مجله مهندسی آبیاری و آب ایران
پیاپی 21 (پاییز 1394)

Employment of hydroelectric power plants is considered as one of the strategies to overcome the water shortages in the world. On the other hand, increasing the generated electricity by using of water energy is of importance. Regarding to the high cost of construction of dam and supplying the required hydraulic head of hydro power stations, the optimum design of these stations has been considered. Penstock, among the components of these stations, has a special place. The importance of penstock is due to its high manufacturing, installation and maintenance costs which assign nearly thirty percent of the plant’s expenditures to itself. Therefore, optimal design of this hydraulic structure will play a significant role in lowering the construction costs of hydro power stations. The use of meta-heuristic optimization algorithms for optimization of different structures has been one of the most important issues in designing of these structures. Among the meta-heuristic algorithms Particle Swarm Optimization has been considered as a powerful method in many fields. The purpose of this research is to present an optima sketch to maximize the power of jet streams reaching the turbines and also reduction the pressure losses through penstocks for controlling the transient flows. The results show that the energy losses have totally been decreased from 29.11meters to 11.92meters. This reduction lead to increasing the efficiency and performance of high pressure pipes. The pressure losses due to sudden changes in flow condition (before optimization) are 315.9kpa which by optimization of the penstocks decreased to 116.7kpa. This reveals that by reduction in pressure losses, the damages caused by transient flows are greatly decreased. Also, the power of flow increased from 25MW to 28MW, which equals 11%.

Weir and Gate are widely used in control, diversion and measurement of flow in irrigation projects due to their simpler and relatively exact relationship. There are sediment and suspended materials in the direction of channels. The accumulation of sediments and suspended materials in the back side of weir and gate caused change of canal shape and reduction of water measurement accuracy. The combined model of weir- gate have the capability of passing settling down from under the gate and suspended materials over weir simultaneously and prevents from accumulation of sediment and suspended materials in the back side of the weir and helps to the accuracy of water measurement and passing flow. The present research investigated ten combined model of labyrinth weir- gate on the effects of plan shape change and gate height on discharge coefficient in the laboratory. The results showed that the existence of gate and increasing of opening height, increased discharge coefficient in combined model of labyrinth weir- gate. On the other hand, existence of gate in combined model of rectangular labyrinth weir- gate in low total upstream water height to weir height have higher effect on the increasing of discharge coefficient. Whereas in combined model of trapezoidal labyrinth weir- gate, with the same of total upstream water height to weir height, had uniform effect on the increasing of discharge coefficient. The results showed that increasing of upstream water height caused interference of water jets of cycles of labyrinth weir and also interference of water flow passing under the gate and flowing water over the weir. Therefore discharge coefficient was lower in deeper depths. On the other hand, in the same depth, the trapezoidal labyrinth weir had less flow interference with respect to rectangular labyrinth weir, which caused higher increase in discharge coefficient in combined model of trapezoidal labyrinth weir-gate with respect to combined model of rectangular labyrinth weir- gate.

As a crucial issue in aqua sciences, optimizing dam reservoirs exploitation has been studied with a variety of optimization techniques. One of these methods is using Meta-Heuristic algorithms such as Firefly and Ants Algorithms. Using the firefly algorithm, this study studies the exploitation optimization of Doroudzan reservoir in a 99-month period. The most sensitive parameter in sensitivity analysis of Firefly Algorithm, α, is known as the mutation rate. Selecting its appropriate value by Firefly worms leads to an appropriate solution and increases the efficiency of the Firefly Algorithm dramatically. To determine the efficiency of this algorithm in optimizing the utilization of the dam reservoir, the obtained results were compared with the results of Continuous Ant System and Ranking Ant System. The findings indicated that FACC algorithm with objective function rate of 4.196 had a satisfactory performance. ACOrCC and ACOrankCC algorithms with the values of 17.004 and 26.156 followed it respectively. In addition, FACC algorithm with a value of 0.959 had the highest reliability coefficient. The results indicated that regarding Chain constraints, all program performances led to feasible solutions; however, ignoring chain constraints, the Continuous Ant System algorithm was unable to find a feasible solution. Hence, applying these constraints in the main structure of this algorithm would enhance its efficiency significantly.

