Iranian Water Research Journal

Abstract Gravity currents form when a heavier fluid propagates into a lighter one in a predominantly horizontal direction. They are frequently encountered both in the environment and engineering applications. Gravity currents can be driven by density differences of the fluids involved, or by differential particle loading. In natural or human-made aquatic settings such as lakes, oceans or reservoirs, there is a myriad of possible contributors to these density differences including temperature differences, salinity contrasts, suspended material, both organic and inorganic, as well as combinations of these mechanisms. In water resources management, to prevent sedimentation and drain sediment from dam reservoirs, in most cases, is tried to remove fine sediments by using of hydrodynamic forces. One of these methods is removing sediment by the gravity current dynamics. The gravity currents are the most important effective events on reservoirs' sedimentary processes (transmission, distribution and deposition of particles). Therefore, identifying the factors affecting on this type of flow is very important. Both bed slope and surface roughness are the most important parameters on gravity current dynamics and have a considerable effect on velocity distribution of the body.
This study investigates the effect of bed roughness on the gravity currents characteristics and obtaining relations between effective parameter on gravity currents and finding their influences in body velocity distribution on rough and slope beds. In this study to determine the bed roughness effect on the velocity distribution, a series of gravity currents experiments was performed on beds with the rough natural element sizes of 4, 8, 12 and 15 mm and slopes from 0 to 2.2%. The experiments of saline gravity currents were carried out in three inflow discharges with amounts of 0.7, 1 and 1.3 (lit/s) and with three concentrations of 10, 16 and 20 (gr/lit). All Experiments was done on a Plexiglas flume with the length of 10 meters and width of 35 cm and in hydraulic models laboratory in Shahid Chamran university of Ahvaz (Iran). In all experiment, the velocity profile in the body of gravity current was acquired by an Ultrasonic Doppler Velocity meter device.
The results of this study can be summarized as an investigation on variations of velocity profile characteristics and analysis of velocity distribution in tow (wall and jet) regions of gravity current's body. Determination of general equations for velocity distribution in gravity current's body on rough beds showed that by increasing bed roughness the height of maximum velocity rose up to a higher position and the coefficient of velocity distribution equation changed consequently. Based on results of this study, the relationship between relative height of maximum velocity location in the velocity profile ( ), versus relative roughness ( ), was rational type; in which, hm is the height of maximum velocity location, ks is the bed roughness and h is the thickness of gravity current. The relative height of maximum velocity location was equal to 0.3 when was near to zero and by increasing , the value of converged to the constant of 0.65. The investigation on acquired velocity profile showed that the bed roughness was one of the most important factors on velocity distribution. The similarity of the velocity distribution, in both jet and wall flow regions, by Semi-Gaussian and power distribution equations showed that the coefficient of velocity distribution was varied by increasing the bed roughness.
For the velocity profile in jet region, the coefficients of Semi-Gaussian distribution (? and ?) were varied from 1.2 to 2 and 2.2 to 1.8, respectively, by increasing the bed roughness. Also, for the velocity profile in wall region, the coefficient of Power distribution (n) was changed from 0.2 to 0.6.Gravity currents form when a heavier fluid propagates into a lighter one in a predominantly horizontal direction. They are frequently encountered both in the environment and engineering applications. Gravity currents can be driven by density differences of the fluids involved, or by differential particle loading. In natural or human-made aquatic settings such as lakes, oceans or reservoirs, there is a myriad of possible contributors to these density differences including temperature differences, salinity contrasts, suspended material, both organic and inorganic, as well as combinations of these mechanisms. In water resources management, to prevent sedimentation and drain sediment from dam reservoirs, in most cases, is tried to remove fine sediments by using of hydrodynamic forces. One of these methods is removing sediment by the gravity current dynamics. The gravity currents are the most important effective events on reservoirs' sedimentary processes (transmission, distribution and deposition of particles). Therefore, identifying the factors affecting on this type of flow is very important. Both bed slope and surface roughness are the most important parameters on gravity current dynamics and have a considerable effect on velocity distribution of the body.
This study investigates the effect of bed roughness on the gravity currents characteristics and obtaining relations between effective parameter on gravity currents and finding their influences in body velocity distribution on rough and slope beds. In this study to determine the bed roughness effect on the velocity distribution, a series of gravity currents experiments was performed on beds with the rough natural element sizes of 4, 8, 12 and 15 mm and slopes from 0 to 2.2%. The experiments of saline gravity currents were carried out in three inflow discharges with amounts of 0.7, 1 and 1.3 (lit/s) and with three concentrations of 10, 16 and 20 (gr/lit). All Experiments was done on a Plexiglas flume with the length of 10 meters and width of 35 cm and in hydraulic models laboratory in Shahid Chamran university of Ahvaz (Iran). In all experiment, the velocity profile in the body of gravity current was acquired by an Ultrasonic Doppler Velocity meter device.

Abstract By calculating the potential yield of crops, the yield gap can be determined. Also, the management of water and soil resources can be done based on effective factors in production. Attending to limitations in agricultural programs, for increasing the wheat yield, applying a predictive model of yield potential rate could be effective in the yield management based on various parameters including climate factors. A suitable model for this goal is regionalism method based on cropped ecology, in which it is assumed the climatic requirements are prepared and water, nutrients, salinity, pests and diseases do not effect on growth and yield potential. In this study, with the goal of estimating the yield potential in 30 province centers in Iran, by using factor and cluster analysis and considering nine climate factors, the stations were classified. Then, climate data was collected for a period of 30 years (up to 2010) from synoptic stations of provinces' centers. Also, the average values of actual yield for winter wheat were collected from the site of Centre for Information and Communication Technology, Ministry of Agriculture Jahad, in each province. Then the potential yield and gap yield (kilograms per hectare) were determined, using the regionalism method based on cropped ecology.
According to the variance percentage and special values of effective factors, KMO value was equal to 0.598; forwhich, four climatic parameters including mean temperature, relative humidity, wind speed and precipitation were selected in classifying process. Therefore, nine provinces were categorized in dry climate including Birjand, Kerman, Yazd, Zahedan, Qom, Isfahan, Shiraz, Tehran and Semnan. In semi-arid and semi-humid climate there were 15 provinces including Mashhad, Qazvin, Bojnoord, Sanandaj, Kermanshah, Tabriz, Arak, Shahrekord, Zanjan, Hamedan, Orumieh, Ilam, Khorramabad, Yasooj and Ardebil. Three provinces were in humid with low precipitation climate including Busheher, Bandarabbas and Ahvaz. Also, three provinces were in humid-rainy climate including Rasht, Sari and Gorgan. Then, the estimated values of parameters in regionalism method based on cropped ecology and the actual and potential of wheat yield were determined in four regional groups. Also, the percentage of yield gap which caused by the difference between the actual and potential yield due to the lack of climatic requirements was determined in each group.
As a result, regionalism method based on cropped ecology in arid -low precipitation regions of the country could not estimate potential yield of wheat. In the region with semi-arid and semi-humid climate, the lowest and highest amount of yield gap was 30.9 and 53.5 percent in Ardebil and Ilam stations, respectively. Also, the average percentage of yield gap in this group was 43.2 percent. In regions with arid climate, the minimum and maximum of yield gap percentage were in Semnan and Zahedan stations with 10.2 and 52.1 percent, respectivelyand the average percentage of yield gap in this group was 27.5 percent. In humid-rainy region, including the stations of the northern coasts of Iran, the percentage of yield gap was very high. In this group, the maximum yield gap was in the Rasht station with 68.9 percent and the minimum was in Gorgan station with 41.2 percent. Also, the average percentage of yield gap in this group was 55.8 percent. Among the four regional groups, in terms of required climatic parameters, the maximum of yield gap occurred in humid-rainy regions and the lowest was in low precipitation humid climate. Furthermore, among 30 provinces which were studied, the Rasht station from humid-rainy regions had the highest yield gap and the Semnan station from dry regions had the lowest. The results of factor analysis showed that temperature was important for classifying the provinces by climate. Also, the results showed that model had the greatest sensitivity to the average temperature, comparing to the other climatic factors. This caused the lowest yield gap occured in the regions with low precipitation and dry climates with 15 and 27.5 percent, respectively. Also, the moderate climate in rainy climate condition caused more growing and a longer season of growth in the most species. Therefore, the difference between average yield and potential yield has been occcured which caused the average of yield gap in the northern coastal provinces of the country to be 55.8 percent. The conclusion of results represented that the regionalism method based on cropped ecology is one of the appropriate tools for predicting wheat yield and determining yield gap in different climatic regions.

