مجله پژوهش آب ایران
پیاپی 19 (زمستان 1394)

Classification in terms of climate and hydrological variables is one of the basic requirements in water resource planning. The same climate characteristics in the different geographical areas causes that climate scientists, separate the areas with the same climate and put the zones in one group that have similar features. Cluster analysis is one of the multivariable statistical methods that is used to reduce the data and finding homogeneous regions. Principle component analysis (PCA) is one of the multivariable statistical methods that is done by analyzing the eigenvalues of correlation or covariance matrix. The purpose of these methods regionalization or zoning and extending point information to an area which resulted in providing the information for the zones or stations without information or with insufficient information. Evaporation as output of water resources and contrary to that, precipitation, is considered as input of water resources. Then the ratio of these two variables in the given time scale (e.g., monthly) can express the climatic condition of the area in terms of dryness so whatever the rainfall is greater than evaporation, can represent the wetness of the area and success of dry farming. In addition to the total annual rainfall in dry farming, the distribution of rainfall during the period of growth is the important parameter. Existence of enough moisture in the process of budding is necessary for growth and plant establishment. Also in the spring, which coincides with the flowering and grain growth, due to the warming weather and increasing evapotranspiration, plant water requirement increased. Rainfall in these periods could have significant influence in the crop growth and production.
In this study, in order to investigate the capability of northwest of Iran for dry farming this area was delineated based on the ratio of precipitation to evapotranspiration. For this purpose, the climatic parameters of 22 synoptic and climatology stations of were used during the period from 2000 to 2006. The average evapotranspiration for each station was determined by FAO-Penman-Monteith method and by using the monthly precipitation data, the ratio of precipitation to evapotranspiration was calculated. The missing data were reconstructed by the program written in the FORTRAN programming. The principal component analysis was done by MINITAB software and correlation matrix. Then, by using the scree plot, the first up to fourth factors with high eigenvalues were selected for zoning. In the next step, the same coefficient curves for every selected component, drawn on the map of the study area and the homogeneous regions were specified based on the ratio of precipitation to evapotranspiration. Finally the delineated areas were simultaneously drawn on a map.
Then, by principle component analysis method and six selected principal components after rotation that contain 74.1 percent of data's variance, six homogenous regions based on the ratio of precipitation to evapotranspiration were introduced among which the second region with the mean ratio of precipitation to evapotranspiration equal to 0.5, has the highest priority of the dry farming. By using the WARD method and drawing dendrogam, two homogenous regions were achieved that in autumn, the second region with the value equal to 0.49 of precipitation to evapotranspiration and in spring, the first region with the value equal to 0.59 for mentioned parameter were in the priority of dry farming. By using the S-statistic method, cluster's homogeneity test was performed which was significant at the level of 5%. The F-test between the standard deviation of zones in the WARD method, showed a significant difference between them so that the ratio of the standard deviation (2.68) was obtained greater than the critical value (2.57). Therefore, with respect to the quality of the zone's separation and clustering data expansion, the WARD method was selected. The south of East Azarbaijan Province, has the lowest amount of precipitation to evapotranspiration, in case of appearing water shortage in this area, agriculture and horticulture will be in serious threats so that requires prior planning and appropriate actions. Finally, it can be said that the mentioned method can be used as a guide for proper management and optimal water resources operation on a large scale, such as in the basin or province. Moreover, by using this method, critical areas of water resources can be detected easier and the appropriate coping plans can be prepared to avoid serious damages to farmers of those areas.

Infiltration characteristics of the soil constitute one of the basic and most important parameters for proper design and management of field irrigation systems. The design, operation, management and hydraulic evaluation of on-farm irrigation methods depend on the water infiltration properties of the soil. Empirical equations and physically based equations used to describe vertical infiltration into simple soil systems are compared with experimental data. The direct measurement of soil hydraulic characteristics is troublesome, time-consuming and expensive. Alternative approaches called pedotransfer functions (PTFs) for the predictions of the soil hydraulic parameters have been continuously developed by many researchers in the world. The accuracy and efficiency of the existing methods for estimating soil infiltration rate requires understanding of the performance of each model and its limitations.
The objectives of this study were to evaluate the performance and efficiency of physical equations such as Green Ampt and Philip; three empirical equations including Horton, Holtan and Kostiakov and also pedotransfer functions for estimating the final constant infiltration rate in the soils near the bank of Ghezel Auzan river of Zanjan province. Infiltration rates were measured by the method of double rings on 30 points and with 3 replications. The percentage of soil component was determined by hydrometric method. The initial and saturation moisture content were obtained with gravimetric method and the suction of 33 kPa (FC) was determined by the pressure plate. Saturated hydraulic conductivity (Ks) obtained using the constant head method and EC (ECe) was read by the EC meter. All data were categorized in the database that created in SPSS software and the normalization and homogenization of the data was done with the Shapiro Wilk tests. Prediction performances of these methods were evaluated using RMSE, MAE, ME, RE and EF criteria between the predicted and the measured values. For creating the pedotransfer function models, two multiple linear regression and Ridge regression using easily accessible physical and chemical soil characteristics were used in three input data structure groups.
Results of evaluation of these equations indicated that the Holtan equation had a better performance than Horton and Kostiakov equation. The Green Ampt equation estimated the best final infiltration rate with less error (RMSE =1.89 cm.h-1 and MAE =1.37 cm.h-1) and the higher coefficient of determination (R2 =0.95) compared with other experimental, physical and pedotransfer function models. In comparing the results of the physical and empirical equations, the physical equations had higher accuracy than the empirical equations. Other researchers in their studies showed that the physical equations are better than empirical equations. The results showed that the error was reduced in Ridge regression with exclusion collinearity error in easily accessible parameters than Ordinary regression. The t-test results showed that there was no significant difference between empirical equations, physical and pedotransfer functions at P=0.05. The major differences in these models were in access to needed information and the accuracy of the estimated values. ME index showed that some of the models underestimated and some are overestimated. The estimated infiltration rate of Philippe, Grynampt, Horton and Holtan equations were evaluated with measured data and the finding showed the Grynampt and Holtan equations had the best results of estimation and the equation of Horton's had the lower accuracy. Holtan equation uses the properties of soil and vegetation and land use information so it can better estimate the infiltration rate.
The difference between the values of infiltration rate with t-student test showed that the models with empirical, physical and third group PTFs equations had no significant difference at the 5% significance level. The results indicated that all of the models mentioned in this study were able to estimate the final infiltration rate in the study area with acceptable accuracy, but the main difference between these models was the access to the required information. The results showed that Green Ampt physical equation had higher accuracy in estimating the final infiltration rate; however, other empirical and physical equations and transfer functions are well able to estimate the rate of infiltration. Estimate the final infiltration rate with the use of physical and chemical parameters of soils showed ridge regression is better than the simple regression. In the areas that high estimate of infiltration caused the runoff, especially in the design of sprinkling systems the use of models with underestimated the infiltration rate is preferred. The underestimation of these models can be considered as a safety factor in the design of hydraulic systems.

