Iranian Water Research Journal

Abstract In this study, first an earth dam was embanked homogeneously in a laboratory flume with 6 m length, 60 cm width and height of 1 m. The physical model was constructed with a height of 1 m and a length of 4.5 m in the foundation. The upstream and downstream slopes of the earth dam were (2.5-1), which are conventional slopes in a homogenous earth dam. In order to check and obtain the hydraulic conductivity in the range of the homogenous earth dam, two kinds of soil were blended and finally K was compared with the references. The obtained K was equal to 4 meters per day, which conform to previous studies. Afterwards, the effect of the angle and dimensions of the toe drain on the phreatic line was investigated in the homogenous dams. Lack of enough studies about the optimal size of toe drain and its applied standard is the main aim of this new research; that is why the applied lab model was constructed at Shahrekord University. First, the model was embanked from homogenous material and the data were collected from this model with and without toe drain in 3 situations. In every situation, 3 toe drains were used whose sizes were variable. To plot the seepage line, 30 piezometers were set up and their heads were measured. In addition, observation wells were dug in the body of the model. Therefore, the observation wells and piezometers were used to monitor the phreatic line. After that, the obtained results were compared with each other using the Excel software and the tolerance was calculated. Eventually, the 10 situations were plotted. One of them had no toe drain and 9 of them had a toe drain. For example, in the first experiment, a toe drain with an angle of 45 degrees was used. Subsequently, the other toe drains angles were also examined. For solving the problem of dimension used (p/h) index that p was the height of the drain and h was height of water in reservoir of earth dam. Location of data sampling had been at behind of the homogenous earth dam wall on different height of water. Height of water fixed in 3 states in physical model (30, 60 and 80 centimeter). In state one and state two the phreatic line never coincide the downstream side of the earth dam body. Finally, it has decided to use the data of 80 centimeters. Situation of phreatic line will be monitored by using piezometers installed in different locations of toe drain. Three types of drain with constant angle (45, 60 and 90 degree) were instructed at different heights and the phreatic line was monitored for different experiments on the homogenous earth dam at maximum height of water. The best formation and dimension of stony toe drain is gotten by collation of different equations on phreatic line (based on comparison by experiment without drain). The results showed that the homogenous earth dams can be obtained highest loss in phreatic line when upward of toe drain angle and its top height had 45 degrees and 0.35 maximum height of water in the reservoir. Also in 90 degree toe drain the effect of toe drain on seepage was very well. It means that this toe drain have much head loss in seepage line, but the defect of this mater shown in this way when the toe drain created with big size (p/h= 0.35) and (90 degree) the flux of seepage was too much. So for a solution for this problem was using a form of toe drain which have a perfect head loss in seepage line and have optimum flux that exit in the toe drain that constructed in down slope of the dam. If it decided to show the effect of another toe drain like (p/h=0.35 and 60 degrees) this case, the toe drain with 90 degree has more flux than toe drain with 45 degree, but it hasn’t optimum head loss. Finally, by comparing all of states, the best toe drain that has the optimum loss head and seepage flux was introduced.In this study, first an earth dam was embanked homogeneously in a laboratory flume with 6 m length, 60 cm width and height of 1 m. The physical model was constructed with a height of 1 m and a length of 4.5 m in the foundation. The upstream and downstream slopes of the earth dam were (2.5-1), which are conventional slopes in a homogenous earth dam. In order to check and obtain the hydraulic conductivity in the range of the homogenous earth dam, two kinds of soil were blended and finally K was compared with the references. The obtained

Abstract Compound channels are composed of a main channel and one or two flood plains around it that are relatively shallower than the main channel. Due to the difference between the flow velocity in the main channel and the floodplains, the flow has a complex structure in compound channels. In compound channels, a part of river discharge is carried out by floodplains, thus shear distribution and flow structure becomes complicated due to the transfer of momentum between the main channel and the shallower flow in the floodplains. In the last two decades, the attention of the researchers was devoted to the investigation of flow behavior in compound channels.
In this study, the Fluent 6.3 software was used to solve the governing equations on the open channels with compound cross section. Fluent is a powerful and flexible general-purpose computational fluid dynamics software ideally suited for simulating the flow characteristics in compound channels. In this software, the volume of fluid model (VOF) is used to solve the equations. The VOF formulation relies on the fact that two or more fluids (or phases) are not interpenetrating. The VOF method consists of three ingredients: a scheme to locate the surface, an algorithm to track the surface as a sharp interface moving through a computational grid, and a means of applying boundary conditions at the surface. To generate the mesh as well as to introduce the channel geometry, the Gambit pre-processing software was used. Gambit is an integrated preprocessor program for CFD. It can be used for geometry construction and import, mesh generation with structured and unstructured elements, mesh quality examination and definition of boundary zones. The distance among the meshes was 5 mm, albeit, it was 2.5 mm near the walls and channel bed. For simulating the flow turbulence, the Reynolds stresses model was used. The results of simulations was compared with those of experimental data. The simulated channel was a flume with 12.5 m length, and a 0.4 m * 0.4 m compound cross-section. The flow depth in the main channel was 0.08 m, and the flood plain changed from 0.02 m to 0.06 m. the width of main channel was 0.2 m.
In this study, the effect of the ratio of flow depth at the floodplain to flow depth at main channel on the velocity distribution and the location of the maximum velocity at a compound channel was investigated. In addition, the effect of flood plain roughness on the above parameters was studied. The results showed that by changing the ratio of flow depth at floodplain to flow depth at main channel, the velocity distribution in the channel changes significantly. At the junction of main channel with flood plain, two vortices were appeared, named as flood plain vortex and main channel vortex. Both of the vortices reached to the flow surface and occupied the zone limited by . At the distance of , a secondary flow was formed near the free flow surface from channel wall to the axis of the channel, named as free surface vortex. This vortex is generated because of the anisotropic turbulence. The free surface vortex and the main channel vortex meet together at the central axis of the channel . At the zone , another secondary flow is established known as bottom vortex. The simulated iso-vel curve were in good agreement with the observation of previous researchers. The dip phenomenon was observed in compound channels. As the flow depth over the floodplain decreases, the location of maximum velocity gets further away from the flow surface as well as from the junction of main channel and the flood plain. To investigate the effect of roughness on the velocity distribution at the compound channels, two cases of smooth flood plain and roughened flood plain were studied. The results showed that there are good agreement between the results of Fluent and the experimental data. In this case, the maximum velocity occurred at z/H=1.375, y/H=0.8. The roughness changed the shape of iso-vel curves at the flood plain. As the height of roughness at the floodplain increases, the velocity decreases in this zone and the iso-vel curves move to the main channel. By increasing the height of the roughness, there was no changes in the shape of iso-vel curves at the main channel.