Abstract Clean water is one of the important factors in any region's development. Since Iran is located in an arid and semi-arid area with scarce water resources, preservation of water required for various uses and maintenance of its quality takes redoubles this importance. Evaluation of surface water is normally a costly and time-consuming process. Therefore, a method is preferred which has the minimum number of hydrochemical parameters and can yield a relatively accurate prediction of water quality. One of the most significant qualitative parameters of water for agricultural uses is the sodium absorption ratio (SAR), the factor which should be estimated and evaluated accurately. This research employed various hydrochemical parameters, a model tree using the M5-Rules, and a Support Vector Machine to study the feasibility of estimating the qualitative index SAR in the Ajichai River located in East Azerbaijan Province. The four statistics of correlation coefficient (R), Nash-Sutcliffe coefficient (NSC), Root Mean Square Error (RMSE), and Mean Absolute Error (MAE) were used to determine the accuracy of both M5 model and the Support Vector Machine.
The study region was the Ajichai River on the northern hillsides of the Sahand Mountain. Hydrochemical data from the Hydrometric Station in Vanyar was used to evaluate and predict the SAR in the river. The Vanyar Station has the longitude of 46?24 ? east, the latitude of 38? 7? north, and the altitude of 1460 meters. Effects of Total Dissolved Solids (TDS), Electrical Conductivity (EC), PH, chlorine (Cl-), sulfate (SO42+), calcium (Ca2+), magnesium ( Mg2+) and sodium ( Na+) parameters on SAR were determined in SAR estimation. The model tree M5-Rules is a new data mining method. The main goal of this model is derived from regression trees. The difference is that this model has regression functions in its leaves instead of constant values and classification tags. The major advantage of the model tree M5-Rules over regression trees is that the model tree M5-Rules is much smaller than regression trees. Furthermore, regression functions normally do not include many parameters. A decision tree usually consists of four parts of root, branches, nodes, and leaves. Each node corresponds to a certain characteristic, and the branches represent values of the intervals. These intervals consider known values for each of the characters. The branching operation takes place with one of the predictor variables. The branching intervals are selected in a way that the sum of squared deviations from the mean of the data in each node is minimized. The branching criterion indicates the amount of the error in the related node, and the model calculates the minimum expected error as a result of each characteristic testing in the related node. The model error is generally assessed by measuring the predicted unobserved target values accuracy. In this research, the WEKA software which is developed at Waikato University in New Zealand was used to model the M5 method. Modeling was performed with this software using the option of M5-Rules which present simple and linear rules. Support Vector Machines are data mining algorithms similar to the model tree M5 and the artificial neural network. There are two groups of Support Vector Machines: Support Vector Classification (SVC) and Support Vector Regression. Furthermore, Support Vector Machines are based on the concept of decision planes that define decision boundaries, i.e. a decision plane separates data with different tags from each other. The goal in a linearization algorithm with the help of a Support Vector Machine, the assumptions of the input value of xi, and the output value of yi is to find a function with the minimum deviation (?) from the yis (? is the amount of deviation). In this research, the Statistica software is used for modeling the SAR values employing Support Vector Regression.
In the modeling of the SAR values by using the tree model M5-Rules, the best answer was obtained when 66 percent of the data was allocated to training and the rest to testing. To model the SAR values using the Support Vector Machine, various functions were tested as kernel functions, and it was found that the RBF function exhibited the best performance in the modeling of the SAR values. Among the 10 scenarios studied in this research, the best one was selected. The four statistics of correlation coefficient (R), Nash-Sutcliffe coefficient (NSC), Root Mean Square Error (RMSE), and Mean Absolute Error (MAE) were used to determine the accuracy of both M5 model and the Support Vector Machine. The obtained values of these calculations were: R =0.98, N-SC=0.97, RMSE=6.22 (mg/l), MAE=6.06 (mg/l) for the Support Vector Machine method; and R=0.98, N-SC=0.96, RMSE=7.33 (mg/l), and MAE=3.9 (mg/l) for the M5 model. Results of the comparison indicated that both methods studies in this work, i.e. Support Vector Regression and the M5 model, were highly capable of predicting the SAR values in the Ajichai River, using the available data. However, the M5 model is recommended to be used due to the fact that the formulas employed in this method are so simple and linear.

Abstract On the one hand, the limited energy resources and on the other hand increasing energy demand are the factors that enhance the importance of energy management in micro and macro programs, in developed and developing countries. The head loss in different parts of pipelines causes an increase in the amount of energy consumed by the pumps. Therefore, reducing it is critical. One of the most important and easiest ways to reduce energy consumption during fluid supply is using friction-reducing materials in the flow.
In this study, a setup was conducted to find out the effect of adding a small dose of three different polymers (Karaakryl30, Karaakryl58 and Sodium carboxymethyl cellulose) on changing friction losses and its effect on the spray radius of sprinklers in a pressurized irrigation system; in which three Hunter type sprinklers were used. To investigate the effects of these three polymers, the irrigation system consisted of a galvanized tank, a valve to control the flow rate at the beginning of the pipeline, polyethylene pipes with a diameter of 20 mm and a length of 40 meters, three Hunter sprinklers. And two amount of pressure were used. In the first stage, pure water was used to measure the flow rate and the head loss. In the first stage, the experiments were related to the control treatments in which pure water was used to measure the flow rate and energy loss. First, the tank was filled with water. Then, the initial and final sprinklers' output were closed. The sprinkler's nozzle at the end of the path was opened to measure the discharges. And then the control valve fully opened. By switching the pump, water from the sprinkler's output flowed out. After this stage, the discharge valve fully opened and the head loss was measured. Then, by adjusting the control valve (reducing the flow), the amount of flow and pressure were measured again. Adjusting the control valve was performed in 5 different conditions with pure water. The polymer Karaakryl30 was tested with the concentration of 100 mg per liter which was once dissolved in water and then stirred after half an hour again. After that, the pump started immediately. In the same way of the pure water measuring, the pressure and flow rate were measured. Then the Pump was turned off and all three sprinklers were installed, adjusted and fasten to fulcrums in the given situations. After pump working, the radius of spraying was measured. In the next stage, without any changes to the system compared to its previous state, the tank was filled with water again and the pump was turned on. After pumping all the water in the tank, the spraying radius was measured and compared with a spraying radius of Karaakryl30 solution (100 mg per liter). All the above steps for each of the three materials were tested at three concentrations. By fitting a curve for discharge and head loss data, the relationship between them was obtained, for pure water and the three polymers in three concentrations. Using these relationships, the head loss values were obtained in the same discharges. Considering that friction-reducing material reduces head loss in the pipeline, it increases the pressure in sprinkler nozzles and as a result increases the spraying radius. In this aspect, the effect of adding the polymers on spraying radius was studied, in three concentrations.
The results showed that Karaakryl30 and Sodium carboxymethyl cellulose had the better effect on reducing the head loss and increasing the spraying radius, comparing to the Karaakryl58. The amount of head loss in the discharge of 0.423 lit/s for pure water, Karaakryl30, Karaakryl58 with the concentration of 1000 ppm and Sodium carboxymethyl cellulose with the concentration of 150 ppm was 20.04, 12.8, 16.09 and 12.39 meter, respectively, at the pipe length of 40m and diameter of 20mm. Karaakryl30 with 1000 ppm concentration led to maximum reduction of friction (36.1%) in pipelines and maximum increase in sprinkler spray radius (11.6%), comparing to pure water. Using polymer Karaakryl58 at the same level of concentration increased the same parameters 19.6 and 5.9 percent, respectively. Sodium carboxymethyl cellulose (150 ppm) increased the same measured parameters to 38.1 and 15.6 percent, respectively.
Thus, Karaakryl30 and Sodium carboxymethyl cellulose could be recommended to use in sprinkler systems in short-time and emergency situations such as high evapotranspiration for which it is not economical to consider the pipes with larger diameters in design.

Abstract Hydraulic jumps in sloping channels were first classified by Kindsvater (1944). An A-jump is the jump that starts at the foot of the chute. For the B-jump, the toe of the jump forms on a positive slope and the roller ending on the downstream stilling basin. The C-jump begins on a positive slope and the roller length ending at the foot of the chute and finally the D-jump that its roller length entirely occurs on the chute. The most common type of jump in practice is the B-jump which from the point of hydraulic calculation, is more complicated than others (Hager, 1988). For a jump on sloping beds, application of the one-dimensional (1-D) momentum equation is not easy to compute the sequent depth ratio because some additional information is needed to estimate both the weight component of the jump and the bottom pressure acting on the sloping channel portion (Carollo et al, 2011). Hence, for B-jump sequent depth ratio, previous researchers developed several empirical equations to compute the sequent flow depth of the jump. Although, many researches have been done about jump on smooth sloping beds, so far there has not been a study on roughened sloping beds. The primary aim of the present study was to evaluate a general equation to calculate the sequent depth ratio of different types of jump on the roughened sloping bed. For this purpose, different types of jump on both the smooth and the roughened sloping bed were investigated experimentally in a wide range of relative roughness (0.032 – 0.54), different slopes of chute (14.5, 20.5 and 27.5 degree) and Froude number (1.3 – 7.4). Using -Buckingham theory of dimensional analysis, the effective parameters for determination of sequent depth ratio on smooth and rough bed were obtained and by applying of the incomplete self - similarity theory, a general equation was derived. Then, the coefficients of the general equation were derived and its accuracy was determined, using experimental data from present study and previous published resources.
One of the main reasons of using roughened beds is to dissipate some of the kinetic energy of the flowing water over the chute. In order to examine the effect of the roughness size, the Froude number at the start of the jump and the sequent depth were calculated. In this study, The variation between the sequent depth ratio and upstream Froude number for different types of jumps and for relative roughness sizes (ks/yc) was figured. A parameter E is introduced by Hager (1944) and defines as the location where the jump begins. The results showed for a given range of E, by increase of the relative roughness, the upstream Froude number and sequent depth ratio decreased. In order to develop a functional relationship for computing the B-jump sequent depth ratio on sloping smooth beds, the function m should be determined from experimental data. Therefore, the procedure of Carollo et al (2011) was followed and the values of m(?,E) were calculated for different slopes. In this function, for a given chute angle ?, the function m decreases as E increases, and for a fixed E value, m decreases as the angle ? increases.
The form of relation between the function m and the variable E is exponential. The empirical relationship ( ) was fitted to each experimental series corresponding to a given ? value. In which a and b are coefficients that have to be experimentally determined. For smooth beds, the coefficients a and b depend only on the chute slope (?). In order to illustrate the effect of roughness height on the function m (or the sequent depth ratio), for each slope, the m values were plotted versus E values for various roughness heights. For example, the results of chute with bed angle of 14.5 illustrated that the coefficients a and b depended not only on the slope of the chute, but also on the roughness height. Also, the measurements, for different roughness sizes, indicated that m decreased as E increased and, for a fixed E value, m slightly decreased when the roughness size increased. A comparison between the rough and hydraulically smooth bed conditions shows that boundary roughness reduced m and the sequent depth ratio. This result confirmed the findings of previous investigations. The coefficients a and b was obtained from the investigations of Carollo et al (2011) in the analysis of the data in this study. Using experimental data, two equations obtained for a and b coefficients. Thus, a general equation for sequent depth ratio (Y) obtained. A comparison between experimental Y values and those calculated by main Equation was illustrasted in this study. The lines representing the 15% error range are also illustrated.
The results showed that the general equation has high accuracy and the average percentage error is about 7.5%. Also, the result showed that increasing relative roughness decreased the sequent depth ratio and the Froude number of the upstream flow and when relative roughness is about 0.54 the upstream Froude number and sequent depth ratio decreased about 50%.

