فهرست مطالب

Hydraulic Structures - Volume:5 Issue: 2, 2019
  • Volume:5 Issue: 2, 2019
  • تاریخ انتشار: 1398/06/10
  • تعداد عناوین: 6
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  • Alireza Dariane *, Mahboobeh Ghasemi, Farzaneh Karami, Shadi Hatami Pages 1-17
    The water crisis is one of the important issues in the Middle East countries. Many lakes are ‎drying up and/or facing critical situations, exerting tremendous impacts on the socio-economics ‎of their region. Lake Urmia, in northwestern Iran, currently is facing critical situations and is on ‎the brink of total ‎shrinkage and environmental disaster. This paper investigates the roots of crises ‎through trend ‎analysis of hydrologic variables and shows the impact of the lake desiccation on ‎altering the ‎local climate. The results indicate an increase in temperature, a decrease in lake ‎inflow, and ‎limited significant trends in precipitation. They also indicate that increasing ‎agricultural water ‎consumption is the main cause of the current crisis of Lake Urmia. Further ‎investigation reveals a ‎significant change in the local climate as a consequence of Urmia Lake ‎water shrinkage. This change occurs in the dominant wind direction where before its desiccation ‎the lake was acting as a cooling medium. This phenomenon vanished after the desiccation of the ‎lake causing a sharp increase in the temperature of the affected areas. ‎‎
    Keywords: climate change, trend analysis, local climate alteration, Urmia Lake‎
  • Pejman Aminian *, Ahmad Ahmadi, Samad Emamgholizadeh Pages 18-31
    Sediment Bypass Tunnels (SBTs) are deviant channels that convey the current containing sediments from the upstream of the reservoir to the downstream of the dam. In this research, by applying submerged plates on the entrance of a 90-degree diversion channel for sediment transport, the effect of hydraulic parameters of flow and changes in the angle of plates on sediment transport and deviated flow are studied and compared with the state without using submerged plates. The experiments were conducted on a 10-meter-long Laboratory Flume, with a main channel of 60 cm width and a secondary channel of 30 cm width and a height of 75 cm. In this regard, the variables of Froude number and flow depth in three angles of 30, 45 and 60 degrees were considered. The results of this study highlight that an increase in Froude number on average would result in reduction of 22.2% of the channel deviated flow and reduction of 53.3% of the deviated sediment to the secondary channel. The 60-degree angle of the plates is effective in decreasing the deviated flow while the 30-degree angle is responsible for the increased deviated sediments. With a decrease in Froude number and depth along with submerged plates with a 30 degree angle, the optimum condition in conveying sediments is achieved where the maximum amount of sediments are conveyed in the minimum flow rate. Based on prediction results, the best equation to calculate the deviated sedimentation flow using the Genetic Algorithm (GA) is suggested.
    Keywords: sediment conveyance, Sediment Bypass Tunnel, performance, secondary flow, submerged plates
  • Amir Houshang Ayati *, Mohammad Hadi Ranginkaman, Amin Ebrahim Bakhshipour, Ali Haghighi Pages 32-48
    The accuracy of leak detection and calibration of pipe networks by means of the inverse transient analysis (ITA) is highly affected by the number and location of the measurement sites. This study introduces a conceptual decision-making model, the Decision Table Method (DTM), for the measurement site design of pipe networks with the aim of inverse transient analysis. Through the Decision Table Method, near optimum measurement sites are decided based on two criteria of the maximum sensitivity of measurement sites and the maximum diversity of sensitivity with respect to unknown parameters of leak areas and friction factors. The main advantage of DTM is that even in case of large networks, calculation of the Hessian matrix and the utilization of any optimization algorithm is not required. To evaluate the efficiency and applicability of the method, it is applied on two pipe networks of small and large size from the literature and the results are compared with the previous methods. Accordingly, the DTM is found reliable as well as easy to understand and implement.
    Keywords: Inverse Transient Analysis (ITA), Measurement site design, Decision making, Leak detection, Calibration
  • Abolfazl Ostovarzijerdi, Akbar Ghanbari *, Mohammad Karkon Pages 49-70

    One of the important issues in the construction of dams is plastic concrete cut-off walls. Careful study of the behavior of the used plastic concrete and the factors affecting it are essential concerning the failure in understanding its proper behavior that may cause irreparable damages. In line with determining the correct behavior of plastic concrete, investigating the effect of loading rate on the behavior of this concrete is considered as one of the factors affecting the stress-strain curve. In this research, in addition to studying fiber effects on the plastic concrete behavior, concrete samples were made with no fibers rather than polypropylene fibers, hooked and corrugated metal fibers with 0.19 % vol. that were under pressure load for 28 days at loading rates of 0.4, 0.6, 0.8, 1.0, 1.2 and 1.4 mm / min. The results indicated that an increase in the loading rate from 0.4 to 1.4 mm / min increased the compressive strength up to 18.8, 17.3, 11.1 and 23.2 percent, respectively; Besides, it increased the elasticity modulus of samples made of plastic concrete, with no fibers rather than polypropylene fibers, hooked and corrugated metal fibers up to 29.1, 31.8, 7.9 and 25.6 percentage. In addition, by adding fibers to plastic concrete samples, the stress-strain behavior of samples was improved by increasing the surface under the stress-strain curve and strain hardening.

    Keywords: Loading rate, plastic concrete, polypropylene fibers, hooked metal fibers, corrugated metal fibers
  • Saghar Ahmadian, Adell Moradi Sabzkouhi *, Ali Haghighi, Mohammad Hadi Ranginkaman Pages 71-89
    The rapid population growth and urban development have notably influenced the role of water distribution networks (WDNs) compared to the past. This issue encourages operators to adopt new smart tools to better system management. Such a smart system is expected to play an effective role in both crisis and normal services. For fire extinguishing services, a WDN needs to be well-equipped to supply the fire flow efficiently. In this sense, WDNs are required not only modern fire-fighting equipment but also a systematic program to satisfy the fire demand in the right place at the right time. This paper aims at introducing a pre-processing (not real-time) approach for smart pressure management using the regulation of control valves. The problem is formulated as a mathematical programing in which the reliability measure is maximized and the valve opening positions are decision variables. Using a self-adaptive Genetic Algorithm coupled with EPANET, the problem is solved. The proposed algorithm is applied to a case study from the literature and produces the optimum pattern for regulation of valves. Such results can be an appropriate guide for operators to practically maneuver valves in fire situation. The case study manifests that by applying the model the reliability of system can be increased up to 40.7%.
    Keywords: Water Distribution Network, Fire Extinguishing, Smart Pressure Management, Reliability, Optimization
  • Ali Gorjizade *, Heidar Zarei, Alimohammad Akhoond, Ali Hesam Seyed Kaboli Pages 90-106

    Human activities have led to increased greenhouse gas emissions in the atmosphere area and it caused internal climate changes. These influences are effective on the climate parameters, which increases the temperature rate and, consequently, elevates the rate of evaporation from the free surfaces. The reservoirs of dams are influenced directly by this temperature rise as the main place of water storage, causing the annual loss of a large amount of water in them due to the evaporation phenomenon. In this research, the effect of climate change on the evaporation from Dez dam reservoir was studied considering the uncertainty of climate change scenarios. Also, the changes occurring in temperature ranges and evaporation rates in future periods were examined under climate change scenarios. The results suggested that in the coming period of 2020-2044, the annual evaporation rate will increase in all three greenhouse gas emissions scenarios, and with a probability of occurrence of 90%, the highest evaporation rate would occur in May under the A1 scenario.

    Keywords: Evaporation, climate change, Climate Change Scenarios, Uncertainty, Dez dam