جواد فرهودی

Nowadays, the successful countries in agricultural water management have attempted to address the challenges in this sector by “reducing their being in charge” and "transferring the management of agricultural water to stakeholders". In Iran, despite valuable experiences in efficient traditional water management and water users’ associations, significant achievements have not been gained. Therefore, the aim of this paper is to accurately identify the factors influencing the participatory management, its contexts, motivations, impediments, and ultimately to propose some mechanisms for implementing participatory management in agricultural water management. A content analysis method was employed, utilizing library resources (A total of 78 cases from 1971-2024). The results of this research indicate that the main reasons for the lack of successful achievements in participatory water management are mainly embedded in the absence of belief and conviction at the national level and the lack of necessary will among decision-making institutions to institute for participatory water management; the dominance of a technocratic approach in the water sector; the unclear legal status of water user associations and their weakness in technical, financial, economic, legal, and cultural aspects for accountability; the instability of supportive policies in establishing and organizing these associations. To institutionalize participatory irrigation management, it is essential to establish and formalize water user associations, delegate responsibilities and authorities in accordance with the country's seventh development plan, clearly define and provide water services, ensure mutual participation and accountability between the government and stakeholders, and ultimately establish a demand-driven support system based on cost-sharing.

Data and information play a special role in the transparency of water governance. On the other hand, witnessing contradictions in water resources data and information, inconsistent readings and narratives about water assets, outdated hardware equipment, and to some extent software enhancement in the preparation and presentation of water resources information compared to global advances, necessitates a serious review of water resources data collection and processing systems. In this regard, artificial intelligence methods, sensors, and remote sensing technologies are considered in accurate water resources accounting. This article is a systematic review of about 100 international articles that present the latest findings related to software and hardware equipment for monitoring hydrological cycle meta-indicators. These meta-indicators include precipitation, water depth/water level/flow velocity and discharge of rivers, and groundwater level. In each case, while providing a list of the most important technologies, the application level of these technologies in monitoring surface and groundwater resources in Iran was evaluated. The conducted studies prove the unfavorable application technologies in monitoring hydrological cycle in Iran. For example, out of a total of twenty-six known technologies related to surface flow measurements, only two technologies have been widely used Iran; four technologies have reached the knowledge frontier and widespread production by domestic knowledge-based companies, and eleven technologies have not yet reached the knowledge frontier Iran. In this paper, suggestions were presented to outline the path for developing new technologies for water cycle data collection and transformation in the modernization of Iran's water resources data collection and data processing infrastructure.

Examining the changes in the water quality parameters of the Karun River using satellite data and determining the modified quality indicators can be used to assess the vulnerability of irrigation water. In this research, the data of seven qualitative parameters: Na+, SAR, pH, Cl-, HCO3-, EC and TDS were used in six water measuring stations of Abbaspur, Ahvaz, Farsiat, Gotvand, Molasani and Soosan of the Karun River (1392-1398) and NSFWQI general water quality index was calculated. Correlation relationship and estimation errors were determined for two principal component reduction (PCA) and multivariate linear correlation methods. The results showed that multivariate correlation method is more suitable. The coefficient of determination for the seven water quality parameters was calculated as 0.44, 0.43, 0.03, 0.43, 0.09, 0.45 and 0.46 respectively, and for the NSFWQI index it was calculated as 0.46. The statistical correlation for pH and HCO3- is at a very low level; but for the other five parameters and the NSFWQI index, it is in average state. The significance level of estimation for Na+, SAR, Cl-, HCO3-, EC and TDS parameters is acceptable (P<0.001), and for pH is unacceptable (P<0.122). In general, there is an acceptable correlation between the bands extracted through the Landsat 8 satellite and most of the quality parameters of the Karun River, but necessary actions are proposed to improve the correlation relationships. Also, the NSFWQI index shows that the quality of water in the Karun River along the Khuzestan plain is not good enough.

