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In a traditional automated upstream controlled canal with a downstream buffer reservoir, the process to fill the buffer reservoir requires one step: the inflow to the canal is increased, and the flow change eventually arrives at the buffer reservoir. This paper describes an attempt to shorten the time necessary to stabilize the new flow rate at the buffer reservoir. The method requires calculated, remote manual adjustments to all the canal check structure gate positions in addition to two flow rate changes made at the head of the canal, followed by a return to automated upstream control. The method was tested in the Upper Main Canal of the Central California Irrigation District both through simulation and in the field. With a canal flow of approximately 20% of the maximum, simulation modeling predicted that a flow rate change arrival at the reservoir would be about 5.5 h in a typical operation, with final stabilization in about 16 h. Simulation of an improved procedure indicated an almost instantaneous increase in flow at the reservoir of half the flow change, with final flow stabilization at 11 h. The field test resulted in almost the full flow change arriving at the reservoir after about 20 min, with gradual stabilization occurring over the next 11 h. Important differences between simulation and actual results are discussed. [ABSTRACT FROM AUTHOR]

The work presented here is an extension of previous papers that updated the calibration of round (Armco-type) meter gates (three sizes: 0.30, 0.46, and 0.61 m), developed ratings for rectangular gates (two sizes: 0.46 and 0.61 m) on round pipes, and examined errors and uncertainty related to using these devices for water discharge measurement. Previous works examined gate discharge ratings under low supply-channel flow velocity perpendicular to the gate discharge pipeline. Here, additional testing was conducted to test the hypothesis that higher velocities in the supply channel would show decreased meter gate flow compared to the low-velocity ratings, but that the published gate calibration method would still yield accurate flow-rate calculations. All testing was conducted in a test facility with the gate discharge pipe set perpendicular to the supply channel, as is common in field installations. Velocities up to 0.94 m=s (3.1 ft=s) were tested with the smaller gate and 0.66 m=s (2.2 ft=s) for all other gates. These velocities are on the upper end of velocities found in common earthen irrigation canals (and in many lined channels at the farm delivery level) in California. Interestingly, results indicate that the Froude number of the supply-channel flow did not have a statistically significant (at an α-level of 0.01) influence on gate discharge coefficients. Discharge percent error and uncertainty were examined to compare the discharge coefficients presented in the literature to the discharge measured during the testing at different supply-channel velocities. Under recommended operating conditions, the uncertainty was within ±5% without adjustments for supply-channel velocity. This extended work supports earlier recommendations that meter gates can be an accurate flow measurement device for farm water delivery flow measurement if installed and operated correctly. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) has been extensively studied for controlling irrigation canals. Most of the studies use lumped models and fixed target for the controller. This setup works fine if the water delivery is on demand. However, in the case of on-supply delivery, balancing mismatches between demand and supply and spreading mismatches among all users are crucial. A fixed control target will not meet the request due to the mismatches. In this paper, a dynamic target trajectory approach is proposed to calculate changes of control targets that are used by MPC. The dynamic target trajectory calculates the percentage change of each setpoint based on the total volume mismatch spreading over the available capacity in each canal pool. The approach is applied to the Central Main Canal in Arizona. The results demonstrate that the dynamic trajectory can help the optimization find the optimum more quickly and facilitate tuning of the controller. Moreover, the mismatches can be better distributed over canal pools. [ABSTRACT FROM AUTHOR]

The main objective of this study is to determine the optimal distribution of water between upstream and downstream users in a main irrigation canal with a limited supply of water in order to maximize the net revenue derived from existing farming activities. To this end, an economic positive mathematic programming (PMP) model is employed to determine the economic value of the water for each delivery point along the main canal in which there is agricultural activity. This information is added to a model that accounts for the operational aspects of a realistic, large irrigated district in the center of Iran, which is used by a model predictive controller to prioritize the reaches in the main canal according to their potential profit in economic terms. The results show the satisfactory operation of the canal reaches, such that the water levels in the reaches with high economic water value are kept closer to the operational target levels. Accordingly, the water deficit is proportionally divided along the main canals to maximize economic profits from the irrigated district. [ABSTRACT FROM AUTHOR]

