مجله پژوهش آب ایران
پیاپی 33 (تابستان 1398)

A rising trend of the Earth’s temperature and changes in the associated weather conditions across the globe are referred to as climate change. In the absence of suitable mitigation and adaptation measures, climate change is likely to affect the world’s major sectors, such as agriculture, water resources. Climate change as a result of increase in atmospheric CO2 concentration and other greenhouse gases may have major effects on crops productivity in future. Climate change has direct impacts on hydrological process such as evaporation by water surface, plants’ transpiration, precipitation and temperature patterns and hence, may alter the crop water requirements. The performance of pressurized irrigation networks that are designed based on the past climate conditions, may be influenced due to the increasing water demand. Because of the increasing water demand, studying the impacts of climate change on water resources is necessary. The main objective of this study is to investigate the climate change effects on the management system and operation emitters’ hours in the pressurized irrigation network of Sattar Khan Dam. Future climate projections of Global Climate Models (GCMs) under different emission scenarios are usually used for developing climate change mitigation and adaptation strategies. However, the existing GCMs have only limited ability to simulate the complex and local climate features, such as precipitation. Furthermore, the outputs provided by GCMs are too coarse to be used in hydrologic impact assessment models, as these models require information at much finer scales. Therefore, downscaling of the GCM outputs is usually employed to provide fine-resolution information required for the impact models. Among the downscaling techniques based on statistical principles, multiple regressions and weather generators are considered to be more popular, as they are computationally less demanding than the other downscaling techniques. In the present study, the performances of a weather generator (called LARS-WG) are evaluated in terms of their ability to simulate the frequency of extreme precipitation events of the current climate and downscaling of future’s extreme events. To predict the climate change based on the General Circulation Models (GCMs), the LARS-WG tool for downscaling was used. The LARS-WG model was used to generate the temperature and rainfall data for future period under emission scenarios of B1, A2 and A1B. By using the LARS-WG and HadCM3 model with three emission scenarios of A1B, A2 and B1 in 2055 horizon, the temperature and precipitation were investigated. The LARS-WG can be used to synthesize daily data and fill in missing values of a recorded climatic time series. It can also generate data of an ungaged site for the daily climatic parameters, such as precipitation, temperature, and solar radiation (using observed data properties of a neighboring gaged site). It takes the long-term daily information of the climatic parameter of interest as the input for a site. It can also generate the changed climate’s scenarios for a site by perturbing the parameters obtained from the observed data to generate synthetic data, representing future climate change. The CROPWAT software has been employed in order to calculate the irrigation requirement. Further, the generated local climatic data of the future years were used as the CROPWAT model input to estimate the irrigation requirements for subsequent years. The CROPWAT model, developed by FAO Land and Water Management Division (FAO, 1992), is an irrigation management model to evaluate the crop water requirements and irrigation needs. Calculations of crop water and irrigation requirements are carried out with inputs of climatic and crop data. The climatologically data included are maximum and minimum temperature, mean daily relative humidity, sunshine hours, wind speed, precipitation and calculated values for reference evapotranspiration and effective rainfall. The results have shown a rise in temperature and reduction in precipitation. In the other part of the research, based on these predictions, the CROPWAT software has been employed in order to calculate apple irrigation requirement. The results showed that the apple irrigation requirement have increased over baseline under three emission scenarios that are affected by temperature rise and reduced rainfall in the watershed. By increase in temperature and crop water requirement in the basin, and decrease in precipitation, the necessity of the system’s management reforming was determined that increasing the irrigation time is suggested as a possible solution. The results showed that the system operation hours in the watershed over baseline under three emission scenarios, have increased 10.28 percent.

Scouring around water structures, like resting basin, is one of the major issues which designers are always facing. Figure 1 shows the local scouring below the resting basin with a positive step in the Cybercrime deviation dam on the Agri River in Southern Italy (Huger, 1992). Different people have studied the factors affecting the scouring phenomenon in the downstream of resting basin. A study on the effect of floor blocks on hydraulic jump characteristics is done by Habibzadeh et al.(2011 and 2012). In his research, he investigated the effects of various parameters such as block dimensions, block distance from the gate and Froude number. The results showed that as the floor blocks slip away, the jet outlet valve changes; from the formation of the reverse wall jet stream (RWJ), only the diverted surface jet (DSJ) is formed. In the present study, the effect of floor blocks and block spacing from the drainage duct under different flow conditions on scouring the downstream of the resting basin was investigated. The experiments were done at the Hydraulic Laboratory of Hydraulic Structural Engineering Department, University of Tarbiat Modares. The flume used was 0.95 m wide, 1 m high and 12 m long. In order to observe the flow, the right wall of the flume was Plug-Glass and the left and bottom walls of the flume were made of concrete. To pump the water into the flume, an electric pump (type 125-200) was used, which was made by Iranian Pump Company. To regulate the flow rate, a coupling system was used to create a variable speed on the electromotor of the pump. To measure the flow rate, a leftover overflow was used at the flume end. The tailpipe depth was adjusted using a recessed overflow. The depth of water on the resting basin, downstream of the drainage door, was measured using a 0.1 mm precision point height. The moving bed topography was also harvested using a laser meter with a precision of 1 mm in a 5 ×5 cm network. In order to create a hydraulic jump, the sliding door made of Plexiglas sheet at a height of 0.75 m and a width equal to the flume width, at 4 m far from the beginning of the flume, is designed. The flume width decreased by 0.62 m using the ionolyte blocks and the outer surface was covered with vitrified glass. Due to the complexity of the scouring phenomenon, the factors affecting the scouring phenomenon are too many. Due to the experimental limitations in the study, it was impossible to investigate all effective factors. For example, with the provision of full turbulent flow conditions, the effect of the Reynolds number is ignored. Whereas, the gravity acceleration parameter (g) and the Froude number are considered. Research on all effective factors is impossible. Therefore, the effect of some parameters can be evaluated using the dimensional analysis technique and the recognition of effective parameters. It should be noted that the variable parameters in the present research are the Froude number, relative depths and block distance from the gate. Regarding three replications for each variable, 27 of the main tests and eight control tests were performed in the unblocked state; generally, 35 experiments were carried out in the present study.An experimental study was conducted to investigate the effects of baffle blocks on the geometry of scour hole downstream of sluice gate- stilling basins. The dimensional analysis was used in order to determine effective variables and their quantitative impacts. Results show that the inclusion of floor blocks has significant effect on the scour hole geometry. By increasing the blocks distance from the beginning of the gate, the scour hole dimension decreases; and after some distance, the scour hole shape is also affected. The change of the blocks distance from the gate, from 0.18 to 0.54 m, results in a 85% decrease in scour hole volume. Furthermore, the scour hole volume is definitely related to the Froude number, but it does not have a determined relationship with the relative tail water depth. The minimum volume of scour hole occurs for the blocks distance of 0.36 and 0.54 m, and with the relative tail water depth of 6.3.