Water shortage in Iran is one of the main limiting factors for development of economic activities in the coming decades. The multitude of stakeholders and differences in opinions on how best to exploit the available resources commonly lead to conflicts and disputes over the management of watersheds and river basins. A main concern in water resources management is the equitable allocation of water. Conflicts on water rights are not solely limited to economic benefits or costs, but they involve social and political issues as well. In addition to this issue, conflicts arise between stakeholders who use water for a variety of consumptions, such as potation, industry, agriculture and environment. Karoon watershed can be an example of unbalanced demand and supply that the water shortage and losses and environmental problems are the main concerns of the watershed. Hence, to achieve a relative balance in the supply of water is essential and necessary.
The water allocation for Karoon watershed with an area of 67257 km2 located in the western part of Iran is considered based on the conflict resolution approach. There are 6 provinces claim on water resources of the watershed that are Lorestan, Chaharmahal and Bakhtiari, Kohgiluye andBouyer-Ahmad, Isfahan, Markazi and Khouzestan as the stakeholders of the watershed. In order to simulate and manage the water resources of watershed, MODSIM model has been implemented. The foundation of modelling is set on configuration of watersheds which are shaped by links (streamflows and rivers) and nodes (reservoirs, consumption). The MODSIM model is developed to simulate the watershed under seven different scenarios. There are several factors which are considered for definition of different scenarios such as improving the cropping pattern, utilization of drainage and water transition networks, climate changes, environmental issues and improving industry and agriculture. Different methods based on conflict resolution approach, including the social choice and Fallback Bargaining are utilized to select the best scenario. Decision making in the social choice method depends on stakeholders’ votes or opinions. Social resolution is concluded by a voting process and the best alternative will be presented by the majority of the stakeholders’ votes. Three methods such as Condorcet, Borda scoring and median vote rule are subset of social choice approach are selected for the following study. Fallback Bargaining follows the reversible or iterative process for negotiations and bargaining to find the optimum alternative. The process is continued until the minimum utility or satisfaction is expressed by the stakeholders. Also the stability index was used to evaluate and select the best scenario with minimum inequality among stakeholders. In this evaluation method, unlike in the other methods described, alternatives (scenarios) are compared in terms of their degree of stakeholders’ satisfaction or the associated inequities.
In order to evaluate scenarios, they have been compared by implementing above criteria. The Scenario 4 with a score of 7 by the Condorcet method in which the couple competition that occurs between alternatives is in priority rather than others. Scenarios 2 and 5 were in second and third ranks, respectively. By using the Borda Scoring method, stakeholders grade the scenarios based on their benefits and the scenario 4 earn maximum score equal to 44 that was rated as the best case scenario. The other criteria of social choice are the median voting rule. If the answer of median voting rule is obtaining minimum 4 votes, scenario 4, 2 and 5 are in priority, respectively. Also based on the Fallback Bargaining method which follows the iterative procedure to set stakeholders’ minimum satisfaction scenario 4 was selected as the best option. Stability index has a different view than other approaches. This method searches stable alternative instead of stakeholders’ opinions, even though scenario 4 with the stability index of 1.18 is the best answer. This scenario with the lowest value indicates the minimum level of dissatisfaction among stakeholders compared to other scenarios. The selected scenario is including the execution of under study projects along with demand management and aquifer restoration count as proper management options. By evaluating the deficit of groundwater reservoirs, the maximum value belongs to scenario 0 and 1 with a value of 35 million cubic meters while this value is decreased to zero by using scenario 4. Water allocation under a policy of scenario 4 will be stable for Karoon watershed as a case study and majority of stakeholders will vote on selected scenario who benefit from water as industrial, agricultural and domestic consumers.

Mercury is one of the most important heavy metals which, owing to its peculiar physical properties, is used in a wide variety of applications. Due to its toxicity, mercury released to the environment brings detrimental effects; therefore, the removal of which before releasing into the environment has drawn much attention. In the face of mercury’s characteristic, a variety of methods have been used to remove mercury ions from aqueous solutions, including precipitation, ion exchange, adsorption and reverse osmosis. Of these methods, adsorption has been extensively investigated by researchers. In this study, polyaniline/ poly vinyl alcohol composite was used to remove mercury from aqueous solutions. The chemicals used in this study, due to the high purity, were used without further purification, except for aniline monomer which was distilled and stored in the fridge before use. Aniline monomer, sulfuric acid, potassium iodate and poly vinyl alcohol were purchased from Merck. A digital scale model FR200, magnetic mixer model MK20, Arian's Spectra AA series atomic absorption spectrometry and LEO 440i scanning electron microscope were employed. To prepare the polyaniline/ poly vinyl alcohol composite, 1.6 g potassium iodate was initially dissolved in 200 cc of 1 M sulfuric acid using the magnetic mixture, to obtain a uniform homogeneous mixture. Then 0.2 g polyvinyl alcohol was added to the solution under constant stirring for about 15 to 20 minutes, to which 2cc of pure aniline monomer was added and stirred for about 5 h at room temperature. After only a few minutes the solution turned green and darker, which suggested progress in polymerization reaction and the formation of polyaniline/ poly vinyl alcohol composite. After 5 h, the polymer was recovered using centrifugation. To remove oligomers as well as other possible impurities, the resulting polymer was washed several times with distilled water and acetone and then dried in oven at 50°c for 48 hours. The product was finally pulverized in a porcelain mortar prior to use. This experiment was repeated with the addition of 0.4 to 2 g poly vinyl alcohol to the solution, to examine the effects of poly vinyl alcohol dosage present in the composite. Mercury adsorption by the synthesized composites was carried out in batch mode at room temperature. In each experiment, 0.5 g of the synthesized polymer was added to the 50 mg solution containing 35 ppm mercury at a pH of 6. The mixture was stirred using a shaker at 120 rpm for 30 minutes. After reaching equilibrium, polymer was filtered from the solution using filter paper. Then, by determining initial and final mercury concentrations, mercury removal ratio was calculated.
The results of this study indicate that polyaniline and its composites with poly vinyl alcohol have a good performance in the removal of mercury from aqueous solutions and the percentage of mercury removal by polyaniline and its composites is higher than that of activated carbon. The reported ideal chemical structure of polyaniline consists of 1000 or more repetitive units (-ph-n-) containing alternating reduced (benzenoid amine) and oxidized (quinoide imine) states. Mercury adsorption by, Polyaniline/ poly vinyl alcohol occurs due to the presence of nitrogen-containing sites (-NH) in this polymer. Owing to the presence of electron in its s2p3 orbit, this nitrogen could form weak bonds with Hg2 ions, thereby absorbing them. Yet another plausible mechanism concerns the formation of surface complexes between Polyaniline/ poly vinyl alcohol and mercury. Poly vinyl alcohol as an additive surfactant, was able to have a positive effect on the efficiency of synthesized polyaniline and to increase mercury removal capacity of composite. As a surfactant, poly vinyl alcohol is absorbed by the growing polymer particle through hydrogen bonding during the polymerization process, exerting an effect on shape, morphology, uniformity, lateral surface, size and properties of polymer.
Dosage of poly vinyl alcohol used in the synthesis of composite is highly significant, so the dosage needs to be optimized as underuse results in insignificant effect on polyaniline and overuse leads to gelatinized Polyaniline. To estimate the effect of poly vinyl alcohol concentration, varying doses of the compound, as the additive substance, at 1-10 g/l concentrations were investigated in the synthesis of Polyaniline. Optimal mercury removal was observed at 2 g/l concentration of poly vinyl alcohol with 96% removal. Several studies suggest that the single most important parameter in removal of heavy metals by adsorbents is the initial pH value of the solution. This parameter has an impact on metal ion species in the solution as well as on adsorption sites. To evaluate the impact of solution pH on mercury removal, the experiments were conducted in a range of pH from 2 to 6. As the results indicate, the pH approaches more to the neutral point, the higher mercury removal efficiency is achieved. Due to mercury sedimentation, the use of alkaline solutions was avoided. Optimal removal was observed around pH 6 at which polyaniline/poly vinyl alcohol demonstrates the greatest potential for removal. At the neutral pH value, polyaniline/poly vinyl alcohol turns into an oxidizing agent (taking electrons onto itself), then free –N groups in the polymer will be available to form a ligand (binding of large molecules to a central metal atom), thereby increasing the sorption of Hg2 ion. At acidic pH values, –N groups absorb proton, turning into –NH whose positive charge repel Hg2 ions across polyaniline/poly vinyl alcohol. This results in an inhibitory effect on metal uptake. To evaluate the impact of exposure time, adsorption experiments were carried out at pH 6 and initial concentration of 35 mg/l mercury for different periods of time. The results showed that mercury uptake ratio increased as exposure time increased. Optimal exposure time is 30 minutes, after which no significant change in mercury removal is observed.