Canal seepage is an important cause of irrigation water losses. Specific seepage losses of Gongan lateral and Zuosi field canals, which are located in the Hetao Irrigation District of Inner Mongolia in China, are calculated in this study. Specifically, canal seepage losses are calculated by field experiments, empirical formulas, the Kostiakov formula, and numerical simulations. The ponding method is rarely utilized in large irrigation canals and canals with many branches or high slopes. The results of the field experiment are utilized to compare and analyze the calculation results of three other methods. When the empirical formulas are employed to calculate canal seepage losses, more related factors are considered; hence, more-accurate calculation results are obtained. The first empirical formula is mostly used for canals that do not adopt seepage control measures or apply simple forms for seepage control. The second empirical formula is suitable for the case wherein the entire flow section of a canal has been paved with a soil impermeable layer and canal seepage is in a free state. When the Kostiakov formula is employed to calculate canal seepage losses, the parameter values may differ significantly from the actual conditions. Thus, a large difference exists between the calculation results of the Kostiakov formula and those of the field experiment. The Kostiakov formula is widely utilized in the planning and design of canals, as well as being applied to seepage loss estimation during canal water conveyance and distribution under normal canal operating conditions. The numerical method is utilized to calculate canal seepage losses by simulating the actual situation in the site. Except for the result of seepage loss for the lined Gongan lateral canal, the simulation results of seepage losses for the unlined Gongan lateral and Zuosi field canals and the lined Zuosi field canal are relatively reasonable. If sufficient data of the study area can be obtained and finite-element software can meet the computing requirements, the numerical method can be applied to any channel. [ABSTRACT FROM AUTHOR]

Methods of handling drastic inflow fluctuations without any constructional changes in the canal or the off-take structures are studied. Regarding the operational problem, automation of the regulating structures in the main canal is proposed. To this end, a centralized model predictive controller (MPC) is designed to achieve better operational performance in combination with an in-line water storage strategy. The controller is tested in a wide range of operational conditions, representing conventional operation, operation under predictable and unpredictable inflow fluctuations, and operation with and without water storing capabilities within the canal. The test bench is an accurate mathematical model of a canal consisting of five water regulators and seven off-takes. The results show significant improvement for canal operations employing automation. For the predictablefluctuations scenario, the results show that the stored water within the canal effectively handles the fluctuation. Compared to the conventional canal operation scenario, calculated evaluation performance indicators show an approximately 21% improvement for the maximum absolute error (MAE) and a 12% enhancement for the integral magnitude of absolute error (IAE). [ABSTRACT FROM AUTHOR]

Most of the models developed to simulate the cohesive sediment transport processes refer to estuary or marine environments and are generally not developed for the specific characteristics of irrigation schemes provided with the different types of hydraulic structures. The aim of this study is to simulate the cohesive sediment transport in irrigation canals. The fine sediment transport (FSEDT) model was developed using a software program to estimate the sediment transport and deposition rates of cohesive sediments in irrigation canals. The model has been applied in the Gezira Scheme in Sudan, which is threatened by high sediment supply from the Blue Nile River. The model was calibrated and validated using the field data selected during the flood seasons in 2011 and 2012. The hydrodynamic part of the model was verified by comparing the water surface profile obtained by the developed model and by using a microcomputer program for simulating one-dimensional steady/unsteady flow in open canals. The results of the two models show good agreement. The sensitivity of different parameters to the deposition was tested. The model is a useful tool that can be applied to study the mechanism of sediment transport under different operation and maintenance scenarios not only in the Gezira Scheme but also in similar cases. [ABSTRACT FROM AUTHOR]

A Lopac gate is one type of upstream control structures in irrigation canals. Advantages of a Lopac gate include performing as an overflow structure, letting sediments and floating bodies pass simultaneously, as well as easy automation. The structure has recently attracted the attention of researchers for detailed investigations. One effective tool to study control structures is a mathematical model. Due to the unsteady nature of flow in irrigation canals, incorporation of the mathematical model of control structures with hydrodynamic models is necessary. In this research, a mathematical model of Lopac gates is developed and linked with the ICSS (irrigation conveyance system simulation) hydrodynamic model. The Lopac gate model was developed as a boundary condition in four subroutines, including steady flow conditions, operation, unsteady flow conditions, and updating information. The developed model is validated using physical model data. The maximum error obtained was 6%, which is acceptable for practical purposes. The model was tested on a canal of DEZ irrigation network in Iran under many different conditions. The results showed that the model is performing well for tested applications and could be used in various studies of irrigation canals equipped with this structure. [ABSTRACT FROM AUTHOR]