The present study demonstrates a method in groundwater quality assessment using the Empirical Bayesian Kriging and Moran Spatial Autocorrelation Index. In this study, concentration of Arsenic, Lead, Iron, Manganese and Nitrate and also groundwater table and Total Dissolved Solid has been measured for 21 point in Azarshahr Plain (East Azerbaijan). Azashahr study area is one of the Lake’s twelve adjacent aquifers that is located between 45°,46’ to 45°,50’ longitudinal and 37°,43’ to 37°,52’ latitudinal. Its total area is about 457 km2, that its plain has an area about 124 km2. The highest and lowest heights in the study area are 3700m and 1282m, respectively. Its average annual precipitation is about 221.2 mm whereas the average annual evaporation is about 1579 mm. The most important stream in Azarshahr Plain is Azarshahrchai which has a southeast-northwest trend and is eliminated before reaching to the lake because of wide agricultural usage. On the other hand, the total annual discharge of aquifer is about 90.64 million that is one of the groundwater depletion and decreasing the quality of groundwater factors in the study area. Moran’s I is a commonly used indicator of spatial autocorrelation. In this study, the Moran’s I was used as the first measure of spatial autocorrelation. Its value ranges from −1 to 1. The value “1” means perfect positive spatial autocorrelation (high values or low values cluster together), while “−1” suggests perfect negative spatial autocorrelation (a checkerboard pattern), and “0” implies perfect spatial randomness. After that, the appropriate weight has given to the aforementioned parameters, considering the international standard of water quality and spatial autocorrelation index of each of them. After determining the layer rules, the Expert Choice software was applied to calculate the comparing binary matrix of analytic hierarchy process. After that, the final weight for each layer with inconsistency of 0.08 was derived that is less than 0.1 and acceptable. In the conventional geostatistical approaches for interpolation and kriging, the variance structure is estimated first, and then the estimated variance is used for interpolation that whereas a Bayesian approach to the interpolation of spatial processes will provide a general methodology for taking into account the uncertainty about parameters on subsequent predictions. The Bayesian approach generalizes automatically to the case which the variogram parameters are unknown, whereas the classical approach essentially makes the assumption that these are known and only deals with the question of uncertainty of model parameters in a very peripheral way. Then replacing the popular interpolation methods, the Empirical Bayesian Kriging prediction method has utilized to expand every parameter to the whole plain. In order to evaluate the prediction results, the cross validation method was used. The study area was divided to 4 sections, as desirable, acceptable, moderate and non-acceptable. The final obtained map reveals that desirable quality is just located in the southeast of the study area in the upstream of the groundwater input. The acceptable quality of the groundwater is located in the east and southeast of the study area. The center, west and northwest of the study area has a moderate quality. The groundwater in the north, northwest and southwest of the study area has a non-acceptable quality that seems due to anthropogenic activities, especially agricultural and industrial during the recent years. On the other hand, the spatial autocorrelation model of effective parameters on water quality in the on hand and Bayesian kriging method with its precise assessment and prediction in some areas without data have a high applicability. The cross validation technique in model accuracy approving, is a valuable tool. Every three methods played an important role in modifying and improving the analytic hierarchy process of the groundwater quality assessment in the study area. The resulted map revealed that the groundwater quality of the east and southeast of the study area are desirable and acceptable with about 32.53 and 44.38 km2, respectively. The center and west section with area about 69.32 and the north and southwest with area about 27.21 km2 have a moderate and non-acceptable quality, respectively. Upon to the analytic hierarchy process of the groundwater quality assessment of the Azarshahr Plain, it has been revealed that 16 percent of aquifer has non-acceptable quality, about the 40 percent has moderate quality and other has an acceptable to desirable quality in the study area. The result of this study has shown the necessity of the groundwater quality precise monitoring in the study area.

A non-linear spillway is appropriate and acceptable as an economic structure with high efficiency. This hydraulic structure is applied in the dams and irrigation networks as an appropriate option. Effective discharge of the non-linear spillways such as labyrinth weirs increases up to 3 or 4 times of linear spillways in the constant width channels. The Piano keys weirs (PKW) are special forms of labyrinth weirs which were conducted by the Institute Hydrocoop in France. There are several types of piano key weirs that their difference is about upstream and downstream sloped faces. In this research, type “A” of PKW has been studied. In addition, in accordance with previous studies, the inlet pier shape is one of the effective factors on piano key weirs performance. Because the triangular pier has the best hydraulically performance at the many physical models, in this research we have chosen the triangular shape of piers. As has been shown in the previous studies, piano key weirs have relatively high discharge capacity at low head. So that in high head, spillway efficiency is decreased due to submergence in the start of outlet key. According to the literature review there are no studies in field of discontinues parapet wall. In this research, this object has been investigated and the results are compared to continue case. In this research, parapet wall with various slopes have been used that B́ = (0.25, 0.5, 0.75 and 1.0) ×B where B is the entire key length. This object was done to reduce submergence of spillway entrance. To achieve these purposes in addition to sloped parapet walls, the un-sloped parapet walls with discontinues conditions in part of inlet and outlet keys were used. Experiments of this research were done in physical and hydraulically laboratory of Shahid Chamran University (SCU) on a flume with 10 m length, 0.8 m width and 0.6 m height. The walls of the flume are made of glass and its floor is made of stainless steel. However, the bottom slope of the flume was zero. On the base of hydraulic requirement a type A of piano key weirs was designed and built with 3.5 cycles and geometrical ratio, P/Wu, equal to 1.33, relative length, Bi/Bo, 1 and relative width, Wi/Wo, 1.5. The discharges and its head of water were measured after the weir installation and the models of parapet walls on the weir crest. The upstream water level was measured by point gage and flow discharge was measured by calibrated rectangular weir where it was placed end of the flume. However, 22 various models of parapet walls were tested that are described on three categories: 1-piano key weir without any parapet wall as control experiment, 2-unsloped parapet walls (2.5, 3.5 and 4.5 cm height) with discontinues on (a): side crest (b): side crest and inlet key crest (c) entire weir crest and 3-sloped parapet walls in three heights ,2.5, 3.5 and 4.5 cm, with length B́ where B́ = (0.25, 0.5, 0.75 and 1.0) ×B. After accomplishing the tests and gathering data, in order to analyze discharge coefficient, the general equation of weirs was used. According to discontinues of parapet walls, the modified equations were used to calculate the theoretical discharge. The results show that sloped parapet walls on side crest have a little effect on spillway efficiency and could not prevent turbulence and interference flow jets. However, parapet walls with constant height have more effect. Un-sloped parapet walls with discontinues on the inlet and outlet key crest improved the weir efficiency in the high head water. So in the parapet wall with 4.5 cm height, discharge coefficient increased up to 34 percent (rather than control test) with discontinues in outlet key part and high head water. Due to increasing flow volume in outlet key and decreasing of inlet friction (due to discontinue parapet wall), the discharge efficiency increases. Finally, a statistical relationship with suitable regression coefficient using SPSS software was derived for prediction of discharge coefficient. This relationship with upstream Weber Number less and more than 50 were extracted. Moreover, the results of this research were compared to previous studies and it was found that the sloped parapet wall with discontinues in inlet and outlet keys improve the discharge coefficient