Dam removal is one of the methods of restoring the river ecosystem. The decision to remove a dam is based on the multidisciplinary indicators and the type of dam body and its location, as well as the downstream conditions and the type of dam removal method. In the present study, the removal of the Voshmgir Dam on the Gorganrud River, Iran, was considered, because of the high volume of sediment deposition in the reservoir and the loss of its useful life. Three scenarios were selected for the removal of the dam: 1- complete removal; 2- stepped removal of the spillway; and 3- removal with stable sediments. In the first step, numerical modeling for river morphological changes was performed using the HEC-RAS model for unsteady flows with sediment transport. The erosion and sedimentation processes were simulated in six reaches (from the Voshmgir Dam to the Caspian Sea), with total length of 128 km. The results indicated that the second scenario (stepped removal of the spillway) is the best alternative due to the gradual processes of river-bed changes. In the present research, the two-dimensional hydrodynamic and water quality model CE-QUAL-W2 is used for qualitative modeling of Gorganrud River in three scenarios of dam removal, within 128 km downstream of Vashmgir dam to the Caspian Sea Estuary. Qualitative modeling was performed for the existing conditions of Gorganrud (without removing the Vashmgir dam) at two hydrometric stations of Aqqala (68 km downstream of the Vashmgir dam) and and Basirabad (112 km downstream of Vashmgir Dam), where a set of water level and water-quality data was available for model calibration. Model results are presented in the period of rapid river changes after dam removal up to 60 days. Based on the results of qualitative modeling, the amount of dissolved oxygen (DO) has increased in three scenarios of dam removal in two sections of the river (Aqqala and Basirabad). The amount of biochemical oxygen demand (BOD) in the first scenario (complete removal) and the second (stepping removal) has increased slightly (less than 10% of the river conditions before removal). In the third scenario (removal with stable deposition), no significant change in BOD occurred. In three scenarios and in both study periods, the pH changed very little in the two periods, before and after the removal of the dam. The total amount of soluble solids (TDS) in the early days of the simulation is equal to or greater than that before removal. The TDS rate is to be decreased by time. The overall results indicated that the second scenario of the dam removal (i.e. stepped removal of the spillway) is the best alternative due to the less impacts on the river-bed changes, and the gradual processes of river-ecosystem rehabilitation.

Sustainable river management requires the construction and operation of dams that provide environmental flows to support downstream rivers ecosystem. Dam construction in Iran has significantly altered natural flow regimes and caused various environmental issues. The main aim of the present study was to evaluate the hydrologic and environmental alteration of the flow regime in the Jajrud River downstream of the Latian Dam. In this study, a set of long-term flow data (1947-2017) was analyze using the IHA and RVA models. The results show that the degree of alterations for the 24 flow variables is in the range of high to medium, denoting the high hydrological alterations of the Jajrud River. The values of mean, maximum and minimum monthly flows have decreased by 57, 94 and 21 percent, respectively. The overall change is 51%. Magnitude and duration of annual extreme flows have decreased, and in particular, the minimum flows and the base-flow indices have changed the most. The large flood events has been eliminated and small and frequent floods has been damped in the downstream river system. The results indicate that the goals of RVA have not been achieved in the post-construction period of the Latian Dam, and the environmental conditions of the river have been severely damaged. With reference to the eco-hydrological indices, the rehabilitation of the environment status of the Jajrud River requires the dam releases of minimum monthly flows in order of 2.3 to 33.8 m3/s, with an average annual discharge of 6.5 m3/s.

Innovative and sustainable agricultural water management is critical in adaptation programs to climate variability and change, and emerging, eco-friendly irrigation technologies are expected to play a key role in the world's future water and food security. The current study was carried out with the aim of discussing pros and cons of new irrigation and agricultural water technologies in the world, and the possibility of application of these technologies in Iran. These techniques are classified into seven categories: smart technology, nanotechnology, greenhouse technology, superabsorbent technology, cloud seeding technology, deep water technology, and seawater desalination technology. These technologies are analyzed in terms of economics, water and energy usage, and certain environmental factors (such as toxicity and greenhouse gas emissions). The state-of-the-art of modern irrigation and agricultural water technologies in Iran is examined, and the issue of their domestic application is matched with the country’s potentials. According to documentary studies, our country is at the beginning of the road in terms of intelligent technologies for agricultural water management and nanotechnology, and further study is required to employ these technologies. However, intelligent irrigation management utilizing crop growth and yield models, mobile phone applications, and micro-irrigation implementation was proposed as a feasible solution. The use of silver nanoparticles was suggested for the disinfection of water in remote areas, and the use of titanium dioxide for areas that do not have power supply problems. Employing the vertical farming is not recommended in the country due to the problems of electrical power supply and air pollution and presence of unlimited arable land. The technology of artificial light and solar panels has been adopted in Iran and more research is needed to justify their applications in greenhouses. Cloud seeding, deep water, and seawater desalination technologies have become indigenous to Iran. Cloud seeding is ineffective to alleviating droughts and strengthening aquifers. Because of the environmental consequences, the employment of deep-water technologies is not recommended. Employing of seawater desalination technologies for drinking and industrial (not agricultural) uses is cost effective.

