مجله مهندسی آبیاری و آب ایران
پیاپی 37 (پاییز 1398)

Open channel junctions are so important in water conveyance networks. As a result, the researchers have been focusing on study of flow characteristics in these parts of water systems. Numerical simulation allows us to achieve the answer for engineering problems without encountering the experimental difficulty and with minimum cost. The aim of this study was, developing a 1D analytical model for simulating open channel junctions base on continuity, energy and momentum equations and some simple assumptions and comparing the experimental results in order to validation of analytical results. In experiments, side slope of main channel was 45 and 90 degrees. The studied variables were the ratio of depth at the junction. Investigation of results showed that increase of Froude number and inlet discharge ratio would lead to increase of turbulence which would decrease precision of analytical model. Also the increase of side slope of main channel caused less turbulence and more precision of the analytical model. In analytical model maximum reported error was about 15% for angle of 90 degrees, with relatively high discharge and depth in main inlet channel and minimum reported error was about 5% for angle of 45 degrees, with relatively low discharge and depth in main outlet channel

There are direct relationships between leakage and consumption in the distribution network with the pressure. Due to the relationship between leakage and consumption with pressure, those can be reduced by the reduction of the pressure. One of the best and most cost-effective methods in order to reduce the leakage is pressure management. By installing pressure reducing valves, we can reduce the network pressure. In order to operate the pressure reducing valves better in the network, it is important to determine their optimum position and regulated pressure. In this research, we investigated the optimal position for installing pressure reducing valves in the water distribution network. The study is conducted by using a dynamic link between MATLAB and EPANET and a review of all possible states for installing pressure reducing valves. The research is considered as a multi-objective case. It was considered as a multi-objective case. The objective functions in this research are: minimizing the rate of leakage and consumption in the network, Minimizing the points with the pressure more than the tube's capacity and minimizing the number of nodes with a pressure lower than the standard rate. These analyzes were conducted over a 24-hour period. Based on the results, by installing three pressure reducing valves in optimal position and pressure-regulation from 40 m to 33 m in Birjand network, the average of consumption and leakage in 24 hours was reduced to 48.24 liters per second, compared to the situation with the same number of pressers reducing valves were installed in different position. As it is derived from the results, this approach has a very high efficiency in reducing the leakage and consumption in the water distribution network.

Density current is one of the most important phenomenon in reduction the useful life of dams, that it is the main cause of the sediment movement in the dam reservoirs. Therefore, Study of density or gravity current hydrodynamics plays an important role in increasing the economic life of dams though reduction in sediment accumulation. In this research the effect of the height and distance of successive obstacles and bed slope on the head and body velocity of density current has been studied. In the experiments, four types of height models and 3 types of distance model were used for obstacles. Also, the experiments were carried out in 3 slope and 2 concentration and in two sedimentary and salty types. In total 117 experiments were carried out. The results showed that the head and body velocities decreased with increasing height and distance of obstacles and increased with increasing bed slope. Also, the results showed that using of 3 rows of obstacles can reduce the head and body velocity of salty density current about 31 and 20% respectively, in comparison with the conditions without obstacles. In sedimentary density current numerical values of this reduction was 33 and 19.5 respectively for the head and body velocity. The Keulegan coefficient for estimating head velocity results decreased about 27% in comparison with the conditions without obstacles, with its mean value being obtained about 0.48. However, increasing the bed slope reduces the effect of obstacles in decreasing of head and body velocity. Finally, two equations were developed using Spss software to estimate the head and body velocities of density current based on height of each three obstacles, distance of obstacles and bed slopes.

In horticultural plants, determining of evapotranspiration because of problems in the direct measurement such as installing large lysimeter and length during tree growth, estimated indirectly on the basis of meteorological data. With regard to the spatial variability of meteorological parameters and sometimes inappropriate distribution of meteorological stations estimating evapotranspiration is not possible with sufficient accuracy. Therefore, use of procedures such as the methods remote sensing based that consider these changes may be best. In this study, evapotranspiration pomegranatee trees measure and were determined with direct and indirect methods in Tarom district of Zanjan at different physiological growth stages and In 1393 and 1394 growing seasons. In the direct method were measured Water balance components and the indirect method were determined with the help of satellite images actual evapotranspiration trees with SEBAL algorithm. Then The crop coefficient was determined using evapotranspiration obtained by the two methods and determination of the reference evapotranspiration based on meteorological data of day of receiving the image, and the results are compared and evaluated. The correlation coefficient in evapotranspiration for first and second year was 0.83 and o.79 respectively and a total of two years was 0.63, respectively, and about of crop coefficient this coefficient was 0.97 and 0.94 and a total of two years was 0.94