In this study, a systematic framework is introduced to prioritize several practical canal operation alternatives applying to modernization and rehabilitation projects. Several operation techniques, ranging from improved manual canal operation to centralized automatic operation, are considered. Ten different operation methods are selected as alternatives for the modernization and rehabilitation project. Mathematical models of the proposed alternatives are designed and potential applications of them are examined. The designed models are tested on an accurate simulation model of a large canal system in Iran. In regards to multicriteria inherent in selecting an appropriate operation method, multiple criteria are considered including 13 technical, social, operational, and economic criteria. Two well-known multicriteria decision-making (MCDM) methods of technique for order preference by similarity to ideal solution (TOPSIS) and simple additive weighting (SAW) have been applied to prioritize alternatives. The relative weights of each criterion are determined based on aggregation of entropy method and decision-maker's preferences during the decision making procedure. The obtained results show that Alternative 9, representing a centralized control method, has been the first-ranked alternative with the score values of 0.845 and 0.854, respectively, based on TPOSIS and SAW methods. Based on demands and expectation of the local water authorities, each of the proposed alternatives can be selected with different levels of satisfaction. According to the results, in the cases that automatic control application is restricted, the improved manual methods would be reasonable operational alternatives. [ABSTRACT FROM AUTHOR]

One of the main problems in the water management of irrigation canals is the control of water distribution among users' outlets. This is because of the difficulty of measuring the removing flows correctly because they are highly variable in both time and space. To help solve this problem, a mathematical algorithm, the so-called canal monitoring algorithm, which determines the history of lateral extractions, is propounded. It uses the water depth measurements at checkpoints and the gate and other control device trajectories, which are implemented on the canal during a past period of time, and then obtains water withdrawals that happened at the outlets. The method also gives an estimation of the current state of the canal for model predictive control purposes. The algorithm solves the classical inverse problem, in which the unknowns are the parameters that define the flow rate trajectories of canal outlets, which are defined as piecewise functions of time in this paper. The algorithm is on the basis of the Gauss-Newton method and uses the complete Saint-Venant equations for the computation of the least-squared function. Numerical tests with excellent results have highlighted its computational efficiency, converging in a few iterations to the exact final results. These properties make the algorithm adequate to operate in real time. A laboratory canal test for verification shows accuracy in detecting water withdrawals at canal outlets when the Manning roughness coefficients are known. The test also reveals a functional relationship between the discharge removed and the empirical coefficients. [ABSTRACT FROM AUTHOR]

Normal and critical epths are important parameters in the design, operation, and maintenance of open channels. Semielliptical, prefabricated channels are widely used as tertiary canals in irrigation networks. In semielliptical channels, the governing equations are highly nonlinear in the normal and critical flow depths; thus, the solution of the implicit equations involves numerical methods. The main challenge with semielliptical sections is the calculation of the wetted perimeter. The wetted perimeter of semielliptical sections can be expressed in terms of incomplete elliptic integrals of the second kind. The elliptic integrals can be computed simply using commercial mathematical software, but most engineers who use a simple tool such as Microsoft Excel need a simple yet accurate expression for computing the wetted perimeter. Because elliptic integrals cannot be directly computed using Excel, a simple and accurate expression with maximum error less than 0.07% (near exact solution) is proposed for computing the wetted perimeter. In this study, explicit solutions for semielliptical channels have also been obtained using the nondimensional forms of the governing equations. The maximum errors of critical and normal flow depths are less than 0.1%. Proposed explicit equations have high accuracy, easy calculation, and wide application range. [ABSTRACT FROM AUTHOR]

This paper presents the application of a distributed model predictive controller (DMPC) to the control of an accurate model of an actual irrigation canal in Spain. The canal is modeled using the Saint-Venant equations and implemented using the well-known Simulation of Irrigation Canals (SIC) modeling software for irrigation canals. The DMPC algorithm has been implemented in Matlab and interfaced to SIC. In the distributed-control algorithms, the local controllers exchange information so that their control policies are optimal in the sense of getting the best value of a performance index. The results show that the proposed distributed-control algorithm obtains better control performance than a more-conventional decentralized control scheme without information exchange. This better performance translates directly into money and resource savings. [ABSTRACT FROM AUTHOR]

Storing water in main irrigation canal reaches could be an influential strategy to improve the existing operational activities in the irrigation canals. However, the control of such a canal system will become much more complicated due to freeboards of the reaches temporarily decreasing. In this paper, Model Predictive Control (MPC) is applied to control the water level of an accurate model of a realistic main canal, which consists of 13 canal reaches, using an in-line storage operational strategy. Four different test scenarios are selected to cover a range of conventional to unconventional operational strategies by imposing limitations on the head-gate opening. Different target bands are created between the predefined allowed maximum and minimum water level for the canal reaches and the MPC is obliged to keep the water levels within these ranges. The results show that the in-line storage improves current operational performance of the canal system by compensating the existing delay times of flow traveling in the canal and gradual increasing and decreasing of the inflow that avoids large wave occurrences in the canal reaches. [ABSTRACT FROM AUTHOR]