Abstract Being aware of such phenomena like dam break may seriously prevent human and environmental disasters. Dams' breakage may lead to devastating waves in downstream valleys, which cause casualties, severe damages to infrastructure and human loss of life. Therefore, leaves huge economic burdens to the governments. Studies related to dam break, especially the flood wave, are necessary for safety management in the downstream of dams. Wave velocity and bed roughness are the two main parameters affecting the qualitative and quantitative changes of flood spreading in downstream. Bed roughness can produce more resistance against flood flow and thus, reduces the wave velocity and increases the depth of flow. It can change the form of wave profile, as well.
The flood wave caused by dam break phenomenon can be simulated experimentally and numerically. In the laboratory, a dam break can be produced by an abrupt opening of sluice gate, which is installed in a flume. In this research study, the dam break has been numerically modeled by using the three- dimensional Flow-3D model. The measured water elevations and velocities of flood wave were provided from another research study, which was carried out in the laboratory of Water Sciences Engineering Faculty, Shahid Chamran University of Ahvaz. Flow-3D model is powerful software in CFD, which has been developed by Flow Science Inc. and is generally used for open channels flow modeling. In this software, five turbulence models are applied and each of them is able to produce a calculation mechanism to quantify the effect of turbulence fluctuations on flow parameters such as the average velocity and the depth. In this study, the geometry model was produced in AutoCAD software and the appropriate grids in upstream and downstream of the sluice gate were developed by the Flow-3D model. The positions of the small triangular pieces used to generate rough bed in downstream were defined as the fixed points in the model. Defining the boundary conditions, the wall conditions were used for the bed and symmetry condition assumed for walls. The initial conditions were defined as constant water elevation in upstream and downstream of the sluice gate.
In this laboratory study, 4 values for downstream water depths (0, 3, 6, 9cm), 3 values for upstream head (24, 28 and 32cm) and 3 types of bed roughness (soft, regular and zigzag patterns of small triangular pieces) were the variables and the water elevation and velocity profiles were provided using the image processing method and a suitable software. In this software, the user was able to specify the wave profile at any time of wave propagation and any place. In this numerical simulation, the upstream head was just 24 cm, so for all 12 water elevations, the profiles were simulated and were compared with the corresponding measured profiles. All five turbulence models were used, to complete the numerical simulation. Comparison of the simulated and measured water elevation profiles showed that the Prandtl and one equation turbulence models were not able to simulate the flow conditions, accurately. The RNG turbulence model showed the best performance among all the proposed turbulence models. Therefore, after verifying the RNG turbulence model, it was possible to print out the water elevation and velocity profiles at any time and for any type of bed roughness and downstream water depths.
Analyzing the simulated results showed that the bed roughness was an important parameter in progressive wave velocity and acted as a resistant factor. It was found that, for the zigzag pattern of bed roughness, the longitudinal decreasing slope of the wave velocity was higher than the regular pattern. And this could be due to the form of ordering the small triangular pieces. The turbulence in the flow, near the bed, was greater for the zigzag pattern in comparison to the regular pattern, due to the interface of pieces and water which caused more resistance, lower velocities and higher depths in longitudinal profile, in the same hydraulic boundaries. Downstream depth was another parameter which affected the form of longitudinal velocity and the water elevation profiles. The average wave velocity decreased with increasing downstream water depth. It was obvious that increasing the downstream water depth amplify the effect of bed roughness in decreasing the velocity. The maximum effectiveness was simulated for the zigzag pattern with 9cm downstream water depth. The other effect of downstream water depth was in the form of the wave break, immediately after the dam break.
According to the results of model predictions and measured values, it was found that the effect of downstream water elevation on reducing wave velocity was much more than the bed roughness. For example, the average of reduction in velocity, soft bed to rough bed, was calculated %24. However, this value for 0 and 9cm downstream depth was %71.

Abstract The flow duration curve (FDC) is one of the most important and widely used signatures of catchment runoff response. It has been used in numerous hydrological applications as a part of planning activities related to agriculture, industry, urban water supply, navigation, flood control, reservoir and sedimentation studies, in-stream flow assessment, water quality management, and impacts of land use changes. The FDC is a graph of river discharge plotted against exceedance frequency and is normally derived from the complete time series of recorded river flows. Representation of the relationship between the frequency and magnitude of stream flows, making it a compact signature of a catchment’s functioning; it can be used to diagnose the rainfall-runoff responses in gauged catchments at a holistic functional level, as well as to regionalize them to ungauged catchments. For these reasons, in the past few decades, considerable effort has been expended towards detailed studies of FDCs, especially in the context of predictions in ungauged basins (Smakhtin, 1998, 2001, Castellarina, 2004, Niadas, 2005, Santhi, 2008. Li, 2010). However, most recent studies on the FDCs have been empirically based, which generally fall into two categories: graphical and statistical. The graphical approach focuses on exploring the controls of catchment climatic and physiographic characteristics on the shape of the FDC (Smakhtin et al), while the statistical approach employs statistical distributions to fit the FDC and then relates the parameters of the distribution to the catchment’s physical characteristics (Castellarin et al., 2004; Li et al., 2010). Several studies have been conducted on the impact of geometric and hydrologic parameters on the FDC. (Booker and Snelder, 2012. Brown, 2013). In unregulated streams, the shape of FDC is controlled chiefly by the geology of the basin and research on the effects of lithology on FDC in a certain area, leading to obtaining information for use in water resources management (Bloomfield, 2009).
Although both graphical and statistical methods demonstrated that different climatic and landscape characteristics impact the shape of the FDCs in different regions of the world (Li et al., 2010), it has been difficult to generalize the results from one region to another.
The aim of this research was to determine the factors affecting the flow duration curve with emphasis on the role of lithology in the estimation of flow duration indices.
The study area comprises 18 basins with areas from 69.1 to 3941 km2 which are located in the North part of Iran and is underlain mostly by rocks belonging to the hard formations. Carbonate formations in this area are appropriate distribution and cover about 28% of the studied area. Mean annual rainfall varies from 427 to 1131 mm/ year. Median slopes vary from 2.85 to 15.9%.
In this research, using data from the daily flow of rivers, flow duration curve indices, in eighteen hydrometric stations of the Caspian Basin were determined. Physiographic parameters extracted from the GIS environment and the various factors of climate, geology and land use were also calculated. Lithological units using digital geological map, with a scale of 1: 250,000 and based on expert opinions were divided into 4 classes and the area covered by each unit was calculated. Land use map based on satellite images with the division of forest, pasture, agriculture, surface water resources, and rock outcrops were prepared. Factor analysis and cluster analysis were conducted and the regression equations were derived. The accuracy of models using the coefficient of determination and standard errors were investigated. Finally, the most appropriate models in 1% and 5%, significant of levels extracted.
Factor analysis of 21 variables showed, six factors were chosen as the most important independent factors. In the multivariate regressions between agents of geologic formations, particularly carbonate hard formation and alluvial and between morphometric parameters, slope, and main river length and from land use classes, agricultural land use was determined as the best predictor of duration curve indices. Also, according to the power and exponential models, annual precipitation as the most important factors between climatologically factors was diagnosed. The validation results showed that the distributions of errors in all models were normalized and Durbin-Watson index was varied between 1.5 to 2.5.According to regional relations obtained, the contribution of hard carbonate formations along with Quaternary deposits, indicating their role in ensuring the continuity of the region's rivers.