Increasing global temperature and its impacts on the water cycle as well as increasing population growth are problems that nowadays focus on better resource consumption and better management for accurate planning to meet future needs. Various hydrological models such as the water and soil assessment (SWAT) model are used to solve this problem. In this study, changes in the outflow of Tajan basin from 2005 to 2015 were simulated using the SWAT model. Then, the results were calibrated, verified and uncertain analysis using SWIT-CUP software using flood measurements at Solomon Strait station and SUI2 algorithm. Then, the results were calibrated, verified and uncertain analysis using SWAT-CUP software using outflow measurements at Soleymantange station and SUFI2 algorithm. The accuracy of the SWAT model was evaluated in the simulation of the outflow using the parameters of P-factor, R-factor, Nash-Sutcliff coefficient (NS) and correlation coefficient (R2). The values of NS and R2 for the calibration stage were 0.57 and 0.58, respectively, and in the validation stage were 0.7 and 0.71, respectively, that indicating a good correlation between the observational and the simulation data. The uncertainty results showed that the simulation curve was well arranged in the uncertainty range, and the distance between the peak points was minimum, in other words, the maximum discharge was simulated with high accuracy (the coefficient of agreement equal to 0.8). Therefore, the SWAT model is a suitable tool for simulation of flow rate in the Tajan basin.

Loss function is an internal module in HEC-HMS model. In combinations with transfer function it provides a continuous rainfall-runoff. Baseflow, as a repetitive for groundwater, also will be included to total flow. Behesht-Abad basin is among those areas where due to the hydrodynamic characteristics of groundwater, base-flow plays a significant responsibility in the shape of hydrograph.  Since HEC-HMS is a component-based hydrological model, it allows user to select the type of internal functions. Each of which requires different input data. For instance for base-flow there exist a number of methods that could be selected optionally.  The aim of this study was to evaluate different methods for base-flow methods for the case of Behesht-Abad Basin. In this study, time series of temperature, precipitation, discharge, and evaporation and transpiration for the period of 1998 to 2015 were used to calibrate the HEC-HMS model. Model was tested against a number of base-flow methods.Results showed the constant monthly and bounded recession methods were performed better   with Nash Sutcliffe efficiency coefficient 0.64 at 0.69 in the calibration and validation, respectively. The visual and statistical interpretation of observed and simulated hydrographs indicated that   bounded recession generally has exhibited better performance. The high sensitivity of the model to type of base-flow shows groundwater plays a key role in the study area.

Awareness of spatial variations of qualitative parameters is an important tool in order to understand the capabilities of the region and how to manage the lands. Through the current study, the spatial and temporal changes of EC, SAR, TDS and TH parameters were analyzed using geostatistical methods during the two statistical periods of 2004 and 2014 in groundwater's. For this purpose, the data related to the analysis of 44 water wells in Jiroft plain, where has a middle hot desert climate were obtained according to the latest sampling in 2014. The Geostatistical methods used to zone the mentioned parameters include ordinary kriging and inverse distance weighing (IDW) with different powers. In order to evaluate the geostatistical pitch methods, the mutual evaluation technique used applying the RMSE, MBE, MAE and R2 criteria between actual and estimated data. The results of the ranking of evaluation criteria showed that for the EC and TDS parameters, the Kriging method with a spherical model, and for the SAR and TH, the method of inverse distance to the power of 2 and 3 respectively, has the least error. The performed studies show that the spatial correlation of the qualitative parameters mentioned in the Jiroft Plain is very high. The error of the semi-variogram model of the measured sodium absorption ratio during the statistical period of 2004-2005 with a nugget effect of 0.97 and a range of effect, 23 km, is equal to 14.2%, and the error of the semi-variogram model during the statistical period of 2014-2015 with a nugget effect of 0.23 and a range of effect, 28 km, is equal to 14.2%. The results of the anomaly maps of the qualitative parameters in Jiroft plain indicated that the most of the changes are in the eastern part (Jebalbarez District) and northwest (Sarduiyeh District) and the least of the changes are in the southern parts of the plain

Climate change is crucially important in Iran given its arid and semiarid climate. It influences water resources, thereby affecting many activities and even threatening human life seriously. The assessment of the extent to which climate change can influence water use and resources can play a decisive role in macro-policymaking. Present study uses positive mathematical programming (PMP) in the context of four climatic scenarios (normal climate change, climate change, climate variability, and concurrent climate change) to explore impacts of these changes on agricultural water use and water resources of Iran in a 20-year period. The results showed that in the context of concurrent climate change and also climate change, in spite of the decrease in water use by the agricultural sector, water resources of Iran are reduced with much higher rate than that under other climatic conditions. According to results, average annual agricultural water use under four studied scenarios will be 35,103.65, 26,533.8, 35,216 and 26,510.69 million m3, and average rate of annual loss of water resources will be 4,422.2, 11,165.6, 4,438.24, and 11,267.45 million m3, respectively. Accordingly, changes should be applied in approach to water demand and supply management. Also, policies should be adopted to cope with climate change.

Precipitation is an important component of the hydrological cycle which links atmospheric and surficial process. Therefore, accurate modeling and estimation of parameter are needed for water resources management, irrigation scheduling, agricultural management and water allocation. SARIMA model is the most popular model for monthly precipitation simulation. The weakness of model is to ignore the inter-monthly variation within each year. Therefore, the aim of paper is the improvement of SARIMA model which takes into account the interannual, inter-monthly variation and comparison the performance of improved model with SARIMA model in Ardabil station. Ward's method for clustering of monthly precipitation time series and linear regression model for determination the relation between statistical characteristic of each cluster and monthly precipitation have been applied. 24.05%, 17.24% and 28.48% decreasing of RRMSE, RMSE and MAE from SARIMA to improved SARIMA model indicated the acceptable performance of improved model. The comparison of observed and simulated values showed the overestimation of improved model simulation. 51.16% RRMSE decreasing in seasonal precipitation simulation was expressive of accuracy increasing of improved model basis on the clustering analysis. The correlation coefficient between simulated of improved SARIMA model and observed precipitation data was increased and reached to the significant level. Therefore, the clustering analysis and improvement of SARIMA model, increased the accuracy of model.