Interaction between both centrifugal force and pressure gradient in river bends and the resulted vortex and spiral flows, causes erosion in outer bank and deposition in inner bank, which in turn, leads to gradual change in river form. Spur-dikes are among those structures which, through improving flow pattern and reducing secondary flow power, control and reduce erosion in river bends. But, as a result of reduced flow cross section and making strong vortices, they themselves are subject to scour. The rate of scour around spur-dikes depends on various factors such as permeability and their position angle, with respect to flow direction. In this study, the effect of the successive permeable spur-dikes position angle in three states of absorbing (120 degree), vertical (90 degree) and repulsive (60 degree) for mild 90° bend has been investigated. In order to achieve this goal, experiments were conducted on 33% permeability spur-dikes and effective length equal to 20% of flume width with four Froude numbers 0.21, 0.23, 0.26 and 0.28. Distance between the spur-dikes in all experiments was constant and set at 4 times of the spur-dikes effective length. Flow was induced in the flume after structures were installed and sediment bed was graded. To start the flow, first, the sliding valve at the end of the flume and drain valve were tightly closed. When the water level was raised, the water depth was maintained at 14 cm by opening the end sliding valve and increasing the flow to the expected amount. The starting point of the experiment was when the water level was steady at the specified depth. After three hours, the end valve was closed, the flow was stopped, and the sediment bed was completely drained. Then, the bed topography was surveyed via laser gauge. Gathered data from the experiments and surveying of the bed topography, were analyzed using “Surfer” software. To investigate changes in the scour dimensions due to position angle, the spur-dike which the highest sour occurred on its peripheral sides, was considered as the critical spur-dike. In all experiments, the critical spur-dike position was at an angle between 80 to 90 degrees of the bend or at the straight path toward the outlet. After the critical spur-dike was indicated, the scour dimensions on its peripheral sides were studied. Results indicated that among three angles of 60, 90, and 120 degrees, the 60 degrees (repelling) spur-dike had a better performance regarding the spur depth, comparing with 90 degrees and 120 degrees, and in all cases had the lowest scour depth, in a way that the maximum scour depth in Froud number 0.28 was 0.54 times of the flow depth in absorbing condition, where this value was 7.4% more than vertical position, and 11.1 times more than repelling condition. The maximum scour length belonged to 60 degrees (repelling), and the minimum length was related to 120 degrees (absorbing). The maximum scour length in Froud number of 0.28 was calculated 1.92 times of the flow depth for repelling condition, where this was 9.2 times more than vertical position, and 14.8% more than repelling condition. The highest value of scour width belonged to 60 degrees (repelling), and the lowest amount of width was related to 120 degrees (absorbing). The maximum scour width in Froud number of 0.28 for repelling case was calculated 2.35 times of flow depth, which was 6% more than vertical position and 15.1% more than absorbing condition. It was observed that with an increase in Froud number, the scour dimensions in all three repelling, vertical and absorbing states were also increased. This could be explained by the fact that since greater Froud number implies increase in flow velocity and thereby higher shear stress exerted by the flow, hence the flow impinges more rigorously and at a higher velocity on the spur-dikes, resulting in more severe scour. Based on the results of this study, it can be concluded that the maximum scour depth was occurred when the spur-dike was positioned in absorbing condition, and the minimum depth was related to placing the spur-dike in repelling condition. Also, the maximum scour length and width belonged to repelling condition, where the minimum values referred to absorbing condition. Finally, higher Froud number in all cases resulted an increase in the scour dimensions.

Modeling the erosion and sediment transport is one of the major problems which discussed in river engineering projects such as river intake and dam construction. In some cases, careless estimation of the river sediment load causes failure of river engineering projects. Bed load of the river sediment is one of the main parameters for assessing the stability of river form and evaluating the river power flow. The bed load measurement has much more difficulty in comparison with the suspended load, so measuring the sediment load of rivers is limited to the suspended load measurement. Estimating the river sediment load is conducted with study on the river hydraulic, flow regime, river morphology grading materials of the sediment load. Control and minimization of defection to the hydraulic structure caused by the river sediment load needs to define the river flow regime, sediment motion, erosion and degradation mechanism. The erosion in river has several effects on the river flow regime such as descending the water surface elevation that may cause a decrease in the efficiency of hydraulic structures such as intakes and pump stations. River management, regarding to the sediment transport conditions, causes an increase in the operation period. Study on the sediment transport in rivers are usually conducted with laboratory experiments and field study. In this regard, due to the high cost of experiments and field study, researchers attempt to model the sediment transport using the mathematical approaches. In order to achieve the purpose, the flow equations for rivers such as Saint Venant equation is coupled by sediment transport equations such as Akers-White, Englund-Hansen, Laursen, Meyer-peter Muller, Tofaletti (field and laboratory) and Yang, and numerical is solved by advanced numerical methods. Free or commercial powerful software packages have been provided in order to facilitate the use of mathematical approaches. Mike 11, as commercial software, and HEC-RAS, SSIM, FLUVIAL and GSTARS, as free software, could be mentioned. Several studies are done using free software packages such as HEC-RAS. Jabary et al (2014) used the HEC-RAS software to model the sediment transport in Abhar River. They stated that the Yong formula is more accurate among the other empirical approaches to model the river bed elevation. They considered the graded material of sediments, river cross sections and flood hydrograph with 25 years return period as input parameters for the model. They stated that the HEC-RAS model has suitable performance for modeling the sediment transport in Abhar River. Alami (2003) used HEC-6, River Intake and GSTARS-V2 to model the sediment transport in reservoir of dams and stated that the GSTARS is more accurate in comparison with the other software packages. Seyedian et al (2006) used the GSTARS-3 to model the sedimentation of river load in the Voshmgir Dam and predicted the volume of sediments for the next seven years. Shahinejad et al (2009) used the GSTARS-2.1 to model the morphological variation of Karun River within the Ahvaz City. They evaluated the river bed elevation for the next seven years. Due to high important effects of modeling the river sedimentation on the success of river engineering projects, modeling the sediment transport in Telvar River using the GSTARS-3 is considered in this paper. The Telvar River is a main river in the Kordistan Province, western Iran. The catchment area of the Telvar River is about 147 Km2 and about 26.1 Km of the river was considered as case in this study. The GSTARS was developed by Molinas and Yang (1985) to model the alluvial rivers, this model has been modified with Yang et al (2006) and nowadays the GSTARS-4 is the last version of the GSTARS. The GSTARS is in involved four parts: First, using the energy and momentum equations for the water surface calculation. Second, using the concept of flood routing for routing the river sediment load. Third, using the concept of intensity of energy losses, in other words, using the minimum power flow theory for modifying the width and depth of flow and fourth, evaluating the Criteria of slope stability. The GSTARS included 14 equations for modeling the Non-cohesive sediments. The aim of this study is analyzing the longitudinal erosion of the river bed and also evaluating the cross section width variation and at the end, selecting the suitable empirical formula which has suitable performance for modeling the case study area. The model validation was conducted by a trial and error process because of evaluating the erosion such as sedimentation depends on the empirical formula and graded material curve. Therefore, a number of formulas which had more suitable performance were selected. During the model validation process the result of model was compared with the measured data which was recorded at the 2013 and found that the Yang method is more suitable for modeling the river bed elevation. The results of this study showed that the GSTARS model has suitable performance for modeling the erosion and sedimentation in the Abhar River, and this software can be used for modeling the cross section erosion and finding the area which has high potential for erosion and sedimentation.