Although polyacrylamide (PAM) use for reducing soil erosion and increasing water retention is common in agriculture, research suggests PAM application may also be effective in reducing seepage in unlined irrigation canals. A polymer application test was conducted on a 457-m-long section of the Bordeaux lateral canal near Wheatland, Wyoming. Flow rating curves were developed by combining discharge and water level data, and the curves were used to convert real-time water level data into real-time discharge data. Falling head permeameters (FHP) provided a spatial method of quantifying seepage. Real-time stage discharge data showed a mean pretreatment flow loss over the entire test reach of , whereas the mean posttreatment loss was (), which corresponds to a 21% increase in seepage. The FHP tests also showed an increase in seepage as a result of PAM treatment. On the basis of the results of this study, it appears that PAM and suspended sediment concentrations were too low during the test to cause significant seepage reduction. [ABSTRACT FROM AUTHOR]

Irrigation districts in the American West and throughout the world have extensive canal networks that could be utilized to generate a significant amount of hydropower. As the world attempts to become less dependent on carbon-based energy resources, small-scale hydropower (SSH) is an attractive potential resource for new energy development. The Middle Rio Grande Conservancy District (MRGCD) in central New Mexico has an extensive canal network, and hydropower is being considered as a viable form of renewable energy. Currently, the MRGCD has identified and categorized nine potential hydropower sites within its system with the goal of maximizing its contribution to the region's energy needs. This paper addresses key issues related to hydropower in irrigation districts and examines the feasibility of incorporating hydropower generation in the MRGCD canal system. With full year-round implementation of SSH generation at the nine locations investigated, the MRGCD could have a generating capacity of 2.2 MW and produce over during the year. This represents an income from power generation for the MRGCD of $1.032 million at the current power prices. More importantly, implementation of SSH would result in 1,340 homes being powered by clean, renewable energy while concurrently delivering water to irrigators. It is the hope of the authors that the case study presented will aid irrigation districts investigating the incorporation of hydropower in their canal networks. [ABSTRACT FROM AUTHOR]

The flow characteristics around two partially buried objects, a short cylinder (SC) and a truncated cone (TC) were examined experimentally and numerically. Experiments were conducted in a large tilting flume with vertical walls made of acrylic plastic and steel floor covered by a 24-m long sand pit. For each experiment, the object was placed on a flat sandy bed, the flume was filled to a water depth of 41 cm, and a steady unidirectional current was established at high Reynolds numbers while sinking of the object was tracked over time. Velocity records were taken with an acoustic Doppler velocimeter (ADV) probe at the final stage of burial and scour hole evolution. The flow structure around each object was further investigated using a model that solves the Reynolds-averaged Navier-Stokes (RANS) equations coupled with a turbulence closure model, and results were compared to the experimental measurements. Measurements and numerical simulations allowed identification of regions of high and low velocity and turbulent kinetic energy accounting for zones of potential sediment erosion and deposition that dictate the burial of the object. The turbulence closure model was shown to reproduce the experimental mean flow velocity and turbulent kinetic energy with acceptable accuracy. [ABSTRACT FROM AUTHOR]

The dynamics of the Grand River plume, a major tributary of Lake Michigan, was studied in the vicinity of the Grand Haven coast on the east side of the lake. The river spread laterally from the mouth and formed a thin surface buoyant plume with various shapes that have not been previously reported. To understand the influence of different driving forces, primarily wind, buoyancy, and ambient currents, extensive field experiments were carried out over four periods in August and June 2006, and June and July 2007. They included aerial photography over the plume, acoustic Doppler current profiler (ADCP) deployments, meteorological buoys, drifters, SF6 and Rhodamine WT tracer releases, three-dimensional (3D) CTD profiling over the plume, and CTD casts at the river mouth. The results showed more flow classes than included in previous studies. A modified classification scheme based on the relative magnitude of the plume-crossflow length scale and a Richardson number were devised that includes longshore current components and onshore-offshore wind effects. A ratio of length scales and the Richardson number could predict whether the plume was shore attached or unattached, and how the onshore wind can spread the unattached plume offshore, deflect it back to shore, or diffuse it. [ABSTRACT FROM AUTHOR]