Sediment related problems are of huge importance in most projects of dam construction and for reservoir management. Worldwide average annual reservoir storage loss due to sedimentation is about 1.0 percent. In order to reduce and remove reservoir sedimentation for sustainable use, different sediment control measures have been developed and used. Some of the more popular methods are watershed management, sluicing, dredging, density current venting, bypassing, and flushing. One of the most effective techniques for removing the deposited sediments from reservoirs is pressure flushing which has less local effects. In flushing methods, the previously deposited sediment would be flushed from the reservoir by opening of the bottom outlets. When the flushing takes place under a sustained water level, only a very limited area of the reservoir is flushed and a scour cone is performed behind the outlet. As the flow around the outlet in the pressure flushing is three dimensional.
The flushing process can be studied in a physical model. This method is, however, relatively costly and time-consuming. Researches for evaluation of geometric characteristics of scouring cone against various shapes of the bottom outlet are necessary, in order to proper design of the bottom outlet. In this study, some experiments performed for investigation effective factors in pressure flushing performance. Experiments were carried out with three outflow discharges (1, 2 and 3 l/s), two water depths above the center of bottom outlet (47 and 64.5 cm), and three bottom outlet shapes (circular, square and rectangular).The experiments were conducted in the hydraulic laboratory of Tarbiat Modares University in Iran. Experiments tests carried out with a flume whose overall dimensions consist of 7.1 m length, 2 m width and 1.5 m height. The front wall of the model will be easy to change to modify different cross sections of reservoir bottom outlets. The sediment height deposits in the main reservoir was 20 cm, with a median diameter of d50=1.15 mm. For the downstream section it was used another stilling basin, which the mixing flow of water and sediment was collected in it. The downstream settling basin was a rectangular flume of 1.4 meter long, 1 meter wide, and 0.8 meter height. At the end of settling reservoir, there was a V-notch weir with an angle of 600 to measure of outflow discharge. For running the experiments, the deposited sediment was flattened and leveled firstly to a specific level above the center of bottom outlet (20 cm), and the model was slowly filled with water until the water surface elevation reached to a desired level. Then, the bottom outlet was manually opened until the outflow discharge becomes equal to the inflow discharge. The equilibrium of scour cone volume and length depends on the reservoir water depth , depth of deposited sediment above the center of outlet , fluid density , sediment density , outlet area , water velocity at bottom outlet , mean deposited sediment diameter , diameter of circle outlet and width of rectangular and square outlets , dam width and gravity acceleration . Therefore, in pressure flushing, scour cone volume may be written as a function of the following variables: .
The pressure flushing method has local effects in sediment disposal and is recommended when local disposal of the sediment deposits is intended. The results of these experiments show that the scouring cone volume depend on outflow discharge, water depth of the reservoir and bottom outlet shape. As for a constant outflow discharge, the decreasing of the water depth leads to increace the scouring cone volume. Also the increasing of the outflow discharge has a positive effect on the flushing cone volume. Scouring cone volume increases 41.3, 41.2 and 19.9 percent with the outflow discharge rise of 150 percent in circular, square and rectangular valves, respectively. Moreover, generally for a constant water depth and outflow discharge, scouring cone volume was greater in square, circular and rectangular outlet shapes, respectively. Finally, based on the statistical analysis on the experimental data, non-dimensional equation is offered for forecasting of the scouring cone dimension. For evaluating the accuracy of the proposed equation, three statistical criteria, including root mean square error (RMSE), mean absolute error (MAE) and R-squared value were used. The comparison between measured and computed scour volume using proposed equations show satisfied agreement. Hopefully, we can share our knowledge to design projects that can sustain the useful lives of existing and future reservoirs.

Understanding the processes of mixing and transporting materials in rivers has been accounted as a main activity in the water resources management. Among the mixing processes, the transverse diffusion is considered as the second important process, after the longitudinal diffusion, affecting the longitudinal and transverse distribution of pollutants in river flows. Determination of the rate of material diffusion and their density are usually carried out based on solving mass conservation equations. The available analytical solutions were only provided for uniform flows in straight channels, so there are needs for numerical methods to solve the governing equations for non-uniform flow in complicated forms of channel geometries. The results from studies on rectangular straight channels show that the transverse diffusion coefficient (TDC) increases with increasing friction factor, while no specific relation between TDC and the ratio of width to depth is provided. Meanwhile, based on laboratory studies, an empirical relationship for estimation of transverse mixing coefficient is introduced for straight channels in uniform flow. An equation is also introduced to show the relationship among the longitudinal dispersion coefficient of pollutants, flow depth, river width, flow velocity, and shear velocity of river flows. Since increasing the amount of roughness of the channel boundaries, provides additional flow turbulence, which in turn results in reducing the perfect mixing length of the pollutant, some laboratory researches have been carried out using the spatial artificial roughness in flumes with single or combined cross sections to investigate the effects of roughness on the coefficient of transverse mixing of pollutants. However, all related tests were mainly carried out within laboratory channels with small widths where the tracer injection was made in the middle of the channels. In this research, we carried out tests in a wider channel, including artificial roughness on the bed to reduce the effects of channel walls where the tracer injection was made from the channel center. In this study, the laboratory tests were carried out in a channel with a length of 7.3, and width of 0.6 meters. The channel had been installed on a metal platform with adjustable slope, but the tests were carried out using a fixed slope. A set of square wooden blocks in three rows and two layouts with upstream ramp were used to make artificial channel bed roughness for increasing the transverse mixing of the pollutants. Salt solution at a concentration of approximately 27 grams per liter was used as the pollutant and an electrical conductivity instrument was used to measure the density of samples taken from two sections (i.e. 135 and 365 cm) downstream of the injection point as well as the density of the tracer concentration inside the tank. For each layout, three discharges of 20, 30, and 35 liter per second have been considered. Due to time and financial constraints, and consequently, limitation on evaluating the various conditions of the flow, number of rows, and different points in laboratory-scale, the FLUENT software was used to improve the results of the present research. The results of the laboratory tests showed that the local roughness has a considerable effect on the reduction of full mixing length. Also, the results of the dimensional analysis showed that the transverse diffusion coefficient is directly related to the ratio of width to depth as well as friction coefficient. As a whole, the results of this research show that the friction factor and the flow depth have a significant effect on the amount of TDC of the pollutant, so that by increasing the amount of friction coefficient, the TDC was increased, the perfect mixing length was reduced and dilution was done in a shorter distance. Moreover, increasing the flow velocity led to increase in the pollutant transport by flow, reduce the amount of TDC of the pollutant, and consequently, increase the perfect mixing length. Based on the results from laboratory experiments and dimensional analysis, a new relationship was introduced to estimate TDC with a mean relative error of 0.059. As mentioned previously, to extend the applications of the results to various situations, using data obtained from laboratory experiments, the abilities of FLUENT software for simulating the different conditions were investigated. It is found that the FLUENT software is able to simulate and predict the mixing processes in rivers with a reasonable accuracy.

Flood currents are considered as a threatening factor which creating local scour along bridge piers. In studying the reasons for the destruction of many bridges, scour resulting from flood currents has been identified as the major reason for the failure. Scour is a natural phenomenon which occurs as a result of erosion in bed and drift riversides by water current. This phenomenon is created locally as a result of mutual effect of water way geometry, bed and current specifications around the pier. As a matter of fact, when a current strikes bridge pier, holes are made around the pier and complex vortex systems are created whose performance causes a hole around piers called a scour hole. The development of this hole around the pier causes under the foundations to get empty leading to their destruction and finally the destruction of the bridge. In order to prevent and decrease scour at the bridge pier, two basic methods have been presented. One of them is the direct method in which the resistance of the bed against tension increases; and the other is the indirect method in which the effect of the destructive forces is reduced by changing the current pattern around the pier. Prediction of depth and the final status of scour hole are the most important cases of hydraulic design of bridges. Geotextiles, which are produced from polypropylene and polyester fibers, form a large group of geosynthetic products. These materials can be used to strengthen river beds adjacent to bridge piers and to control the scour around them concurrently playing the role of riprap and collar. Geotextile spread around bridge piers to prevent the scouring around it. In terms of economics, determine the extent and pattern of suitable geotextile cover is essential.
In this study, coverage area with geotextile around the single pier and a group of two and three piers in the case of clear-water flow over uniform sediment were investigated. The experiments were carried out in a 20m long, 0.60m wide, and 0.60m deep, Plexiglass-sided flume. The piers of Teflon were selected with 5cm diameter and fixed parallel the streamline. The space between the piers was 3 times bigger than pier diameter. The granulated silt of bed materials was chosen so that no ripples are formed in the test area bed. The formation of ripples causes separate small protrusions in the bed; it also causes an increase in current speed compared to the critical speed in the movement threshold of sediments causing some of the upstream sediments of the pier to be washed and carried thus filling the scour hole and causing the scour depth to decrease compared to its real maximum amount. Ripples and non-sticking sediments with mean sized from 0.05 to 0.7 mm develop; hence, the mean diameter of sediments should be over 0.7mm.
The results showed that in group piers the sheltering effect of the first pier decreases 50% of coverage pattern and the reinforcing effect of the last pier increase the coverage pattern about 40%. Sheltering effect in a group of two and three piers let to decreasing scour hole about 50% and 71%, respectively, than the single pier. At the rear pier of a group of three piers, the dimensions of the scour hole were 21% less than a group of two piers because the first and second piers protect the rear pier. With experiment on coverage patterns, it was found that the oval layer in single pier and the semi oval layer in group piers is the best pattern for scour reduction. In this state, after 19 hours, the first signs of scour in downstream are observed whose longitudinal and widthwise progression were about 3cm to the end of the test and its depth, too, reached 0.5cm. Base on the obtained results, with regard to the negligible amount of scour, the semi-oval pattern with more coverage in behind the pier is suggested as the best pattern in geotextile installation. By using geotextile with an appropriate cover, apart from a delay in scouring process, the scour location is transferred to downstream and the scour depth is decreased. In other words, the geotextile layer has a dual performance in decreasing scour. As far as economy and method of application are concerned, the larger layer; and as far as the scour is concerned, the smaller layer would be problematic.