Dam removal is one of the methods of restoring the river ecosystem. In the present study, the removal of the Voshmgir Dam on the Gorganrud River, Iran, was considered, because of the high volume of sediment deposition in the reservoir and the loss of its useful life. Three scenarios were selected for the removal of the dam: 1- complete removal; 2- stepped removal of the spillway; and 3- removal with stable sediments. Numerical modeling for river morphological changes was performed using HEC-RAS model for unsteady flows with sediment transport. The erosion and sedimentation processes were simulated in six reaches (from the Voshmgir Dam to the Caspian Sea), with total length of 128 km. The results indicated that the first scenario causes the highest rate of both erosion and sedimentation in the river reaches. In the second scenario, the intensity of river-bed changes is considerably reduced, and the highest deposition and erosion occurs in the first and the fifth reaches, respectively. The simulation results from the third scenario were uncertain. The second scenario (stepped removal of the spillway) is recommended due to the less impacts on the river-bed changes, and gradual processes of river-ecosystem rehabilitation

One of the structures for controlling and measuring flow in open channels are the sluice gates. In this study, to estimate the outflow from the sluice gates, the existing relationships for orifices evaluated theoretically and experimentally. A new method was established for estimating the contraction coefficient and energy loss coefficient under free-flow condition. Some equations proposed to estimate the outflow from sluice gates under submerged flow conditions using the energy-moment principles and relationships for orifices. In order to evaluate the accuracy of recommended relationships, the outflow from the sluice gates was experimentally tested in a channel of 18 meters long and one meter wide. Comparison of the results showed that all the presented orifice relationships have similarly good capabilities to estimate the outflow from the sluice gates under free-flow conditions. It was concluded that the applying of Henry relationship would be the simplest one in determining the contraction coefficient. Under submerged flow conditions, all the orifice relationships have competent accuracy in estimating the flow rate, with an order of errors less than 10 percent. Under full ranges of free to submerged flow conditions, the discharge coefficient can be determined by the relationship of Rajaratnam and Subramanya as a function of the head loss coefficient, the contraction coefficient and the opening-to-depth ratio.

Iran with a long-term mean annual precipitation of 254 mm (210 mm in short-term of drought period), mean annual potential evaporation of more than 2000 mm, and dominance of arid and semi-arid climates over 85% of its area is located in one of the driest regions of the world. These factors have led to the dependence of most agricultural productions in Iran on the surface water and groundwater. In this article, based on the statistics and documents collected from the reliable sources, the current situation of agricultural water resources and uses in the country has been studied and analyzed. In addition, the adequacy of agricultural water resources under the current and future conditions, the position of the country in terms of water resources and uses in the world, pathology and solutions to get out of the current situation have been studied and analyzed. Examination of available documents shows that despite the increase in irrigation water efficiency and productivity in the field in recent years, lack of attention to climatic and water resources potentials and unplanned development of agricultural lands to meet the food needs of the country's growing population have led to overexploiting the surface water and groundwater resources, and hence, the destruction of aquifers. Reducing water use in agriculture along with increasing agricultural water productivity and implementing groundwater balance plans have been proposed as the key solutions to the existing challenges.

In practical applications, for instance, at the downstream of hydraulic structures, in some cases the width of the basin may be larger than the upstream supercritical flow (sudden expansion in flow section). In such cases, an expanding hydraulic jump with symmetrical or asymmetrical shape will be developed at the downstream. Under the design of three parallel gates, the operation of the side or middle gate can be lead to the asymmetrical or symmetrical hydraulic jump, respectively. According to the position of jump toe, expanding hydraulic jump can be classified into four types. The present study focuses on a T-shaped hydraulic jump which the toe is established at the beginning of the divergence section.Most of the previous studies are related to the symmetrical expanding hydraulic jump. In this case, the downstream diverging channel is symmetric on the central axis of the channel. However, a systematic study investigating the effect of symmetry and asymmetry on the expanding hydraulic jump was not found in the literature. In this study, using the momentum principle, some theoretical equations were derived to determine the sequent depths ratio of symmetrical and asymmetrical expanding hydraulic jump. Also, some regression relations were proposed to estimate the length of expanding hydraulic jump. The new proposed equations were also extended for the presence of a sill. The equations were calibrated using available experimental data from this study and the literature. This research also considered the characteristics of expanding hydraulic jump under the symmetrical and asymmetrical operation of parallel gates.

To calibrate the new proposed relations and investigate the effects of different parameters on the expanding hydraulic jump characteristics, two experimental data sets were used. In addition to the data set from Bremen (1990), the experimental data from the present study were used. The data were collected from a hydraulic model of three parallel radial gates for operating the side or middle gate which corresponds with the asymmetrical or symmetrical expanding hydraulic jump, respectively. The experiments provided a wide range of different parameters as the approaching Froude number, hydraulic jump length, sequent depths ratio, divergence ratio, sill height and relative length of gate separator wall.