Abstract The increase of greenhouse gasses, the so called reason of climate change, may cause the global average temperature to be surged up and consequently, patterns of regional precipitation, evaporation, land use, soil moisture and river flow rates will be altered. Based on climate change, the earth’s temperature continues to rise, it is possible to expect a significant impact on water resources. As temperatures increase, some parameters like evaporation increases, sometimes resulting in rain and droughts. Rainfall and runoff variability are important phenomenon and causes severely impacts on the water resources planning and management. It is the most studied hydro-climate variables because of its significance for sustainable water resources management, water supply, environment, agricultural activities and ecological management. In this research, the outflow of Gharesu River basin, a river in the west of Iran, has been predicted in current and future period. The Gharesou River basin is one of the sub-basins of Karkheh basin with an area of 5354 km2 and is contain of three major streams. In this study, future hydrologic variables and outflow of the basin have been simulated and predicted using climate models and under different emission scenarios. This study has tried to discover the effects of climate effects on hydrologic variables, rainfall and runoff variability of a river basin using a methodology combining climate models, rainfall-runoff model, GIS and predictors.
In this study, the impact of climate change on the stream flow of the Gharesou River for the future period of the years 2046 to 2065 is analyzed, utilizing two climate models, HADCM3 and MPEH5, under three emission scenarios- A1B, A2, and B1. Moreover, MapShed, a rainfall- runoff model that requires GIS layers of surface water, topography, soil type, regional climatological stations, accompanying with precipitation and maximum and minimum data produced by LARS-WG model, was used to simulate the stream flow in a given upcoming period. LARS-WG model produced future hydrological data based upon present precipitation. Major predicted data are maximum and minimum temperature and sunny hours of a day. Then, the MapShed model was calibrated and validated based on the observed stream flow, provided from the Kermanshah regional water authority, for the years 1990 to 1995 and 1996 to 1998, respectively. In order to predict the future condition, the upcoming parameters of the rainfall and the temperature were predicted by downscaling the HADCM3 and MPEH5 models’ output by means of Lars-WG statistical downscaling model. For accomplishing this goal, the past climatic parameters of the period of 1960 to 1995 are used. The output of these climate models (for the period of 2046 to 2065) associated with GIS layers of the basin’s land use, topography, surface runoff and soil texture were introduced to MapShed, a GIS-based watershed simulation model, to produce the future flow of the river basin. The goodness of fit criteria, for flow rate produced by MapShed model, including RMSE, R2 and minimum cumulative errors (CE) indicate good performance in calibration and validation processes for the periods of 1990 to 1995 and 1996 to 1998, respectively. In all model-scenarios except for MPEH5-A2, the future, like long-term observation period, peak flow happens in March. Under MPEH5-A2 scenario, the peak flow was transferred to April. Additionally, model MPEH5, under the A1B scenario and in all months, predicts flow rate less than the observed values, while this model forecasts flow rates more than the observed values for all months of the years. Moreover, most of the model-scenarios indicate a decline of flow rate in the months of February, March, April, September and October and an increase in the months of June, July, August and January.
The results show that the 20-year average of future flow in the Gharesou River under four model-scenarios of MPEH5-A1B, HADCM3-B1, HADCM3-A1B, and MPEH5-B1 will increase and under two model-scenarios of MPEH5-A2 and HADCM3-A2 will decrease, in comparison with the long-term mean of the observed annual flow. It is worth mentioning that most of the scenarios predict the increase of flow rate, with respect to observation period, in the late spring and during summer and the decline of flow rate in the early spring. Like observed period, in the most of the scenarios, peak discharges of outflow of the basin have been estimated in March, and just in MPEH5 scenario, peak discharge happened in April.

Abstract As an indispensable part of water resources, groundwater plays an important role in the ecological environment. This is especially true in arid and semi-arid regions, where changes in groundwater level and hydrochemistry have significant impacts on ecological processes. The interactions between groundwater and surface water are complex. Groundwater and surface water are not isolated components of the hydrologic system, but instead interact with a variety of physiographic and climatic landscapes. River flow changes can influence recharge of regional groundwater aquifers, causing shifts in groundwater levels. Actually, The river plays an important role in recharging groundwater. Streams interact with ground water in all types of landscapes. The interaction takes place in three basic ways: streams gain water from inflow of ground water through the streambed (gaining stream), they lose water to ground water by outflow through the streambed (losing stream), or they do both, gaining in some reaches and losing in other reaches. Therefore, an understanding of the basic principles of interactions between groundwater and surface water is needed for effective management of water resources. Also, climate fluctuations are probably one of the most challenging pressures facing hydrological systems and water resources. Moreover, population growth, expanding areas of irrigated agriculture and economic development are drivers for an ever-increasing demand for water worldwide. Because of these reasons, most plains of Iran have been confronted with declining groundwater levels. Koohpayeh- Segzi Plain is the largest plain in Zayandehrud basin and groundwater is the main resource for supplying the water demand in this plain. Then the aim of this study was to evaluate groundwater resources and relationship with surface water and climate variables in the Koohpayeh- Segzi Plain in the time period of 1995-2009.
In this study, the data of 59 groundwater observation wells along the river, 2 hydrometric stations at the beginning and ending of the plain and 14 meteorological stations in and around of the plain have been used. Parameters of stream flow to the region, precipitation, evaporation, mean temperature and deflation from the water table have been considered and assessed the water table reaction rather to different parameter variations for years of 1995 and 2009 as well as in the different months of these two years. Accordingly, using interpolation methods such as Kriging, Co– Kriging, Inverse Distance Weighting (IDW) and Radial Basis Functions (RBF) as a technique to convert point data into the area, amount of input climate variables (precipitation, evaporation and mean temperature) has been obtained in the well place. Also, because of distribution wells around of the river, the wells were divided into 8 classes based on distance from the river (0-2, 2-4, 4-6, 8-10, 10-15, 15-20 and >20).
The results showed that groundwater level has been declined 3.5 m on average during the considered period. This declination rate has increased around the Zayandehrud River, especially in 30 kilometers of the first part of the river (such as Sharq Gavdari Foka, Shydan Baraan, Amin Abad Qahab and Hasan Abad) and have reached to over 14 meters. Also assessing of climate variables trend by Mann-Kendall tests showed no significant trend in the most of meteorological stations. Therefore, changes of climate variables cannot explain the sharp drop of water table in this plain. Furthermore, the results showed that the water level of the wells located within the 6 km strip width of the river are strongly influenced by river discharge fluctuations during the year, and with increasing the distance from the river is reduced. Actually the results indicated that there was a significant relationship between the groundwater level and river discharge (surface water), as the river discharge is the main factor of supplying groundwater in this plain. A drastic reduction in input flow at the beginning of the plain has caused increasingly pressure on the groundwater resources (near the Choom bridge) for agricultural activities. At the end part of the river (near the Varzaneh bridge) by decreasing stream flow and consequently declining of water table and quality of groundwater resources, agricultural activities have been disrupted that makes less declining rather than the initial region and causing many socio-economic problems in the Koohpayeh- Segzi Plain. Finally, increasing of groundwater level and improvement of groundwater quality have aided greatly in restoring the environmental ecology and improving the quality of life that have been destroyed in recent years.

