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Akram M.,Kamab Pars Consulting Engineers | Azari A.,Yekom Consulting Engineers | Nahvi A.,University of Tehran | Bakhtiari Z.,Mahab Ghodds Consulting Engineers | Safaee H.D.,Kamab Pars Consulting Engineers
Irrigation and Drainage | Year: 2013

Khuzestan, a south-western province of Iran with a hot climate, long growing season and lots of water, is the main region of subsurface drainage. Sugar cane is the major artificially drained crop. In the past, drainage rates had been chosen based on highest water-consuming crop in the cropping pattern. This approach neglects crops with less water demands, natural drainage and direct flow towards perforated collectors or open deep drains, and soil water reservoirs. The drains are installed deeply which bring more saline drainage water out of the underlying strata into the environment. The environmental problems are due to the high volume of very poor quality drainage water. The low irrigation efficiency results in a high volume of drainage water. Deeper drains are also responsible for over-drainage because they usually work longer and bring mined salt water out of the deeper strata. This paper attempts to show that in arid areas with a long irrigation season and/or high deep percolation one does not have to expect secondary salinization provided that the leaching requirement is met. Maintaining higher irrigation efficiency, installation of shallower drains and the application of controlled drainage are measures to reduce salt removal, and hence reduce environmental hazards. © 2013 John Wiley & Sons, Ltd. Source


Hashemy S.M.,Tarbiat Modares University | Hashemy S.M.,Technical University of Delft | Monem M.J.,Tarbiat Modares University | Isapoor S.,Yekom Consulting Engineers | van Overloop P.J.,Technical University of Delft
Irrigation and Drainage | Year: 2013

In this study an in-line storage strategy is applied to improve the existing operational performance of an upstream-controlled 13-pool irrigation canal. Three pools in the upstream, middle and downstream sections of the main canal are considered as in-line reservoirs. Decentralized proportional-integral (PI) controllers are designed to regulate their upstream water levels based on a mixed control method. Each regulator is coupled to its upstream in-line reservoir. The objectives of the controlled system are keeping the upstream water level of each regulator at the target levels; reducing delay times of flow travelling in the canal and compensating for mismatches between upstream supply and downstream demands. Existing and proposed operational methods are compared, using the hydrodynamic modelling package Sobek, considering a severe and sudden increasing- decreasing flow condition. In this case study, the water level profiles and controller performance indicators imply that in-line storage in the main canal decreases water level deviations in most of the pools in the range of 24-57 % in comparison with the current operation. Moreover, using in-line reservoirs decreases the delay times especially in the downstream part of the canal. © 2013 John Wiley & Sons, Ltd. Source


Rahimi H.,University of Tehran | Abbasi N.,Iranian Agricultural Engineering Research Institute IAERI | Shantia H.,Yekom Consulting Engineers
Irrigation and Drainage | Year: 2011

Fine sandy soils have always been known as one of those problematic soils which will erode rapidly and cause piping due to water flow. This phenomenon has caused the destruction of many concrete canal linings around the world. In the present study, the history of the design, construction and operation of a canal in the Moghan Irrigation and Drainage Network, in north-west Iran, is reviewed and the main causes of destruction of the concrete lining of the canal are discussed. Based on the results of geotechnical studies, it was found that the canal was constructed on wind-blown deposits consisting of very fine to fine sand and loess. During operation of the canal, the fine, clean sandy subgrade soil was highly eroded due to water seeping under the canal lining, causing severe piping and consequently destruction of the lining. Following field and laboratory investigations, the main cause of the problem was diagnosed as "physical dispersivity" of the subgrade soil, and application of a geomembrane under the concrete lining was chosen as the most economical and practical measure to remedy the problem. © 2010 John Wiley & Sons, Ltd. Source


Dastgheib A.,Yekom Consulting Engineers | Niksokhan M.H.,University of Tehran | Nowroozpour A.R.,Islamic Azad University at Tehran
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012

Stepped spillways are one of the main energy dissipaters in hydraulic structures. In this paper, a numerical modeling of the flow over different forms of stepped spillway has been developed and the results were compared. The base model was calibrated with experimental data. The computational fluid dynamics model which solves the RANS equations coupled to a surface-capturing algorithm to predict the main features of flow water. This included the determination of water surface, the development of swirling flow, and resulting pressures over the steps. The model was developed using the volume of fluid (VOF) method. In this paper, flow velocity at the end of spillway, and energy dissipation rate were compared in different height of steps. The RNG model of turbulence with wall functions was used to compute the eddy viscosity. Also Structured hybrid grids were used to accommodate the geometry of the stepped spillway included upstream, steps and downstream. Agreement between numerical results and experimental data showed that RNG turbulent model and VOF method for predicting the water surface in the stepped spillway were suitable. This study indicates the capability of a numerical model using the VOF technique to predict the flow variables over the complex stepped spillway. © 2012 ASCE. Source


Abbasi H.,Yekom Consulting Engineers | Afshar A.,Iran University of Science and Technology | Jalali M.R.,Mahab Ghodss Consulting Engineers
Journal of Hydroinformatics | Year: 2010

Valve and pump shut-off in water pipeline systems lead to transient flow. This flow is a complex phenomenon and is potentially a very serious problem causing extra dynamic pressure in the system. Within the last few decades, the evolutionary and meta-heuristic algorithms, such as genetic algorithms, simulated annealing. More recently, however, ant-colony optimization algorithms have received considerable attention. In this paper the procedure and application of the ant-colony optimization algorithm to the design of a water supply pipeline system, considering dynamic pressures arising from valve closure, is presented. A simulationoptimization interaction loop (SOIL) is defined that cycles between the steady-state and transient flow modules to describe the hydraulics of the pipeline and ant colony optimization algorithm. A hydraulic simulation module is coupled with the ant colony optimization algorithm to form an efficient and powerful software program which locates the pumping stations at any possible or predefined locations while optimizing their specifications, along with pipe diameters, at each decision point. The model may equally regard or disregard the dynamic pressures. Two examples are provided to illustrate the proposed methodology which is limited to the solution of any gravity and/or forced water supply pipeline which is typical for water supply systems. © IWA Publishing 2010 Journal of Hydroinformatics. Source

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