Equation (4) was developed to determine the ratio of the sequent depths of expanding hydraulic jump based on the Momentum equation. For the presence of a sill, a combination of Equations (4), (7) and (8) can be used to calculate the ratio of sequent depths under the asymmetric and symmetric developments, respectively.Determining the ratio of the sequent depths requires the calculation of the adjacent water depths of the closed gates. For this purpose, in addition to developing the regression equation (Equation 13), Equation (12) was proposed which based on the calculation of the hydraulic jump profile. It was observed that under the calibration range, the regression equation is more accurate. However, Equation (12) is recommended for the range outside of the experimental observations. The results showed that:As the divergence ratio increases, the ratio of sequent depths approaches to the classic hydraulic jump.By decreasing the relative length of the gate separator wall and decreasing the width of the gate on the downstream channel width, the relative depth at the side gate and consequently the ratio of the sequent depths will decrease.For the lower length of separator wall and under operation of the middle gate, more lengths are needed to develop the jump than the side gate. However, as the length of the separator wall increases, the length and sequent depth of hydraulic jump due to the side gate increases on the middle gate.In the presence of a sill, the relative length of hydraulic jump decreases and the ratio of secondary depths increases.It was observed that the hydraulic jump due to the operation of the middle gate leans toward the left or right side of the channel due to oscillatory behavior.Under operating the middle gate and in the absence of a sill, an asymmetric hydraulic jump is formed in the channel face when the length of the separator wall is less than 38% of the classical hydraulic jump length. For the presence of a sill, the minimum length of the separator wall decreases to about 26%.By decreasing the initial depth of the hydraulic jump on the width of the gate and converting the output jet into a linear jet, the relative development length will increase.
As the sill height increases, the difference in the depths attached to the side gates will decrease and the hydraulic jump will develop more symmetrically.As the relative height of the sill decreases, the minimum length of the separator wall to form a symmetrical hydraulic jump in the flanks, increases.

This research developed a set of theoretical and regression relationships for estimating the length and sequent depth ratio of expanding hydraulic jump. Moreover, the effects of sill height, divergence ratio and the length of the gate separator wall, were investigated. This study compares the effects of side and middle gate operations based on the variation of jump length and sequent depth ratio. The results can be used as a guide for the hydraulic structures operators to reduce the asymmetric severity of the expanding hydraulic jump and achieve the complete development under the minimum length.

One of the most commonly used devices for flow measurements in open channels is the flume, in which the flow velocity increases due to the lateral contraction, raising the bottom of the channel, or a combination of both them. SMBF is a flume with the above mentioned properties, having two semi-cylinders on the side walls of the channel that contract the cross-sectional area of the flow. In this study, the SMBF flume has been studied for measuring the flow in free and submerged flow conditions. Using the experimental data (575 runs) of two rectangular channels, and using eight SMBF flumes, the proposed discharge equations were examined for the wide ranges of flow discharge, upstream depth, and contraction ratio. In the present study, based on the numerical and experimental analysis, and by measuring the velocity distribution at the throat section, non-uniformity of velocity distribution and depth in the contracted section, as well as the two-dimensional nature of flow were studied. Then, by considering the flow correction coefficients in the throat section and applying them into the energy equation, an equation was developed for estimating the flow discharge‎ under free flow conditions. Also, two equations were developed to determine the submergence threshold (as a function of upstream depth and throat width) and for the discharge estimation under submerged conditions. The mean absolute relative error of the estimated flow discharge of the SMBF flumes in free flow conditions and based on three experimental data series (channel 1, channel 2, and other researcher’s data) were respectively estimated to be 2.82, 3.19 and 1.52%. Additionally, the mean absolute relative error of the estimating flow discharge in the submerged conditions was 5.51%. The results showed a feasible application of SMBF structure, as a portable measuring instrument under free and submerged conditions.

Evaluation of scientific journals are required in Iran to study the scientific progress, research activities and research centers. Therefore, the objectives of this study was evaluation of the journals quality in field of water engineering in agriculture (Irrigation) and the related articles and management aspects of the journals publishing these articles in Iran. Twenty-three journals were selected for evaluation in 2014, and ten indices were designed for evaluating the journals and their articles. The evaluation data were statistically analyzed using normal distribution procedure to rank the journals in 5 categories from “very good” to “very poor”. Results indicated that 30.4% of the journals ranked “good”, 39.1% were “intermediate” and 21.7% ranked “poor” and 8.7% were “very poor”. The journals were also compared for five important indices related to innovativeness, applicability, up-to-dateness of articles, practical usefulness and necessity of publication of the journal. Among the evaluated journals, the applicability index for 5 journals (21.7%) was higher than the expected level (higher than 4), further, this index for journal of Water and Soil Science, journal of Water Harvesting System and Journal of Applied Hydrology (13.0%) were much lower than others.  With respect to necessity of publication 10 journal (43.5%), up-to-dateness, 8 journals (34.8%), innovativeness, 4 journals (17.4%) and applicability, 3 journals (13.0%) were preferred. Finally, it is recommended that more emphasis should be put on the quality of articles, publication of very poor journals should be discontinued, and more support should be given to the journals sponsored by scientific societies.
      