Abstract Groundwater is one of the main sources to supply drinking water, especially in arid and semi-arid areas. The interaction of surface water and groundwater is one of the important issues in groundwater management and modeling, and it is essential to understand. This research aims at investigating river and groundwater interactions in the Dezful-Andimesh plain, which is about 2073 Km2 as the largest agricultural plain in the northern part of Khuzestan province, southwest of Iran. This plain contains five smaller plains: western Dez, eastern Dez, Sabili, Deymche and Lor. The Dez, Karkhe, Balaroud, Kohnak and Shavoor rivers are located in the study area. Thus this area is very important for supplying water needs and requires an efficient water resource management, a correct planning and reconsideration of water policy. Only 4% of the region is classified as the urban area and the remaining are agricultural plains. All the plains have irrigation networks except the Lor plain. Although, the irrigation networks supply a great part of the crops demand, in some regions groundwater use is also significant. Wheat, sugarcane and maize (32%, 21% and 16%) are the most common crops in this region. The cultivation period of wheat is usually from November to May, so the maximum recharge of groundwater by irrigation networks occurs in this period. The study area has a semi-arid climate with the mean monthly temperature of 36.5°C in July and 11.8°C in January. The precipitation varies from 296 mm in eastern Dez to 394 mm in Lor. The Dezful aquifer with an average thickness about 100 m is an unconfined aquifer system. There are over 2700 wells which pump about 500 million m3 per year, in this area. The general direction of groundwater flow in the area is from the north to the south. Recharging the aquifer is via direct rainfall infiltration and return water from irrigation networks. Hydraulic conductivity range is from 14 m/day for clayey sediments in Sabili to 49 m/day for sandy deposits, particularly in Lor. In order to model the groundwater, a MODFLOW programming code was implemented in a GMS environment. MODFLOW is a numerical model that is one of the best methods for assessing the quantity and quality of groundwater. The numerical models are difficult and time-consuming. However, in the recent decades' research using simulation models have been developed due to the improvement of high-speed computers. Information related to steady-state flow along river information was used in the model. Water level and bed river data were measured in river-cross sections and hydrometric stations in different months. The model was configured to a steady-state condition in October (2009) and was calibrated using 62 groundwater wells. Also, the model was calibrated in an unsteady-state condition for five years (October 2006 to September 2011). Then, the model was validated for the period of 2011-2012.
According to the results, the regulated rivers such as Karkhe and Dez were the major source of recharging aquifers; however, there was a decrease in their contribution to aquifers in wet seasons. There was an increase in groundwater level during wet seasons due to the groundwater recharge from rainfall and irrigation systems. However, there were no significant changes in the water level of the regulated rivers, and the minimum water level was observed in November. Therefore, an increase in groundwater level could not be related to rivers when the river levels were constant, during the wet season. The Balaroud non-regulated rivers generally drained the aquifers during dry seasons, but not during wet seasons (February), when recharge occurred from these rivers to aquifers. The rivers such as Shavoor and Kohnak and their tributaries drained aquifers in every month. There were not increasing or decreasing patterns in groundwater discharge when there was a change in both rivers and groundwater levels with different patterns in different months of a year.
According to the simulation results over six years, the most river- groundwater interaction was belong to Dez and Karkhe rivers with the highest amount of recharge to aquifers. The Shavoor and Kohnak rivers and their tributaries generally drained groundwater. However, there was no specific pattern of river-groundwater interaction for the Balaroud seasonal rivers. There was more groundwater recharge through regulated rivers in dry seasons compared to wet seasons which was due to the high amount of rainfall (along with the amount of water from irrigation systems) in wet seasons.

Abstract Water is undoubtedly one of the factors of productivity and reducing water consuming reduces the yield. But the decrease in yield due to water stress is inevitable. Because of limited water resources in Iran, deficit irrigation and water stress on crops are inevitable. Also in some regions, saline water is being used for irrigation. The saline lands of Iran are about 44.5 million hectares with various salinity and alkalinity, which are 27% of the area of the country and they are mainly located in the central plateau, southern coasts of Iran and the Caspian Sea coasts. Saline water has been successfully used for irrigating the crops such as cotton, wheat, barley and sugar beet. Deficit Irrigation (DI) is a method in irrigation management and an engineering technique which is used to optimize the yield in water scarcity and increasing water efficiency. In this method, some irrigation events which have less effect on productivity could be omitted or the volume of water in each irrigation event could be reduced. The salinity of water resources and soils in Iran is one of the problems barricades the effective application of these resources in agriculture. However, it has been tried to use unconventional water resources such as Caspian Sea to ease water shortage, especially in droughts in Northern provinces. Various reports have been presented on the effect of salinity on cotton. Some research expressed that irrigating by 6,000 mg of salt per liter had acceptable yield without any bad effect on the quality of cotton fiber and seeds. In this study, the simultaneous effects of periodic water stress and salinity stress due to using the Caspian Sea water on cotton yield was investigated, which was carried out in the agricultural research farm of Gorgan University of Agricultural Sciences and Natural Resources. This research is based on a factorial experiment in completely block design (CRD) including 20 treatments and 3 replicates in the farm of Gorgan University of Agriculture on spring 2012. Three cotton seed of Golestan variety were planted in lysimeters with the diameter of 35 cm and an average height of 70 cm. The distance between Lysimeters was one meter. To measure the cotton water requirement, pan (class A) was used. Also the effective rain during the cultivation was measured with a rain gauge which was installed near the research farm. Periodic water stress in four stages (Initial, early stage of development, the second stage of development, midseason) was applied and the salinity stress was performed at 5 levels (0% 25%, 50%, 75% and 100% mixture of Caspian sea water with ordinary water) .The Salinity was 0.7, 4.1, 11.1, 18.11, 25.1 (dS/m), respectively.
Results of this study showed that the effect of Periodic water stress and salinity from Caspian Sea water on Plant's height, boll weight, seed cotton yield was significant at the 1% level. But its effect on boll number was significant at 5% level. Also, the interaction of water stress and salinity on boll weight, seed cotton yield and plant height was significant at 1% level but the interaction of water stress and salinity at the boll number was not significant. Comparison of mean of the salinity stress in soil was done at each level of water stresses in order to reach a better understanding of the interactions. Depths of the measurements were 0-10 cm and 10-20 cm from the soil surface. By increasing salinity of irrigating water and applying water stress, soil salinity was increased. The highest soil salinity among the different level was occurred in S5 level. Because the soil salinity was increased in all treatments which were irrigated by saline water, considering leaching water in water events is necessary.
Periodic water stress also increased the salinity in soil. This increase was higher in the midseason period due to the length of this period.
By the results, the cotton yield was generally decreased by increasing salinity of irrigating water. The interaction of periodic water stress and salinity had significant effects on the cotton yield. But at the level of 25% mix of Caspian Sea water with ordinary water, in the early stage of crop development, the difference of results were lower than other treatments. So this planning could be an appropriate choice for Northern provinces of Iran in droughts and limitation of water resources.

Abstract Hydraulic jump is one of the most important phenomena in rapid varied flow which occurs in free surface flow by transforming from supercritical into sub critical flow and causes the depth to be increased in a small distance of flow. Changes in the geometrical parameters of the bed including roughness, the slope of the floor, as well as shape change and their effects on the characteristics of hydraulic jump have always drawn the attention of the researchers.
In the present study, the characteristics of the hydraulic jump formed in contractions and expansions with straight and curved walls were investigated for five Froude numbers of 5.8-9.1. In order to create supercritical flow in the contractions, in all experiments, the opening value of the sliding gate was 2 cm and the width of the upper and lower canals were 80 and 40 cm, respectively, (the convergence ratio equals 0.5). Also, in the experiments concerned with expansions, the opening of the sliding gate was 3 cm and the width of the upper and lower canals equaled to 40 and 80 cm (the divergence ration equals 0.5). An audio flume meter model UFM610P was used to measure the discharge flow of the flume. The accuracy of the flow meter was ±0.02 liters per second and its sensors were installed on the hydration pipe of the flume. Also, a bathometer with the accuracy of ±0.1 was utilized to measure the height of the waves’ surface. In addition, a horizon surface, two-dimensional electromagnetic speedometer with the accuracy of ±0.5 was employed to measure the wave velocity of the different parts of the wave.
The velocity profiles showed that, in all sections, the velocity increased as it got away from the floor and after reaching to its maximum, its value decreased. In fact, the occurrence of hydraulic jump causes intense blending of air and water and formation of eddy currents near the water surface. As a result, the energy of the flow decreases and its velocity value reduces, too. Besides, it was observed that by getting distance from the origin of the jump, the boundary layer extends while the maximum values reduce. On the other hand, negative velocity values were observed in the velocity profiles of contractions near the water surface. This phenomenon is a sign of the overcome of the return flows to the main flow of the canal (near the water surface). Indeed, the entrance of the hydraulic jump to the tightening section caused an increase in the intensity of water and air blending and occurrence of the return flow phenomenon. This situation was observed more with the increase of the Froude number. Furthermore, the velocity value in contraction was higher than its counterpart in expansion for a fixed Froude number in the vertical direction. Also, the results showed that the secondary depth and jump length in contractions were more than expansions for the fixed Froude number while the formed hydraulic jump in contractions had less energy dissipation than expansions. In fact, widening of section intensifies flow energy loss in expansions. However, in contractions, the gradual decrease of the width of the section prevents complete flow energy dissipation. For this reason, energy dissipation or flow from supercritical to subcritical takes longer time and consequently the length of hydraulic jump and the depth of secondary jump increase. On the other hand, the results indicated that the amount of tension faced a sudden drop and reached to a negative value after getting to its maximum value. Considering that Reynolds tensions have a direct relationship with fluctuations of point velocity, the sudden drop of the tension value can be due to the intense blending of air and water in jump surface and after that the reduction of range of fluctuations of point velocity. Therefore, a higher negative value was observed in contractions compared to expansions because of more intense water and air blending. It needs to be noted that the contraction with straight wall had higher negative value. Besides, in both types of the conversions, the highest negative value of the tension was observed in the middle section. Also, in contractions, by getting distance from the origin of the jump, the maximum values of Reynolds tension increase. In fact, the progress of the jump in tightening section increases the fluctuations of point velocity and through this increases the intensity of the tension. However, in expansions, the opposite case happened. On the other hand, by comparing the vertical distributions of velocity and tension in both conversions, it can be found that the site of the occurrence of maximum velocity in different sections of the jump relatively matches the site of the occurrence of the maximum intensity. The values of energy dissipation in the expansions with straight and curved walls were averagely obtained 24.95% and 21.23%, relatively. For the contractions, they were averagely obtained 15.93% and 12.49%. Also, the result showed Reynolds tensions increased in the contraction and decreased in the expansion by increasing the longitudinal distance from the origin of the jump.