Abstract Soil erosion is exposed soil caused by the loss of vegetation by water, wind, and ice with the result of reduced soil-water capacity and with the reduced soil productivity due to the losses of sediments, nutrients, etc., by runoff. Soil erosion has been considered as a major form of soil degradation that is a naturally occurring process and that can be accelerated by human activities and it is one of the most serious eco-environmental problems around the world. Soil erosion is often highest during thaw, and it is enhanced by freeze_thaw (FT) cycles. The extreme FT action occurs in the Bojnourd region located in the Northern Khorasan, Iran, due to its unique climate resulting from high elevations and cold temperature. This action causes damage to the surface soil structure, as soil erosion in the Bojnourd region is dominated by FT erosion. Limited by natural and scientific factors, FT erosion, as a typical erosion process along with wind and water erosion, has not been given enough attention. On the other hand, many organic (dairy manure, sewage sludge, compost) and inorganic (polyacrylamide (PAM), polyvinyl alcohol (PVA), fly ash, perlite, vermiculite) amendments have been extensively used for improving the soil structure characteristics. So, in this research, freezing-thawing process of the soil samples collected from the Bojnourd region was carried out by laboratory experiments to determine the runoff volume and soil loss subjected to FT cycle and after PAM application.
The present study aimed to investigate the effects of PAM on runoff volume and soil loss subjected to FT cycle from small experimental plots induced under rainfall simulation condition. A completely randomized design with FT cycle and none use of PAM as control were used to compare the effect of application of different rates of PAM viz. 0.25, 0.5 and 0.75 g.m-2, on runoff generation time, runoff volume and soil loss. A FT cycle was simulated in Soil Erosion and Rainfall Simulation Laboratory of Tarbiat Modares University. The present study was conducted under controlled laboratory conditions with a simulated rainfall. Towards this attempt, air and different soil depth temperatures were analyzed in a natural condition and 10 cm soil depth was targeted for the soil laboratory experiments. The rainfall storm with 72 mm h-1 and 30 min duration was simulated and conducted for the study treatments. The soil was poured in small erosion box with 0.25 m2 surface area in three replicates. A thick filter, draining the lower 20 cm of the soil profile was generated using mineral pumices. The prepared soil sample was evenly packed into the soil plots at a bulk density of 1.3 g cm?3 similar to that measured under natural conditions. The plots were then placed in a saturated pool for 24 h and then left to be drained to achieve an average moisture content of 35% similar to that recorded for the realities in the study area. For each event, the time to runoff initiation was recorded as the elapsed time between the start of rainfall and the time at which surface runoff began entering the runoff collection container located at the end of the plot. Runoff was sampled at different time steps of 2–5 min and its volume was accordingly measured. The collection gutter at the lower end of each box was protected by a shield to prevent rainfall from directly entering the collection container. The amount of soil loss was then measured using a decantation procedure, oven drying at 105 ?C for 24 h and weighing by means of a high-precision scale.
The Analysis of Variance (ANOVA) results showed that the PAM had a significant increasing effect on runoff generation time. Application rates of 0.25 and 0.50 g m-2 decreased runoff and soil loss at the tune of 49, 23 and 77 and 52, respectively, compared to those recorded for the control plot. In contrast, runoff and soil loss increased 1.62 and 4.5 times subjected to 0.75 g m-2 application rate. It was also understood from the results that the PAM with the particle flocculation capability and increasing penetration rate could control the effects of FT cycle, with further effect on soil loss. Whereas, the PAM treatment of 0.75 g m-2 had an increasing effect on runoff yield and soil loss. It can be concluded that more experiments are needed for monitoring and evaluating long-term effects of PAM on soil hydrology and erosion processes with a particular focus on FT cycle.

Abstract The increase of food production for the growing world population makes the assessment of global agricultural water productivities and virtual water flows important. The virtual water concepts together with the water footprint links a large number of sectors and issues, thus providing an appropriate framework to support more optimal water management practices. In other word, to better understand the linkages between humanity's productive activities and this growing pressure on the freshwater resources, the water footprint was developed to measure the amount of water consumed throughout a product's value chain. In this paper, water footprint of agricultural crops was assessed with distinguishing between internal and external water footprints, blue water and green water and the amount of saving and losing water resources by virtual water trade. Agricultural crops in this study included cereal (wheat, barley, rice and maize), fruits (apple, orange, onion and potato) and pulses (chickpea). The total water footprint is calculated as the sum of the use of domestic water resources and virtual water import minus virtual water export. So the total volume of water use in these agricultural crops is calculated based on the total volume of crop produced and its corresponding virtual water content. Similarly, the volume of virtual water export or import is calculated based on the international trade of products and their virtual water content. The blue and green virtual water content of agricultural crop is the volume of blue/ green water used to produce the crop and these are calculated based on blue and green crop water requirements and yields.
The potential of green water in producing agricultural crops is different, on average, 40% of these crops are produced by green water. Estimation of the amount of virtual water content can determine decision making on the production or trade of agricultural crops. Therefore, the high water-consuming products can be removed from the cropping pattern of areas with the water crisis and, instead, replaced by low water-consuming products. In this case, import of high water-consuming products (having high virtual water content) lead to reduced water crisis and providing food security in these regions. As a result, the products like rice and chickpea are suggested to be removed from the crop pattern in crisis areas. On the other hand, the results show that the exported products have a lesser content of virtual water (blue and green) than the imported products. In other words, the pattern of agricultural crop imports during the investigation years has been into the importation of water-consuming products. Therefore, respect to the amount of consumed water, reconsideration in the adoption of the existing policies in the field of export and import of agricultural products is necessary. In general, virtual water import is more than virtual water export so Iran is net virtual water importer and imports 14.3 BCM in this period so it can be remedied for water crisis in Iran and that in effect it partially depend on water resources elsewhere.
The results of calculating virtual water content showed that potato, onion, apple and orange need less blue water than other crops, also rice, orange and potato use less green water. In many agricultural crops, amounts of green virtual water contents are more than blue virtual water contents because of continuous water supply in irrigated lands; these crops have high crop water productivity. Furthermore, wheat and onion have greater and less internal water footprint among of agricultural crops, respectively, so that wheat used 19168 MCM water (57.5% of green water and 42.5% of blue water) and onion used 244.6 MCM (93.3% of blue water and 6.7% of green water) in this period. The results showed that average of the water footprint of crops is 656 m3 cap-1 yr-1 and external water footprint is less than internal (40% of blue water footprint and 29% of green water footprint) and this means that a large amount of agricultural crops produces domestically. About 14611 MCM of water resources is saved by cereal import and 135 MCM is lost by virtual water export. Therefore, on the average, 14476 MCM of water resources is saved during 1997-2001. So we can conclude that international trade of agricultural products significantly influences the water appropriation in the country, a relation that has so far received little attention from both economists and water managers.