Since there are a few reports available regarding the hydraulics of flap gates, it was aimed to conduct a research work on these kind of structures to make it clear whether they could be meet the desired advantages in flow measurement activities. Flap gates are made of cast iron or ductile iron, depending on the type of service. A small differential pressure on the back of the gate causes it to open automatically to allow discharge through levees, sewer lines or drainage conduits. When level of water on the face side of the gate rises above water level on the back side, the gate closes automatically to prevent backflow. Automatic drainage gates must be kept clean if they are to function correctly. The hinged flap acts as a natural skimmer to cause timber, logs or trash to catch between the flap and the seat at low flow. Periodic inspection and cleaning should be scheduled when the water flowing through the flap gate carries floating material. Flap gates provide a simple and cost-effective mechanism to maintain upstream water levels and flow measurement in small canals. Once installed and proper operation is verified, the gate only requires lubrication of its bearings and occasional painting for maintenance. It needs no electric power and no manual adjustment for varying flow rates. This gate can be used in open channels with rectangular section or circular section and ducts under pressure, for flood control, municipal projects, farm levees, sewer outfalls, industrial waste lines, water and sewage treatment plants, tidal drainage, irrigation systems and pump discharge control. In recent years, huge developments have been achieved on flow measurement. However, these achievements were faced with high installation and operational costs as well as highly trained human sources for their better utilization. Therefore, revision in traditional flow measuring tools is needed to get an acceptable precision and low cost of erection and operation. Present research covers the results of a theoretical and experimental investigation on a circular and quadratic flap gates which installed at the exit of a circular channel. Two individual circular pipes of zero slope and diameters of 200 mm and 300 mm were selected as water reach. All experiments were conducted in a circular plexiglas-walled fume, 5.7 m long, having a recirculation flow system. To measure the flow discharge, a sharp triangular weir with apex angle of 90˚ in the upstream of channel and the conveyor to measure the gate opening was used. In this study, the flap gate was tested with different weights. For circular Flap Gate Dimensionless weight (w/ (ρgD3)) varies from 0.0343 to 0.2542 and for square flap gates these values vary from 0.0562 to 0.3305. During tests dimensionless discharge for circular flap gate varies from 0.0123 to 0.2503 and for square flap gates these values vary from 0.010 to 0.258, As well as the circular gate opening which was in the range of 0.0123 to 0.4088 (radian)and for square flap gates these values were in the range of 0.0174 to 0.4012 (radian). The relevant theoretical equations were established to determine the flow discharge and then calibrated by using of experimental observations The research took the advantages of tentative method, basic equation of weir discharge and momentum principles. The values of maximum error (ME), mean absolute relative error (MARE) and root mean square error (RMSE) were computed and used for comparison. The resulting equations of different methods were calibrated and verified by using about 98 laboratory data for circular flap gate and 97 laboratory data for quadratic flap gate. In, basic equation of weir discharge mean absolute relative error for circular flap gate is equal to 4.41% and 5.55% for quadratic flap gate, this amount is in order for momentum principles 5.66% and 6.84%. A comparison of the values from the derived equation with statistical criteria demonstrated a high accuracy basic equation of weir discharge. It was shown that the proposed method would demonstrate high accuracy in estimating the flow discharge of the flap gates under free flow regime. The absolute relative error was ranging from 3.34 to 6.66 for circular gate, and 4.1 to 8.14 for quadratic flap gate. Advantage of theoretical equation in comparison regression equation is it can be used outside of experimental data but regression equation just has interpolation capability.

Most of the previous studies related to radial gates are focused on the estimation of discharge from the gates as a flow measurement structure. However, determination of the gate opening for passing a certain value of the discharge is rarely considered in previous studies as a regulator structure. The present work presents some theoretical equations for explicit estimation of the outflow from the gate (first problem), and gate opening (second problem) for free and submerged flow conditions by combination of Energy and Momentum principles. For any problems, it was developed some criteria to identify flow conditions These equations were calibrated and validated by means of 2657 experimental records retrieved from research conducted on three types of radial gates. The paper would present an analytical approach to illustrate the reliability of proposed equations for estimation of discharge and the opening of the gate by taking benefits from the mean absolute relative errors which observed to be 1.94% and 2.67, respectively. It was noted that the used criteria conform with 99.6% and 98.8% of all observations at first and second problems, respectively. The results show that the tailwater depth under distinguishing limiting decreases by increasing in the gate lip angle and the ratio of turnnion pin height to the gate arm radius. Also, the hard rubber bar gate tends to operate under free flow condition in a wider range in comparison with two other gates.