Abstract Different human activities depend on water availability so most of the civilizations have been emerged and developed in the proximities of rivers. However, such developments lead to polluting water bodies (Alizade, 2004). For sustainable agricultural and industrial developments monitoring the quality of water resources is inevitable. Heavy metals negatively impact water quality as they form complex and poisonous compounds when entering water bodies (Ostan, 2005). Heavy metals exchange between sediments and water and the equilibrium exists between these phases in rivers. Such equilibrium changes by any variation in media reaction, oxidation and reduction condition, the amount of organic matter, microorganisms' activities, concentration of soluble elements and cation exchange capacity of suspended particles. The sources of heavy metals in water resources are anthropogenic (from human activities) or naturally released from mineral weathering (Khosheqbal et al. 2012). Hoba et al. (1983) reported that severe erosion of stones in the Vender river watershed and releasing a lot of Ca2+ led to formation of carbonates of calcium and some heavy metals and also Fe and Mn hydroxides in sediments of the river. Zhao et al. (2012) analyzed heavy metal concentration of fish and crabs' tissues and found a significant and positive correlation between the concentration in legs of crabs, skins and heads of fish and the concentrations in water. Sediments are considered pollutants as they absorb and transport heavy metals. Akhondi et al. (1989) studied heavy metal concentration of the Qomroud River and reported that the concentrations of Cd, Zn and Pb in water are below the permissible threshold for drinking. They expressed that sources of heavy metals are petroleum refineries, metal mills, electrical and textile industries. The Zayanderoud River is one of the main rivers of interior plateau of Iran also a water resource for drinking, industries and croplands in Chaharmahal & Bakhtiari and Esfahan provinces. The river origins from the Zagros Mountains and passes through cultivated lands, orchards, fish farms and proximity of steel mill industries and pours into Gavkhoni wetland in the southeast of Esfahan City. Due to the importance of the river, the objectives of this study were monitoring spatial and temporal variations of heavy metal concentrations in water and sediments of the Zayanderoud River.
Mean annual rainfall of the Zayanderoud watershed is 450mm and the surface area of the watershed is 27100 km2 (Johari, 2010). To fulfill the objective 10 points were selected between the Zayanderoud Dam in the west and Zarrinshahr in the east based on overlook land uses and the accessibility of the river for sediment and water samplings. Water and sediment samples were collected bimonthly according to the Geological Survey of US (1978) in 2012. Sediment samples were collected from the surficial (0-10 cm) of river bed, air dried, grinded and passed through 2 mm sieve. Total heavy metals Pb, Zn, Cu and Cd of sediments were extracted by acid (Sposito et al., 1982) and the extracted heavy metals and the concentration of water samples were measured using Atomic Absorption Spectrometer. Landsat ETM+ data of 2012 were used and the land use map of the study area was delineated.
According to the land use map, the overlooked areas to the river were rangelands, stone outcrops, settlements, rice cultivated areas, orchards and industrial zones. By the temporal and spatial variations of mean Pb concentration in water and sediments, the highest mean Pb concentration belonged to point 10 which was significantly different from of all points except point 9. The results also indicated that the maximum mean Pb concentration of sediments was 20.63 ppm and belongs to point 9. Wang et al. (2012) studied the water quality of the Lancang River and expressed that the exhausted smoke of cars was the source of Pb. The main sources of Pb in the study area could be steel mill industries as point 9 locates in the vicinity of these industries. A significant and positive correlation existed between Pb concentration of water and of sediments in all points. Also, the Pb concentration of water and sediments increased in rainy months which showed possible transportation of Pb by runoff from polluted areas to the river. Significant intercorrelation coefficients among Pb, Zn and Cu indicated possible common sources of these elements which are different from Cd resources. Spatial and temporal variations of Zn mean concentration in water were significant. The maximum mean concentration of Zn in water was 6.2 ppb which was below the permitted threshold for drinking according to the Institute of Standards and Industrial Researches of Iran (2010). Maximum concentration of Zn in sediments was 34.36 ppm. Zn used as a plant micronutrient and a component of insecticides and herbicides in croplands and orchards in the area. On the other hand, maximum Zn mean concentration observed in point 9 (5.6 ppb) and in sediments of point 2. The land use map showed that the overlooked land use of point 2 were orchards while of point 9 were steel mill industries. Therefore, the source of Zn could be fertilizers and insecticides which applied in orchards. Likewise, Wang et al. (2012) reported that Zn application as fertilizer and insecticide in a part of China led to river pollution. Namazi et al. (2014) analyzed the dust in the proximities of steel mill industries and reported that they contain heavy metals consist of Zn. Mean Cd concentration in water increased from the west to the east of studied points. The highest and lowest Cd mean concentration sediments were in points 10th and 1st, respectively. Maximum mean Cu concentration was observed in the sediments of the 6th point.
Regarding the permissible thresholds of studied heavy metals for drinking water (Institute of Standards and Industrial Researches of Iran, 1388), the concentrations of the studied heavy metals were below the threshold and the water in all points was safe for drinking. The results also indicated that industrial areas, croplands and orchards were the main non-point resources of heavy metal for the river and runoff was one of the main ways of transferring pollutants to the river.

Abstract Infiltration is one the most sensitive hydraulic parameters that has more effect on the efficiency of water, especially in surface irrigation design and management. The fact that infiltration is affected by several factors of soil and irrigation method makes it a complex parameter. Evaluating the impacts of irrigation water head on cumulative infiltration and using this parameter in infiltration models will lead to better performance of the models which are widely used in different conditions. So far, many studies have been conducted, in the field of infiltration. Forman et al (2006) investigated the effect of water height on parameters of Kostiakov soil infiltration equation in the soils with Sandy loam, loam and Silt showed that the parameters k and a had the most variability in sandy loam soil texture. However, the parameter k, in the Silty soil texture, showed little variation due to water height changes. Valyntzas et al (2009) studied the effect of water height as an upstream boundary condition on the parameters of Kostiakov equation in Sandy Clay Loam soil texture and showed that by modifying the infiltration coefficient based on water height, the simulation results of infiltration by HYDRUS improved. The purpose of this study was to investigate the effect of different water heights on the infiltration process, in some soil texture in Foumanat plain in Guilan province. In this way, 17 soil samples that had more than 15% Clay and less than 30% Sand were gathered. Infiltration tests were carried out with three replications in a completely randomized design, in a physical model. The factors included soil texture with 17 levels: the height of water with three levels (3, 5 and 7 centimeters) and three levels of the time. The results also showed that height of water on the soil surface had more impact on Loam soil texture than Clay soil texture. Infiltration testing time was 600 minutes and cumulative infiltration values were calculated in 30, 360 and 600 minutes. The physical model includes a water tank, manometer for reading the water level, reservoir water for fixing water level on the surface of soil and polyethylene cylinder with an internal diameter of 15.23 cm and a height of 35 cm, as a soil box. To maintain the soil water level, a float was used. Analysis of variance hypotheses for normal distribution was done. After passing normal distribution test, Analysis of variance and the comparison of averages were done by Tukey’s method at 5% level using SAS software. Results showed that treatment of water height had a significant effect on cumulative infiltration of the four soil samples in Silty Clay and Loam Silty Clay soil textures. Although, the results of statistical tests showed no significant effect between water height treatments (3, 5 and 7 cm) in 13 soil samples, the difference between the amount of infiltrated water in the samples should be considered due to the critical situation of water resources and necessity of increasing in irrigation efficiency. Comparison of the difference percentage of cumulative infiltration in different soil textures showed that, apart from the 3 cm water height treatment, in the two other water height treatments, Clay Loam, Silty Clay Loam, Silty loam and Silty Clay soil textures had the highest percentage of difference between the two time periods, respectively. On the others in estimating of cumulative infiltration, Clay Loam texture has more sensitivity to the cumulative time of infiltration. The difference of cumulative infiltration between treatments 3 and 5 cm was more than the other two treatments (5 and 7 cm), despite the equal difference of 2 cm in the water height. The reason for this result could be explained by reducing the influence of gravity due to increasing the height of water on the soil surface. Investigating the three infiltration time treatments (30, 360 and 600 minutes) showed that in 14 soil samples, there were significant differences between cumulative infiltration in 30 min with infiltration time in 360 and 600 minutes (p < 0.05). The difference was greater in Clay Loam soil. In all soil samples, except the soil sample number 15, steep slope of infiltration curve was similarly. Study of soil particles distribution showed that the percentage of sand in the soil sample number 15 was the least among the other soil samples, which could explain the higher slope of infiltration curve

