of outlet channels on characteristics of the subcritical flow in 90 degrees four-branch open channel junctions with two inlets and two outlets were investigated experimentally. The results showed that as the inlet discharge ratio، bed elevation of lateral channels and height of weirs at the end of outlet channels increased، the outlet discharge in the main channel also increased. Increasing the inlet discharge ratio and decreasing the height of weirs at the end of outlet channels caused more fluctuation in the water surface profile at the junction، but variation of the bed elevation of lateral channels had no effect on fluctuations of the water surface profile. Furthermore، conjunction of the two inlet flows caused changing the velocity profiles in the inlet channels.

Study on the reduction of flow energy intensity in order to reduce damage of the downstream hydraulic structures, always has been one of the potential interesting issues. One of the most important topics in this field is the study on hydraulic jump and its control method. Like other structures, in energy dissipaters considering economic and ease of construction is an essential issue. Therefore, in this study, the effects of the roughness and negative bed slope on water level and velocity profiles of hydraulic jumps for upstream flow in Froude numbers ranges of 4.9-7.8, with three different bed roughnesses and slopes of 0%, 3.1%, 60%, and % 2 were studied. The results indicated some similarities between the measured velocity profiles and some differences between the profiles of water jets as compared with those on smooth beds. Also, the thickness of the dimensionless boundary layer was calculated to be 0.66, which was significantly different in comparison with its value for the flat bed (0.16). Moreover, the bed shear stress on the rough negative sloping bed was at least 10 times greater than the shear stress on the smooth flat bed. Also, the energy and momentum correction coefficients were higher relative to the classic mode.

Side weir structures are extensively used in hydraulic engineering, irrigation and environmental engineering, and it usually consists of a main weir and a lateral channel. Side weirs are also used as an emergency structure. This structure is installed on one side or both sides of the main channel to divert the flow from the main channel to the side channel. Lateral outflow takes place when the water surface in the main channel rises above the weir sill. Flow over a side weir is a typical case of spatially varied flow with decreasing discharge. There have been extensive studies on side weir overflows. Most of the previous theoretical analysis and experimental research works are related to the flow over rectangular side weirs in rectangular main channels. In the current study, the flow conditions over a trapezoidal side weir located in a rectangular main channel in subcritical flow regime is considered. The experiments were performed in a rectangular open channel having provisions for a side weir at one side of the channel. The main channel was horizontal with 12 m length, 0.25 m width, and 0.5 m height, and it was installed on a frame; lateral channel that has a length of 6 m, width of 0.25 m, and height of 1 m. It was set up parallel to the main channel; walls and its bed were made up of Plexiglas plates. The side weir was positioned at a distance of 6 m from the channel’s entrance. A total of 121 experiments on trapezoidal side weirs were carried out. For trapezoidal side weir, effective non-dimensionnal parameters were identified using dimensional analysis and Buckingham's Pi-Theorem. Finally, the following non dimensional parameters were considered as the most effective ones on the discharge coefficient of the trapezoidal side weir flow.in which Fr1= upstream Froude number, P= hight of the trapezoidal side weir, y1= upstream water depth, z=side slope of the trapezoidal side weir and T=top flow width of the trapezoidal side weir. Water surface profiles were measured along the weir crest, the main channel centerline, and far from the weir section. Different elevations in water surface profile depend on the upstream Froude number in the main channel; depth differences in low Froude numbers are at minimum values, and in high Froude numbers are at maximum amounts. The water surface level along the crest drops at the entrance of the side weir to the first half of the side weir; and it has been attributed to the side weir entrance effect at the upstream. Afterwards, the water level rises towards the downstream of the weir. According to the experimental results, measurements of the water in the centerline of the main channel are reliable and water surface drop is negligible. According to the parameters affecting the discharge coefficient for each value of z, discharge coefficient equations were developed with acceptable accuracy such that the effects of this parameter were shown separately. Finally, the general equation was proposed. The general functional form for discharge coefficient is presented as follows where the effect of the side slope parameter, z, is also considered. The mean and maximum percentage errors of the discharge coefficient computed using the proposed equation are as 2.6% and 11.5%, respectively. In this study, the characteristics of trapezoidal side weir overflows in subcritical flow regime were discussed. For this purpose, experimental data related to the water surface profile of the side weir and discharge coefficient were collected and analyzed. The results showed that the most efficient section for measuring water surface profile is located at the center line of the main channel. It was found that for trapezoidal side weir, the discharge coefficient depends on the Froude number, the ratio of crest height to initial depth, the overflow length to initial depth, and the side slope of the weir. In this study, conventional trapezoidal weir theory has been used in order to evaluate the discharge coefficient and provide side weir discharge equation. For this purpose, three reference depths were considered for conventional weir, and for each depth an equation was developed for the discharge coefficient. Comparison between predicted values and experimental data showed that average flow depth results in accurate outcomes for assessing the discharge coefficient. The average value of error for discharge coefficient estimation by the proposed equation is 2.6%. Thus this equation is proposed for use in practice by water engineers.

Submerged vanes are commonly used as hydraulic structures for sediment control at intake entrance. In the present research which was undertaken at the Hydraulic Laboratory in Water Engineering Department of Shiraz University، the hydraulic performance of these structures in sub-critical flows was studied experimentally، and the effects of submerged vanes، angle variations of submerged vanes and discharge rates on intake ratio and water surface profiles in the main channel near the lateral intake with rounded entrance and angle of 55 degree which is named as the best intake angle were investigated. In this study the submerged vanes had four installation angles of 10، 20، 30 and 40 degrees along with the two setups of 2 and 3 parallel vanes across the entrance، considering four levels of discharge values. The results showed that the application of submerged vanes، regardless of their angles، caused in the increase of water surface elevation near the upstream of the vanes as compared to the no vanes condition. The submerged vane cause an increase in intake ratio. Finally the results showed that the submerged vanes with angle of 30 degree and three parallel vane setup across the entrance had the best intake efficiency.