Abstract Construction of weirs and diversion dams in river bends has been inevitable in some cases around the world, and many examples are available to demonstrate the use of conventional types of weirs in the channel bends. The lack of design criteria for the construction of weirs on channel bends is evident. However, the operational experiences of these weirs in river bends indicate the non-uniformity of water surface levels, sediment distribution, and flow rates across the channel bend, hence, the poor performance of intake structures on both sides of the river. The main hypothesis for providing uniform distribution of flow across the bend is the change of the weir-crest profile from horizontal to sloping crest. Review of previous studies indicates a few researches on the performance of sloping-crested weirs in channel bends. The aim of the present study was to test the performance of horizontal and sloping Crump weirs in a channel bend, in order to achieve the most uniform distribution of the unit flow rates across the river bend. In this study, the theory of the design of a weir crest in a channel bend is presented. Flow equation was derived from mathematical and dimensional analysis. The discharge coefficient, Cd, is related to the relative curvature of the bend, the position of the weir along the bend, the geometry of the weir and the upstream head water. Flow characteristics were evaluated in a laboratory flume consisting of a 90 degree bend with a relative radius of curvature 3, with and without the standard Crump weirs. The experiments were carried out using 3 different heights of weir, 4 different weir crest slopes (3 sloping crests, and 1 horizontal crest), and at 7 different positions of the channel (2 cross sections in straight reach and 5 cross sections in curvature reach of the channel). All experiments were repeated under 3 different flow conditions. A total of 252 tests (63 with horizontal weirs and 189 experiments with sloping crested weirs) were carried out. Flow discharge, 2D velocity and water surface profiles at the control sections of weirs were measured.
The results indicated that horizontal crested weirs are appropriate for straight reaches upstream and downstream of the channel bend, and are still sufficient at the entrance and exit of the bend. The control section is parallel to the weir crest. It is located at a distance of (2-4.7)h upstream the weir at upstream and bend’s entrance sections (h is the upstream head). For the horizontal weirs at the downstream of the bend, the control section is located at (1-3.45)h, and on 2B-Downstream of the bend is at (2.1-3.5)h. In the channel bend, sloping crest weirs provide better convergence of the unit flow rates across the river. The slope of the weir crest is recommended to be in the range of 85°

Abstract A significant reduction in the quantity and quality of available water resources and locating Iran in arid and semi-arid area lead to pay attention to modern irrigation systems to increase irrigation efficiency and water use efficiency. Subsurface Drip Irrigation (SDI) is one of these methods which bring losses to a minimum value. The success of a drip irrigation system depends on its design and implementation. The aim of this study was to evaluate the efficiency of subsurface drip irrigation systems implemented in citrus orchards of Kordkuy city and assess the strengths and weaknesses of the system and provide corrective measures for improving its efficiency. The study area covers 6 hectares of Citrus groves and 3 hectares of Peach orchards. In order to evaluation and monitoring the irrigation system in the studied garden, a manifold system was randomly selected and four lateral lines located at the first, in one third and in two thirds of the length from the derivation line and in the last lateral line were selected. Then four points (the first, in one third and in two-thirds of the length of the lateral line and in the last) were selected according to ASAE standard. In the next step, the soil around each side removed enough to allow measure emitter discharges. The volume of water that discharged from all emitters during one minute were measured. The pressure at the inlet and last of lateral tubes were measured by Manometer. For evaluating the performance of the SDI system, the ASAE evaluation criteria (i.e. coefficient of variation of discharge, statistical uniformity coefficient, coefficient of variation of pressure, coefficient of variation of discharge considering the flow hydraulics and the overall performance of the emitter) were calculated. Measurements were performed twice during the season and at the end of the season.
The results of the measurements showed that the discharge rate and emitter’s pressure is not uniform, this difference in values can be occurred due to the following factors: the friction losses, emitters clogging due to soil particles and roots or mineral deposits. The second factor that is a great concern of evaluated system design is connecting the lateral tubes at the end of each block like a circuit, so that the water circulates in each block. This causes the pressure distribution disoriented in the entire of irrigation system. According to the calculated indicators presented in the tables in this article, the coefficient of variation of the evaluated system is unacceptable. The main reason of high coefficient of variation of discharge (25%) is emitter malfunctions. The mean value of emitter discharge is less than the nominal amount (4 liters per hour) which approve above mentioned claim. The average hydraulic pressure of systems for citrus groves and peach orchards were 23 m and 33 m, respectively, which these values are very high for a drip irrigation system. The main reason for the high average hydraulic pressure was removing the disk filters by operator two years after start of system operation. The operator has felt the system cannot provide the required water for trees during the irrigation time and the moisture does not appear at the soil surface. Therefore, he wanted to increase the pressure of the system to increase the emitter discharge by removing disk filters. Although this slightly influenced on emitter discharges, but since the emitters are adjustable, this will only waste the energy. The emitters used in this project are adjustable type and increasing of pressure does not affect on the emitter discharge rate. Therefore, by increasing the pressure up to 5 bar, the discharge of the emitter will not increase more than 5.4 liters per hour. Another flaw in designing of this irrigation system was the installation of filtration station outside the garden. The height difference between the filtration station and the garden is about 15 meters, which is one of the main reasons of non-uniform distribution of pressure in the irrigation system.
Generally, the evaluation results indicated that the observed defects in this system caused by three main factors in the design, implementation and operation of the system. The most important factor causing non-uniformity of emitter discharge is clogging of emitters which is about 80% in this system that caused by several reasons. In design of the system, circuiting of tubes at the end of the blocks in the garden, leads to pressure fluctuations and non-uniformity of pressure distribution in the system.

Abstract The majority of the world's dry lands are still farmed by small scale. In these farms, low cost simple irrigation methods have paid attention by farmers and also international development programs. The buried clay pot irrigation is one of the most important efficient traditional methods that could be of great use on small and medium sized farms and gardens that have not been well studied in Iran. Also, the information on the shape of the wetted zone of soil under buried clay pot plays the great significance in the design and management of this type of irrigation system for many farm lands at arid and semi-arid regions on small and medium sized farms and gardens. Clay pot or porous clay capsules irrigation is able to release water in near root zone with self- regulative. Several parameters such as saturated soil hydraulic conductivity, soil porosity, water supply, pressure head and irrigation time may affect on discharging and soil wetting shape under sub-irrigation with porous clay capsule.
Present research was carried out in 2014 on the field of the faculty of agriculture, Tarbiat Modares University, to study simulated soil wetting shape under two different types of buried porous clay capsule (GBN and GN) in calcareous soil with clay loam texture. The soils are generally deep to moderately deep with clay loam texture, ~ 17% CaCO3 (lime), 0.44% organic matter and moderately soil permeability. The slope in this study area is 0.5 -1.5%. The GBN and GB have different size and discharge. In this paper, wetted radius and depth of GBN (3.5 cm diameter and 12 cm height) and GN (3.5 cm diameter and 3.5 cm height) porous clay capsules as a subsurface point source were measured at 10, 25, 50, 80, 100 kPa of hydrostatic pressure by discharge-pressure automation instrument which was designed for this purpose. The soil wetting shapes measured after 24 hours of irrigation with GBN and GB of buried porous clay capsule under clay loam soil texture. In order to predict the water distribution of clay capsules, several parameters such as saturated soil hydraulic conductivity, soil porosity, water supply, pressure head and irrigation time were modeled by with the Buckingham theorem in dimensional analysis technique. Residual error analysis was used to validate the simulation model.
According to the experimental results, the soil water distribution shape in GN and GBN clay capsules types followed a spherical trend, which is due to the low discharge of clay capsules. The analysis results of residual errors showed that the average of ME, RRMSE and R2 were 9.82, 23.78, 89.48 and 10.92, 57.97, 90.4 for GB and GBN, respectively. Therefore, dimensional analysis models have good accuracy in determining the wetted radius and depth of two clay capsule types. These shows that developed model can be used to simulate the wetting pattern under porous clay capsule irrigation system with a point source of water application. Also, the results showed that wetted radius and depth of GN at 100 kPa pressure head was similar to GBN up to 50 kPa. On the other hand, irrigation engineers can selected and used GN instead of GBN for places with high pressure ability. Because, the run of smaller nozzle (clay capsule of GN) is easier in related to the GBN at the fields.
Water distribution in the soil is important for the design, operation, and management of irrigation system for arid and semi-arid regions. In this study, four equation were developed to simulate soil wetted depth and width with the Buckingham theorem in dimensional analysis technique under two types of buried porous clay capsule (GBN and GN) at point source of water application. It is important to know that the discharge of clay capsules increased with increasing pressure head and the relationship between discharge and hydrostatic pressure trend to non-linear in GB and GBN. Based on our experimental results, these equations can be used as a reliable method to predict the wetted soil shape in clay loam soil and had good accuracy for practical project to help in deciding depth and intervals of porous clay capsules and designing a subsurface irrigation scheme. In other hands, the simulated values by models were followed a distribution similar to the observed values in both of porous clay capsule types. The main conclusion drawn from the two porous clay capsule size is that the soil wetted shape in GN type was similar to GBN type at the high pressure head. This point is important for designing suitable irrigation systems and appropriate management.