Recent droughts and limitation of water resources have required Proper use of water, measurement and analysis of water productivity indices in different irrigation (surface and pressurized irrigation systems) methods. So this project was conducted to evaluate irrigation water productivity and economic analysis of alfalfa crop production in Hamedan- Bahr plain. In order to 16 alfalfa farms which had sprinkler and surface irrigation were selected and examined. Volume of water consumed was calculated by measuring the water discharge (using Flume method or Water Meter), sprinkler discharge, irrigation hours per irrigation and total number of irrigation. Economic analysis of the alfalfa production was carried out by using the present value of net benefit, Benefit cost ratio and Economic productivity of water with consideration of government grants and regardless of government assistance in the sprinkler irrigation system and surface Irrigation. The average amount of water consumed and water productivity in surface and sprinkler irrigation were estimated 12447 and 7875 cubic meters per hectare and 1.6 and 2.7 kg.m-3 respectively. In this way, the sprinkler irrigation system with a 37% reduction in water consumption has increased the water productivity by 69%. In this way, the sprinkler irrigation system with a 37% reduction in water consumption has increased the water productivity by 69%. The results of economic analysis showed that the present value of the net benefits of alfalfa cultivation in sprinkler irrigation system relative surface irrigation is more than about 74437 thousand rials with government assistance grants. The benefit-cost ratio in sprinkler irrigation systems is 3.8 and 3.2 with or without government subsidies respectively

Water is critical to human survival. The availability of proper and desirable water for human life and all-round development is essential. Water scarcity is one of the main problems of the 21st century, which has already affected nearly all countries of the world, including the countries of the dry belt, such as Iran. One way to deal with water scarcity is to save water. Media and information technology are important tools for education and awareness of people. This article examines the impact of media and information and communication technology on the optimal use of water. The statistical population is Torbat Heydariyeh city. Using random sampling method, 363 of them were selected as samples. The results showed that awareness of the optimal use of water through the internet, social media and television has impacts on environmental concerns. The television has the highest effect on the knowledge of the optimal use of water and environmental concerns for people older than 40 and those with the poor education. The Internet and social networks affect the people under 30 and people with higher education. The overall result of this research is that internet, media and social networks play a significant role in the consumption and conservation of water resources.

Increasing surface and groundwater pollution by ammonium and nitrate makes it necessary to find solutions with minimal environmental impacts. Surface absorption is current method to remove soluble contaminations from aqueous medium. For this purpose, using herbal remedies offers cost-effective and availability and environmentally remediation technique. Using herbal nanoparticles as absorbent due to high specific surface and intense reactivity, results in high absorption efficiency.
In this study investigate nitrate removal using Conocarpus Nanostructure as absorbent in aqueous solution. In order to improve absorption capacity Conocarpus Nanostructure has been modified by a chemical method.
The effect of pH, time and absorption dosage has examined in batch system. The equilibrium time and optimum parameters were determined and the kinetic and isotherm models were checked.
The equilibrium time was determined 90 minutes and the optimum adsorption efficiency occurred in pH=3. The optimum absorbent concentration in nitrate solution was determined 0.6 mg/l. the Coefficients and constants related to the kinetic and isotherm models were find. The kinetic and isotherm models evaluation shows that the Ho et. al. and Froundlich models offer the best description.

Surplus application of nitrate can lead to contamination of groundwater resources. Accurate knowledge of nitrate distribution in the root zone is essential for the design and management of drip irrigation systems. In this study, artificial neural network (ANN) model is used based on strong pattern recognition technique that made reasonable relations between input and output parameters. In order to simulate the nitrate distribution pattern, the Experiments were set on three different soil textures for surface and subsurface drip irrigation systems. The drippers were installed at 3 different soil depths (i.e. 15, 30 and 45 cm). The emitter outflows were considered as 2.4, 4 and 6 lit/hr. The fertigation treatments include treatments with nitrate concentrations of 125, 250 and 375 mg/liter. The effective variables include the initial nitrate of soil, nitrate concentrations in fertigation, initial soil moisture content, radial distance of points, applied water volume, saturated hydraulic conductivity, emitter discharge, emitter installation depth, soil bulk density, and the proportions of sand, silt and clay of soil. The mentioned variables were utilized for estimation of nitrate distribution pattern of surface and subsurface drip irrigation systems using ANN model. The comparisons results of simulated and measured values indicated that ANN models were capable methods for prediction of nitrate distribution. The values of correlation coefficient (R) were ranged 0.9-0.94 and 0.8-0.96 for surface and subsurface drip irrigation systems, respectively.