Laboratory flume experiments were conducted to study the flow field and sediment dynamics in a mobile-bed channel bend with and without the presence of stream barbs (upstream-angled submerged groynes). This paper presents spatial distributions of the vorticity field and the turbulent Reynolds shear stresses, kinetic energy, and integral scales. The objectives of the present paper were to (1) advance understanding of the role that vorticity and turbulence play in the erosion process in channel bends with and without barbs, and (2) optimize barb design for reducing erosion along the outer bank regions of channel bends through consideration of flow-field turbulence and vorticity. Results indicate that (1) increased -vorticity occurred in the outer bank scour zone for all runs with and without barbs; (2) for the runs without barbs and with moderately sized barbs, increased streamwise-cross-stream Reynolds stress () was found to coincide with locations of scour; and (3) for the run with large barbs, all three Reynolds shear stresses increased, but was most consistently associated with scour locations. In general, local scour near the barbs was associated with increased -vorticity, tke, and nonprincipal Reynolds stresses ( and ). Furthermore, it was observed that the outer bank region (particularly between adjacent barbs) may be susceptible to increased erosion if stream barbs, due to their size and layout, generate excessive turbulence and secondary velocities. [ABSTRACT FROM AUTHOR]

The controllability of an irrigation canal depends on its physical characteristics, on the control algorithm used, and on the actual condition of the canal in relation to the algorithm tuning conditions. The flow conditions and controllability in an irrigation canal may change if the hydraulic friction changes. Great variations in friction were observed in an irrigation canal in Spain owing to the presence of Rhizoclonium hieroglyphicum, a type of algae that grows in clear water. Such large variations in friction may have a significant effect on the stability and performance of automatic canal controllers. Using the unsteady-state model Simulation of Irrigation Canal (SIC), the influence of roughness on the performance of the study canal under distant downstream control of its four coupled pools was investigated. A set of proportional-integral (PI) controllers was tuned for different values of Manning's n. The controller's performance under real conditions is sensitive to the roughness conditions under which the control gains were tuned, and a method to robustly tune the gains of the PI controllers is proposed. [ABSTRACT FROM AUTHOR]

The operation of main irrigation canals is complicated in situations in which the operator does not have full control over the canal inflow, or in which there are very long transmission distances from the point of supply, or both. Experienced operators are able to control the canal, but often supply errors are simply passed downstream, thus creating problems further down the system. In previous work, the writer showed that it is important to contain such errors and not let them pass downstream. With automatic upstream-level control, all flow errors are passed to the downstream end of the canal. Distant downstream water-level control requires full control of canal inflow. Without this, errors will occur at the upstream-most canal pool. An alternative scheme is offered here in which the canal check gates are controlled on the basis of the relative water-level error between adjacent pools. The scheme uses a simple linear model for canal pool response. The scheme is implemented as a multiple-input, multiple-output scheme and is solved as a linear quadratic regulator (LQR). Thus, all gates respond to relative deviations from water-level set point. The scheme works to keep the relative deviations in all pools the same. If inflow and outflow do not match, it effectively treats the canal as a storage reservoir. When in equilibrium, operators will be able to judge the actual flow rate mismatch by the rate of change of water levels. The scheme acts like a combination of upstream-level and distant downstream-level control. It was tested on a simulation model of the Central Main Canal at the Central Arizona Irrigation and Drainage District (CAIDD), Eloy, AZ. [ABSTRACT FROM AUTHOR]

The sides and bottoms of earthen irrigation channels are erodible. The main design criterion for the earthen channel is to minimize or eliminate channel erosion under design flow conditions. The Manning formula and the tractive force equation were used as governing equations to design erodible and riprap channels. The traditional design approach involves a tedious trial procedure to find the bottom width of trapezoidal channels. Some hydraulic engineering problems require the solution of the bottom width from the Manning formula for nonerodible channels. An approximate equation is available for determining channel bottom width, but it is not applicable for channels with side slopes z<1 (1 vertical and z horizontal), which are encountered in practice for nonerodible channels. This technical note presents a direct and accurate equation for determining the channel bottom width (with errors less than 0.1%) using the tractive force concept and a dimensionless form of the Manning formula. The proposed direct solution facilitates the design of erodible and riprap-lined channels. Moreover, the proposed equation can be used to accurately determine the bottom width of rigid (nonerodible) channels for any side slope. [ABSTRACT FROM AUTHOR]

A study conducted by the Utah Water Research Laboratory assessed the accuracies of a wide variety of flow measurement devices currently in service. During the study, a wide variety of flow measurement devices, including flumes, weirs, and rated sections in open channel systems, were evaluated; magnetic and ultrasonic meters in closed-conduit systems were also tested. The specified design accuracies for each device are presented. Actual flow measurements were determined at 70 sites and were compared with the theoretical discharges of each device. Comparison of actual and theoretical flow indicates that only 33% of the measurement devices tested currently measure flow within manufacturer-designed specifications. Field data is presented, and possible reasons for the flow measurement errors and their corrections are discussed. [ABSTRACT FROM AUTHOR]