Nowadays, environmental pollution, especially water pollution, is rising as a consequence of advances in technology and raise in life standards. Since the environmental contaminants cause different kinds of problems, it has drawn the majority of scientist and politician’s attention to itself. Industrial, agricultural and house hold pollutions are increasing due to the human activities holding modern technology in advanced countries. Since water is the most vital and essential stuff for living things, it is highly essential to keep it from contamination. According to the purposes of the study, in the current step, the physical model was built in the S.C.U.O.A hydraulic laboratory. Therefore, the parameters are presented dimensionless. The experiments were performed to measure the trajectory centerline concentration at 15, 30 and 60 g/lit concentrations and to analyze the dispersion limits at 5, 8 and 15 mm diameters at 15, 30 and 90 convergence angles. The model is consisting of: 1. Water supply and pumping system 2. Jet injection reservoir and mixture pump to homogenize the jet fluid 3. Experiments on flume and jet injection pump 4. Fluid conveyance system 5. Drainage system equipments 6. The jet setup at various convergence angles at initial 5, 8 and 15 mm diameters. The equipments needed for various parameters measurement include accurate flowmeter for the jet flow discharge measurement [0.2 percent accuracy], portable digital EC meter [0.1 microsimence/cmAccuracy] to determine the EC, flume water and reservoir Nacl instantaneous temperature. Additionally, at every 15 cm, an accurate ruler at 1 mm accuracy and 1 meter height was vertically attached. Linear rulers printed on transparent greaseproof paper were attached on the body of the flume. During the experiments, receiving fluid is conducted to the flume through pump and supply reservoir and it fills the flume at a certain height. The jet flow is discharged into the receiving fluid surface exiting in laboratory flume through the injection reservoir relevant pump and the jet circular nozzles subsequently. A ceratain volume of salt was conducted the jec flow injection reservoir which was cube-shaped. A water solver colorful material was used to determine the Nacl direction through the receiving fluid. The jet fluid density was measured standardized by buoyancy method calculations and laboratory measurements by mean of a 151H accurate hydrometer. When the trajectory was completed, the data were read from the rulers and photos were photographed by canon camera, model hs50SX, simultaneously. To make sure the measurements accuracy, both data and photographs were compared. In this part, we render our findings dense flow by means of circular superficial jet affected by the convergence angle. The flow centerline concentration was measured through trajectory by digital EC meter and salinity concentration relation. The dense flow superficial discharge, outlet flow progress by momentum horizontal force and buoyancy vertical force at receiving area. At the primary segment of the flow, on account of the momentum force velocity, the flux will be horizontal and adjacent to the water surface. As its impact force reduces, the jet flow progress velocity decreases. In this case, the buoyancy force overcomes the momentum force and flow is no longer adjacent to the water surface and turns to a submerged state. As the jet nozzle angle increases, the momentum force which makes the flow to progress increases. It makes the jet flow move and doesn’t allow dispersing and displacing the salt particles and receiving fluid moleculy. According to the results, 90 degrees possesses the most concentration. At this angle, the flow lines momentum is maximum due to sudden shock to convergence angle which initially causes the proportion of centerline concentration at an equal situation for every three angles to be maximum at 90 degrees. As the buoyancy force increases, the curve decreases and leads to the flow diffusion which itself decreases the centerline concentration of the curve. Finally, the concentration degree will be equaled for every three angles at the impact point and it approaches to receiving flow concentration. The experimental data analysis showed that the dense fluid concentration increase from 15 to 60 g/lit increases the concentration by 52 percent through trajectory centerline. Also the concentration through the trajectory centerline increased to 27.5 percent by mean of contraction angle change from 15 to 30 degrees. While contraction angle increases from 15 to 90 degrees, the concentration through trajectory centerline increased to 73 percent. Statistical comparison of the data showed that the concentration through trajectory centerline increase from 30 to 15 kg/m3 reduces 12.5 percent and concentration through trajectory centerline increase from 60 to 15 kg/m3, reduces 37.7 percent , during the advance of stream profiles.

Considering the importance of precipitation and scarcity of water resources, spatial analysis of daily rainfall together with corresponding time intervals is one of the requirements. Among the atmospheric factors affecting the rainfed farming, precipitation is the most important factor in numerous studies about the rainfed cultivation. In order to reduce the destruction threat of water resources and resolve the future’s food needs of the people, the importance of rainfed agriculture would be inevitable. In this regard, one of the effective measurements that can be done to find rainy areas with the possibility of rainfed cultivation. The greatest water consumption is corresponding to the agricultural sector. According to the water crisis in the country, decline in the groundwater levels and the importance of agriculture in job creation, the water resource management is essential. Therefore, it will have a value of higher management to determine for the fertile lands in the current situation. Despite the reduction in rainfall, it is also necessary to analytically study the rainfed and determine the fertile lands in the country, especially in the Urmia Lake basin. This study aimed to introduce an index for identification of the suitable areas from the viewpoint of rainfed ability, by using daily rainfall in corresponding with the time intervals for each year in the east part of the Urmia Lake basin. First a program is written in Fortran, using the rainfall data, the proportion of rainfall intervals is determined, then the Fortran program is developed for this propose, based on the concept of the temporal intensity precipitation and their related mechanistic, an index is defined which is the main outcome of the Fortran programming. The index was a criterion for analysis and disintegration of the rainfed quantity. The idea of introducing an index is based on the ratio of rainfall to the interval corresponding. If the ratio quantity was high, it represents the water supply, in other words, the rainfed capability will be great which can play the role of an index rating. In this index, the rainfall depth has positive role and intervals have negative role in the assessment. When the index amount is high, the rainfed capability will increase. Because the amount of precipitation must be bigger (which is the sign of the large amount of rainfall or the smaller interval time) an increase in the amount of rainfall would be followed, or in compound, causes an increase in the proportion, which shows the increase of rainfed ability. The statistical period was 1992-2014 for 23 rainfall stations. The index values were calculated for each year of all stations. Clustering is one of the most useful classification methods. In the cluster analysis, one attempts to actual observations of each cluster, which have the most similarity in terms of variables together. In this study, the clustering methods of the K-Means and Ward were carried out to deline the homogeneous regions based on the developed index values. Clustering in the rainfall stations was considered as a variable, the correlation matrix 23 * 23, where 23 is related to the number of the years stations used. The homogeneity of the clusters were checked through the H-Statistics method and the homogeneous clusters were shown in the GIS environment. In order to use the K- Means method, the whole study area was considered as two clusters and the results of the H-Statistics homogeneity test showed that the two clusters are homogeneous. The first cluster has a mild homogeneity while the second one is completely homogeneous. In the clustering index using the Ward method, the study area was divided into two clusters. The observation of thehomogeneous clusters with the H-Statistics homogeneity test showed that the both clusters are mild homogeneous. On the other hand, from the viewpoint of spatial variation, Iso-Index lines were drawn over the study area. Identifing the rainy areas was conducted by examining the lines of these areas w are suitable for the rainfed agriculture and have a better temporal rainfall distribution. The comparison of two maps regionalization with two methods and the Iso-Index lines show that the regionalization by K- means method, the first part of this regionalization with Iso-Index lines have the same incremental direction, that suggests more rain stations in this area in comparison with the second area. The second cluster of homogeneous region was obtained using the Ward method, having similarity with Iso-Index only in the limited stations. The comparison of the regions resulted from clustering methods with the spatial distribution of the Iso-Index lines over the study area implied that the K-Means method isolated the regions better than the Ward method. The results show that the south, northeast, northwest and the center parts of the study area were more eligible for the rainfed agriculture than the other parts. These areas, regarding to agriculture, temporal distribution of precipitation and richness of groundwater, are better.