Nowadays, removing pollutants from water and wastewater is of utmost importance. The pollution of water resources due to indiscriminate disposal of heavy metals has been causing a worldwide concern for the last few decades. Chromium is one of the heavy metals which is found in weaving, currier and fertilizer factories. Many methods of treatment for industrial wastewaters have been reported in the literature. Amongst these methods, the most popular are neutralization, precipitation, ion exchange and adsorption. For low concentrations of metal ions in wastewaters, the adsorption process is recommended. The process of adsorption implies the presence of an “adsorbent” solid that binds molecules by physical attractive forces, ion exchange and chemical binding. It is advisable that the adsorbent is available in large quantities, easily regenerable and cheap. Usage of natural adsorbents as replacements for imported chemical adsorbents is important for developing countries. theapplication of several adsorbents such as Wheat bran, Sawdust, Tea, Modified Sand and Activated Carbon prepared were reported in the literature. Tamarisk is the only tree which can grow in Sistan plain and its sawdust is abundantly found in factories. The purpose of this research is to use of local adsorbent modified Tamarix sawdust for removal of hexavalent chromium from aqueous solution. In practice obtained adsorption from discontinuous studies capacity may not represent accurate information in pilot scale in a column system. Therefore, continuous studies in column system are required to estimate breakthrough curve of the column, determination of breakthrough point and evacuation point of the column. Several mathematical models are represented to design adsorbent columns such as BDST, which is extensively has been used in literature. Batch sorption was studied to determine optimal pH, equilibrium time and isotherm model parameters. In adsorption isotherm experiments 1-20 gr/l of adsorbents and 8 mg/l of Cr(VI) solution were reached to 100 ml. Isotherm models such as Freundlich and Langmuir were used to fit to experimental data in non-linear form of the equations. Also for removal of chromium in continuous condition a 30 cm bed depth glass column with diameter of 3 cm was used as a fixed bed with gravity water flow. Operation of the column was investigated under flow of 5, 6.5 and 8 ml/min, bed depth of 10, 12 and 14 cm and Cr(VI) concentration of 6, 8 and 10 mg/L. Finally, the absorber column behavior using BDST, was studied and model parameters were determined.
Adsorption efficiency of Cr(VI) decreases with increase in pH. Minimum adsorption efficiency occurs at pH=5, therefore all the experiments were done at optimal pH (pH=1). The predominant form of Cr(VI) is HCrO4- at pH values lower than 1, while the adsorbent surface is ready to adsorb. However, at higher pH values predominant form of Cr(VI) is as H¬2CrO4 and CrO3 forms, which have no tension to react. As a result OH- will be adsorbed more, therefore the most adsorption of Cr(VI) occurs at pH=1. With increase in contact time, Cr(VI) adsorption increases for a fixed mass of adsorbent, as in 0-30 min adsorption rate is very high.
The results of this research showed that maximum adsorption efficiency by modified sawdust occurred in equilibrium time of 120 min. The Langmuir and Freundlich models were used to explain the equilibrium data. The Freundlich model showed better fit to the data with a correlation coefficient of 0.9637. Also column studies show that the time to reach the breakthrough point increases with increase in bed depth. With increase in bed depth, gradient of breakthrough curve decreases. As a result, mass transfer zone expands and it takes more times to effluent. Also with increase in flow rate and initial concentration, gradient of breakthrough curves is more and leads to reduce the breakthrough time. On the other hand, the adsorption capacity increases with increase in bed depth and decrease in flow rate and initial concentration. The breakthrough time of the column decreases with increasing the flow rate and initial concentration, but it increases with increase in bed depth. The results showed that surface adsorption of Cr(VI) is highly dependent on flow rate, initial concentration and bed depth. Evaluation of column parameters showed that BDST model has a good concordance with experimental data.parameters showed that BDST model has a good concordance with experimental data.

To pass the extra water and flood from upstream to downstream in dams, a hydraulic structure called spillway uses, which is one of the important appurtenant structures in each dam. Selecting the type of spillway is a function of topographical conditions, the amount of design flood and type of dam. Spillways are made in different forms that the most common of them are overfall and overflow (overpass) spillways. Free or uncontrolled overfall spillways are the most reliable choice. These spillways usually impose higher construction cost and causes in wasting a considerable amount of water or live capacity of the reservoir. Employing Fusegates might be a way of reconciling dam safety with maximized storage capacity. Fusegates were invented in 1989 by François Lempérière as a simple, robust, and a safe system to increase live storage or spillway capacity. The system has been patented by Hydroplus International in the United States, Europe, and most other countries. It is implemented in more than 40 dams in 14 different countries across 5 continents. This spillway consists of three main components; 1) A bucket made of metal or reinforced concrete, 2) A base, and 3) An intake well which is connected to the chamber in the base. Fusagates consists of three types of Narrow Low Head (NLH), Wide Low Head (WLH), and Wide High Head (WHH).
Tests were done in a horizontal flume with a rectangular cross section in the hydraulic laboratory of Water Engineering Department at Sari Agricultural Sciences and Natural Resources University. This laboratory flume has a length of 5 m, width of 75 mm and height of 175 mm (the walls are made of transparent Plexiglas to see the flow from two sides). In this study, the effect of 6 wells with different heights over WLH model of Fusegate has been studied and two weights with different mass were used for the equilibrium of the structure. The investigated spillway is made of Plexiglas and has a height of 50 mm. To balance the model, two iron weights with a mass of 43.7 and 55.8 gr were applied, which are placed on the chamber’s floor. The position of this model is at the 1 meter upstream the outlet of the channel, for reducing the inflow turbulence and water surface fluctuations at the upstream of the structure. The range of the flow discharge was about 0.2 to 1.8 lit/s. In every test, the water depth was measured at 30 cm upstream of the structure. A total of 228 tests was done, that 20 percent of them were selected randomly for verification the equations. In this study, the RMSE was used as evaluation criteria.
In order to find a relationship between effective factors on discharge coefficient in Fusegate spillway, dimensional analysis was done on the effective parameters. The discharge coefficient can be dependent on geometry, kinematic and dynamic variables (h, ρ, v, σ, μ, w, H). Four obtained dimensionless parameters are including discharge coefficient, Weber, Reynolds and h/H. According to dimensional analysis, Reynolds number was removed, because the flow was turbulent. Since, the spillway was a physical model with a small-scale, surface tension was not negligible and the Weber number was affective. Finally, a power relationship between the discharge coefficient and two dimensionless parameters (Weber and the upstream water level to the bucket’s height (h/H)) of Fusegate spillway was created. The coefficient of determination (R2) was used for calibration and root mean square error (RMSE) was used for verification. When RMSE values are near zero, indicates that the computational and observational discharge coefficients are closer together and the equation has a higher accuracy. When R2 values are near to 1, shows that the most suitable values for constant parameters were selected. The maximum value of R2 is related to the second well with a weight of 55.8 gr, and the lowest value was belong to the forth well of this weight. The discharge coefficient range was approximately between 0.33-0.58. In a constant h/H, the highest discharge coefficient and discharge was related to the second well. In the other word, the lowest upstream water level was related to the well with a height of 57 mm, which shows that during the flood, this well can prevent flooding of upstream adjacent land. By increasing the Weber number, the discharge coefficient decreases. In fact, in high discharge coefficients that the upstream water level is low, the effect of surface tension is undeniable. At a constant discharge coefficient, the highest value of Weber number that shows the lowest surface tension, was related to second well. With increasing height of well from 52 to 62 mm for the first and second weights, with increasing the tilting discharge, the tilting head increases. But with increasing height of well from 62 to 77 mm, increasing discharge does not effect on the tilting head. Because, the motive forces overcome the resisting forces that makes Fusegate to be in an unstable state, before the water enter into the well.
The test results showed that in the WLH model of Fusegate spillway, the dimensionless parameters (h/H) and (We) are effective on the discharge coefficient. By increasing (h/H), the discharge coefficient decreases as parabolic. In fact, by enhancing the water level above the spillway, the discharge coefficient declines due to downstream submergence. Also, this result is valid for enhancing the Weber number. In a constant (h/H) and (We), the discharge coefficient of the second well is more than others, because of having less surface tension and lower head of water at the upstream. Finally, a power relationship between the discharge coefficient, h/H and We extracted in 15 cases, that the calculated statistical parameters indicate high accuracy of equations.