Abstract Comprehensive management of water resources nowadays demands accurate and complete meteorological and hydrological data. Simulation of runoff hydrograph for hydraulic structures design often requires rainfall characteristics such as the amount, duration, and temporal rainfall distribution. The design storm is one of the main factors in flood estimation in watersheds. Considering the temporal variations in heavy storms, precise recognition of the rainfall temporal pattern is very important. Temporal rainfall distribution is one of the significant features of rainfall affecting the quantity and quality of runoff and erosion, which has unfortunately attracted less attention. Temporal rainfall distribution means the amount of rainfall volume per temporal periods of precipitation. In fact, the temporal rainfall distribution pattern indicates the changes in rainfall intensity. The effect of rainfall characteristics, especially temporal rainfall distribution and its intensity, on simulation of runoff events is more understandable. A huge part of errors in the simulation of rainfall-runoff models is due to the uncertainties regarding regions’ rainfall distribution patterns. Therefore, provision of rainfall distribution pattern for each region by using rainfall data is very important since the pattern varies in regions with different climates. In the studies in Iran, with regard to the variety of mechanisms causing rainfall events (altitude, proximity to the sea, and general circulation systems), it is impossible to consider a predominant distribution pattern for all parts of Iran. In this regard, presented 6 and 24-hour rainfall patterns of American Soil Conservation Society have been used. The SCS patterns which are broadly used in Iran and other countries in order to simulate runoff and designate hydraulic structures.
In this research temporal rainfall distribution has been evaluated in the Sanganeh research watershed. The Sanganeh watershed is located in the north-east of Khorasan Razavi province (60?15' E, 36?41' N), with the area of 50 ha. According to the collected data from the climatologic station and Domartan coefficient of 10.2, the climate of the watershed is classified as semi-arid. The area receives less than 180 mm annual precipitation. In this study, for determination of temporal rainfall distribution Pilgrim method has been used. In this method, in every time duration based on this fact that in which quarter the maximum rain has happened, the first, second, third and fourth rainstorms were defined and temporal rainfall distribution pattern was evaluated by use of the data obtained from rain gauge station. In this study, by investigating all observed storms in the Sanganeh research station in the period of 2005-2013, all individual storms have been derived in the different durations of 9 hr. Then, the Pilgrim method was used based on storms separation in four quarters. By averaging ranks in each quartile, the index rank the final pattern for each time-duration was specified. To statistically evaluate the obtained patterns with durations of interest, Chi square test was used after establishing a contingency table and estimating the rainfall percentage for each quartile and ranking. By averaging ranks in each quartile, index rank of the final pattern of each time-duration was determined.
The obtained results showed that most of the storms which occurred in Sanganeh region were in the first quadrate. So the assumption that the highest amount of precipitation occurs in the middle of time duration is doubtable. Also, with increasing of the storms duration, the number of the storms decreased in the first quadrate and increased in the second to fourth quadrates. Moreover, 61% of erosive storms had the duration of fewer than 3 hours and most of them were in second and third quadrate. Chi square test was used for statistical evaluation of the obtained patterns with distinct durations. The results showed that in the duration of 9 hours, there was a significant relationship between the rank and the quadrate. These patterns had high ability to use while in the others durations, the patterns were not reliable. In addition, comparison of the obtained logical pattern with SCS type patterns showed that only rainfall temporal pattern of the second quadrate rainfalls had a high correlation coefficient with IA type. Thus, as the most of the storms in the Sanganeh watershed were in the first quadrate and had the duration of 1 to 3 hours, using SCS type pattern in this region should be precautionary.

Abstract The groundwater contamination by hydrocarbon products has been a common problem in industrial areas in recent decades. Leakage from storage tanks or during the transportation seeps through the soil and pollutes the groundwater resources. Materials such as benzene, toluene, ethyl-benzene and xylene (BTEX) are common compounds of gasoline and can be found frequently in subsurface layers. In order to understand the behavior and to analyze the distribution of this kind of contamination in subsurface layers, a laboratory experimental were carried out as part of this research. An experimental sand tank was constructed in University of Tehran Laboratory to simulate the movement of BTEX in unsaturated and saturated porous media. The dimensions of the tank were 70, 50, and 8 cm for length, height, and thickness, respectively. The walls of the tank were made of Plexiglas to make the movement of the plume visible and possible for photography during the experiment. Since BTEX is colorless, SUDAN III, a red soluble substance, was added to BTEX. Image processing technique was used to estimate the concentration of BTEX in porous media in different time steps. In this experiment, 200 milliliters of BTEX with a flow rate of 15 milliliters per minute injected into the soil layer 2 cm below the surface. A groundwater flow in the saturated zone was applied with the rate of 10.4 cm per day. The upgradient depth of water was 12 cm and that for the downgradient was kept at 11.8 cm.
The profiles showed that the maximum degree of saturation happened 50 seconds after the start of the experiment with 0.92. The thickness of BTEX plume in the unsaturated zone reached 4 cm after 650 seconds. The degree of saturation and BTEX velocity were decreased with depth and increase in water saturation. After stopping the BTEX injection, the degree of saturation decreased in upper layer until it reached the residual saturation. The degree of saturation was increased above the water table and since it could not penetrate the saturated zone, it spread laterally.
The image processing technique using MATLAB software was used to estimate the BTEX degree of saturation at different location of the plume and for different time steps. The concept behind image processing algorithm is that the intensity of the pixel in a photograph is directly related to the degree of saturation of the plume. High degree of saturation means that the presence of the BTEX is higher in that location and the red color has higher intensity. The correlation between the pixel color intensity and BTEX saturation degree was obtained by calibrating the pixel intensity verses the measured saturation. The calibration process showed that there is a linear relationship between saturation degree and pixel intensity. The saturations extracted by image processing technique were used to produce the iso-lines of BTEX saturation for different time steps using Surfer 10.0 software. These plumes were compared to photographs for each time step to additionally confirm the accuracy of the technique.
The results of the image processing technique and comparison with the laboratory results showed that the proposed technique can accurately estimate the plume distribution. In addition, the results showed that in the initial stages of the BTEX injection, the gravitational force is the dominate force and lateral movement is negligible compare to vertical movement. Once the plume reaches the capillary fringe, BTEX may migrate laterally as a continuous, free-phase along the upper boundary of the water saturated zone due to gravity and capillary forces. BTEX saturation and accumulated volume increase in the capillary fringe and they depend on the depth of the capillary zone, BTEX viscosity, hydraulic head of the injection source, and volume of the injected BTEX. BTEX depressed the capillary fringe by approximately 4 cm. Ultimately, BTEX plume stopped above the water table.
The importance of groundwater, as the source of agricultural, industrial, and drinking water, makes it imperative to protect this precious resource. Understanding the behavior of the petroleum hydrocarbons in saturated and unsaturated zone can help to better prevent the pollution or remediate the contaminated groundwater. The successful application of the image processing technique in BTEX saturation estimate proved that this method can reduce the cost of laboratory experiment and can be used in evaluation of the numerical models, as well

Abstract The world's growing population has caused irrecoverable variations on natural resources. Groundwater as one of these resources has an important role in the health and economy of countries. Nowadays, groundwater is the first source of drinking water in arid and semi-arid regions such as Iran. In order to manage the consumption of groundwater resources, knowledge of groundwater recharge in spatial and temporal scales before detailed exploration such as pumping test and geoelectrical studies is required. Hence, preparing and analyzing the factors affecting groundwater recharge in the GIS (Geographic information system) can be very helpful. The existence of a groundwater recharge potential (GRP) map is vital in regions where groundwater is the most important source of water supply. The aim of this study is to provide a GRP map for Kore river basin in the Fars province considering the interaction between the factors affecting groundwater recharge. Quantitative estimate of recharge due to precipitation using remote sensing (RS) and GIS is another aim of this study. Kore river basin is located in the south of Iran and north of Fars province, between geographic coordinates of 560000 to 740000 and 3250000 to 3450000 (zone 39) in the Mercator scale (UTM). This basin has 5 sub-basins including Khosro-Shirin, Bakan, Dozkord-Kamfirooz, Asopas and Marvdasht-kherameh with an area of 8284 km2. The annual rainfall of the study area varies from 300 mm in the southeast (plains) to more than 800 mm in the northwest (mountainous region). Geologically, this area includes two different carbonated and non-carbonated parts. Carbonated formations with fractures or karst systems cover 40 percent of the study area. These formations are Asmari, Sarvak, Ilam, Tarbur, Daryan in the mountainous regions while non-carbonated formations cover other parts of the study area (lowland regions).
Satellite data (Landsat images) of the study area were interpreted in the Erdas Imaging, Envi and Arc GIS software. In this study, thematic maps of 7 factors including lineament, and longitudinal density drainage, lithology, karst terrains, land use-land cover, land slope and rainfall for Kor River basin were prepared. Then, each of the factors was classified in 9 classes and their maps were designed. These classes are in the numerical range for lineaments, drainage, lithology, slope and rainfall while they are in the descriptive manner for karst domain and land use. The interactions between the factors were considered using a schematic pattern and the internal rate of each factor was extracted. Then this rate was multiplied by the specific weight of each factor. In this way, the effect of each factor on GRP was obtained in terms of percentage which is known as refereeing method. Then, by assigning an internal weight and considering the interaction of these parameters with each other in regard to GRP a weighted rating was calculated for every parameter in GIS software. By applying these weighted rates and using the final weight of the parameters a classified map of GRP in five classes from very high to very low grades was prepared. Taking into account more factors and their interaction is the advantage of this study compared to previous studies.
Based on the obtained recharge rates using RS and GIS, the areas of recharge zones and annual rainfall, the volume of recharged water was estimated. This estimate was equal to 1090.59 MCM which is about 20 percent of annual rainfall in the Kore river basin. In order to verify this estimated recharge, hydroclimatological balance was applied to recalculate the recharge volume. Considering the lack of hydrometery data in the Kore river basin, the SCS method was used to calculate the runoff volume regarding different land use. By these methods, the percentage of recharge from rainfall was estimated to be 18 percent. Accordingly, recharge volume was equal to 954.13 MCM. Finally, by comparing recharge estimation in this article with that of hydroclimatological balance method, it was revealed that there is about 14% difference in the estimated values of each of these methods. It should be mentioned that in this study, the effect of unsaturated zone properties on the GRP has not been considered. This methodology can be applied in similar basins in arid and semiarid regions in order to estimate the percentage of infiltration resulted from monthly excess water in the hydroclimatological balance method.