Due to water shortage, increasing production by increasing cultivation area is limited in arid and semi-arid regions and approach to optimize the use of rainfall and limited irrigation to be considered, in order to increase water productivity. Development of rainwater harvesting systems and supplemental irrigation can be effective in increasing semi-irrigated cultivation area and decreasing water shortages. Rainwater harvesting is defined as a method for inducing, collecting, storing and conserving local surface runoff for agriculture in arid and semi-arid regions. The supplemental irrigation in condition which rainfall alone cannot have a good performance can be effective to improve the yield. The objective of this study was to investigate the effects of rainwater harvesting system and supplemental irrigation on water productivity index in winter barley (Hordeum vulgare L. Var. Abidar). A field experiment was conducted in a semi-arid region at Research Field of Tarbiat Modares University, located 16 kilometers of west of Tehran, Iran during the 2011-12 growing season. The land was located at 5110  E. longitude and 3535  N. latitude, at a height of 1269 m above the sea level. In order to cultivation, first it was attempted to plow to a depth of 30 cm, formed lumps were compacted using disc ,then seeds with a density of 130 kg per hectare were planted in furrows at 20 cm intra-row space and finally seeds were covered by soil using trowel so that the depth of cultivation was 4-5 cm. The size of each plot was 3×6 m considering the catchment and cultivate area ratio was 1:1. The experimental plots spacing were 1 m apart to avoid side effects. The maintenance of barley plants during the growth season was made by removing the weeds and applying fertilizer urea at a rate of 85 kg/h (half at the seeding and half in the spring). During the planting season, it was attempted to remove the weeds over the rain water harvesting catchment. The supplemental irrigation was applied during the grain filling stage. The volume of applied water was calculated based on the soil moisture deficit up to a depth of 45 cm. The amount of applied water in each plot was measured using the flow meter. The experiment was a split plot in a randomized complete block design with three replications. Irrigation treatments at five levels (twice with water, twice with treated municipal wastewater, once with water, once with treated municipal wastewater and without irrigation) as main plot and rainwater harvesting surface treatments at three levels (compacted, incompacted and natural surface soil) is defined as sub-plots and rainfed was defined as control. The analysis of variance was carried out using the generalized linear model (GLM) and after ensuring, normal distribution of residuals was tested using the SAS software. The comparison of treatment means was made using the least significant difference (LSD) at the level of 0.05. The results indicated that the use of rainwater harvesting system had increased the yield and the total water productivity in comparesion with the rainfed condition. The supplemental irrigation maximized the total water productivity (in grain and biomass yield) and increased significantly (by 6.3% and 13.2%) compared with non-irrigated plots respectively. The compacted surface plots had significantly higher values of the total water productivity in grain and biological yield (15.8% and 14.9% respectively) in comparesion with natural surface treatment. There was no significant effect of supplemental irrigation with treated municipal wastewater on the yield and yield components. The use of compacted catchment in the rainwater harvesting system caused an increase in the number of spikes m - 2 and the application of the supplemental irrigation during grain filling stage could increase the thousand grain weight by increasing the grain filling period, resulting in the desired yield. Applying the supplemental irrigation by treated municipal wastewater made the renewed pressure not exert on the surface and groundwater resources for the production of crops. Using this project can be helpful for the lands beside the smaller cities and rural areas, where there is not possibility of sustainable rainfed farming, to be planted using rainwater harvesting system and to be irrigated supplementary by the treated municipal wastewater

Due to its especial geographic condition, Iran, as a semi-arid country, suffers from water shortage for domestic, industrial and agricultural usages. As limited water supplies, the use of non-conventional water resources, such as industrial or municipal wastewater, is a common practice in many parts of the world including Iran. It is estimated that at least 20 million hectares in 50 countries are irrigated with raw or partially treated wastewater. Also, it is estimated that the potential volume of wastewater in urban and rural areas of Iran will be 4369 and 823 million m3, respectively. On the other hand, the use of sewage sludge in agricultural soils has been widespread in many countries around the world, also in Iran. The use of sewage sludge in agricultural has been shown to improve the soil’s characteristics such as organic matter, nutrients, porosity, aggregate stability, bulk density and plant productivity. Despite the growing interest in wastewater and sewage sludge usage, excessive use of them may have some harmful effects such as human health problems, runoff and leaching of nutrients to surface and groundwater, undesirable chemical constituents, pathogenesis, accumulations of heavy metals in plants and soils, negative environmental and health impacts. So, wastewater and sewage sludge use should be under controlled conditions to minimize the health risks of pollution to agricultural products, soil. Heavy metals are extremely persistent in the environment; as they are non-degradable and thus, readily accumulated at toxic levels. Metals can also accumulate in the soil at toxic levels due to long term use of wastewater. There is potential for inorganic nutrients and heavy metals present in wastewater and sewage sludge that transfer in the soil column and pollutant surface and groundwater. Today, medicinal plants are cultivated commercially in the polluted environments where soil, water and air contain rather high levels of pollutants. These plants appear to be a good choice for phytoremediation since these species are mainly grown for secondary products (essential oil) thus, the contamination of the food chain with heavy metals is eliminated. Aromatic and medicinal plants also have a demonstrated ability to accumulate heavy metals. The Mint (Mentha spicata) is a medicinal plant which has received considerable economic importance due to the large demand for its essential oil in food, pharmaceutical, cosmetic and hygiene industries. The purpose of this study was to determine the leach of heavy metals (Zn, Pb, Niand Cd) from the wastewater and sewage sludge to the soil column under Mint cultivation. This study was conducted at the Bu-Ali Sina University greenhouse located in Hamedan, western Iran. The experiment was run in May 2015- February 2016), including 5 months for soil preparation (in lysimeters) and 5 months for crop cultivation and harvesting. To evaluate the use of wastewater and its sewage sludge on on transferring heavy metals in soil column under Mint cultivation, a factorial experiment based on completely randomized was designed with three replications in 27 lysimeters. The factors included three types of watering: tap water (W1), raw wastewater (W2) and treated wastewater (W3), and three sewage sludge levels: 0 (S1), 50 (S2) and 100 tha-1 (S3). Therefore, 9 treatments (W1S1 to W3S3) were considered for investigation. 27 volumetric lysimeters were applied as cultivation beds (26 × 30 × 30 cm). The soil had two layers: the upper layer (0 to 50 cm) with sandy loam texture, and the bottom layer (50 to 110 cm) with sandy clay loam texture. After beds preparation, Mint (Mentha spicata) was planted in them. The raw and treated wastewaters as well as sewage sludge were prepared from wastewater treatment plant of Hamedan. Overall, 13 irrigation programs with 10-day intervals were applied. Zn, Pb, Ni and Cd concentrations in leachate were measured after each watering. The results showed the effect of watering and sewage sludge on heavy metals concentration of drainage water was statistically significant. Also, the result showed that wastewater and sewage sludge increase all (except Cd) leached heavy metals comparing to the control. In all treatments, concentrated Zn, Pb, Ni and Cd in the soil profile ranged from 0 to 1.66, 0 to 0.05, 0 to 0.05 and 0.0 to 0.0 mg/l, respectively. The concentrations of all heavy metals in drained water, was very lower than the FAO standard. By performing continuous irrigations, the trends of heavy metals (zinc, lead and nickel) were irregular schema (especially the use of wastewater and sewage) at different times. The first five irrigations showed an upward and the others showed a downward path.