Abstract Nowadays farmers often use N-fertilizers to increase crop yield. On the other hand, in agricultural lands nitrogen fertilizers, usually lost quickly by leaching, cause contamination of water resources and soil that reported as the most important source of pollutant. Also, treating and reusing drainage water is necessary because of a shortage of water resources, especially in arid and semi-arid regions. Although biofilters are useful for removing nitrate from drainage water, but many researches show that they need an external carbon source to sustain denitrification. Many researchers have studied on different method, but most of them need equipment or material that becoming use in the laboratory experiment. For example, mixing these biofilters and soil in large-scale underground drainage systems is very difficult and costly. So this study describes laboratory experiments that investigated nitrate removal from drainage water with barley straw in different percentages layered or mixed with soil in columns. The columns’ nominal diameter and height were 9 and 30 cm, respectively. There were two groups of treatments in this study. In the first group, the columns were filled with 3 layers of soil and 2 layers of barley straw between them (layered treatments). In the second group, the columns were filled with a mixture of soil and barley straw (mixed treatments). In both groups, barley straw was used in three levels of 10, 20 and 30 percent of volume. In layered treatments, the thickness of the 2 layers of barley straw was equal and proportionate to the percentages of its usage. The experiment lasted for 77 days. The influent drainage water contaminated with nitrate of 80 mg/L concentration.
According to the results, the concentration of nitrate from all effluent of treatments decreased with the passing of time. The highest percentage of barley straw was more effective in removing nitrate than the treatments. The control treatment (without barley straw) reduced less than 25% of the nitrate concentration of the influent. So the lump of earth cannot often reduce nitrate denitrification significantly due to a shortage of carbon source while water passes through it. Ammonium concentration of the effluent in all the treatments has decreased with the passing of time. On the other hand, the results show that a small amount of ammonium could be consumed under the anaerobic condition owing to the growth of anaerobic bacteria cells. The pH and EC values didn’t have a particular procedure during the experiment, the effluent values almost followed the influent procedure, but the pH effluent values have been always less than the influents. These values fluctuated between 7.18 and 7.95, which are close to the pH of soil saturation extract. This may be due to unexpected variation of the influent pH and soil buffering characteristics that did not allow dramatic changes in pH. Also maximum nitrate removal by denitrification occurred in the pH range of 7.2-8.4, that was about the pH of the soil in this study. The results showed that as long as pH was between neutral to a little alkaline denitrification effect was excellent. On the other hand, high acidic and alkaline environment was not fit for denitrification, and pH value played an important role in nitrite accumulation. The main reason was that pH influenced the enzyme activity of bacteria.
In this study, biological nitrate removal was investigated applying 10, 20, and 30% volume of barley straw (as layered or mixed treatment) in soil columns, under water flow for 11 weeks. Layered and mixed treatments were compared because mixing barley and soil in large volumes needed in underground drainage systems is sometimes difficult or impossible, costly and requires advanced equipment. Results proved all the treatments to be profitable. Also, the results showed that the optimum treatment with maximum nitrate removal efficiency (80%) was the 20% layered treatment. Ammonium concentration of the effluent decreased in all treatments with the passing of time, but it was almost close to influent values. Furthermore, variation of pH levels of the treatments didn’t have a particular procedure during the experiment and almost followed the influent procedure. So the application of the barley straw in layering method is a practicable inexpensive solution to achieve higher nitrate removal efficiency compared to mixing method or other bioreactors without having to be worried about of side effects and dangers of pH in effluent drainage water that can be used in artificially recharge systems or reusing wastewater as irrigation water.

Abstract The prediction of stream flow from a catchment outlet has been of concern to hydrologists and water resource community. To this end, the unit-hydrograph approach proposed by Sherman has evolved into one of the most powerful tools in applied hydrology. A unit hydrograph is defined as the direct runoff hydrograph (DRH) resulting from the unit depth of effective rainfall hyetograph (ERH) falling uniformly over the drainage area at a constant rate for an effective duration. The unit hydrograph (UH) at a specific point on the stream (gauging site) in a catchment is generally determined by using effective rainfall and surface runoff data observed in the gauging site. The relationship between hydrologic and geomorphologic parameters, can lead to estimate the hydrologic response of basins and is applied to the similar areas, in terms of geomorphology, that are ungauged. For ungauged watersheds and for anticipated post development conditions, synthetic unit hydrograph (SUH), based on watersheds, geomorphology and climatic characteristics, is typically used. Such conditions are common in Iran, as most watersheds lack gauging stations along its rivers and streams discharge outlets. Catchments and storm characteristics are the primary parameters that affect complex watershed responses to rainfall events. The production and behavior of runoff are functions of land use types and changes. The hydrological response of a river basin is based on the relationship between basin geomorphology (catchments area, shape of the basin, topography, channel slope, stream density and channel storage) and its hydrology. In this context, several methods have been proposed. This study has been compared the consistency, accuracy and reliability of geomorphologic, geomorphoclimatic and Rosso instantaneous unit hydrographs and SCS unit hydrograph, in estimating outlet runoff hydrograph characteristics in Manshad watershed. The Manshad watershed encompasses an area of about 60 km² and is located in central Iran in the western part of the Yazd province. A hydrometric station is located at the outlet of the watershed (Dare Station), and a raingauge station (Manshad Station) is located at the upstream of the hydrometric station. In the present study, six single rainfall- runoff events, in which snow did not melt, were selected. Both rainfall and runoff data were recorded automatically with 1 h intervals. Then, for separation of the effective rainfall from the recorded storm for each chosen event, the CN-SCS method was applied. Flow velocity was obtained by calibrating historical data or with methods appropriate for ungauged basins. Arcview GIS software was used for extracting geomorphic information on the area, slope, length of the main river basin and Horton’s geomorphologic ratios such as area ratio (Ra), bifurcation ratio (Rb) and length ratio (Rl) in the studied watershed as inputs for the models leading to the runoff simulation. Geomorphologic parameters, namely the average value of the bifurcation ratio (Rb), stream length ratio (Rl), and stream area ratio (Ra), were determined to be 5.29, 2.40 and 6.09, respectively. The Strahler’s ordering scheme was followed for ordering of the river network. The study basin was discovered to be a fifth-order basin. Then, the GIUH, GCIUH, Rosso IUH and SCS models have been developed for estimation of the DSRO hydrographs for the catchment.
Comparisons of calculated and observed hydrographs, that have been carried out by using the Mean Relative Error, the Root Mean Square Error and the Nash-Sutcliffe indices confirm the high potential of all the methods in simulating the amount of flood volume (with an error less than 12%). These results are in agreement with the results of Sorman (1995). Thus, they can be used as appropriate methods for simulating this parameter in similar catchments. In estimating peak discharge, Geomorphologic and Rosso IUH (with error of 39.03% and 42.35%, respectively) have better performances, comparing to other methods. They have weak performances in simulating time to peak and the shape of hydrograph. Also, Geomorphoclimatic and SCS methods have weak performances in estimating peak discharge, time to peak and the shape of hydrographs.
The GCIUH and SCS models had weak performance for estimating time to peak, peak discharge and the shape of outlet DSRO hydrographs and the GIUH, Rosso IUH had weak performance for estimating time to peak and the shape of hydrographs. This may relate to exposing the watershed to human activities in the form of urban development and land use changes which cause changes on watershed hydrographs.