Abstract This study is presented to investigate the effectiveness of simultaneous use of cable and collar in reduction of local scour depth in groups of two and three piers. The experiments were carried out in a 20m long, 0.60m wide, and 0.60m deep, Plexiglas-sided flume. The working section, in which piers were located, was 8m long with a recess on the bed 0.2m deep and was situated 8m downstream from the entrance of the flume in order to generate fully developed flows. The recess was filled with uniform sediment with the mean particle sizes of 0.71mm and geometric standard deviation of particles was ?g=1.135. Cylindrical Perspex pipes with diameter of 60mm were used as pier models. The tests were conducted on a group of three piers in line. For each group, the spacing (S/b where S is the distance between the piers sections and b is the pier diameter) of the piers was varied. The collar with the diameter of 3 times wider than the pier diameter was developed at the bed level around group of three piers. The cable with the diameter equal to 0.15 of the pier diameter with a torsion angle equal to 15° and combination of them around each pier was studied.
In experiment of group piers with collar, two different spacing of S/b=2 and 3 were tested for a group of three piers in line. The experiment with spacing S/b=3 the space between two piers were not completely covered with collar. The scour hole was developed at back of the third pier. Also, two grooves were gradually developed at the down-stream rim of the collar and gradually developed and extended upstream and eventually reached the upstream edge. At this moment, the flow was intensified through the groove, reducing the side slope of the groove and with sediment removal from the grooves, the scour hole extended upstream of the pier and below the collar. By penetration of the flow beneath the front edge of the collar the rate of sediment removal increased. Maximum depth of scour hole is equal in front of the first pier with and without collar. In the first pier, both spaces had the same delay time and maximum scour depth because the space between piers had no effect on efficiency of collar. The results of experiment with cable showed that reduction of scour depth in the second and third pier is more than the first pier, due to sheltering effect of the first pier on the second and third piers. Also, in this case, with increasing the space between the piers the reduction of scour depth was decreased slightly. The simultaneous use of cable and collar showed that reduction of scour depth in upstream of group of three piers with S/b=2 is about 20%, 45% and 53% respectively. Since the strength of wake vortex reduces, reduction of scour depth in upstream of the pier protected with cable and collar is more than the reduction of scour depth of the pier protected with collar and pier protected with cable. In this case, comparison of delay time reveals that using collar caused the delay in scouring mechanism and when the collar and cable combined the delay time is increased. In the first pier, cable and collar cannot cause salient reduction in maximum scour depth due to the reinforcement effects counteract the effect of collar and cable. In the second and the third piers when the collar and cable combined, the delay time and equilibrium time are increased. In these piers, the maximum scour depth is decreased as well. The efficiency of cable and collar to reduce the scour depth in the third pier is greater than the second pier due to increasing the sheltering effect.
The results indicate that the scouring is postponed and reduced in protected pier with cable and collar more than protected pier with collar; therefore cable increases the efficiency of collar. The space between the piers has a considerable effect in reducing the scour depth, so that the scour depth was decreased and the delay time was increased, with increasing the space between the piers. The most reduction of scour depth was observed for group of three piers with S/b=2, in which the scour depth of the first, second and third piers reduced to about 20%, 45% and 53% respectively. In situation that a pier protected with cable and collar with S/b=3, the scouring postponed was maximum. So, use the cable with the collar can greatly reduce the risk of bridge destruction.

Abstract Several formulas have been proposed for the calculation of the Instantaneous Unit Hydrograph (IUH). The concept of series reservoirs is one of the methods to calculate and predict the flow Hydrograph in the catchment. Inverse gamma model is one of probability distributions, which depends on two parameters: n and k. And several formulas have existed for the estimation of the Inverse gamma’s instantaneous unit hydrograph. The accuracy of estimating the parameters n and k in Inverse gamma model directly affect simulation results. This study for the evaluating parameters of the Inverse gamma model used different methods such as moment, optimization and Rosso. The results showed that using optimization method in estimating parameters n, k had the most compatibility with the observed hydrographs. In all these methods, output runoff volume has been calculated with the error less than 11%. The optimization, Rosso and moment methods were successful in computing the time peak and the peak discharge. But in 5 rainfall event, the moment method, in computing the peak discharge has more than 50% of the difference with the observed value. Thus regionalization of Inverse gamma’s model parameters (n and k), by the mentioned methods, is advised for development and application of this hydrological model, in similar catchments.Several formulas have been proposed for the calculation of the Instantaneous Unit Hydrograph (IUH). The concept of series reservoirs is one of the methods to calculate and predict the flow Hydrograph in the catchment. Inverse gamma model is one of probability distributions, which depends on two parameters: n and k. And several formulas have existed for the estimation of the Inverse gamma’s instantaneous unit hydrograph. The accuracy of estimating the parameters n and k in Inverse gamma model directly affect simulation results. This study for the evaluating parameters of the Inverse gamma model used different methods such as moment, optimization and Rosso. The results showed that using optimization method in estimating parameters n, k had the most compatibility with the observed hydrographs. In all these methods, output runoff volume has been calculated with the error less than 11%. The optimization, Rosso and moment methods were successful in computing the time peak and the peak discharge. But in 5 rainfall event, the moment method, in computing the peak discharge has more than 50% of the difference with the observed value. Thus regionalization of Inverse gamma’s model parameters (n and k), by the mentioned methods, is advised for development and application of this hydrological model, in similar catchmentsSeveral formulas have been proposed for the calculation of the Instantaneous Unit Hydrograph (IUH). The concept of series reservoirs is one of the methods to calculate and predict the flow Hydrograph in the catchment. Inverse gamma model is one of probability distributions, which depends on two parameters: n and k. And several formulas have existed for the estimation of the Inverse gamma’s instantaneous unit hydrograph. The accuracy of estimating the parameters n and k in Inverse gamma model directly affect simulation results. This study for the evaluating parameters of the Inverse gamma model used different methods such as moment, optimization and Rosso. The results showed that using optimization method in estimating parameters n, k had the most compatibility with the observed hydrographs. In all these methods, output runoff volume has been calculated with the error less than 11%. The optimization, Rosso and moment methods were successful in computing the time peak and the peak discharge. But in 5 rainfall event, the moment method, in computing the peak discharge has more than 50% of the difference with the observed value. Thus regionalization of Inverse gamma’s model parameters (n and k), by the mentioned methods, is advised for development and application of this hydrological model, in similar catchments..Several formulas have been proposed for the calculation of the Instantaneous Unit Hydrograph (IUH). The concept of series reservoirs is one of the methods to calculate and predict the flow Hydrograph in the catchment. Inverse gamma model is one of probability distributions, which depends on two parameters: n and k. And several formulas have existed for the estimation of the Inverse gamma’s instantaneous unit hydrograph. The accuracy of estimating the parameters n and k in Inverse gamma model directly affect simulation results. This study for the evaluating parameters of the Inverse gamma model used different methods such as moment, optimization and Rosso. The results showed that using optimization method in estimating parameters n, k had the most compatibility with the observed hydrographs. In all these methods, output runoff volume has been calculated with the error less than 11%. The optimization, Rosso and moment methods were successful in computing the time peak and the peak discharge. But in 5 rainfall event, the moment method, in computing the peak discharge has more than 50% of the difference with the observed value. Thus regionalization of Inverse gamma’s model parameters (n and k), by the mentioned methods, is advised for development and application of this hydrological model, in similar catchments.

Abstract The purpose of this study was to evaluate the Snowmelt Runoff Model (SRM) to estimate of daily runoff at Galinak hydrometric station in Taleghan watershed, Iran. In this study, the input variables of the model such as hydrology and meteorology variables and physical condition of the catchment area were calculated and a total of 72 pass from satellite images of MODIS was used to determine the snow cover area. Comparison of measured and calculated hydrographs was carried out using the efficiency coefficient of Nash-Sutcliffe (R2) and difference of volume percent (Dv). The R2 and Dv values were found equal to 0.95 and 2.07 percent in the calibration period and equal to 0.86 and 4.81 percent in the validation period for Galinak hydrometric station. The results show that the model proved to be an excellent alternative, performing high-quality daily snowmelt runoff prediction.