The structure of turbulent flow over the scour hole is important for understanding the sediment particle entrainment and transport. In the present study, stochastic nature of turbulent flow around a bridge pier under a clear water regime has been investigated experimentally. Inside the scour hole, near the bed, the flow does not have enough energy to transport the particles; hence, the sedimentation occurs in this region. The particles in the scour hole near the bed are lifted up, however, they cannot move along the flow and finally they return to the bed. By comparing depth average values of the occurrence probabilities at the pier upstream, it was found that the sweep events probability is more than other events, which followed by ejection, outward and inward interaction. Since the sweep events are dominant phenomena at the pier upstream, the maximum scour depth takes place at this region and the eroded sediments are transported heading downstream. Scour is a natural event caused by the erosive action of flowing water on the bed and banks of streams, which also takes place on region near the bridge piers and abutments. The stochastic nature of turbulent flow around the bridge pier has been investigated only in handful studies; therefore, the precise effect of pier on sediment transport is yet unclear. Kline et al. (1967) have introduced the concept of bursting phenomenon as a mean to describe the momentum transfer between the turbulent and laminar region near the boundary. Lu and Willmarth (1973) introduced the quadrant analysis for studying the the bursting phenomenon structure. The quadrant analysis was employed to determine the occurrence frequency of each individual event within a bursting process, i.e. outward interactions, ejections, inward interactions, and sweeps. Jafari and Keshavarzi (2010) investigated turbulence flow and sediment entrainment over the ripples by using quadrant analysis. However, despite the importance of coherent structures of turbulence and in particular the bursting events around the bridge pier; their characteristics have not been investigated in detail. Since the quadrant analysis is a powerful technique to recognize the structure of the bursting phenomenon and consequently to find the susceptible regions for sediment entrainment and deposition, this technique is considered in the present study to investigate the coherent structure of turbulent flow in scouring process around the bridge pier. The experiments were carried out in a smooth rectangular flume with 8 m length, 0.4 m width and 0.6 m height. The channel entrance was filled with sand in order to generate fully developed flows. The working section, in which piers were located, was 1.6 m long with a 0.15 m recess on the bed and was located 4 m downstream from the flume entrance. The recess was filled with 0.72 mm mean particle size uniform sediment and the standard geometric particles deviation was 1.12 mm. Uniform sand, having the same size as that used for the scouring test, was glued over the false floor. The velocity profiles were measured around the bridge pier. In each vertical profile at least 20 points were measured within the flow depth from the bed. The ADV readings were taken when the scour hole was at the equilibrium condition. The variation of the fractional contributions, |Si, H|, as a function of the hole size H for each of the four quadrants at z/h=0.2 (near the scour hole edge) at the up and downstream of the pier are shown in Fig. 1. At z/h=0.2, quadrant (II) and (IV) events are dominant and quadrant (I) and (III) events appear to contribute weakly to the Reynolds shear stress production. Generally, by increasing the hole size, the contribution of each event to the Reynolds shear stress generation becomes small. As indicated in Fig. 1, at the pier upstream at z/h=0.2, ejection (|S2,0|≈0.8) is the dominant event which is followed by sweep (|S4,0|≈0.6). The sweep contribution tothe Reynolds shear stress production becomes negligible for H>10, whereas the ejection contribution is significant even at H>20. On the other hand, the contributions of outward and inward interactions to the Reynolds shear stress are rather weak (|S1,0|=|S3,0|≈0.2). These contributions vanish when H>6 and H>10 for quadrant (III) and (I), respectively. At the pier downstream, the contribution of each event to the Reynolds shear stress production is more significant than pier upsream. In this region, at z/h=0.2, the contributions of ejection and sweep become comparable (|S2,0|=|S4,0|≈1.4) and both are greater than the outward (|S1,0|≈0.9) and inward interaction (|S3,0|≈1). For each of the four quadrants at z/h=0.2 in the pier downstream the contribution of each event to the Reynolds shear stress is still significant for hole sizes as large as H>20. Therefore, at the pier downstream, although quadrant (II) and (IV) are more significant, each of the four quadrants has important effects on the Reynolds shear stress.

Introduction There is a wide agreement in the international scientific society that climate change will modify climatic variables and hydrological extremes. Increasing greenhouse gases in the atmosphere leads to change air temperature and precipitation. Changes in air temperatures and precipitation have significant effects on the hydrological cycle. Today, general circulation models (GCM) are the most powerful tools for evaluating the effects of climate change. The outputs of this model are presented as inputs of hydrological models. Hydrological models act as a valuable tool for assessing the hydrologic characteristics of diverse catchments and effective evaluation of the hydrologic consequences of climatic change. Amidst hydrological models, there is a physically based model that does not require long-term data, and in small catchment areas, which do not have long recorded data, they can be used. No significant work has been done to Simulation of Climate change impact on water balance component of Kasilian representative basin. The Kasilian Representative catchment is a part of Kasilian basin with an area of 67 km2. Kasilian River is considered as one of the headwaters of Talar River that eventually flows into the Caspian Sea. The geology of the catchment is dominated by sedimentary rocks. The aim of this study was to simulate the role climate change impacts on stream flow and water balance components in Kasilian representative basin as a small and forested watershed. Methods In order to find out the relationship between the rainfall-runoff process, basin characteristics, and the parameters of a water balance model, the BROOK90 model, has been implemented. BROOK90 model is a physically-based, parameter-rich, hydrologic model written and supported by Anthony C. Federer. Below the ground, the model includes many soil layers ranging from 1 to 25, each with its own thickness and having different physical properties. The Penman-Monteith equation is used to estimate the rate of evapotranspiration. The model uses the Shuttleworth and Wallace (1985) method to separate transpiration and soil evaporation from sparse canopies. The soil water characteristics are defined using a modified approach of the Brooks and Corey (1964), and Saxton et al. (1986) from 11and 10 classified textural classes, respectively. The water movement through the soil is simulated using the Darcy–Richards equation. It considers water stored as intercepted rain, intercepted snow, snow on the ground, soil water in from one to many layers, and groundwater. Snow accumulation and melt are controlled by a degree-day method with cold content. Evaporation is the sum of five components: evaporation of intercepted rain and snow, snow and soil evaporation, and transpiration. Stream flow is generated using the following simplified processes: stream flows by source area flow or subsurface pipe-flow and delayed flow from vertical or downslope soil drainage and first-order groundwater storage. Further details are provided in the BROOK90 documentation manual (Federer, 2015). Twenty years of hydro-climatology observation data (1992–2011) were used for setting Brook90 for the basin. Data from the period 1992–1997 was used for calibration, and the interval 1998–2000 was considered as the validation period. The calibration of Brook90 and validation of model performance were based on daily discharge data from the catchment outlets and was done by trial and error. Visual inspection of the measured and simulated discharge curves mean bias error (MBE), Correlation Coefficient, Coefficient of Determination, and Nash–Sutcliffe model efficiency coefficient were the indicators for model performance. Statistically downscaled GCM data were used to show hypothetical climate change scenarios. The hydrological responses of the catchment were simulated for several hypothetical climate change scenarios. The results were compared with the reference or base case (present climate conditions). Results Results of the simulation showed good accordance between the observed and simulated values with the final parameter sets using the BROOK90 model. The simulation results demonstrate that the model can give a fair estimation of the water balance components of this basin. The estimated increase of precipitation causes an increase in all water balance components, especially in runoff components. The estimated variation of precipitation (Sc1-Sc4) will considerably affect Annual runoff in the future period. The increase in annual runoff based on model predictions was estimated to be 53.3% for the Sc3 scenario at the catchment. Between all runoff components, the SRFL component shows the most sensitivity to increasing precipitation. Evapotranspiration components do not show significant sensitivity to estimated variation of the precipitation. The estimated increase of temperature (Sc5-Sc7) will significantly affect evapotranspiration rates and runoff in the future period. The increase in annual evapotranspiration based on model predictions was estimated to be 13.14% for the Sc7 scenario at the catchment. This would be a change from 654.2 mm yr-1 in the control period (base run) to 730 mm yr-1 in the future (Sc7). Annual runoff at Kassilian was predicted to decrease from 363.6 mm yr-1 in the control period to 238.5 mm yr-1 or 34.4% for Sc7 scenario in the future. These increases in winter minimum temperatures above the freezing point would be reflected in changes to the period of snow cover and mean lengths of snow cover. Based on the results, the BROOK90 featured its simplistic approach to simulate the role climate change impacts on stream flow and water balance components in a small and forested watershed. With an estimated increase in temperature, the annual runoff is expected to decrease, and the annual cycle will change significantly. Winter runoff is expected to increase, the runoff maximum will shift, and runoff in spring and summer will decrease notably. This condition plays an important role in increasing the potential of flooding and a decrease in groundwater storage in the basin. The estimated increase of precipitation causes an increase in all water balance components, especially in runoff components. Therefore, it is possible to expect more flood and water shortages event in the future.