Abstract Water deficit and consecutive droughts currently caused most of the world facing water crisis condition. In order to save water consumption in the agricultural sector, new technologies and several materials are used. One of these materials is superabsorbent polymers which are capable of absorbing high amounts of precipitation or irrigation and make them available for the plants use. Since the application of superabsorbent has significant impact on improving the morphological and phytochemical characteristics and has not been investigated on hot pepper till now, the aim of this study was to investigate the effect of superabsorbent polymer (A200) under drought conditions on some of phytochemical characteristics of hot pepper (Capsicum frutescence) such as: Vitamin C, Total Soluble Solids, Ion Leakage, Chlorophyll Content and Water Productivity.
This Research was carried out in the research greenhouse of the department of horticulture at Sari Agricultural Sciences and Natural Resources University. Mentioned research was planned in a factorial based on a randomized complete design with three irrigation regimes (50, 75, and 100% of water requirement) and four levels of superabsorbent polymer (0, 0.1, 0.2 and 0.3% weight) in four replications. Plants were planted in 30 cm diameter and a height of 35 cm pots. A total of 4 TDR were installed in the root effective depth (18 cm) treated with full irrigation surface (water requirement of 100%) and different levels of superabsorbent. A digital Reflectometer device was used to calculate the total soluble solids (TSS). The method of Luts et al. (1996) was used to determine the ionic leakage. Chlorophyll a, b and total were determined based on methods of Pora et al. (1989). Vitamin C was determined via Saini et al. (2001) method. The fresh weight of each harvested fruit weighted by digital scale and were recorded as total fruit fresh weight per plant at the end of the experiment.
The interaction effect of irrigation levels and superabsorbent levels on ionic leakage was significant at 1 or 5 percent level (p

Abstract Water is one of the most valuable natural resources in the world, which will be in demand by various sectors. Water deficit is one of the important challenges of environmental crisis in the Middle East, including Iran. The agriculture sector is the largest consumer of water by irrigated agriculture in every region that is intensified because of consecutive droughts in recent years. One of the methods for managing this crisis is water pricing that uses the economic value of water in agriculture sector. Farmers pay far less than the real price of utilization water in the agricultural sector. They also pay lower taxes for water than other nonfarm consumers. Therefore, the allocation of water among farmers is inappropriate. This mechanism is the main reason of non- optimal use of water and it led to excessive extraction of water resources.
Qorveh and Dehgolan townships are the main agricultural region of Kurdistan Province. They are producing a quarter of the province's agricultural products and 42000 tons of Alfalfa produced annually in these regions. As these have the second rank in producing Alfalfa over the country. In addition, given the high number of livestock, factories and dairy industry need to hay crops, especially alfalfa for grown in the province of Kurdistan.
In this study, the data were collected via 100 questionnaires that completed by farmers and plantation owners by authors and utilized stratified sampling in 2010-11 year. The Cochran sampling method is used to calculate the sample size. In the present study, flexible and non-flexible functions including Translog Production Function, Generalized quadratic Production Function, Generalized Leontif Production Function, Transcendental Production Function and Cobb– Douglas Production Function were investigated for determining the best model to estimate the shadow price by some test and statistics. The results showed that the Cobb - Douglas function had better performance than other considered functions. This function has more suitable form relative to other functions. R2 and F statistic were used to evaluate the goodness of estimates and significance of the regression in five considered functions, respectively. Based on the JB statistic the distribution of error correction functions is Normal. In addition, the maximum likelihood test was used to compare the Cobb – Douglas Production function as conditioned function and other functions as non-conditioned functions. The values of LR statistics confirmed the superiority of Cobb-Douglas function than other considered functions. According to the above-mentioned criteria, it can be concluded that the Cobb-Douglas function form is more suitable than other functional forms for investigating alfalfa crop production in the study area. The MP will be achieved from the coefficients of the variables in the equation of the above function. Based on the results, inputs such as seeds, fertilizers and cultivated area have positive elasticity, so they consume in optimal region. But labor, water, machinery and pesticides have negative elasticity, due to the excessive consumption of these inputs. Therefore, these inputs are used in the non-optimal and non-economic in alfalfa products. Then, the consumption of these inputs must decrease. The highest and lowest average productivity belonged to the cultivated area and water. Marginal productivity show cultivated area and seed inputs are used efficiently. Also, other inputs, especially used water are inefficient consumption by farmers. This result confirms the obtained previously outcomes. Also water pricing for farmers is 28.51 Rails per cubic meter while the estimated economic value is 84.94 Rails per cubic meter in the study area. Thus, farmers have to pay only 30 percent of the economic value of water. In this study, as well as studies in the mountainous region, that conducted by Ahmadpor and sabouhi (2009) and Ehsani and et al (2010), the market price and water economy is low. Because, the water price which government takes from farmers is lower than the real price to promote sprinkler irrigation system in the region. The other reasons are that the Ghorveh and Dehgolan Townships are located in a mountainous region which the water deficit is not serious and important. The above factors caused the lake of the markets and economy water in this area. Also the obtained price elasticity is equal to -2.59 and it is less than minus one, which indicates the importance of this pricing policy to control excessive water consumption .Price policies could be an important factor in controlling Non- optimal consumption of water in the world.
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Abstract Industrial development increased concerns of heavy metals in wastewater. Heavy metals in the industry have caused many problems. Heavy metals are the first hazardous materials in pollutants, which have hazard for the environment and harmful for Human health. Chromium is a heavy metal could be found in industrial sewage systems like metal polish, loom, leathery, fertilizer manufactures. Chrome, often in the form of hexavalent chromium, is one of the metals in aquatic environments. Chrome is harmful to human health and has adverse effects on human and animal bodies; therefore, the use of absorbent material to remove it from the water and wastewater treatment is essential. Trivalent chromium (Cr(III)) ion is possibly required in trace amounts for sugar and lipid metabolism, although the issue remains in debate. In larger amounts and in different forms, chromium can be toxic and carcinogenic. The most prominent example of toxic chromium is hexavalent chromium (Cr(VI)). Abandoned chromium production sites often require environmental cleanup. Rice is one of the cheapest and frequent absorbent due to its cellulose and carbon fiber capacity. The aim of this study is to evaluate the effect of particle size on the amount of rice chromium removal from aqueous solution. To do so, milled rice stems were collected from rice fields of Lenjan, Isfahan. After that, the particles were sieved with 75, 300, 850 and 1200 µm meshes. In this study, four levels of rice amount including 1, 1.5, 2, and 3 grams with 75, 300, 850 and 1200 ?m were used. To prepare a solution of hexavalent chromium, potassium dichromate was used (95% purity, prepared by Merck Co., Germany). The standard solution for testing, were prepared using the dilute solution. A chromium concentration of 10 mg/lit has been selected for all experiments. In this study, several non-equilibrium models, including Lagergren, Ho and colleagues and the intermolecular distribution and equilibrium models of Langmuir, Freundlich, Redlich- Peterson and Sips were used. To test the results of equilibrium and non-equilibrium models, the nonlinear equations were used (Matlab ver. 7.8.).
pH of the solution is an important parameter influencing chemical reactions and biological process of sewage. Changes in pH affect the absorption of chromium. This response will affect the relationship between absorbent and absorption material. In other words, positive surface absorbent and electrostatic adsorption increases its tendency to absorb anions. Equilibrium time determines the capacity of equilibrium as well as the maximum capacity of absorbent material. For a specific amount of absorbent, equilibrium time is the duration of completing absorbent capacity (unattraction of absorbent element). Absorbent particle size (specific surface area), determines the absorption capacity as the most important feature of absorbent material. In general, when the absorbent material decreases the specific surface area increases exponentially, therefore, their area of irregular shapes are increased and consequently the amount of absorption capacity due to the speed of the process will increase. The results showed a significant (p?0.05) relationship between absorbent particle size and equilibrium time as well as absorbent particle size and maximum absorption capacity.
The maximum adsorption efficiency in 1 gram of rice stem with the 75 micrometer particle size in pH=2 and 98.25 percent was occurred. The synthetic adsorption assessment shows that, none equilibrium model of Lagergren (Correlation coefficient 1) and Ho et al. (Correlation coefficient= 0.999) models were clarified adsorption of chromium by rice stem very good. Also, the balance time was increased logarithmically by increasing in the particle size of rice stem, to which the balance time in the particle size of 75, 300, 850 and 1200 micrometers provided 30, 90, 90, and 120 min, respectively. The isotherm adsorption assessment shows that, in 75 micrometer particle size of rice stem, Langmuir (Correlation coefficient= 0.993), Ferundlich (Correlation coefficient= 0.989), Redlich- Peterson (Correlation coefficient= 0.993) and Sips (Correlation coefficient= 0.994) models were clarifying isotherm adsorption, respectively. Maximum adsorption was decreased linearly by increasing in the particle size of rice stem. Adsorption capacity of chromium by Langmuir model for the rice stem particle size of 75, 300, 850 and 1200 micrometers were shown as 3.096, 2.490, 1.820 and 1.456 (mg/g), respectively. Comparing the maximum capacity of absorption of rice stem in this study with other absorbents in the other studies showed that the gridded rice stem is an elegant absorption material to remove chromium of wastewater.

