Developing Optimal Reservoir Operation for Multiple and Multipurpose Reservoirs Using Mathematical Programming

Over the last decades, the increasing water demand has caused a number of problems, to which reservoir operation optimization has been suggested as one of the best solutions. In this research, a model based on mixed integer linear programming (MILP) technique is developed for the systematic operation of multireservoirs that are used to cater for the different needs of the Tehran-Karaj plain. These reservoirs include Laar, Latian, and Karaj dams. The system configuration was accomplished through the nodes and arcs of the network flow model approach and system component implementation including sources, consumption, junctions, and the physical and hydraulic relationship between them. The following were performed via comprehensive developed software: system configuration, objective function and constraints formulation, linearization, determining penalty values, and setting priorities for each node and arc in the system. A comparison between the MILP developed model’s results against the periodic data shows 21.7% less overflow, 11.6% more outflow, and 15.9% more reservoir storage, respectively. The outcome of the MILP-based modeling indicates superior performance to the historical period

Experimental Study of Hydro-suction Dredging Blockage Depth Under Different Hydraulic Conditions

Hydro-suction is an appropriate and economical method for dredging deposited sediment at reservoirs. In this study, a physical model was made and some experiments were designed to analyze the ranges of blockage depth in different hydraulic conditions. In the model, 80 tests were conducted using three diameters (d), three water heads (H) and different diving depths of pipe inlet (Z) from the sediment level to the blockage depth. In general, the results indicated that the more increase in the diving depth, the higher hydro-suction efficiency. In some of the experiments, a vortex flow was observed under the pipe inlet. The results indicated that the formed vortex flow have a positive effect on the hydro-suction efficiency. The results associated to the blockage depth approved that hydro-suction systems with larger pipe diameter and more water head have a greater blockage depth (Zb). The Froude number (Fr) analysis indicated that an increase in Fr would cause increment efficiency and blockage depth of hydro-suction system. Subject to a constant pipe diameter, the results revealed that increasing the H/d ratio equal to 66.66 and 133.33%, would enhance the Zb/d ratio equal to 58.89 and 112.22%, respectively

Evaluation of Environmental and Agricultural Sustainability Indices of Zarrinehrud and Siminehrud River Basins

In the arid and semi-arid regions, agriculture has led to decline in water levels in major lakes such as the Aral Sea, Urmia, Hamoun and Bakhtegan lakes. The major objective of the present study was to evaluate the environmental and agricultural sustainability of Zarrinehrud and Siminehrud river basins as the largest sub-basin of Urmia Lake basin. The sustainability index was calculated using reliability, resilience, and vulnerability performance criteria. In this study, the irrigation water deficit (IWD) index was calculated for the irrigation districts. Irrigation demand and irrigation water deficit indices were calculated using WEAP21 model. Results showed that the environmental sustainability of Zarrinehrud and Siminehrud river basins to supply the environmental flow requirements of the Urmia Lake during the studied period was 0.39 and 0.41 respectively. Nevertheless, the agricultural sustainability index of Zarrinehrud and Siminehrud river basins was 0.64 and 0.74 respectively. Moreover, the amount of IWD index showed that water demand for all irrigation districts has not been fully met. The above results indicated that the Zarrinehrud and Siminehrud river basins were unstable both in terms of the environment and agriculture. Whereas during the study, the changes in land under cultivation in most irrigation districts had an increasing trend, ttherefore, it can be concluded that agricultural development and the addition of water harvests for agricultural use have been the main cause of environmental and agricultural instability

Analysis of the Effects of Water Management Strategies and Climate Change on the Environmental and Agricultural Sustainability of Urmia Lake Basin, Iran

In arid and semi-arid areas, unsustainable development of irrigated agriculture has reduced the water level of large lakes such as Aral, Urmia, Hamoon, and Bakhtegan. Urmia Lake, as a hyper saline and very shallow lake, located in the northwest of Iran, has water level reductions of about 40 cm each year over the past two decades. In this research, the indices of environmental and agricultural sustainability are evaluated using performance criteria influenced by climate change and water management strategies for the Zarrinehrud and Siminehrud River basins as the largest sub-basin of Urmia Lake basin. Modeling of hydrologic behavior of these basins is performed using WEAP21 model. The model is analyzed for three future emission scenarios (A2, A1B, and B1), for the period of 2015–2040 and five water management scenarios: (1) keeping the existing situation; (2) crop pattern change; (3) improving the conveyance and distribution efficiency; (4) combining the improvement of conveyance and distribution efficiency with improving the application efficiency using modern technology; and (5) the combination of crop pattern change with the improvement of total irrigation efficiency. The results show that the highest values of indices of environmental sustainability and agricultural sustainability are related to the scenario of combining the crop pattern change with improving the total irrigation efficiency under the B1 emission scenario (B1S4)

Experimental Study Demonstrating a Cost-Effective Approach for Generating 3D-Enhanced Models of Sediment Flushing Cones Using Model-Based SFM Photogrammetry

Accurate measurements of sediment flushing cone geometry (SFCG) are essential for determining sediment removal efficiency in reservoirs. SFCG measurements are related to the point-to-point height that affects bathymetry accuracy, and they are used to develop a digital elevation model (DEM). Conventional bathymetry monitoring techniques require a longer time for data processing and output data with insufficient accuracy despite being inexpensive and simple. In the current research, a close-range photogrammetric method called the structure from motion (SFM) method was investigated to determine the SFCG in an experimental study. The regular geometric shape of a cube was used to verify the SFM. Additionally, measurements between model control points (MCPs) on the flushed sediment bed were compared with those from the SFM method. The results indicated that the calculated SFM values were consistent with the measured values. To determine the SFCG, two sets of images were captured with 70% average overlapping before and after the completion of each test. After processing and post-processing via the SFM tool AgiSoft Metashape, a georeferenced 3D model was achieved. The accuracy of the surveyed data in terms of the dimensions, cross-sections, and temporal developments of the sediment flushing cone was investigated to verify the SFM method. Finally, the results revealed good agreement (R2=0.99 and average error of 0.03–0.74 mm) between the DEMs created by the SFM method and the actual model

Influence of different skew angles of the submerged vane on pressure flushing performance

Abstract Siltation significantly threatens a reservoir’s original storage capacity and lifespan. Pressure flushing is an effective measure against siltation through the partial drawdown of the reservoir water level with limited flushed cone volumes in front of the bottom outlet. In this study, a novel configuration with submerged vanes has been proposed and tested experimentally to increase the flushed sediment volume during pressure flushing. In the new configuration, submerged vanes aligned with ten skew angles (θ) of 10°, 20°, 30°, 45°, 70°, 110°, 135°, 150°, 160°, and 170° to the flow direction in noncohesive sediment bed materials were used. The results showed that increasing the skew angle at 45° ≤ θ ≤ 160° increased the flushing cone geometry. The minimum and maximum flushing cone dimensions and volume occurred at skew angles of θ = 45° and 135° ≤ θ ≤ 160° around the bottom outlet. The sediment flushing volume in the presence of submerged vanes at 135° ≤ θ ≤ 160° increased 25 times compared to tests without submerged vanes. Eventually, nonlinear regression analysis yielded an equation for estimating flushing cone volumes. The developed equation was tested in real case studies of a target reservoir, and an acceptable correlation between the calculated and experimental results was obtained