Understanding the reasons behind the occurrence of significant storms and their rainfall distribution is a fundamental issue to increase the accuracy of the Meteorological and Hydrological predictions. The rainfall pattern is helpful in managing flood in urban basins and designing control structures for flood transmission. The time distribution patterns of heavy rainfall events have not been investigated much in Iran. This paper investigates the temporal rainfall distribution based on an analytical numerical method in southwest of Iran. This study selected the storm that happened on 12-15 November 2006 with precipitation of over 50 mm. First, rainfall data were calculated using the result of WRF numerical weather prediction model. Then, a temporal distribution of a logistic function has been fitted on rainfall data and the logistic coefficients of the rainfall curve were computed for the mentioned great storm event.
Rainfall information in the entire basin is not available due to irregular distribution and limited number of measuring stations. Thus, to study in detail and quantify the amount of rainfall in the entire basin with a regular grid, the best method is a simulation of Numerical Weather Prediction (NWP) models. Therefore, rainfall was simulated with the Weather Research Forecasting (WRF) model in two regular nested domains with the horizontal resolution of 27 and 9 km, from 47.5E to 53E degrees longitude and from 30.5N to 34N degrees latitude. The input Final operational Global Analysis (FNL) data was provided by National Center Environmental Prediction (NCEP). After running the model, three-hour interval rainfall outputs at all grid points were collected for the storm. The time distribution of rainfall in each grid point was computed based on the rainfall outputs of WRF and a three-parameter logistic function. To select the best values of the coefficients a and b, we used minimum Sum of Square Error (SSE) in the logistic curve fitting for every grid point. Since the greatest change in the slope of the logistic function is in the 70% middle of the temporal distribution curve of rainfall, the best values of the coefficients a and b are determined without 15% beginning and 15% end of the logistic curve. Since the range of the coefficient b is very large, the transfer function (B) reduced its variance. Changing the coefficients a and B leads to appearing logistic curve in various forms, which are the main parameters of the rainfall distribution. If the coefficient a increase as well as the logistic curve slope, more precipitation occurs at a fixed time in the dimensionless temporal rainfall distribution curve. Moreover, the time delay of the onset of the precipitation increases by changing the coefficient B.
Finally, maps of the coefficients a and B were drawn by using the IDW method in SURFER software.
The results show that the value of the coefficient a of the logistic function varies from 0.2 to 0.4 for southeastern and central parts and to 0.7 for northern and southwestern parts. Thus, in the north and south-west of the studied area, rainfall intensity becomes greater than in southeastern and central parts. Furthermore, the increase in coefficient is seen in the latitude from the bottom to up and changes of coefficient are not related to the longitude from west to east. However, it is related to changes in the topography of the area. The values of the coefficient B of the logistic function vary from 4 in southeast and central parts to 14 in south and north parts of the region. Therefore, any increase in coefficient leads to increase the time delay of the onset of the precipitation. To reveal more differences in the temporal distribution of rainfall, the studied area was zoned out to nine regions (A1, A2, A3, B1, B2, B3, C1, C2, C3) and the temporal distribution of rainfall was plotted for each region. Results show the maximum of rainfall intensity occurs from 0.42 to 0.58 of the total rainfalls time period in types A1, A2, A3, B3 and C2. Maximum rainfall intensity of types B1, B2 and C3 falls from 0.25 to 0.42, 0.25 to 0.67 and 0.42 to 0.83 of the total rainfall time periods, conversely. Additionally, the most of the total rainfall falls before 1/3 of the total rainfall time period in type C1. Thus, the maximum rainfall intensity occurs in early start time of rainfall.

Groundwater level control is an important issue in construction projects. In order to find the flow rate and appropriate locations for pumping the simulation models are often used. The problem with the simulation models is the number of simulation runs to find the best possible scenario. Even though it is not guaranteed to have the optimum solution. However, combination of optimization and simulation models can be used to predict the groundwater behavior and to find the optimal operation scenario. Two main approaches in groundwater optimization-simulation modeling are solving linear and nonlinear relationships between groundwater level and extraction. Using nonlinear relationships leads to complex formulation and the computation cost is usually high. The objective of this research was to use a simulation-optimization approach to find the optimum groundwater model operation in conjunction with the construction projects. The proposed approach was tested for Tabriz Aquifer in northwest of Iran. Tabriz City is a growing city and it is the capital of the East Azarbaijan Province. As part of the city’s development plan, Tabriz subway is under construction and main parts of the tunnels is below the groundwater table. The subway plan consists of four lines within the City limits and Line 1 is approximately 18 km. Due to the shallow thickness of the aquifer, the tunnel in Line 1 obstructs the groundwater flow in many areas. Some of the stations are also constructed below the groundwater level. The path of the Line 1 is located in the area which the groundwater level is already high and close to the ground surface. The basements of many houses in this area suffer from the groundwater seepage and the municipality of Tabriz is pumping continuously groundwater to decline the groundwater level. In order to formulate the relationship between groundwater extraction and water level, MODFLOW was used to simulate the groundwater behavior in Tabriz Aquifer. MODFLOW is one of the most commonly used groundwater models in the world and has been tested in many areas. Tabriz Aquifer is a two-layer aquifer with shallow unconfined aquifer on top and deep confined layer at the bottom separated by a clay aquitard. Groundwater level at monitoring wells was used to calibrate and validate the groundwater flow model using MODFLOW. Hydraulic conductivity, groundwater extraction, porosity, and infiltration rate at each cell were the calibration parameters. Each optimization problem consists of a set of decision variables, an objective function, and a set of constraints. Groundwater extraction by wells in each management cell and a binary variable which was 37 wells along the subway line were considered as the decision variables. The binary variable was used to determine if a well is required to be added or not. The objective function was the cost of operation of existing wells and increasing costs due to adding new wells. The objective function was subject to constrains including the upper and lower limits of the well discharge, upper and lower limits for groundwater level fluctuation, and maximum and minimum number of active wells in each management cell. GWM software was used for optimizing the groundwater level. GWM uses the linear programming and links the results of the MODFLOW to the optimization part. It is developed using the FORTRAN programming language and uses a response-matrix approach to solve linear, nonlinear, and mixed-binary linear groundwater management formulations. Several simulation runs were used to determine the upper and lower limits of the pumping rates considering the capacity of the aquifer, well and geological conditions. The results of these simulations were used to extract a linear relationship between the groundwater level and pumping rate in each management cell.
The objective of the optimization was to reduce the water level below the subway tunnel level, to facilitate the construction, operation and maintenance of the tunnels. The priority was given to the use of the existing wells by changing the operation schedule or increasing the well discharge rate and the second option was to drill new wells. The initial results showed that the existing wells alone cannot reduce the water level to desired depth. The results showed that by increasing the groundwater pumping rates of existing wells in six management cells and adding only 13 new wells out of 37 proposed wells, it is possible to withdraw the groundwater level below the subway tunnel within three years. To check the impact of the linear assumption, the results of the optimization model were used in a simulation model to predict the groundwater level. The model showed that, assuming linear behavior between groundwater level and pumping rate has little impact on the accuracy of the results.