Using state-of-the-art computational techniques, a genetic algorithm (GA) and an accuracy-based learning classifier system (XCS) were shown to produce optimal operational solutions for gate structures in irrigation canals. An XCS successfully developed a set of operational rules for canal gates through the exploration and exploitation of rules using a GA, with the support of an unsteady-state hydraulic simulation model. A computer program which implemented the XCS was used to develop operational rules to operate all canal gate structures simultaneously, while maintaining water depth near target values during variable-demand periods, and with a hydraulically stabilized system when demands no longer changed. This model can be applied to canal networks with constant or variable demands within the limits of current hydraulic simulation capabilities. The program output is a set of feasible and optimal operating rules for multiple gate structures, facilitating the automation of open-channel irrigation conveyance systems. Results from sample applications of this technique are presented in the companion paper. [ABSTRACT FROM AUTHOR]

A downstream controller is designed for an irrigation canal reach using a design technique called quantitative feedback control theory (QFT). The performance of this controller is compared to a proportional, integral, derivative (PID) controller and a linear quadratic regulator (LQR) controller. In this study, the QFT controller is designed for a single canal reach because it best demonstrates how a controller is designed. Previous research for this canal model provided data for comparison. For the operating conditions that are defined in this paper, the QFT controller is shown to have slightly better performance than the PID controller and better performance than the LQR controller. When the canal hydraulic roughness is increased, the QFT controller still performed better than the PID controller. [ABSTRACT FROM AUTHOR]

There is renewed interest in developing calibration methods for gates operating in submerged conditions in irrigation canals. In the present study, a new method based on a generalization of the standard energy-momentum method that accounts for variations in the energy and momentum velocity coefficients is proposed, for the following reasons. First, it was found that the assumption of uniform submerged jet velocity to account for the kinetic energy head and momentum flux is in reality equivalent to assuming a parabolic relationship between the Coriolis and Boussinesq coefficients. Second, literature investigations showed that the coefficients for the downstream side of submerged gates are notably greater than unity, and the implicit parabolic relationship between these coefficients in the standard energy-momentum method is inadequate, at least for high submergence conditions. The proposed energy-momentum method was evaluated using the data obtained from four gates operating in an irrigation canal in Southern Spain. Improvements in accuracy compared to the standard energy-momentum method (with a constant contraction coefficient Cc=0.61) were obtained. The results indicate that the calibration of coefficient approach provides a means to improve the energy-momentum method by (indirectly) accounting more accurately for nonuniform velocity effects in the energy-momentum equations. [ABSTRACT FROM AUTHOR]

A supervisory and control system developed for a Portuguese irrigation canal system equipped with motorized sluice gates and buffer reservoirs is presented. The article discusses the development and tuning of the canal system’s controllers: manual controllers for direct control of gate position and gate flow controllers, which maintain discharge at predefined values; automatic controllers for water depth control upstream from check structures. System hydraulics was simulated using an unsteady flow open-channel model based on the complete Saint-Venant equations. After field calibration and validation, the model was used for tuning the water depth controllers. The automatic upstream water depth control is based on local proportional-integral controllers. Controller gains were determined using optimization tools provided by the hydraulic simulator. These procedures tune the controller parameters globally, considering a given set of inflow variations. Finally, the paper presents simulated control tests results and an analysis of controller performances. Under the test conditions, the controller was able to drive water levels back to their setpoint rapidly and without instabilities and also guaranteeing stable gates movement. [ABSTRACT FROM AUTHOR]

This paper is devoted to nonlinear observer and controller design for water level control of open-channel flow in irrigation canals or dam-river systems. A finite-dimensional model, previously developed by orthogonal collocation methods, based on Saint Venant equations and used for control design, is now further used for online flow rate and water infiltration estimation. This is done by a so-called state observer. In particular, the estimates obtained in this way can successfully be used in a controller previously proposed, resulting in a water level control law using only two level measurements along the canal (instead of the four measurements previously needed). The study is restricted to the case of a rectangular wetted section and subcritical flow. The results have been validated by simulations, on an implicit finite difference simulator based on a Preissmann scheme for various scenarios. [ABSTRACT FROM AUTHOR]

This paper focuses on an experimental study of the two-phase flow downstream of a laboratory model fish bypass. Experiments were performed on a 1:24 scale laboratory model of a fish bypass under consideration for construction at Wanapum Dam, on the Columbia River in Washington. The model was operated at the design condition of skimming flow regime and at the possible off-design plunging and surface jump regimes. Void fraction data were collected using an optical phase detection probe on a three-dimensional grid, and the phase indicator function was recorded at selected locations. It was found that in the laboratory model, the skimming flow regime effectively prevents bubbles from reaching deep into the tailrace, resulting in a considerably lower void fraction than plunging and surface jump regimes. For this geometry, the surface jump regime entrains air deeper than the plunging regime. To observe trends, the instantaneous source of total dissolved gas was estimated for the three regimes using the model data and several simplifying assumptions. Time distributions of the indicator function are also reported. [ABSTRACT FROM AUTHOR]