The purpose of this study was to evaluate the Snowmelt Runoff Model (SRM) to estimate of daily runoff at Galinak hydrometric station in Taleghan watershed, Iran. In this study, the input variables of the model such as hydrology and meteorology variables and physical condition of the catchment area were calculated and a total of 72 pass from satellite images of MODIS was used to determine the snow cover area. Comparison of measured and calculated hydrographs was carried out using the efficiency coefficient of Nash-Sutcliffe (R2) and difference of volume percent (Dv). The R2 and Dv values were found equal to 0.95 and 2.07 percent in the calibration period and equal to 0.86 and 4.81 percent in the validation period for Galinak hydrometric station. The results show that the model proved to be an excellent alternative, performing high-quality daily snowmelt runoff prediction.
The purpose of this study was to evaluate the Snowmelt Runoff Model (SRM) to estimate of daily runoff at Galinak hydrometric station in Taleghan watershed, Iran. In this study, the input variables of the model such as hydrology and meteorology variables and physical condition of the catchment area were calculated and a total of 72 pass from satellite images of MODIS was used to determine the snow cover area. Comparison of measured and calculated hydrographs was carried out using the efficiency coefficient of Nash-Sutcliffe (R2) and difference of volume percent (Dv). The R2 and Dv values were found equal to 0.95 and 2.07 percent in the calibration period and equal to 0.86 and 4.81 percent in the validation period for Galinak hydrometric station. The results show that the model proved to be an excellent alternative, performing high-quality daily snowmelt runoff prediction.
The purpose of this study was to evaluate the Snowmelt Runoff Model (SRM) to estimate of daily runoff at Galinak hydrometric station in Taleghan watershed, Iran. In this study, the input variables of the model such as hydrology and meteorology variables and physical condition of the catchment area were calculated and a total of 72 pass from satellite images of MODIS was used to determine the snow cover area. Comparison of measured and calculated hydrographs was carried out using the efficiency coefficient of Nash-Sutcliffe (R2) and difference of volume percent (Dv). The R2 and Dv values were found equal to 0.95 and 2.07 percent in the calibration period and equal to 0.86 and 4.81 percent in the validation period for Galinak hydrometric station. The results show that the model proved to be an excellent alternative, performing high-quality daily snowmelt runoff prediction.
The purpose of this study was to evaluate the Snowmelt Runoff Model (SRM) to estimate of daily runoff at Galinak hydrometric station in Taleghan watershed, Iran. In this study, the input variables of the model such as hydrology and meteorology variables and physical condition of the catchment area were calculated and a total of 72 pass from satellite images of MODIS was used to determine the snow cover area. Comparison of measured and calculated hydrographs was carried out using the efficiency coefficient of Nash-Sutcliffe (R2) and difference of volume percent (Dv). The R2 and Dv values were found equal to 0.95 and 2.07 percent in the calibration period and equal to 0.86 and 4.81 percent in the validation period for Galinak hydrometric station. The results show that the model proved to be an excellent alternative, performing high-quality daily snowmelt runoff prediction.

Abstract In this research, the biophysical potentials of agricultural crops were analyzed in Qazvin irrigation and drainage network using DSSAT crop models. These models were calibrated and validated using field data or proper input coefficients were selected for the crops without such data. Land Units (LUs) were extracted by overlaying soil mapping units (SMUs) and weather grids using GIS. Weather grids were mapped using Thiessen method assuming each unit as a homogeneous area. Crop growth simulation was carried out using the DSSAT crop models. For each crop, two irrigation regimes (surface and pressurized) and 2-3 planting dates were considered. The results revealed the difference of crop production for each planting date and irrigation regime. Among the major crops in the study area, the values of spatial coefficient of variation were mediocre for Wheat and Barley, but lower for Corn. In relation to Tomato, Soybean and Cotton, significant differences were found between LUs and this issue must be taken in consideration when determining cropping pattern. The index of time coefficient of variation can also be used as a measure of risk in relation to the studied crops. The results of this research can be used as inputs of a spatial planning support system (PSS).In this research, the biophysical potentials of agricultural crops were analyzed in Qazvin irrigation and drainage network using DSSAT crop models. These models were calibrated and validated using field data or proper input coefficients were selected for the crops without such data. Land Units (LUs) were extracted by overlaying soil mapping units (SMUs) and weather grids using GIS. Weather grids were mapped using Thiessen method assuming each unit as a homogeneous area. Crop growth simulation was carried out using the DSSAT crop models. For each crop, two irrigation regimes (surface and pressurized) and 2-3 planting dates were considered. The results revealed the difference of crop production for each planting date and irrigation regime. Among the major crops in the study area, the values of spatial coefficient of variation were mediocre for Wheat and Barley, but lower for Corn. In relation to Tomato, Soybean and Cotton, significant differences were found between LUs and this issue must be taken in consideration when determining cropping pattern. The index of time coefficient of variation can also be used as a measure of risk in relation to the studied crops. The results of this research can be used as inputs of a spatial planning support system (PSS).In this research, the biophysical potentials of agricultural crops were analyzed in Qazvin irrigation and drainage network using DSSAT crop models. These models were calibrated and validated using field data or proper input coefficients were selected for the crops without such data. Land Units (LUs) were extracted by overlaying soil mapping units (SMUs) and weather grids using GIS. Weather grids were mapped using Thiessen method assuming each unit as a homogeneous area. Crop growth simulation was carried out using the DSSAT crop models. For each crop, two irrigation regimes (surface and pressurized) and 2-3 planting dates were considered. The results revealed the difference of crop production for each planting date and irrigation regime. Among the major crops in the study area, the values of spatial coefficient of variation were mediocre for Wheat and Barley, but lower for Corn. In relation to Tomato, Soybean and Cotton, significant differences were found between LUs and this issue must be taken in consideration when determining cropping pattern. The index of time coefficient of variation can also be used as a measure of risk in relation to the studied crops. The results of this research can be used as inputs of a spatial planning support system (PSS).In this research, the biophysical potentials of agricultural crops were analyzed in Qazvin irrigation and drainage network using DSSAT crop models. These models were calibrated and validated using field data or proper input coefficients were selected for the crops without such data. Land Units (LUs) were extracted by overlaying soil mapping units (SMUs) and weather grids using GIS. Weather grids were mapped using Thiessen method assuming each unit as a homogeneous area. Crop growth simulation was carried out using the DSSAT crop models. For each crop, two irrigation regimes (surface and pressurized) and 2-3 planting dates were considered. The results revealed the difference of crop production for each planting date and irrigation regime. Among the major crops in the study area, the values of spatial coefficient of variation were mediocre for Wheat and Barley, but lower for Corn. In relation to Tomato, Soybean and Cotton, significant differences were found between LUs and this issue must be taken in consideration when determining cropping pattern. The index of time coefficient of variation can also be used as a measure of risk in relation to the studied crops. The results of this research can be used as inputs of a spatial planning support system (PSS).

Abstract Increasing the efficiency of the agricultural water pumping stations is important because of the high percent of cost and energy consumption. The performance of pumping stations in the evaluation of irrigation and drainage networks has been ignored up to now, whereas any impairment in pumping station will cause the destruction on priming and thereupon disruption of network performance. Since, there is not specific assessment for pumps' performance, therefore, in this study, a quantitative evaluation method named data envelopment analysis, was introduced and applied. In this regard, after the introduction of this technique and its various models, the performance of Sabili main station located in Khuzestan province was calculated during 2001 to 2010 with DEAP2 software. In this method, the average performance of Sabili main station was calculated 69 percent. This station had the highest efficiency in 2001, 2002 and 2010 (100 percent) and it had the lowest efficiency in 2009 (21 percent). Most of the inefficiency was due to the high cost of electricity consumption. Hence, maximum potential efficiency could be accessible with energy consumption reduction activities.
Increasing the efficiency of the agricultural water pumping stations is important because of the high percent of cost and energy consumption. The performance of pumping stations in the evaluation of irrigation and drainage networks has been ignored up to now, whereas any impairment in pumping station will cause the destruction on priming and thereupon disruption of network performance. Since, there is not specific assessment for pumps' performance, therefore, in this study, a quantitative evaluation method named data envelopment analysis, was introduced and applied. In this regard, after the introduction of this technique and its various models, the performance of Sabili main station located in Khuzestan province was calculated during 2001 to 2010 with DEAP2 software. In this method, the average performance of Sabili main station was calculated 69 percent. This station had the highest efficiency in 2001, 2002 and 2010 (100 percent) and it had the lowest efficiency in 2009 (21 percent). Most of the inefficiency was due to the high cost of electricity consumption. Hence, maximum potential efficiency could be accessible with energy consumption reduction activities.Increasing the efficiency of the agricultural water pumping stations is important because of the high percent of cost and energy consumption. The performance of pumping stations in the evaluation of irrigation and drainage networks has been ignored up to now, whereas any impairment in pumping station will cause the destruction on priming and thereupon disruption of network performance. Since, there is not specific assessment for pumps' performance, therefore, in this study, a quantitative evaluation method named data envelopment analysis, was introduced and applied. In this regard, after the introduction of this technique and its various models, the performance of Sabili main station located in Khuzestan province was calculated during 2001 to 2010 with DEAP2 software. In this method, the average performance of Sabili main station was calculated 69 percent. This station had the highest efficiency in 2001, 2002 and 2010 (100 percent) and it had the lowest efficiency in 2009 (21 percent). Most of the inefficiency was due to the high cost of electricity consumption. Hence, maximum potential efficiency could be accessible with energy consumption reduction activities.