Channel-river confluences are an important issue in open channel studies. Variation in quantity and direction of velocity and discharge value causes the erosion of the bed and banks near the confluence. Adequate knowledge about the process of forming a scour hole can be helpful to determine the proper distance of protective structure from channel confluence and river bank. The dynamic of river confluence is as a function of the momentum ratio of reaching flows and the geometry of the channels confluence location. By considering this fact that these conditions do not exist in nature and usually the banks of rivers are included. The slope of the banks causes the changes in three dimensional flow patterns in the place of confluence in relation to septum with 90 degrees that can be the reason of changing the pattern of scouring.
The main objective of this study is to investigate the effect of side slope of the channel on the maximum depth of the erosion at the confluence with a main channel. First by using the dimensional analysis, dimensionless parameters are derived. Then, by building a physical model, the effect of various parameters, including side slope of the channel (Z), discharge ratio (Qr), downstream densimetric Froude number, and downstream Froude number, on the maximum depth of bed erosion (ds) in a perpendicular confluence is investigated. The experimental tests were conducted in a main flume (6 m length, 80 cm width and 50 cm depth), a tributary flume (5 m length, 24 cm width, and 50 cm depth). The bed slope of two channels is considered as horizontal. Changes are made to form the false floor and movable bed, and also the width of the main channel is decreased from 80 to 50 centimeters to enhance the ability of turning the main channel wall to a sloping shape. Main and tributary channels with wooden platform with 14 centimeter height and the width that equal to width of main and tributary channels are raised. The space between these three false floors is connected as experimental region and then is filled with sediment. The side slope of the main channel is considered as 45, 60 75 and 90 degree. For all experiments, the input discharge of the flume was regulated as 15 lit/s. By considering four wall side slopes, four of discharge ratios and four different flow depths, four Froude numbers and four densimetric Froude numbers are applied. To regulate the water surface at the end of main channel, we used stop logs with one centimeter height and by omitting each stop log, one Froude number is produced. The experiment was ended when the equilibrium condition for erosion and scouring hole is created. By considering this fact that the most equilibrium time will take in the slope of 45 degrees in comparison with the other slopes. The experiments with the slope of 45 degrees were done at the most and least of ratio discharge and finally, after six hours, 90 percent of scouring was produced. Therefore, for all the experiments, the experiment time is considered equal to six hours.
Immediately after the experiments are started, because of contacting the tributary and main channel flow, two rounding vortices are made. These vortices moved in contrary to each other. It is the main factor to start the scouring of bed materials in the place of confluence. Rounding vortices that are nearer to the place of confluence, act stronger because of the contraction of flow. The bed material in downstream confluence is shouted to the surface of water and moved to the downstream of the channel. When the discharge ratio is going to be increased, because of the increasing of momentum of tributary channel, the tributary flow enter the main channel with an increasing intensity and this make the vortices and down-flow stronger and causes bed scouring especially in the first stages of the experiment. Bed materials that are shooting to the surface of the flow, after becoming nearer to the water surface, they lose their energy and when they are falling, the secondary flow transported them to the downstream confluence and by settling these particles, we could see little by little sediment bar.
The results indicate that the depth of scour at confluence increases with increasing the side slope of the channel, discharge ratio, densimetric Froude number, and Froude number, whereas it decreases as flow depth increase. The best performance in decreasing scour (equal to 46% in comparison with side slope of 90 degrees) belongs to side slope of 45 degrees and the discharge ratio of 0.2. The derived relationship for predicting the maximum depth of scour at the confluence shows that scour depth is more related to Froude number and downstream densimetric Froude number than the other parameters (i.e. discharge ratio, side slope of the channel and relative depth). The best performance in decreasing the scour was belong to side slope of 45 degrees and the discharge ratio of 0.2 which was equal to 46 percent. Since the side slope of 75 degrees is close to slope with 90 degrees, it doesnt show the appropriate operation, especially in high discharges ratio and it has 9 percent decreasing of scouring. In the present study a dimensionless equation was presented which can be applied for prediction of scour depth at river confluences with the variable side slope.

Side or lateral weir is a flow measurement structure that is extensively used in irrigation and drainage networks and sewer systems. The main channel cross-section and side weir shape completely modify the flow conditions. Up to now, many studies have been conducted on side weirs. Most of the previous theoretical analysis and experimental research works are related to the flow over rectangular side weirs. This study focuses on a circular sharp-crested side weir located in a rectangular main channel in subcritical flow regime. This kind of side weir has some advantages, in comparison to other general weir types. Since the height of this side weir varies along its length, it can control flood better than other side weirs in flood conditions. In addition, because of its circular shape, it has a greater discharge coefficient.
The governing equation of the circular sharp-crested side weir has no analytical solution and thus should be solved by numerical methods. In order to simplify the solution, the equation of inline circular weir with discharge coefficient as a calibration parameter is used. The reference flow depth which should be used in this equation is an important point. In this study, three reference depths were considered (average depth 0.5(y1), center depth and initial depth y1).
In this research, the equation of conventional circular weir presented by Vatankhah (2010) is used for circular sharp-crested side weir:where Qa=actual discharge; Cd = discharge coefficient; g = gravitational acceleration; and η=H/D, with H being flow depth above the circular sharp-crested weir of diameter D.
For circular sharp-crested side weir, effective non-dimensional parameters were determined using dimensional analysis and Buckingham's Pi-Theorem. Finally, the following non-dimensional parameters were considered as the most effective ones on the discharge coefficient:where Fr= Froude number and B= main channel width.
The experiments were performed in a rectangular open channel having provisions for a side weir at one side of the channel. The main channel was horizontal with 12 m length, 0.25 m width, and 0.5 m height which was installed on a frame. The lateral channel has a length of 6 m, width of 0.25 m, and height of 1 m that was set up parallel to the main channel; the walls and its bed were made up of Plexiglas plates. The side weir was positioned at a distance of 6 m from the channel’s entrance. A total of 123 experiments on circular sharp-crested side weirs were carried out.
Different depths were considered as the reference depth. According to the experimental analysis, the discharge coefficient is a function of the upstream Froude number and the dimensionless ratio of its diameter to the main channel width.
The proposed empirical equations for discharge are as: (Average depth 0.5(y1) as the reference depth)
(Center depth as the reference depth)
(Initial depth y1 as the reference depth)
The average errors of the proposed equations are less than 2.4%, and only 5.5% of the experimental data have error more than 5% if the averaged and center depths are considered as the reference depth. However, 8.1% of the experimental data have error more than 5% if the initial depth is used as the reference depth.
In this research, the characteristics of the circular sharp-crested side weir overflows in subcritical flow regime are discussed. For this purpose, experimental data related to the water surface profile of the side weir and discharge coefficient were collected and carefully analyzed to develop accurate and simple discharge equation. The results showed that the most efficient section for measuring the water surface profile is located on the center line of the approaching channel. It was also found that for the circular sharp-crested side weir, the discharge coefficient depends on the Froude number and the ratio of weir diameter to the main channel width. In this study, the conventional circular sharp-crested weir theory has been used in order to evaluate the discharge coefficient and provide a side weir discharge equation. For this purpose, three reference flow depths were considered for conventional weir (average depth 0.5(y1), center depth and initial depth y1), and for each flow depth an equation was developed for the discharge coefficient. Comparison between predicted values and experimental data showed that the average and center flow depths result in accurate outcomes for estimating the discharge coefficient. The average value of error for discharge coefficient estimation by the proposed equations is less than 2.4%. Thus, these equations are proposed for practical use.