The paper reviews several methods to convert discharge into gate opening. A control algorithm for one or several reaches of an irrigation canal sometimes uses a discharge as the control action variable even though the device to be manipulated is a gate or a weir. In this case a slave controller has to convert the discharge into a gate opening or a sill elevation in the case of a weir. This is usually done by inverting the static relation between discharge and gate opening. An improved method can be based on the characteristics theory to estimate the deviations of the water levels. However, both methods underestimate the gate opening deviations required to deliver a desired discharge deviation, because water levels vary continuously over time when the gate is operated. The paper proposes a method to take into account this dynamic behavior of the pool-gate interaction by using a simple linear model for the pools’ dynamics, the integer delay zero model. The proposed method enables us to better estimate the gate opening necessary to get a desired average discharge. The method is evaluated in simulation and on a gate of the Gignac Canal, located in the South of France. A dimensionless analysis of the problem is finally performed to evaluate the methods’ applicability. [ABSTRACT FROM AUTHOR]

This paper presents the need, value, and concept of flexible irrigation water supply systems that can deliver water with flexibility in frequency, rate, and duration under the control of the farmer at the point of application using a limited rate arranged-demand or other schedule. It introduces the needed terminology including “congestion”—how much reserve time and capacity is required to assure water delivery at the frequency and rate desired. An illustrative design procedure for the necessary pipeline and reservoir capacities is illustrated. The techniques discussed emphasize the conversion of the economical steady supply canal flows to flexible on-farm usage through the use of service area reservoirs located between the secondary and tertiary systems, and of semiclosed pipelines and/or level-top canals as automated distribution systems which facilitates the farmers’ need for daytime only variable on-farm deliveries to permit optimization of on-farm water management. This improved management is the ultimate source of increased food production after improved crop, land, and water resources have reached their maximum. The coordinated use of return flow systems is described. [ABSTRACT FROM AUTHOR]

This paper presents a method to automatically tune decentralized proportional integral (PI) controllers for an irrigation canal pool. The auto tune variation (ATV) method is based on a relay experiment, which generates small amplitude oscillations of the canal pool. The ATV procedure can be used to get the integrator delay model parameters of a canal pool, which in turn can be used to tune a PI controller using classic rules, or other rules such as the ones proposed by Litrico and Fromion. This method does not require advanced automatic control knowledge and is implemented in the SIC software developed by Cemagref, which also incorporates a supervisory control and data acquisition module for real-time control. The ATV method is evaluated by simulations and experiments on a real irrigation canal located in the South of France, for local upstream, local downstream, and distant downstream controller tuning. [ABSTRACT FROM AUTHOR]

Results of experiments conducted in a 2 m high flume at large Reynolds numbers are reported in this paper. The flume was partitioned into two compartments. Flow entered the bottom of the upstream test compartment as a wall jet, at jet Reynolds number ranging from 11,000 to 170,000. Periodic oscillations of the free surface in the two compartments resembling the oscillatory flow in a liquid-filled U-tube, and large coherent structures formed above the potential core of the wall jet were observed. Coupling of the U-tube oscillations and vortex shedding is attributed to fluid-dynamic and fluid-resonant feedback processes. For test compartment length, Lc=0.8 m, fluid-resonant feedback was found to be dominant, and the shear layer was observed to oscillate at the natural frequency of the two-compartment, U-tube system. The observed U-tube oscillations are initiated by the oscillations of the shear layer at a frequency equal to the subharmonic component for the U-tube. The flow oscillations were generally weaker for Lc=1.2 and 2.0 m with oscillation frequencies governed by fluid-dynamic feedback, verified from a comparison with the results from a previously reported study. [ABSTRACT FROM AUTHOR]

Simulation models for unsteady open channel flows have been commercially available for more than 2 decades. Most of these models are now available for personal computers and can be used to study the control of irrigation canals. Studies on automatic control methods and algorithms have been performed on at least half a dozen of the available unsteady-flow simulation models. Although, many of these automation studies have been conducted by the institution that created the simulation model, these simulation models were not created with automatic gate control in mind, and thus one has to be intimately familiar with the source code in order to implement sophisticated control features. Three commercially available unsteady-flow simulation software packages that allow automatic control of gates based on algorithms written by users are: CanalCAD from the Univ. of Iowa, Hydraulics Lab; Mike 11 version 3.2 from the Danish Hydraulic Institute; and Sobek from Delft Hydraulics. In this paper, we describe the various features of these unsteady-flow simulation packages and how they interface to control engineering software/code. There are a number of tradeoffs between simplicity and functionality. All these models present difficulties and have limitations. The hope is to provide guidance on the next generation of unsteady-flow canal simulation models so that control functions can be routinely applied. [ABSTRACT FROM AUTHOR]