Flap gates are used to measure the flow in canal and are considered as a hydraulic engineering topic, which lacks enough attention so far. Use of flap gate as a measuring tool requires extended studies in order to be recommends as a measuring device for different types of gates. The structures could provide an acceptable economic condition in flow measurement applications where, low costs of manufacturing, installation, and operation could be achieved. This paper presents the discharge estimation from flap gates in rectangular canals under free and submerged flow conditions by using regression and analytical techniques. The derived discharge equations are resulted from the combination of energy and momentum equations. The suggested equations were validated by means of experimental observations, which showed an average error of 1.06% to 1.91% at free flow and 2.28% to 5.26% for submerged flow conditions. The paper also presents some diagrams for estimating the discharge coefficient of flap gates in both flow conditions.

Present research covers the results of a theoretical and experimental investigation on a circular and quadratic flap gate, which installed at the exit of a circular channel. This study would employ an experimental program in a horizontal channel of circular cross section of 200 and 300 mm diameters, equipped with either a circular or quadratic flap gate to explore the basic parameters affecting the flow discharge estimation of these devices. In this study, of three ways such of the first form Stage-Discharge technique, incomplete self-similarity theory and the second form Stage-Discharge technique have been used for estimating the discharge for circular and quadratic flap gate under free flow conditions. The research took the advantages the main difficulties during the experiments were the vibration of the gate as well as accurate measurement of gate opening. The use of second form Stage-Discharge technique would overcome such weaknesses. The most accurate of these methods is incomplete self-similarity theory. In this theory, mean absolute relative error for circular flap gate is equal to 3.34% and for 4.1% for quadratic flap gate.

Discharge measurement by sluice gates is one of the classical issues in hydraulic engineering. Based on the energy conservation relation, this study presents a novel method for estimating the discharge coefficient of sluice gates under free and submerged flow conditions. This method gives the discharge coefficient of sluice gates only as a function of upstream depth and bottom pressure measured by manometers located under the gate lip and is independent of flow conditions (free and submerged), gate opening and tailwater depth. For evaluating the applicability of the proposed equation in this research for estimating the flow discharge, the experimental results (418 runs) of two sluice gates with 25 and 40 cm widths are used in the conditions of presence and absence of end baffle blocks for both free and submerged flows. Independency of discharge coefficient from the tailwater depth has important advantages such as: continuous estimation of discharge coefficient under free and submerged flow conditions using a unified equation and higher accuracy at the lower submergence. Also being independent of tailwater depth makes easy flow estimation even at the presence of baffle blocks on the stilling basins. The results show that, applying the energy loss coefficient in the proposed equation decreases the mean absolute relative errors to 0.4% and 2.6% for free and submerged flow conditions respectively. Also the proposed equation has a relative error less than 5% under submerged flow conditions. The proposed method is very sensitive to bottom pressure head especially under higher submergence levels.

In recent years, considerable accomplishments were devoted for developing non-hydrostatic models for simulation of water level in open channel flows. The main constraint to develop such models, arises from true definitions of water surface boundary condition. Some costly techniques such as VOF and MAC are used for these purposes. These techniques are confronted with high computational costs as well as durability limitations beside their apt accuracy. Another group of non-hydrostatic models determines the water surface elevation using kinematic equation of free surface. These models are of suitable efficiencies if the water level gradient is negligible. Generally, in such conditions, equal number of cells in column and varied height of cells in surface layer are considered. If water level gradient is high, a considerable parts of flow field are solved in hydrostatic condition which frequently occurs in water level of groundwater.
To overcome these limitations in this research, the number of cells in each column was selected proportionate to varied water level which resulted in considerable improvements of water level and flow field. In fact, this technique falls in between VOF and the kinematic boundary condition of water level calculations. It was observed that the accuracy of this method is higher than the kinematic boundary condition with a lesser computational works and stability limitation than VOF. It is noteworthy to mention that, in wave interaction with porous structure test, with time step 6 times greater than VOF model, the current scheme is stable and considering running time, 480 percent more efficient.
The number of cells in each time increments was adjusted commensurate with water level.
This article details a vertical two dimensional non-hydrostatic model for simultaneous simulation of open flow level and water level in porous media. The governing equations are the developed forms of Navier-Stocks equations which commonly applied to fluid and porous media. These equations were discredited by means of finite volume method in Cartesian coordinates and solved by means of pressure bearing approach. The developed model is capable of solving the pressure field taking the advantages of the kinematic free water level and developed form of Navier-Stocks equations. The standard model of was used to model the turbulence.