Integrated management of groundwater and surface water is an important issue, particularly in the basins that considerable interactions exist between surface and groundwater resources. Reliable estimates of the total catchment water balance and hydrological water level fluctuations requires the aquifer- river assessment.
Modeling is one of the indirect ways of studying the groundwater resources which has gained a lot of attention nowadays, due to its high efficiency and low cost compared to other methods.
In this study, a quantitative groundwater model has been made for Dosalagh plain with an area of 816 km2, which is located on the south of Andimeshk and west of Karkheh River.
The main objectives of groundwater modeling in Dosalagh plain is to get a quantitative understanding of groundwater interaction between the river and aquifer. The results of this study provide valuable information for the optimized management of aquifer and further detailed studies of aquifer such as qualitative simulation.
The Groundwater Modeling System (GMS) Import and pre- and post-processing tools (collectively herein called as the GMS Import tool) have been developed to facilitate the linkage of GMS groundwater models with existing models associated with the Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES). The GMS Import tool allows a GMS user to easily execute a reactive Multi-Species Transport in Three-Dimensional (RT3D) module or Modular Three-Dimensional multi-Species Transport Model (MT3DMS) module in FRAMES from a GMS-based RT3D-calibrated or MT3DMS- calibrated groundwater simulation. Through pre- and post-processing tools, the “created” RT3D or MT3DMS module in FRAMES has the capability to access and modify inputs to RT3D or MT3DMS without having the GMS user interface and without invalidating the GMS calibration. Although the GMS Import tool allows the FRAMES user access to modify input information to RT3D or MT3DMS and consume output from RT3D or MT3DMS. The basic design is applicable to all models housed within GMS or other such systems.
The program's modular design enables the user to select modules in custom combinations, allowing the user to choose only those groundwater modeling capabilities that are required. Additional GMS modules can be purchased and added at any time. The software will dynamically link to these subsequent modules at run time - automatically adding additional modeling capability to the software. The purpose of this study is to construct a simulation model capable of simulating the groundwater system as well as the groundwater- surface water interactions.
A three-dimensional, finite-difference ground-water flow model (MODFLOW) that incorporates a new stream-aquifer interaction package did the flow simulation. First, a steady state simulation was performed to represent mean annual conditions. Then groundwater flow in the plain was calibrated under unsteady state condition from October 2008 to September 2009 and verified during October 2009 to September 2010. After reaching the conclusion that the model could simulate the groundwater flow in the plain, it was used to evaluate various scenarios for management, including increasing withdrawal, decreasing recharge and increasing recharge and aquifer- river interactions in all scenarios were assessed by zone budget package of MODFLOW.
The results of the groundwater model showed that in the third scenario (increasing recharge) water flows from the river to the zone 1 of the Dosalagh aquifer during the wet season. Since in the wet season, the water exchanges decreases from  to  cubic meters per day due to increase of aquifer hydraulic gradient. In the zone number 2 water flows from aquifer to the river from -6800 to -7530 cubic meters per day and in the zone 3, the exchange of water from the aquifer to the river increases from -497.5 to -547.081 cubic meters per day.
After the calibration and verification, the model simulated the natural condition of aquifer properly and was used as a management tool for evaluating different management plans.The results of the groundwater model showed that in the third scenario (increasing recharge) water flows from the river to the zone 1 of the Dosalagh aquifer during the wet season. Since in the wet season, the water exchanges decreases from  to  cubic meters per day due to increase of aquifer hydraulic gradient. In the zone number 2 water flows from aquifer to the river from -6800 to -7530 cubic meters per day and in the zone 3, the exchange of water from the aquifer to the river increases from -497.5 to -547.081 cubic meters per day.
After the calibration and verification, the model simulated the natural condition of aquifer properly and was used as a management tool for evaluating different management plans.

Recently, researchers have made significant efforts to investigate tide induced groundwater fluctuation in coastal aquifers. Different methods have been adopted for developing solutions to the problems using analytical approaches, numerical techniques, and experimental studies. Although numerical solutions lack many interesting features, compared with analytical ones in providing accurate results, they are the only alternative which enables one to satisfy necessary conditions on irregular boundaries in dealing with aquifer with different geometry. To the best of our knowledge, analytical solution for a heterogeneous coastal aquifer system with finite length has not been reported in any published literature.
Coastal aquifers are usually heterogeneous due to variations in depositional and post depositional processes. In this paper, an analytical solution was developed to tide induced groundwater fluctuations in a heterogeneous coastal aquifer system with finite length. This aquifer system contains an unconfined aquifer on the top, a semi-confined aquifer at the bottom, and an aquitard between them. The storage coefficient of the aquifer is assumed to be negligible with respect to those in the unconfined and confined aquifers. All the layers have been considered to be heterogeneous. The coastal aquifer system is infinite in y direction, and it is finite in x direction. The coastal aquifer system is influenced by the tide fluctuation from both left and right hand sides. The linearized Boussinesq equation is considered for the unconfined aquifers. The flow in the unconfined aquifer can be described by the linearized Boussinesq equation when the thickness of the unconfined aquifer is much greater than the tidal amplitude. The analytical solution is developed using the method of separation, and the closed form solution is obtained for hydraulic head in both unconfined and confined aquifers.
A hypothetical example is given to illustrate and investigate the effect of inhomogeneity on the tide-induced groundwater fluctuation. To address the effect of inhomogeneity, dimensionless hydraulic parameters are defined for the unconfined, semi-confined aquifers and the aquitard, as Lm=L1/L2, Sm=S11/S12, Tm=T11/T12, SB=S21/S22, TB=T21/T22, where L1 and L2 represent the leakage of the left and right aquitards, respectively, and S11 and S12, are storativity of the left and right unconfined aquifers, respectively, T11 and T12 are the transmissivity of the left and right unconfined aquifers, respectively, and S21 and S22, are storativity of the left and right semi-confined aquifers, respectively, T21 and T22 are the transmissivity of the left and right semi-confined aquifers, respectively. The results showed that the amplitude of groundwater head fluctuation in the unconfined aquifer increase with the leakage, however, the fluctuation in the semi-confined aquifer decreases as the leakage increases. When l1=l2=100 m (l1 and l2 are the length of the left and the right aquifers), the minimum groundwater fluctuations in the unconfined aquifers occur at the x=100 m for all leakage values, while in the semi-confined aquifer, for Lm=1, Lm=0.25, and Lm=5, it occurs at x=100 m, x= 120 m, and x=90 m, respectively. Time lag decreases as Lm increases in unconfined aquifers, however, it does not change significantly with varying of Lm, in semi-confined aquifer. Also, the results show that time lag is greater in semi-confined aquifer with respect to that in semi-confined aquifer. In the left unconfined aquifer, the groundwater head fluctuation increases with increase of Tm, and in the right unconfined aquifer, for Tm>1, it increases as Tm increases. The amplitude of head fluctuation in the semi-confined aquifer increases with increase of TB, however, the rate of increasing decreases with increase of TB. The reason may be, with increasing of transmissivity the velocity increases, therefore tide propagates rapidly in the aquifer. For Lm=0.25, and for large values of TB groundwater head fluctuation is almost constant. Also, the results show that, the groundwater head fluctuation in the unconfined aquifer decreases as Sm increases, the reason seems to be, with increasing of Sm, the damping effect of the system increases, therefore the head fluctuation in the aquifers decreases, this result had been in agreement with the results of previous researchers. The groundwater head fluctuation in the semi-confined aquifer is almost constant with variations of SB, meaning that SB has less effect on the head fluctuation in the semi-confined aquifer. It is interesting to note that, previous works that they considered a coastal aquifer system with infinite length, would be a special case of this work, when l1→∞.