Providing safe and sanitary drinking water is one of the goals of moving toward sustainable development, and dealing with aridity crisis is an important issue. Groundwater supplies 99% of the total available fresh water. The increasing need for more and more water resources and the finitude of water resources have led to the extraction of unauthorized withdrawals from groundwater resources. The first step toward achieving management goals and operating correctly is studying and recognizing the groundwater resources system. For studding groundwater behavior, one of the new methods is studying mathematical and computer models of groundwater that, in its turn, is an advanced and complete management tool. In this regard, a groundwater computer model called Groundwater Modelling System(GMS) was used to simulate the aquifer which is able to simulate stable and unstable conditions and has a wide variety of hydrogeological properties. It simulates groundwater flow using finite difference method(FDM). A wide range of information and a complete description of the flow system including hydraulic parameters, boundary conditions, and the pressure and stress applied to the flow are essential for the effective use of the GMS. The purpose of this study is to investigate the interactions between Lake Urmia water level changes and Meghitalu aquifer groundwater level changes in a distributed system.

Meghitalu aquifer is located in north of Urmia in Kahriz region that has interaction with Urmia lake. In order to simulate groundwater flow in Meghitalu basin and aquifer, MODFLOW module were used in the GMS model. According to geological and hydrogeological studies, the target aquifer was considered as an unconfined aquifer. The basin was considered by a three-dimensional mesh consisting 2491 cells with variable sizes between 25 and 150 square meters in 1 layer. The amount of the aquifer parameters were determined based on the geological and meteorology and geo-electrical studies and logs of the wells in the area. The location of the aquifer, the surface layers of the ground, bedrock, hydraulic conductivity, evaporation depth and supply and drain resources were procured using GIS software, and then they were added to the model after being processed.Considering that the changes in Urmia Lake water level are influencing factors on aquifer recharge and discharge, the years 1995-1996 as the highest water level, 2001-2002 as the normal condition of water level, and 2009-2010 as the lowest level were selected. The average water level of the Lake during 1965 to 2010 was 1274 meters. After implementing the model controller and ensuring that the conceptual model is unmatched by any error, the model ran in both stable condition that is based on the average annual data and in the unstable condition that is based on daily data for the length of the year.

The results of the simulation for the years 2001-2002 show that the lake recharge the aquifer in the stable condition, and rainfall and evaporation are not able to feed the aquifer; the range of hydraulic head changes in the aquifer cells is between 1254-1243 m. In unstable condition at the beginning of the year, all cells of the aquifer are wet and groundwater level are above the lake level and after 9 months of water year, status of drainage changes and the Lake starts to recharge the aquifer . The range of hydraulic head reduced from 1273 - 1412 meters in the first time step (October) to 1273-1241 meters in the last time step (September). Simulation for the years 1995-1996 and 2009-2010 demonstrated the influence of lake level on the recharging and discharging of the aquifer. The range of hydraulic head in the aquifer wet cells is reduced from 1255-1301 meter in the years 1995-1996 to 1257-1271 meter in the years 2009-2010 at the end of the simulation period . In all model implementation scenarios, wet cells with higher hydraulic head are in areas with high hydraulic conductivity. Overall, despite the lack of information in the study area, the results of the simulation were successful and the effects of tension changes were well displayed. When the groundwater level is lower than the level of Urmia Lake, the lake will feed the aquifer and the feeding will continue until the seawater is at the same level as the groundwater.

Stepped spillways are technically and economically regarded as one of the most efficient options for energy dissipation of spillway flows. A remarkable amount of the flow energy is dissipated due to the hydraulic resistance of rough elements or those steps. Therefore, the energy dissipation obviates the need to build an energy dissipation system at the end of the downstream and reduces its size to a large extent. Considering the mentioned point and the required technology to use RCC in building such spillways, it is indispensable to thoroughly examine the hydraulic processes and the flows passing through them. The flows passing through the stepped spillways are divided into three types of nappe, transition, and skimming. Most studies concerned with stepped spillways have focused on nappe and skimming flows, while transition flows have not been fully addressed. Moreover, most of the stepped spillways’ designs have been based on nappe and skimming flows types. Therefore, the present study employed laboratory methods to examine the flow formation in transition mode in order to determine the upper and lower limit of the transition flow regime, and finally, provides more space for studying its characteristics. The flow regimes’ type depends on the step discharge and geometrical shape. Due to variations in the depth and velocity of flow, air concentration and energy dissipation in the three different regimes, it is essential to evaluate the flow in the regimes. Thus, the flow regimes’ onset has been the subject of many laboratory studies. The previous experiments and studies have shown that the nappe flow onset is a function of the height and length of step and also, the critical depth. This research was conducted in Water Research Center of Power Administration in order to determine the range of transition flow regime and hydraulic parameters of various flow regimes, including dynamic pressure at the steps’ bottom and the depth of flow passing over the steps as a flow profile. To do so, spillways’ models of Siahbisheh dams were used, which were constructed with the scale of 1:15 and 1:20. The flow will be fully developed, after passing through the spillway crest and the aeration inception point. The upper and lower limits of the transition flow regime were determined by letting different discharges pass over the spillways. To detect the nappe flows’ entrance into the transition flows, i.e. the lower limit of transition flow regime, the inception of water spray can be used. The water spray level will be higher in sloped spillways. Moreover, the flow jet has more fluctuations in the transition flow regimes of pool; in other words, it will be in immersion mode. In addition, some flow rotation works can be noticed. The criterion for determining the threshold for the onset of skimming flow, i.e. the upper limit of transition flow, is the flow slipping from the edge of one step onto the next. It is worth mentioning that existence or lack of air holes does not play any role in proving this. This is in contrast to Chanson’s theory; however, it is in line with Chamani and Rajaratnam’s view. The onset of flow rotation in the pool below the step was also taken into account; these rotations are not still complete enough to enter the skimming flow section. After determining the flow regimes, the dynamic pressure and profile of passing flow were measured in transition regimes. In order to measure the pressure exerted on the steps’ bottom, 3 piezometers at (y/l), which are equal to 0.14, 0.45, and 0.71, were installed on four spillways. Transducer system adapters, computer systems and an information processing software were used in order to measure the dynamic pressure moment-by-moment. The pressure sensors used in the experiment were 0.150 kg/〖Cm〗^2 (150 mbar). The pressure fluctuations in each piezometer were recorded during 30 seconds with the frequency of 100 hertz. To measure the flow profile, without accounting for water spray, a point gauge was used. The results of the study revealed that the increase in the spillway slope reduces the area for occurrence of transition flow regime. Moreover, as the ratio of h/l increase the ratio of y_c/h decreases, which shows faster formation of a skimming flow. In the nappe flow regime, it is noticed that pressure increases from the step bottom to the edge, where it moves with a slight slope to the middle of the step and then, continues with a steep slope. In the nappe flow regime, increasing the spillway slope, increases the pressure from the step bottom toward the edge. Moreover, the maximum and minimum pressures occur near the step edge. With respect to the transition flow regime, the pressure remains almost constant from the step bottom up to y/l=0.4 and then continues with a steep slope toward the step edge. In addition, in the transition flow regime, the maximum and minimum pressures occur on the step edge. In the skimming flow regime, the mean pressure increases from the step bottom toward theedge. This increasing trend has a direct influence on the spillway slope. The maximum pressure occurs in the middle of the step and then decreases with a slight slope. Similarly, the minimum pressure occurs in the middle of the step and then, increases toward the step edge. Finally, in the skimming flow regime, increasing the spillway slope is followed by a decrease in the maximum pressure.