Direct outlets from rivers are the most common structures to supply water for agriculture, industry and drinking water uses. Among the various methods of river intake, construction of a diversion dam and lateral intake is the most common way to supply water for irrigation network. This method is based on diverting a part of the river flow using a diversion dam. Since the river flows often contain sediment load, sedimentation usually occurs near the intake structure. Consequently, during the time it causes blocking the intake inlet and decreasing capacity of intake canal. Many researches have been done about the optimal design for connection between a main canal and the intake inlet and also different methods have been suggested to control sedimentation. Often they have not considered the diversion dam in the vicinity of intake inlet. However, the comprehending of flow and sedimentation patterns requires the attention to all components of a flow diversion system. Nowadays, with progression of numerical models, the application of numerical simulation of flow pattern in such structures is provided. Among numerous released software for numerical simulation, the Fluent is a powerful software for analysis and simulation of fluid flow which widely used by researchers. In the Fluent the users can define new physical properties and boundary condition with especial functions. This software uses a finite-volume method for solving the Reynolds averaged Navier- Stokes equations. In this research, three-dimensional simulation of flow pattern in the lateral intake, with taking into account diversion dam structure, dividing wall, sluice way and entrance sill height was done by using the Fluent. The results of numerical model are validated with experimental tests which had been carried out in the Irrigation and Reclamation laboratory of Tehran University. Then different characteristics of the flow separation zone, flow patterns, vortex, and secondary flows were compared. The experimental tests consist of a Plexiglas flume with a lateral canal, main canal, diversion dam structure, dividing wall, and sluice way. The main canal consists of a rectangular cross-section with a width of 0.90 m, height 0.60m and 18m in length. The lateral intake with 0.4 m in length and width was installed at 120° (at the left side) to the main canal. The longitudinal slope of the flume was set to 0.0008. The diversion canal and sluice way were perpendicular to flow alignment of the main canal. The width and height of diversion dam are 0.6 and 0.27 m, respectively. The lateral intake was separated of diversion dam with the sluice way. It is 0.29 m in length and 0.1 m width. In the first, the canal invert was covered with sediment, and then flow characteristics were measured at different levels and the diversion ratios of 0.5 and 0.65. In this study, the magnitude of flow velocity (z velocity) near the intake and sluice way is used for verification of numerical simulation. The 3D geometries and meshes of intake system were generated by using the Meshing Tool of Gambit software. Computational domain was built with 218000 grid nodes. In this study, the governing equations are discretized by first order upwind method and the pressure is decomposed from the velocity by SIMPLE algorithm. The standard k-ε turbulent model is used to describe the flow separation. The Volume of Fluid (VOF) method is used to track the fluid interfaces. The considered boundary and initial conditions included: (1) inlet velocity condition and a water depth of 23 centimeters is assumed at the main canal inlet, (2) the outflow condition is used at the intake outlet, and (3) it is assumed that the sluice way is closed. The results of numerical model showed that the flow pattern in the vicinity of the intake canal has been simulated good. Comparison of small amounts of z velocity between experimental and numerical models, particularly in diversion ratio equal to 0.5, indicated suitable model reliability for simulation in the lateral intake. The result showed that the average error rate of the numerical model at three different levels was about 13%. After model verification, impacts of shape of the entrance intake on the flow pattern formed at the intake inlet have been studied. The results of the numerical model for angled upstream wall inlet, revealed that the low-velocity zone was removed from this region, as the width of the eddy zone has been reduced from about %8 to near zero.

The paper describes the evolution of local scour hole downstream of an adverse stilling basin. The research was conducted using a wide range of Froude number, sediment size, tailwater depth, length and slope of stilling basin. The maximum depth of scour and its distance from the stilling basin attained 87.5% in the first 24 hours and 86.3% when the experiment was continued for 54 hours. A power equation was adopted describe the characteristic dimensions of scour hole, time scale as well as geometry of stilling basin and sluice gate. The results showed a certain similarity among the scour profiles developed at different times. However, the shape of the holes was influenced with the change in length and slope of stilling basin. As the slope of stilling basin increased by 15%, the volume of sediment removed from the unit width of the hole, was increased by 30%.

In this paper, the characteristics of free and submerged outflow from the sluice and radial gates were studied by using energy and momentum equations, and experimental data of other researchers. An equation has been given to approximate the energy loss of the gate along with its application in improving the accuracy of the discharge coefficient under free flow condition has been demonstrated. A theoretical equation is also developed for estimating the discharge coefficient of sluice gates and three types of radial gates, namely Hard-Rubber, Music Note, and Sharp, under submerged flow condition. It was observed that at a certain condition, the outflow from Hard-Rubber type radial gate is larger than Music Note and Sharp types. It was realized that the mean energy loss of these types of radial gates, under submerged flow condition, is dependent on the ratio of the axial height of the gate to its radius which was used to improve the discharge coefficient. Under a certain condition, it was observed that, the discharge coefficient would decrease if the angle of gate lip is increased. It was also observed that under certain circumstances, the outflow from three types of radial gates, is much larger than sluice gates. It is noteworthy to mention that the application of the developed equation for estimating the discharge coefficient of the Sharp radial gate for Hard-Rubber and Music Note types may cause considerable errors.

