مجله محیط زیست و مهندسی آب
سال دوم شماره 1 (بهار 1395)

The presence of trace amounts of phosphorus in treated wastewaters from municipalities and industries results in eutrophication.Therefore, its removal is crucial for controlling eutrophication in receiving water. Hence, the aim of this study was to evaluate the phosphor adsorption from aqueous solution using single wall carbon nanotubes (SWCNT) as a sorbent. The batch experiments were performed at laboratory scale. The SWCNT was characterized using scanning electron microscope (SEM). The effects of operational parameters such as adsorbent dosage, pH, and initial phosphor concentration on initial phosphor removal were evaluated. The isotherm and kinetics of phosphor adsorption were determined. The results showed that phosphor removal was directly proportional with increase in adsorbent dosage and it was reversely proportional with increase in initial phosphorous concentration. Therefore, with adsorbent dosage increased from 0.1 to 0.4 mg/l, the percentage of removal increased from 83.0 to 92.5%. Moreover, the pseudo-first order, pseudo-second order kinetic, and intraparticle diffusion models were used to describe the kinetic data. The experimental data fitted well with pseudo-second order kinetic model. Equilibrium isotherms were analyzed by Langmuir, Freundlich, and Tempkin adsorption models. It was found that the adsorption isotherm was correlated reasonably well with Freundlich isotherm. The high adsorption capacity of SWCNT indicates that this adsorbent might be a suitable alternative to remove pollutants from aqueous media. It is concluded that the SWCNTs have a high potential for phosphor adsorption and can be used as an effective adsorption for removal of phosphor form effluents.

Great progress and development in geographic information systems technology has provided users the ability to use this discipline to evaluate changes resulting from natural and human factors, and to determine these changes. In this research, the changes trend in rainfall in the region of Marivan Plain and groundwater level changes were studied using GIS. The geographical coordinates of 23 rain gauges in the GIS were used to produce maps of their distribution using Thiessen polygon method. The study area was delineated from the interpolated map. Monthly precipitation data for a period of 15 years (1997-2011) were obtained from stations in the study area, and the mean precipitation for the area was calculated using the Thiessen polygon method. First, a point map was created using 23 rain gauge station coordinates of the plain, which was then interpolated using the nearest point method. The slope of the regression line reveals increase in rainfall amount during the year of study. Fluctuation of ground water table was studied for the years 1997-2011. Using coordinates of 27 wells dug in the study area, a point map was created. Average yearly groundwater table data related to observational wells in 1997 and 2011 were used to interpolate the point map using the moving average method. The results revealed 2509316 m3 declines in volume of the water.

More than 85 percent of current ground water resources extractions are supplying agriculture water demands in Birjand Plain. Because of the importance of water quality for irrigation, 47 samples collected from piezometric wells in Birjand Plain, to determine ground water quality suitability for agriculture. pH and EC values measured at filed campaign beside laboratory analysis of water samples for major ions concentrations. After chemical analysis of water samples, different geo-statistical models had used to model Cl, HCO3, SAR, pH and EC water qualities parameters. Then the error of each simulation was calculated. Finally, the best method was performed to prepare spatiality maps of Cl, HCO3, SAR, pH and EC parameters in Birjand aquifer based on FAO classification. The interpolation errors assessment highlighted Kriging as the most accurate method for all investigated parameters, in compare to Inverse Distance weighting (IDW) and Radial Basis Functions (RBF). The spatiality maps based on FAO classification show that ground water resources in Birjand plain are not applicable for agriculture due to extremely high values of SAR, Cl, and HCO3, where its usage has limited a little for agriculture by EC and its quality has a suitable range of pH.

Simulation of moisture distribution pattern in the root zone and accurate determination for design can be considered as one of the criteria for improving yield productivity and utilization management in surface irrigation systems. In this study, experiments were carried out in a transparent plexy-glass physical model (0.5×1.22× 3 m) on three different soil textures (fine, heavy and medium). The emitter outflows were considered as 2.4, 4 and 6 l/hr with irrigation duration of 6 hrs. Then, using the p theorem of Buckingham and Dimension Analysis (DA), equations were developed to estimate the pattern of moisture distribution (horizontal and vertical) in three soil textures in subsurface drip irrigation. These equations were as function of initial moisture, radial distance of points, applied water volume, hydraulic conductivity and emitter outflows. Comparison between simulated and observed values showed that these equations are capable in predicting the pattern of moisture distribution in different directions. The average of Root Mean Square Error (RMSE) values in clay soil and for emitter outflows 2.4, 4 and 6 l/hr were 0.039, 0.08 and 0.036, respectively. These values for loamy soil were 0.15, 0.044 and 0.091, respectively; while for sandy soil were 0.018, 0.019 and 0.02, respectively. Using these equations in designing surface drip irrigation systems, the moisture distribution could be simply simulated and optimum management can be accordingly applied.