This paper is devoted to the nonlinear control of open-channel water flow dynamics via a one-dimensional collocation control model for irrigation canals or dam-river systems. Open channel dynamics are based on the well-known Saint-Venant nonlinear partial differential equations. In order to obtain a finite-dimensional model an orthogonal collocation method is used, together with functional approximation of the solutions of Saint-Venant equations based on Lagrange polynomials. This method can give a more tractable model than those obtained from classical finite-difference or finite-element methods (from the viewpoint of both state dimension and structure), and is well suited for control purposes. In particular it is shown how such a model can be used to design a nonlinear controller by techniques of dynamic input–output linearization with the goal of controlling water levels along an open-channel reach. Controller performance and robustness are illustrated in simulations, with a simulated model for the canal chosen as more accurate than the one used for control design. [ABSTRACT FROM AUTHOR]

Presents a study which provided graphical solutions to calculate the normal depth of irrigation canals in various cross sections. Solutions for round-bottomed triangular sections; Form of equations used to approximate parabolic sections; Description of the round-cornered rectangular sections.

Focuses on a study which presented a risk-based approach for the design of infiltration basins. Details on the distributions of rainfall and runoff depths; Soil water storage capacity; Basin storage volume; Evaluation of infiltration basin by overflow risk; Conclusions.

Presents a study which described a design for an irrigation canal section with minimum seepage-loss in nonpolygonal canal sections. Categories of canal sections; Mathematical equations for canal seepage flow.

Presents a study which described a flap gate design developed by the Irrigation Training and Research Center in California Polytechnic State University for automatic upstream canal water level control. Description of the Microsoft Excel spreadsheet program used in the flap gate design procedure; Factors which were considered in the design; Discussion.

Presents information on a study which investigated the design of minimum cost irrigation canal sections. Cost function; Constraint function; Design example; Conclusions.

Presents a study which featured the set of sensitivity indicators that enable the identification of sensitive structures and assessment of operational tolerance along irrigation canals. Relationship between the sensitivity of the structure and canal control; Background on sensitivity analysis of irrigation structure; Conclusions.

Presents a study which developed an optimal resource allocation strategies for a canal command in the semiarid region of Indian Punjab. System used in optimally allocating land and water resources to different crop; Results and discussion; Summary and conclusion.

The article discusses a systematic laboratory study of the hydraulic performance and flow characteristics of different staged labyrinth weir geometries. Topics include the accuracy of a simple prediction method for head-discharge base on superposition principle, review of various problems associated with the design of labyrinth weir, and the hydraulic behavior of piano key weirs (PKW) and rectangular labyrinth weirs.

Presents a model for the design of water level controllers for irrigation and drainage canals that describes the essential characteristics of the processes relevant for canal control (such as water movements and control structures). Two ways the accuracy of the model is evaluated; Function of an irrigation canal; Possibilities that exist to realize a water level control strategy.

Details a study that proposed a design and tuning method of a simple water level controller for irrigation and drainage canals. Description of the structure of the controller; Demonstration of the applicability of the controller; Conclusions.

Presents information on a study which established analytical relationships between the control of canal water depth, the sensitivity of irrigation delivery structures and the resulting internal performance. Derivation of a system sensitivity indicator; Degree of influence exercised by the cross-regulator on offtakes; Behavior of irrigation systems in Sri Lanka and Pakistan.

Presents information on a study on controlling irrigation canals. Details on the measurement of the depth of flow per pool; Methodology; Results and conclusions.

Studies irrigation canal regulation under demand delivery operation formulated as an optimal control problem. Application of the linearly optimal control theory; Simulated performance of the global feedback control algorithm; Optimal control and estimation.

Presents a control algorithm to maintain a constant water depth at every pool of a multireach irrigation canal. Effectiveness of the control algorithm; Calculation of control adjustments; Variable reach characteristics; Water level and gate openings.

Proposes a method for the automatic control of irrigation canals. Characteristics of the Preissmann Implicit scheme, Linear quadratic Optimal control, Tracking of variables and Estimation of perturbation (PILOTE) controller system used in the study; Overview of the application; Purpose of the control system.