From ancient times, flood and its mitigation methods have been important to human in order to reduce damages threatening people and nature. Detention rockfill dams which are from the structural methods can control the flood risks in downstream by decreasing the maximum discharge of the flood and increasing the total time of its hydrograph. In order to have an efficient design of these dams, the important conditions of sediment transportation through dam body and also the optimum thickness of the dam should be known. The optimum thickness of detention rockfill dam leads into the maximum reduction in flood peak discharge and also causes the increment of flood duration to get minimized. To find this optimum thickness, some experiments were done on a simulated porous media in a lab. Then, the experimental results were utilized in Monte Carlo probabilistic method in order to find the percentage of sediment transportation probability. Results depict that by using mixed sediment with non-cohesive mean diameter of 0.6 mm within the water flow, optimum thickness would be 7 to 8 times greater than the rockfills with mean diameter of 2 cm in the dam body; while using non cohesive sediment with mean diameter of 0.2 mm in the flow causes the optimum thickness of the detention rockfill dam to be 7 times greater than body rockfills with diameter of 5 cm.

Drought is a phenomenon refers to precipitation less than normal value which is possible in any climate and geographic location. In this study, the Standardized Precipitation Index on a scale of 1, 3 and 12 months used to determine the intensity, duration and frequencies of Shiraz droughts and the graphical mann-kendall test used to analyze the shifts or possible trends in both annual and seasonal time scales. The data used was monthly precipitation data of Shiraz synoptic station ranged from 1984 to 2013. Results indicated the increase in the intensity, duration and the frequency of droughts and trend of normal years to drought. Also the drought of 1386-1387 was the biggest with the duration of 16 months and the maximum intensity of -2.57. Since the negative trend of annual and seasonal precipitation scales is not statistically significant at 5% level, the trend of decadal moving averages was applied to examine the whole trend. Due to the low variability of decadal moving average from fluctuations, the trends were determined in high confidence level. Results indicated that precipitation averages decreased by 100 mm in the last ten years and negative trends were identified with high confidence of 99.99% in annual scale and winter. Also, results showed that negative slope of winter precipitation trend line is steeper than reduction of annual precipitation.

In recent decades, Evolutionary algorithms have been applied successfully in various water resource engineering and management issue especially in optimal operation of reservoirs. In this research, a metaheuristic algorithm called Wolf Search Algorithm (WSA), has been developed in MATLAB software, with the purpose of optimal allocation strategies of a Multi-reservoirs system (Golestan and Voshmgir dams) located at Gorganrood Basin (North of Iran), for a five year period (from 2007-2008 to 2011-2012). At first, the performance of the developed model was investigated through several standard test functions. Next, the developed model is applied for monthly allocation of Golestan and Voshmgir reservoirs system. The results of the developed model were compared with Genetic Algorithm (GA). The objective function was defined as the “minimization of the total deficit for the study period”. In order to performance evaluation of the investigated Algorithms, two criteria of reliability (temporal and volume) and vulnerability have been used. The WSA and GA were capable to supply 95.37 and 87.07 percent of Golestan dam water demand, respectively. For the Voshmgir dam, the mentioned models could supply 93.8 and 87.59 percent of water demand, in same order. The temporal reliability (α=0.9) for WSA and GA models, was obtained 81.67 and 26.67 percent for Golestan dam and 83.33 and 38.33 percent for Voshmgir dam, respectively, revealed that the WSA was superior in optimal allocation of Multi-reservoirs system.

Groundwater drought occurs when groundwater as a source of water supply, are affected by prolonged Meteorological drought. In groundwater drought process, at first groundwater recharge, later groundwater levels and finally groundwater discharge are decreased by other Droughts effects. In this Condition, An integrated water resource management based on awareness of spatial and temporal distribution of this type of drought will be essential. in this research, standardized water level index (SWI) and Groundwater Resource Index (GRI) have been used to assess detail of spatial and temporal of groundwater drought occurrence in Marvdasht Kharameh study areas aquifer. Thus, Groundwater level data of 67 Piezometric wells has been used for 2001 to 2011. Drought Index maps generated in Geographic Information Systems (GIS) environment with Inverse Distance Weight (IDW) method. Analysis and interpretation maps and result of calculations of two indexes reveal that the Groundwater Drought began from 2007. And three characteristics of drought include: Duration, Severity and Frerequency are increasing with increasing time scales. The spatial coverage of this type of drought gradually shifts from northern of case study to middle and finally shifts to southern part during the time study.