Estimation of reference crop evapotranspiration is one of the most important elements in optimizing agricultural water consumption and in management of water resources. Forecasting the daily and weekly reference evapotranspiration can be used in predicting of crop water requirements and in short range planning irrigation. The aim of this study was to evaluate the performance of three types of artificial neural networks: MLP (multilayer perceptron), RBF (radial basis function network), and SVM (support vector machine) in forecasting the daily and weekly reference evapotranspiration at Tabriz synoptic stations. For this purpose, the meteorological data of 39-year period (1971-2009) were used. To train the neural network, 80 percent of time series data was selected randomly and 20 percent of data was used to validate the different models. To create the time series of daily and weekly reference evapotranspiration in a given period, the standard Penman-Monteith FAO 56 equation was used. Different combinations of input data (different delays) were used to evaluate the models. The results of daily forecasting of reference evapotranspiration showed that SVM with RBF kernel with input set of M5, RMSE=0.51 mm/day and R2=0.92 had the best performance. Moreover, the results of weekly forecasting of reference evapotranspiration showed that SVM with polynomial kernel with inputs set of M8, RMSE=3.88 mm/week and R2=0.95 had the best performance.

The breakwater as structures that have an important role in the protection of coastal facilities was used to create calm in the harbor, reduce wave energy and also protect the coast against wave attack. Wave overtopping is an important parameter to design breakwater. In this paper, a new formula will be proposed to estimate wave overtopping on the reshaping breakwater. In this research, further effective parameters such as stone diameter (Dn50) and water depth at toe of the structure (d) were considered to estimate wave overtopping. Wave overtopping occurs when water level goes higher than the crest of the structure. To derive a new formula, at first a relation was proposed using hydraulic and structural parameters associated with wave overtopping and then the dimensionless parameter was used by Buckingham theory. A comparison was made between the new relation and the relations proposed by former studies. This research indicated that the proposed formula is accurate in estimating wave overtopping on reshaping berm breakwater.

This research was conducted to investigate the potential of scale forming and corrosiveness of drinking water in the reservoirs and drinking water distribution network in Shiraz, Iran.The area under study was divided into 17 zones. During winter, spring, and summer 2011, 144 water samples were collected from the water reservoirs and the various sites of water distribution system. The chemical parameters were measured. Then, values of the Langelier (LI), Rayznar (RI), Larson (LI) and aggressive (AI) indices were calculated for each sample. In this research, 41 samples of home pipes were collected from different zones of Shiraz and the rate of scale formation was calculated for each sample. The scale composition of 33 home pipe samples and 8 network pipe samples were analyzed by X-ray diffraction method. Results showed that the mean values of LI, RI, LS, and AI were 0.07 (considered as slightly scale forming), 7.1 (non-scale forming), 1.2 (corrosive), and 14 (non-corrosive) respectively. The average rate of scale formation and their values for the drinking water of Shiraz pipes is 0.26 mm/yr. The research found that the main compositions in the scale samples were calcium carbonate, calcium sulfate, magnesium carbonate, magnesium sulfate, hematite, maghemite, magnetite, goethite, zinc oxide, gypsum, vivianite, dolomite, hydroxyapatite, and troilite. The main elements in the scale samples were magnesium, silicon, phosphorus, sulfur, zinc, copper, and lead. According to the results of this research, zones located in the east, south, and southeast of Shiraz, because of high levels of hardness and sulfate exhibit more scale formation as a problem.

Sustainability and water resources management is an important issue. Therefore, appropriate organization management of demand and regulating consumption patterns may build sustainable solutions for moderated in water resources dissipation. By having a proper planning respect to the utilization pattern of land (i.e. the optimal cropping pattern) we may manage the demand for water. The current study attempted to design cropping pattern, for the purpose of increasing the productivity of water resources in agricultural sector of Dehgolan County and apply respect to virtual water. The necessary data collected from 110 farms through simple random sampling and to find the cost of cultivation the statistical year book of agricultural organization used. The optimal cropping patterns were determined in three different scenarios such as increasing agricultural strategic crops price policy, with existence of strategic crops and use of total area under cultivation for the sample farms including Less than 10 hectares, between 10 to 20 hectares and more than 20 hectares. The result showed that, Wheat, potato, cucumber and alfalfa crops are main products in the cropping pattern for three groups of fields and according to the results of three concerns scenarios, the application of increasing price policy strategy had positive impact on the farmer's income and use of this policy along the policy use of available total land was more effective in the sustainability of water resources.