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In this study, a model is developed for short-term flood control of a complex multi-reservoir system located on one of the largest basins in Turkey. The managing body of the reservoirs requires that short-term real-time flood control is used in conjunction with the long-term operation for energy maximization. For this purpose, a novel operating framework is developed to couple short-term and long-term decisions. The resulting optimization problems are a large scale and nonlinear. Hence, the solution is maintained by developing an improved epoch-based particle swarm optimization (PSO) method. The proposed solution is general and can be used for any watershed with different layouts of several reservoirs having anticipated inflows and pre-defined release and storage constraints. It is the first time PSO is used for such a complex large-scale problem within flood control context. The developed optimization model was applied to a sample basin having 10 reservoirs with general layout of the mixed structures. The results obtained were compared to the real operational data and it was found that a solution with less flooding and more energy production would have been possible if the proposed methodology were utilized.

Discharge measurement and control structures are widely employed in hydraulic engineering applications. The objective of this study is to numerically investigate the modelling of two different structures, namely sharp-crested weirs as Problem 1 and combined weir and gate systems as Problem 2. The research methodology herein is based on the comparison of results of numerical simulations with experimental data for both problems separately. For the purpose of performing numerical simulations, the Reynolds-averaged Navier-Stokes (RANS) equations are solved by finite volume formulation using commercially available Flow-3D software. Assessment of empirical data and numerical findings for both problems reveals that discharge rates agree reasonably well. In addition, using the capabilities of numerical modelling, weir and gate discharge coefficients in the combined system are calculated separately which were not easy to obtain in experimental studies. It is seen that gate and weir discharge coefficients of the combined system are different and higher than the corresponding coefficients of the individual systems. (c) 2020 John Wiley & Sons, Ltd.

Booster disinfection stations are the solution alternative to maintain required disinfectant residual concentration in water distribution networks. In the present study, an optimisation problem to determine the optimum injection rates is solved. The minimisation of the total injected mass is considered as the objective function which is subjected to bound constraints on chlorine concentration. Two formulations are used for the linear optimisation problem, with and without considering the initial concentrations as unknowns. Determination of variable network hydraulics and chlorine concentrations is achieved by EPANET. A C++ code was developed to interface with EPANET by means of the EPANET Programmer's Toolkit for optimisation of the disinfectant mass applied to the network. Finally, a cross check is achieved in EPANET software for both disinfectant residual concentrations and linear superposition principle.

Hydraulic model tests of the intake structure of Beyhan 1 Dam having four units were carried out at Hydromechanics Laboratory of Middle East Technical University, Ankara. In order to investigate the flow pattern, and formation, development and dissipation of vortices at the intake structure under different operation conditions of the units, and to determine the types of anti-vortex devices to avoid the air-entraining vortices, a model of 1/29.43 length scale was constructed. The model area covers an about 200 m × 300 m section of the Beyhan 1 reservoir, the intake structure having four units, the trash racks and penstocks. Experiments were carried out at various reservoir water levels with specified unit operation discharges for various unit operation conditions. From the observations and experimental results, it was concluded that air-entraining vortices were forming at the intakes when the reservoir water level was minimum, RWL=977.0 m. Flow separation zones were forming; along the inner lengths of the side walls surrounding the intake structure and behind the trashrack piers at any RWL tested. In order to reduce the strengths of the vortices forming and to prevent the intakes from air-entraining vortices, in the first phase of the experimental study, several anti-vortex devices; continuous plates constructed on top of the intakes, continuous projected head walls and continuous projected head walls with vertical unit-separation walls were tested under various flow and unit operation conditions to find the anti-vortex device that gave the best performance. It was also stated that the arrangements to be made on the geometries of the side walls and trashrack piers, if possible, will improve the flow conditions at the intakes.

Hydraulic model tests of the spillway of Yukarı Kaleköy Dam and Hydroelectric Power Plant (HPP) were carried out at Hydromechanics Laboratory of Middle East Technical University (METU), Ankara. In order to investigate the flow conditions in the approach channel, over the weir structure, around the spillway piers, along the spillway chute channels and after the flip buckets, and also to observe the performance of the aeration devices, a model of 1/70 length scale was constructed. The model area covers an about 400 m × 450 m section of the Yukarı Kaleköy reservoir, the whole spillway structure and a part of the river area of about 150 m × 200 m downstream of the flip buckets. Experiments were carried out at various discharges; QPMF, Q1000 and Q100 with fully open radial gates as well as with partly open radial gates at Q1000. Flow depths, pressure heads of the flows along the spillway structure were measured, cavitation indexes and air concentrations of the flows were determined. From the observations and experimental results, it was concluded that the flow conditions in the approach channel of the spillway, over the weir structure, around the spillway piers, along and after the flip buckets are quite good from the hydraulics point of view. However, the flows were not sufficiently aerated in the spillway chutes, in Channels I and II, after the available aerators presented in the original design of the spillway. After the experiments conducted on the “original model” it was decided that some modifications should be done. In order to improve the performance of the available aerators, the heights of the aerator deflectors were increased by 0.20 m by keeping their lengths in the flow direction almost as before.