Abstract Scouring phenomena around bridge abutment is one of the most significant causes of bridges failure. Investigation on erosion around bridge abutments and present a reliable method to protect them against scouring is necessary because of significant and vital rule of these structures in transportation. There have been many studies to reduce the maximum depth of scouring at abutments such as using a protective collar, riprap mattresses, Geo bag, etc. But most of them are not economical and efficient to countermeasure the abutments with different shapes and length. Using a protective collar at abutment is one of the simplest and most applicable techniques to countermeasure of abutments in comparison with other protective methods. Simple application and appropriate performance of collar, lead to widespread investigations on it. To study the performance of collar, shapes and lengths (La) of the collar are the most effective parameters in reduction of maximum depth of scouring. While, the performance of collar varies for different flow intensities. For smaller flow intensities, using collar may lead to diminish the scouring at the tip of the abutments. But for higher flow intensities (near the threshold of the bed material), the efficiency of collar reduces and flow can be able to scour below the collar and reach to the tip of the abutment. As a whole, there are two types of abutment (short and long abutments) in terms of length. In short abutments, the ratio of the length of the abutment to the flow depth is less than one ( ), while for long abutments this ratio is more than unit ( ). In the previous investigations, the applicability of using collars in reduction of scour depth at short abutments has not been studied widely. Also, there are no many studies on the effects of various flow conditions on the efficiency of collar for both short and long abutments and no comparing between them. In this study, scouring around two kinds of rectangular abutments (short and long abutments) were investigated. All experiments were conducted in a 1 m width, 1 m depth and 14 m length rectangular flume located at the Porous Media Laboratory of Amirkabir University of Technology. The test region, where the abutments were placed in the flume, was selected in a way that a uniform flow was established and fully developed turbulent flow was reached. The bed materials are uniform with a median size of 0.91 mm and a geometric standard deviation of 1.38. The experiments were conducted under the clear water and various flow conditions (U/Ucr=0.95, 0.85, 0.75). The discharge of the flow was adjusted by an inlet valve and measured by a rectangular weir at the end of the flume. In this investigation, long duration (70 hour) tests were conducted to determine the equilibrium depth of scouring. Equilibrium depth of scouring was defined as a depth with less than 1 mm change after 2 hours of experimental run. According to the conducted tests and obtained time duration data, 40 and 50 hours were adopted as the equilibrium time for short and long abutment experiments (with and without collar), respectively, in which 95% maximum depth of scouring was occurred. The experiments were continued until reach the relative equilibrium state. The experimental results for scouring of the bed materials for the various flow intensities of U/Ucr=0.95, 0.85 and 0.75 showed that the use of collar with 2La in length for short abutment and La for long abutment at bed level, causes the reduction of scouring about 46%, 57% and 100% for short abutment and 26%, 24% and 60% for long abutment, respectively. The start time of scouring at the tip of the long abutment in the same flow condition and using collars with the same sizes, took place 405, 490 and 760 minutes after experiments run, respectively. Also, the start time of scouring at the tip of the short abutment protected by collars at bed elevation took place 300 and 255 minutes for U/Ucr=0.95, 0.85 flow intensity and no scouring on the tip of abutment during 40 hours of test run. Furthermore, applying collar on abutment led to reduce the scouring volume around the abutment equal to 37%, 64% and 25% for short and 34%, 43% and 44% for long abutment in U/Ucr=0.95, 0.85 and 0.75 flow intensities, respectively.