Stilling basins are one of the common structures for dissipating the kinetic energy in high speed flows. Among all types of stilling basins, the basins with the inverse slope of the bottom, because of its appropriate performance regarding the hydraulic jump’s parameters, are suitable alternatives for classic stilling basins. Since the weight of the hydraulic jump on the reverse slope affected the resultant forces on the volume control, extracting the mathematical equation for the profile of hydraulic jump and the actual length is necessary for accurate estimating of this component. Therefore, it would be worthwhile to find a solution that could consider an actual profile for the hydraulic jump and also remove the length of jump as an unknown from final equation. In this research, the linear, quarter-elliptic and parabolic profiles were considered to extract explicit equations for estimating the sequent depth of hydraulic jump on adverse slope. Comparing the results of extracted equations with experimental data showed that the theoretical equations based on the parabolic and linear profiles had lower error than the elliptic profile in estimating the sequent depth of hydraulic jump.

In this research simulation model of sedimentation in dam reservoirs in the arid and semi-arid basins (Water Availability in Semi-Arid environments-SEDiments) was developed. Rainfall-runoff, erosion-sedimentation processes and sediment transfer in the river's catchment, can be simulated by WASA-SED. In this research a new module was added to the WASA-SED model. This module was developed by Fortran programming and will about a decision supporting system for reservoir desilting that supported by engineering relationships that allow the quantification of basic parameters. The model helps to evaluate the technical and economic feasibility of implementing the life cycle management approach. Validation of the model has been made using prototype data (Barasona dam in Spain). The computer simulations agree well with the prototype measurements and show that the model is a promising tool for feasibility study and economic evaluation of alternative strategies for reservoirs desilting. The results from the economic optimization routine identify the preferred sediment management technique for sustainable use of the water resource infrastructure.

Scouring is one of the issues that is important in the design of various types of hydraulic structures. One of these structures is a stepped spillway. The aim of this study is to evaluate the similarity between the profiles of scour holes downstream of the stepped spillway. To do so، results of 67 experiments in two different experimental models were used; these results were in a wide range of particle Froude number، the stilling basin length، downstream depth، sediment particle size distribution and two different slopes of stepped spillway. In this study، 5 different lengths of stilling basin، from 37 cm to 120 cm، were used. Also، the range of utilized discharge was from 8. 43 lit/s to 88. 95 lit/s. Duration of the tests were selected to be 6-hours، 8 hours، 12 hours and 24 hours and، in total، 834 scour profiles and approximately 85000 points to were used derive required relations and to performother analyzes. Based on the experiments results، the similarity between scour-holes located in downstream of stepped spillway was analyzed. In this process، two methods were used to make the profiles dimensionless. Based on statistical parameters، best method was selected and similarity of downstream profiles were shown. Relations that predict maximum scour depth، the distance from maximum depth to the end of the stilling basin and volume of transported sediments are developed based on the dimensionless parameters in different time periods. Furthermore، impact of different parameters on the geometry of scour holes were studied. When the Froude number increases، while all other parameters are constant، the dimensions of the scour-hole increases. When the stepped spillway slope increases، the dimensions of the scour-hole decreases and، moreover، when the tail water depth increases، while all other parameters are constant، a deeper hole with longer longitudinal distance forms. Overall، 8 cross section profiles under different conditions were taken. These profiles indicate transverse development of the scour-hole، in addition to longitudinal development.

In this article the new sediment module of WASA-SED that aims at simulating the process of sedimentation in reservoirs is developed and evaluated. To evaluate this new module of WASA-SED، the process of sedimentation in Barasona dam reservoir (Spain)، located in a region with high erosion، was examined. The most important parameter in the simulation of sedimentation in reservoirs is to determine the thickness of the active layer. Hence، for the calibration of the model، the relevant data of two time intervals when one was related to the period of normal operation of the reservoir (1986-1993) and another one to a period of the operation time along with the flushing (1995 to 1997) were used. After determining the active layer thickness، the sedimentation process was simulated for the period 1998-2006. The results of the simulation were compared with the dam reservoir hydrographic information. The results of the comparison showed that the new module of WASA-SED for simulation of sedimentation in dam reservoirs in regions with high erosion had a proper accuracy.