In recent decades, due to the importance of water quality issues and controlling the proposed environmental damages, the study of the pollutants behavior in water bodies has also became important. Sulfur compounds are contaminating factors in water bodies which should be considered in deep water bodies such as lakes and reservoirs of dams. The most common sulfur compounds in deep water bodies are sulfate and hydrogen sulfide. Accurate prediction of the interactions between these compounds can be helpful in designing hydraulic structures and water quality management. The present study examines this context and consider how they interact with each other. The international experiences in dealing with high concentrations of sulfur compounds in the reservoirs of dams and lakes are investigated in this study. This study also examines the relationship between the physical, chemical and biological reactions of the sulfur cycle in aquatic environments. The modeling will focus on two main sulfur compounds in the water, namely sulfate and hydrogen sulfide. To simulate the water quality in the reservoirs, the CE-QUAL-W2 model, which has recently been upgraded to the simulation of the sulfur cycle, has been employed. After model setup, its calibration is performed. Another point to be noted is that the spatial and temporal distribution of sulfur compounds is influenced by reaction factors and parameters affecting the temperature, hydrodynamics and the distribution of these types of pollutants. Setting the coefficients and parameters effective in the process of biological deterioration can be caused by the behavior of sulfur compounds. The access to the field data is a challenging task in this effort. In order to reduce the error of the concentration of sulfur compounds in this research, the choice of these coefficients is based on the quantities available in valid references. Modeling the concentration of sulfur compounds in the water due to the multiplicity of factors affecting the biological and chemical reactions of the sulfur cycle in aquatic environments is essentially a difficult and challenging issue. Therefore, studying this problem in water bodies seems to be necessary. On the other hand, no studies have been conducted to identify, investigate and use numerical models to simulate the sulfur compounds (sulfate and sulfide hydrogen) in water bodies in Iran. It seems that this research can be the first tackle to resolve the uncertainties and problems associated with the sulfur cycle in aquatic structures, and to examine the behavior of this cycle in the actual reservoir of the dam in Iran. In general, the objectives of this study are classified into two general sections. First, the study of the behavior of sulfur cycle in deep water bodies, such as lakes and reservoirs of dams, playing an important role in the behavior and performance of reservoirs of dams. Then, identification and prediction of the behavior and effects induced by the sulfur compounds in a case study using CE-QUAL-W2. In fact, the behavior identification and assessment of the contaminants effects are an essential step to ensure from the proper execution of a project and method for determining, predicting, controlling and changing their effects on the entire environment, public health, and the health of ecosystems that sustain life and survival of humans. In this study, the status of the sulfur compounds is simulated in various scenarios, along with the important quality factors such as thermal stratification and dissolved oxygen distribution in the platform of a real case study (Seymareh Dam reservoir). Additionally, based on the model results and analyzing these scenarios, analyzing the time trends and predicted depth profile for probable concentrations of the sulfur compounds (sulfate and sulfide hydrogen) and analyzing the behavior sensitivity of these compounds are examined in comparison with different parameters. The results of the present study revealed: (1) a significant relationship between the dissolved oxygen status and the distribution of the sulfur compounds along the reservoir depth exists, so that the hydrogen sulfide concentration is increased as the dissolved oxygen decreases; (2) the behavior of the sulfur cycle is significantly related to the interaction of main biological agents in the sediments of the reservoir bed; (3) by increasing the sulfate concentration in the reservoir, the amount of the sulfate reduction increases and it leads to an increase in hydrogen sulfide in the reservoir; (4) considering the limited capacity of dissolution of hydrogen sulfide in water, this substance is released as bubbles from the water so that the amount of hydrogen sulfide emissions increases rapidly with increasing sulfate content in water

As urban agglomerations grow, they face management challenges in terms of providing water and sanitation services to an ever-growing population, the impact of urban development on natural resources and the effects of extreme weather events. Simulation scenarios of future climate change using Global Circulation Models showed that the surface water supplies in Central Asia will be reduced due to reduced thickness of glaciers. Iran is also one of those arid regions. Therefore, the performance of management operation on water resources is mandatory. Coordinated management of the surface and groundwater resources guarantee the water supply in face of water stress situations. One of the most important instances of management plans is to estimate the relationship between these two sources of water. The groundwater recharge methods vary from small-field scale to large irrigation schemes and from simple water balance estimations to complex recharge models. In this research, for the first time, the isopotential map and Lohman method have been used for calculating the recharge and discharge between Zayandehroud River and the Isfahan aquifer. The semi-arid Zayandehroud River Basin is one of the most strategic river basins of Iran. The Zayandehroud River, as one of main river in central Iran is selected as the domain for the present study. Originated from the Zagrous Mountains, the Zayandehroud River with an average flow of 1400 million cubic meters (MCM) per year is the most important available water resource for domestic, industrial and agriculture consumptions in the basin. The study area includes an unconfined aquifer which its slope is from the South to the North and West to East. The elevation of Isfahan is about 1570 meters above sea level and its annual rainfall is about 160 mm. Zayandehroud River enters in the west area of the city, with water level of height around 1587 meters and exits in the East of Isfahan with water level of height 1560 meters. Over recent years in Zayandehroud basin, excessive amounts of surface water and groundwater have been used for different consumptions. Therefore, Zayandehroud River is alternately dry and wet periods. This phenomenon has been significantly affected the hydrologic balance of the basin and resulted in marked decrease in groundwater level. In this study, in both dry river and wet conditions of the Zayandehroud River in the Isfahan reach, the groundwater table was measured at 23 points. Then, using the geophysical and geotechnical data sets, the hydraulic conductivity of the aquifer was determined. Finally, using the Lohman equation, the amount of water transported from each aquifer section was calculated. The difference between flow rate for mentioned periods (i.e. River water less and River wet periods) is the role of Zayandehroud River in recharging the Isfahan aquifer. The results show, when the river was dry, the recharge point almost is relevant to southern part of Isfahan and the discharging point is related to the north western and north eastern parts of the city. In this situation, the river plays no role on Isfahan aquifer. In the river wet period, the river recharges Isfahan aquifer in both sides, from upstream to Shahrestan Bridge area. After Shahrestan Bridge, the recharging behavior of the river is the same as dry period. According to the obtained results in the dry period of the river, the groundwater flow rate in Isfahan aquifer in the area of Zayandehroud from southern part of the aquifer to its northern part is about 7356 m3/day. In contrast, when water flows in the river (i.e. river wet period), the above-mentioned groundwater flow rate has been increased to about 62384 m3/day. Therefore, the recharging rate of the river to the aquifer is about 55028 m3 /day. In other words, the recharging flow rate from the river to the aquifer in the region of the Isfahan city is about 0.64 m3/sec. Therefore, a perennial flow rate equal to 0.64 m3/sec in the Zayandehroud River can prevent hydrological imbalance and its impacts such as land subsidence, water shortage and salinization of groundwater. These results represent a strong and effective relationship between groundwater and the Zayandehroud River, which more emphasis on the role of recharging by the River to the groundwater, and wet period of the River plays a significant role on the aquifer of Isfahan city.