Considering the high water use by agriculture in comparing to the other sectors of Tehran and Alborz Provinces, optimization of cropping pattern and water allocation in deficit irrigation condition can play an important role in water demand management. For this purpose, in the present study, the optimization is performed on the two levels (by two sub-models). The first level was the allocation of intra-seasonal and second level was the integrated optimization of irrigation water allocation and cropping pattern in a dry year condition by second sub-model. The amount of net benefit estimated with regard to the different deficit irrigation and then a benefit function were developed for each crop. In this study, the non-linear programming (NLP) was used due to existing non-linear relationship between net benefit and irrigation water and thus the non-linear objective function is applied. Considering the various scenarios in the amount of available water, optimal cropping pattern and water allocation of individual crops determined. The results of the model indicate that the net benefit of agriculture is improved %36 in Tehran and Alborz Provinces by changing in cropping pattern and using deficit irrigation.Considering the high water use by agriculture in comparing to the other sectors of Tehran and Alborz Provinces, optimization of cropping pattern and water allocation in deficit irrigation condition can play an important role in water demand management. For this purpose, in the present study, the optimization is performed on the two levels (by two sub-models). The first level was the allocation of intra-seasonal and second level was the integrated optimization of irrigation water allocation and cropping pattern in a dry year condition by second sub-model. The amount of net benefit estimated with regard to the different deficit irrigation and then a benefit function were developed for each crop. In this study, the non-linear programming (NLP) was used due to existing non-linear relationship between net benefit and irrigation water and thus the non-linear objective function is applied. Considering the various scenarios in the amount of available water, optimal cropping pattern and water allocation of individual crops determined. The results of the model indicate that the net benefit of agriculture is improved %36 in Tehran and Alborz Provinces by changing in cropping pattern and using deficit irrigation.Considering the high water use by agriculture in comparing to the other sectors of Tehran and Alborz Provinces, optimization of cropping pattern and water allocation in deficit irrigation condition can play an important role in water demand management. For this purpose, in the present study, the optimization is performed on the two levels (by two sub-models). The first level was the allocation of intra-seasonal and second level was the integrated optimization of irrigation water allocation and cropping pattern in a dry year condition by second sub-model. The amount of net benefit estimated with regard to the different deficit irrigation and then a benefit function were developed for each crop. In this study, the non-linear programming (NLP) was used due to existing non-linear relationship between net benefit and irrigation water and thus the non-linear objective function is applied. Considering the various scenarios in the amount of available water, optimal cropping pattern and water allocation of individual crops determined. The results of the model indicate that the net benefit of agriculture is improved %36 in Tehran and Alborz Provinces by changing in cropping pattern and using deficit irrigation.Considering the high water use by agriculture in comparing to the other sectors of Tehran and Alborz Provinces, optimization of cropping pattern and water allocation in deficit irrigation condition can play an important role in water demand management. For this purpose, in the present study, the optimization is performed on the two levels (by two sub-models). The first level was the allocation of intra-seasonal and second level was the integrated optimization of irrigation water allocation and cropping pattern in a dry year condition by second sub-model. The amount of net benefit estimated with regard to the different deficit irrigation and then a benefit function were developed for each crop. In this study, the non-linear programming (NLP) was used due to existing non-linear relationship between net benefit and irrigation water and thus the non-linear objective function is applied. Considering the various scenarios in the amount of available water, optimal cropping pattern and water allocation of individual crops determined. The results of the model indicate that the net benefit of agriculture is improved %36 in Tehran and Alborz Provinces by changing in cropping pattern and using deficit irrigation.

This study is carried out with the purpose of developing the effective methods to release sediment out of dam reservoirs. Piles and submerged Vanes are employed in front of bottom outlet to enhance vortex flow and their effects were tested. The piles are embedded in different distances from each other and bottom outlet. The results indicated that Piles performance was improved with minimum distance and the rate of sediments evacuated in the water levels of 50, 30 and 15 cm, were increased about 76, 113 and 141%, respectively. The submerged Vanes were also fixed in different distances from the outlet and three different angles with respect to flow direction. The results showed that when the Vane distance from outlet was minimum and the angle of the Vane was less, the intensity of vortex flow was increased. As a result, the amounts of sediment evacuated in the water levels of 50, 30 and 15 cm, were increased about 163.5, 337.1 and 481%, respectively. In general, the results indicated that in releasing sediments from reservoirs the submerged Vanes have better performance than piles.This study is carried out with the purpose of developing the effective methods to release sediment out of dam reservoirs. Piles and submerged Vanes are employed in front of bottom outlet to enhance vortex flow and their effects were tested. The piles are embedded in different distances from each other and bottom outlet. The results indicated that Piles performance was improved with minimum distance and the rate of sediments evacuated in the water levels of 50, 30 and 15 cm, were increased about 76, 113 and 141%, respectively. The submerged Vanes were also fixed in different distances from the outlet and three different angles with respect to flow direction. The results showed that when the Vane distance from outlet was minimum and the angle of the Vane was less, the intensity of vortex flow was increased. As a result, the amounts of sediment evacuated in the water levels of 50, 30 and 15 cm, were increased about 163.5, 337.1 and 481%, respectively. In general, the results indicated that in releasing sediments from reservoirs the submerged Vanes have better performance than piles.This study is carried out with the purpose of developing the effective methods to release sediment out of dam reservoirs. Piles and submerged Vanes are employed in front of bottom outlet to enhance vortex flow and their effects were tested. The piles are embedded in different distances from each other and bottom outlet. The results indicated that Piles performance was improved with minimum distance and the rate of sediments evacuated in the water levels of 50, 30 and 15 cm, were increased about 76, 113 and 141%, respectively. The submerged Vanes were also fixed in different distances from the outlet and three different angles with respect to flow direction. The results showed that when the Vane distance from outlet was minimum and the angle of the Vane was less, the intensity of vortex flow was increased. As a result, the amounts of sediment evacuated in the water levels of 50, 30 and 15 cm, were increased about 163.5, 337.1 and 481%, respectively. In general, the results indicated that in releasing sediments from reservoirs the submerged Vanes have better performance than piles.This study is carried out with the purpose of developing the effective methods to release sediment out of dam reservoirs. Piles and submerged Vanes are employed in front of bottom outlet to enhance vortex flow and their effects were tested. The piles are embedded in different distances from each other and bottom outlet. The results indicated that Piles performance was improved with minimum distance and the rate of sediments evacuated in the water levels of 50, 30 and 15 cm, were increased about 76, 113 and 141%, respectively. The submerged Vanes were also fixed in different distances from the outlet and three different angles with respect to flow direction. The results showed that when the Vane distance from outlet was minimum and the angle of the Vane was less, the intensity of vortex flow was increased. As a result, the amounts of sediment evacuated in the water levels of 50, 30 and 15 cm, were increased about 163.5, 337.1 and 481%, respectively. In general, the results indicated that in releasing sediments from reservoirs the submerged Vanes have better performance than piles.

In this paper, using the one of the most robust optimization technique, Ant Colony Optimization Algorithm (ACO) the minimum number of required sampling points was determined in Hashtgerd plain. The ACO technique is based on the minimum distance between the food source and the ant nest. In Hashtgerd plain using ACO about 30% of sampling point were reduced. In this aquifer, the number of sampling points for contamination research where in 25 location and after the application of ACO technique results showed that only 18 sampling points is enough and the 7 number of sampling points is not necessary and introduced more expenses for the contamination study. In addition, the results of nitrate contamination contour plot before and after reducing the sampling points from 25 to 18 shows a small change in contour maps. The maximum RMSE after reduction 7 sampling points is about 0.3198 that shows the minimum error for optimized network.

Snow is one of the major sources of water in most part of the world. In the hydrology and climate studies, determination of the snow cover surface area is one of the most important parameters. One of the tools that have a lot of use in the watershed snow cover survey and hydrological properties is remote monitoring by satellite images. In this research, we used the MODIS images and NDSI index for mapping of snow cover. We calculated the NDSI index and we used the threshold in 2, 4 and 6 bands for discrimination between snow and other wet lands. After calculating NDSI, the snow-covered surface was then interpolated for days without satellite images by Malcher algorithm. The results showed that the NDSI index assistant with the thresholds and Malcher algorithm had good performances in determining the snow cover surface area. In this research, the average error of snow cover maps, including the error of NDSI index is less than 20%. At the end, we calculated the snow cover with Malcher algorithm and NDSI index for 2006-2007.