Abstract Evapotranspiration and precipitation are the most important climatic variables for revealing the climate change and temporal-spatial patterns of variables influencing the eco-hydrological processes, which control the evolution of the surface ecosystem. This type of inquiry is fundamental to understand the coupling between ecosystem dynamics and the water cycle, in particular in arid and semi-arid environments in Iran. The goal of this study was to investigate the temporal trends on reference Evapotranspiration (ET0) and annual precipitation (P) time series over semi-arid region of the Urmia Lake basin, located in the northwest of Iran. For this purpose, meteorological observations collected from five high quality meteorological sites over a 30-year period (1976–2005) were used and statistically significant ET0 trends in annual time scale were detected using the nonparametric Mann-Kendall (MK) and Sequential Mann-Kendall (SMK) tests at the 5% significance level. The ET0 monthly data were prepared using a pre-validated solar radiation hybrid model to estimate monthly Rn values required in the original FAO56 model. In this study, we developed the Hybrid-PMF56 model to improve both Rn and ET0 estimates. Furthermore, to eliminate the effect of serial correlation on the test results, the Trend Free Pre-Whitening (TFPW) approach was applied.
The analysis was based on monthly meteorological data at five synoptic stations located in the basin consist of Urmia, Tabriz, Khoy, Saghez, and Mahabad during 1976-2005. At first step, monthly ET0 rates at each station were estimated using a newly developed model, known as PMF56-Hybrid. Then the non-parametric Mann-Kendall and the Theil-Sen slope tests were applied. In addition, the sequential Mann-Kendall test was used to detect abrupt changes in the time series. The Mann–Kendall test requires time series to be serially independent. The presence of serial correlation in the time series makes trend tests too liberal, i.e. the null hypothesis trend is rejected too frequently, speci?cally if there is positive serial correlation. For this, von Storch (1995) suggests that the time series should be ‘pre-whitened’, i.e. eliminate the effect of serial correlation before applying the Mann–Kendall test. This study incorporates this suggestion. The data must be serially independent in the case of the non-parametric tests. According to previous studies, the existence of serial correlation will increase the probability for significant trend detection. This leads to a disproportionate rejection of the null hypothesis of non-trend, whereas the null hypothesis is actually true. Therefore, the influence of serial correlation must be eliminated
Annual trend analysis on precipitation data showed that there is a decreasing trend at all stations except Mahabad. Furthermore, annual ET0 data at the 5% level in the same period did not show any significant increasing trend. The Theil-Sen test results showed the highest positive slope rate at Khoy station (3.44 mm/year). In addition, the minimum and maximum of the Sen-slope rates were 4.2 and 2.88 mm/year at Khoy and Tabriz stations, respectively. The Sequential Mann-Kendall test revealed that Khoy and Tabriz stations faced an abrupt change with a decreasing trend in annual precipitation data but non-significant at %5 except at Khoy station. For the PMF56-Hybrid based ET0 time series data, abrupt changes are not significant at all stations during 1976-2005. As shown, the majority of the annual precipitation series was characterized by negative trend which were mostly insigni?cant. In addition, the signi?cant decreasing trend was only observed at Sanandaj at the rate of -42.61 mm /decade which began in 1975 (Table 5).
In this study, temporal trends in ET0 and precipitation data for five synoptic stations located in the Urmia Lake basin were analyzed. The results showed an insignificant trend in ET0 time series at all stations. At seasonal time scale, all stations have increased trend which only at Tabriz and Saghez station during autumn; we found a significant increasing trend. The initiative coupled model of Hybrid radiation and FAO56 methods, was applied in the study area to improve ET0 estimations. Furthermore, pre-whitening was applied to eliminate the effect of serial correlation on the Mann–Kendall test. The results indicated that the climatic data were serially correlated showing the data were not independent. The main sources for abrupt changes in climate data include station relocations, changes in observation times, methods used to calculate daily means, changes in gauged locations, and changes in instruments, increased urbanized area and global warming. Another factor that could lead to climate changes is the change in atmospheric circulation. The results also suggest the need for further investigation on compressive trend analysis of different climate variables which help to understand the major causes of climate change in this semi-arid region.
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Abstract The sluice gates are widely used for flow regulating and discharge measuring in irrigation and drainage projects. For this reason, determination of the discharge coefficient for sluice gates is an important issue. Sluice gate discharge coefficient depends on geometric and hydraulic parameters of the flow and type of gate. In this study, with a simultaneous solution of Bernoulli and momentum equations and regression techniques, effective non-dimensional parameters in determining the discharge coefficient and the relation of these parameters and discharge coefficient were determined. Also comparison between some analytic and experimental results for determining discharge coefficient was carried out. Results showed that the nonlinear equation got better results in comparison with the linear equation in modeling discharge coefficient. All numerical computations in procedure of this study were performed by Wolfram Mathematica v.6 software. 

Abstract Using specific capacity data is a suitable method for estimating aquifer transmissivity. Usually the specific capacity data are more easily available compared with time-drawdown data, therefore, by using specific capacity data can increase the number of transmissivity estimates in an aquifer. Numerous researchers have tried to obtain the relationship between specific capacity and transmissivity and many methods have been proposed which among them, the analytical approach based on the Theis formula is the most commonly used method. In this research, a simple approach using the Microsoft Excel software is proposed which is based on iteration algorithm, providing fast estimates of hydrodynamic coefficients in more points. This approach has been used in two different locations of Qom aquifer successfully, which in both of two considered places, the calculated hydrodynamic coefficients from the proposed approach are logically consistent with ones obtained from curve matching methods.

Abstract In recent years, the water market has been considered as an efficient mechanism for optimal allocating of water resources and overcoming some challenge in the water sector. However, there are many questions about the water market such as its economic consequences. This study investigated the economic consequences of local water markets in Ardabil county, Iran. For this purpose, after estimating the production function, the value of marginal product of water was calculated and compared with water price in the market. Results show that farmers have been relied heavily on the local water market so that they bought 23% of their required water from local water markets during the farming year of 2009-2010. Water was traded at 841 Rials/m3 that is closed to the economic value of water (930 Rials/m3). Therefore, it can be said that the water trades in local markets based on its economic value. Results also show that after participating in the water market, farmers' income was increased up to 1.8% - 23.9%. According to the results, the water markets can be considered as a useful mechanism to alleviate excessive demand for irrigation water, optimal water allocation, increasing efficiency of water use and decreasing the government expenditures.

Abstract

Abstract Musa Estuary is one of the most valuable aquatic ecosystems in the in Khuzestan Province. Previous studies on sediment and organisms in this ecosystem found some indications of mercury pollution in this area and have emphasized that mercury concentrations are above global standards. The aim of this study was to evaluate the mercury concentration in the waters of Musa Estuary. For this purpose, five creeks (Zangi, Jafari, Petroshimi, Ghazaleh and Majidieh) of Musa Estuary were investigated. Water samples were collected in November 2009. The extraction of dissolved mercury from water samples were conducted according to the APHA standard method and the level of Hg were determined using cold vapor atomic absorption spectrometry. Mercury concentrations in water samples ranged from 3.66 to 12.00 μg/l. The highest Hg concentrations were observed in at Ghazaleh and Majidieh creeks and the lowest mercury contents were found in Zangi creek. The results of this study indicated that Hg concentration in waters of Musa Estuary exceeds the maximum acceptable level (0.2 μg/l) and warning limit (2.0 μg/l) for mercury in seawater which is a critical environmental issue for this region.