Analyses of data from reservoir surveys and sediment rating curves are compared to predict sediment yield in three large reservoir watershed areas in Turkey. Sediment yield data were derived from reservoir sedimentation rates and suspended sediment measurements at gauging stations. The survey data were analysed to provide the volume estimates of sediment, the time-averaged sediment deposition rates, the long-term average annual loss rates in the reservoir storage capacity, and the long-term sediment yield of the corresponding watershed areas. Four regression methods, including linear and nonlinear cases, were applied to rating curves obtained from gauging stations. Application of the efficiency test to a power function form of a rating curve with nonlinear regression yielded the highest efficiency values. Based on the analysis of the sediment rating curves, sediment load fluxes were calculated by using average daily discharge data at each gauging station. Comparison of these two sediment yield values for each reservoir showed that the sediment yields from the suspended sediment measurements, SYGS, are 0.99 to 3.54 times less than those obtained from the reservoir surveys, SYRS. The results from the reservoir surveys indicate that all three reservoirs investigated have lost significant storage capacity due to high sedimentation rates. ResumeCet article compare les analyses de donnees provenant d'enquetes realisees sur des reservoirs, et de courbes de tarage sedimentaires, pour estimer la production en sediments de trois grands bassins versants alimentant des reservoirs en Turquie. Les donnees de rendement en sediments ont ete obtenues a partir des taux de sedimentation dans les reservoirs et des mesures de sediments en suspension aux stations de jaugeage. Les donnees de l'enquete ont ete analysees pour fournir les estimations de volume de sediments, les taux moyens de depot des sediments, la moyenne a long terme des taux de pertes annuelles de capacite de stockage du reservoir, et la production de sediments a long terme des bassins versants correspondants. Quatre methodes de regression, incluant les cas lineaire et non lineaire, ont ete appliquees aux courbes de tarage obtenues aux stations de jaugeage. L'application d'un test d'efficacite a une forme de fonction puissance d'une courbe de tarage avec la regression non lineaire a donne les meilleures valeurs d'efficacite. En se basant sur l'analyse des courbes de tarage sedimentaires, les flux de charge de sediments ont ete calcules en utilisant la moyenne des donnees de debits journaliers a chaque station de jaugeage. La comparaison de ces deux valeurs de rendement en sediments pour chaque reservoir a montre que les rendements de sediments a partir des mesures de sediments en suspension, SYGS, sont de 0,99 a 3,54 fois moins eleves que ceux obtenus a partir des enquetes sur les reservoirs, SYRS. Les resultats des enquetes sur les reservoirs ont indique que les trois reservoirs etudies ici ont perdu de maniere significative leurs capacites de stockage en raison de taux eleves de sedimentation.

Quality of municipal water is sustained by addition of disinfectant, generally chlorine, to the water distribution network. Because of health problems, chlorine concentration in the network is limited between maximum and minimum limits. Carcinogenic disinfectant by-products start to occur at high concentrations so it is desired to have minimum amount of chlorine without violating the limit. In addition to the health issues, minimum injection amount is favorable concerning cost. Hence, an optimization problem which covers all of these considerations should be modeled. However, there are uncertain factors as chlorine is reactive and decays both over time and space. Thus, probabilistic approach is necessary to obtain reliable and realistic results from the model. In this study, a linear programming model is developed for the chance constrained optimization of the water distribution network. The objective is to obtain minimum amount of injection mass subjected to maintaining more uniformly distributed chlorine concentrations within the limits, while considering the randomness of chlorine concentration by probability distributions. Network hydraulics and chlorine concentration are computed by the network simulation software, EPANET.

Various applications of slurry transportation through pipelines exist. A transportation problem is formulated to determine the pipe diameters and amounts of transported slurry from the production to the consumption points. The minimisation of the cost consisting of the pipe and energy cost terms is considered as the objective function. Pipe cost is given as the function of pipe diameters and the energy cost is defined as the function of pipe diameters and slurry amounts. Energy cost is obtained by using the relation that is previously determined after the experimental studies have been made for the magnetite ore. Genetic algorithm is used as the optimisation method and to apply this method a commercially available software written in the C language is used and modified. The proposed methodology to solve this non-linear programming problem is applied to a transportation system and it is found that the proposed methodology has made the complex, labour-intensive solution process very convenient for the users.

Simultaneous flow over weirs and below gates for free flow condition is experimentally investigated. Combination of a sharp-crested rectangular weir and rectangular gate is considered as a flow measurement structure which is named as H-weirs. H-weirs are defined by the width of the weir and gate openings, the height of the gate opening and the vertical distance between bottom of the weir and top of the gate. Laboratory experiments are conducted by measuring the discharge and the depth of water at upstream for different H-weirs. The present study aims to determine the discharge for a given H-weir simply by reading the depth of water at upstream of the combined structure. The compatibility of various formulations of the discharge–depth of water relationship is investigated by using the collected data and two new formulations are suggested based on the analysis of these data. After obtaining and comparing percentage errors of each equation, it is concluded that the new proposed equations can be used to accurately predict the discharge through H-weirs within the given ranges of the experimental study.