Because the lack of precipitation in arid and semi-arid regions and therefore limitation of surface water resources in theirs, water usage in agriculture, industry and drinking heavily dependent on groundwater. For this reason, the study and evaluation of the quality of these resources is more important. The present study was done in order to classify groundwater quality of Ghir plain using statistical techniques, including factor analysis (FA) and Hierarchical clustering techniques (HCA) (Based on K-means/K-medians cluster analysis (KCA) method), on qualitative data (14 parameters) in a 10-years period (1391-1381) and SYSTAT13, SPSS 18 and PcOrd softwares. Factor analysis results showed that the variables of SAR, Cl, Na, PH, SO4 and HCO3 with the highest factor loading respectively are the most important parameters to performing clustering analysis. In order to determine the optimum number of clusters used from Davis- Boldin index and according to this index, five clusters were determined for classification of wells. The Results revealed that the KCA and HCA methods have jointed 100% in order to classification. According to the classification results, amount of the parameters of groundwater samples increasing from first to fifth groups. However the wells are placed in Group 1, have the best water quality.

The accuracy of the classical methods to calculate evapotranspiration of plants for use in large areas may not be sufficient and therefore less useful. Thus, the choice of high-precision approaches, despite of restrictions ahead seems necessary. The purpose of this study is calculation of sugarcane evapotranspiration in Ahvaz, Khuzestan province using two methods. In method one, soil evaporation and crop transpiration were separately calculated using NDVI index extracted from MODIS images in. In the second approach, evapotranspiration was estimated using single crop coefficient approach known as FAO 56 method using available coefficients. Besides, crop coefficient values were calculated using SimDualKc software during entire growing season and FAO Penman-Monteith equation was worked out accordingly.The results were also compared to a lysimetric dataset. Correlation coefficient of ET estimations using single and dual crop coefficient approaches with lysimetric measurements were 0.954 and 0.885, respectively. A. On the other hand, the standard error for single coefficient approach was 67.29 and 29.34 dual approach. The results showed that the remote sensing-based dual coefficient approach provides acceptable estimations of sugar cane in the region. More studies are recommended for further scrutiny.

Morphology of rivers constantly changes due to their dynamic features, and these changes can negatively affect the structures in riversides, agricultural lands, etc. Meanders are considered as important indicators of environmental change. This study examines the changes of the sealing degree and meander shapes of the Kashafroud river using 1966 aerial photography, 1987 Landsat TM sensing images, and 2013 Google Earth images. In this study, morphological parameters of 16 meanders in a range of 11 kilometers along the Kashafroud river was determined for each period. The results of the paired t mean comparison showed that changes in the sealing degree ranging from 1966 to 2013 have a significant difference at level of one percent. To determine the effects of changes in some meanders parameters on sealing degree, multivariate linear regression model was used. The results showed that in case of change in the sealing degree, meanders reduce along the river. In addition, Spearman correlation analysis showed that changes in the parameters of sealing level and meander shape are strongly interdependent, so that there is a significant correlation between changes in sealing degree and meander shape at level of one percent. With increasing degree of sealing, meander shapes convert into U and Ω shapes, and meanders tend to close. In meanders with reduced sealing degree, such as meanders number 2, 3, 11, and 12, the path will mainly change into a strait one, and a part of the river will be separated as bovine horn ponds.

Currently, agriculture is a crucial support for the national food security as well as economic sustainability. Among all factors, water is the most important and limited production factor. The simulation models of yield response to the water and irrigation water salinity are expected to play an increasingly important role in the optimization of water productivity (WP) in agriculture. AquaCrop model is a powerful and valuable tool for improvement of water management in the field and calculating water productivity. In this study, canopy cover, yield, biomass and evapotranspiration of cotton were simulated by using AquaCrop model under different levels of water salinity and deficit irrigation condition. The treatments included three levels of irrigation water salinity and three levels of irrigation depth. The experiment design was laid out with split-split plot in a factorial design with three replications. Results showed that the model can simulate different parameters with high accuracy (d>0.95). By reducing the amount of irrigation water and increasing of irrigation water salinity, simulation error was increased, but simulation results were in the acceptable range. For low levels of water and salinity stress, there was no very difference in the simulation results. AquaCrop model can be valuable tool in water and salinity management.