Sharp-crested rectangular weirs used for discharge measurement in channels and laboratories are experimentally investigated. Height and width of weir plate are the two parameters characterizing the head-discharge relationship. Laboratory experiments are conducted by measuring the discharge and the head over the weir for variable weir heights and widths. Applicability of various formulations for the discharge coefficient are investigated. Experiments indicate that discharge is independent of weir height, when the weir is operated within an appropriate discharge range. Average velocity over the weir plotted against the weir head displays universal characteristics such that it can be used in the expression of discharge over the weir, eliminating the need for a discharge coefficient. The head-discharge relationship for a rectangular weir has distinct features for the partially contracted weirs and for the fully contracted slit weirs.

Application of optimization techniques for determining the optimal operating policy of reservoirs is a major issue in water resources planning and management. As an optimization Genetic Algorithm, ruled by evolution techniques, have become popular in diversified fields of science. The main aim of this study is to explore the efficiency and effectiveness of genetic algorithm in optimization of multi-reservoirs. A computer code has been constructed for this purpose and verified by means of a reference problem with a known global optimum. Three reservoirs in the Colorado River Storage Project were optimized for maximization of energy production. Besides, a real-time approach utilizing a blend of online and a posteriori data was proposed. The results obtained were compared to the real operational data and genetic algorithm was found to be effective and can be utilized as an alternative technique to other traditional optimization techniques.

Generally, measurement of flow in natural streams is accomplished by measuring the flow depth. Hence, the relationship between the water level and discharge should be obtained in advance. However, in streams with high sediment load, the bottom level may change due to sediment deposition, preventing the single relation between water level and discharge. This paper summarizes the application of a flow-measurement structure for sediment-laden streams. The proposed structure is designed and built in Turkey and has been under operation since 1998 without any sedimentation problem. The agreement between the real data obtained from the structure and the theoretical rating curve is quite reasonable.

A numerical simulation of minimum B-jumps in horizontal rectangular channels having an abrupt drop is given. Gradually varied, steady, supercritical flow is assumed as the initial condition. An unsteady flow is created by increasing the downstream depth. One-dimensional, unsteady Saint-Venant equations are solved by using the MacCormack and the dissipative two–four explicit finite difference schemes. The steady flow solution is obtained by treating the time variable as an iteration parameter and letting the solution converge to the steady state. The abrupt drop is treated as an interior boundary and solved by the method of characteristics. The results are compared with experimental and analytical studies. Copyright © 2007 John Wiley & Sons, Ltd.

The optimum values of the section variables (side slope, bottom width, flow depth, and radius) for triangular, rectangular, trapezoidal, and circular channels are computed by minimizing the cost of the channel section. Manning's uniform flow formula is treated as the constraint of the optimization model. The cost function is arranged to include the cost of lining, the cost of earthwork, and the increment in the cost of earthwork with depth below the ground surface. The optimum values of section variables are expressed as explicit functions of unit cost terms. Unique values of optimum section variables are obtained for the case of minimum area or minimum wetted perimeter problems. Key words: open channel design, optimization, minimum cost, best hydraulic section.

A numerical simulation of the A-type hydraulic jump at a positive step, which is an example of mixed supercritical-subcritical flow with a discontinuity at the channel bed, is given by using an integral approach. A gradually varied subcritical flow over a rectangular, horizontal, and prismatic channel with an abrupt bottom rise is considered as the initial condition. Then, the upstream depth is decreased to a value producing a supercritical flow and remaining unchanged during computations. The resulting unsteady flow is solved by using both the MacCormack and the dissipative two-four schemes for the one-dimensional, unsteady Saint-Venant equations. In the numerical simulation, the step is treated as an internal boundary. At the downstream and the internal boundaries, the method of characteristics is employed to compute the relevant parameters. The numerical simulation is verified by comparing the results with the available data and analytical methods.Key words: hydraulic jump, positive step, numerical simulation, internal boundary.

A new methodology has been developed for determining the optimal operation of water distribution system pumps with water quality considerations. The methodology is based upon describing the operati...

Slit weirs designed to measure small discharges in open channel flows are investigated. Experimental data available in the literature are added to study the effect of the slit width. An explicit relation for the discharge coefficient is obtained by a conventional Reynolds number definition. The discharge coefficient is modified to increase the working range of slit weirs for small values of head to slit-width ratios.

Local energy losses occur when there is a transition in open channel flow. Even though local losses in subcritical open channel flow due to changes in channel width have been studied, to date no studies have been reported for losses due to changes in bed elevations. Steps are commonly used in engineering applications to stabilise the flow in open channels. Hence, it is important to estimate local losses for design purposes. The aim of this study was to formulate the local energy losses at positive and negative steps in subcritical open channel flows. Flow rates and water depths before and after the step were measured for varying step heights of abrupt and 45o inclined steps. Empirical equations relating the local losses to the Froude number on the step and the relative step height are proposed for positive and negative steps. In addition, practical values of local loss coefficients are determined.