نشریه دانش آب و خاک
سال بیست و ششم شماره 1 (بهار 1395)

It seems that the presence of soil organic matter (SOM) increases P availability to plants. This effect has commonly been ascribed as competition between the decomposition products of SOM and P for soil sorption sites resulting in P concentrations increase of soil solution. This study was carried out to obtain information about soil organic matter (SOM) influence on kinetics and thermodynamics of P sorption in three collected calcareous soil samples of east Azerbaijan province. Sorption kinetics was studied at 100 mg P L-1 solution as initial concentration before (B) and after (A) SOM removal and observations were carried out for 336 hours. SOM was removed with NaOCl solution. According to the results, P sorption increased rapidly up to about 48 hours beyond which a near steady-state condition was attained. Zero-order, first, second- and third-order equations did not adequately describe P sorption kinetics. Simple Elovich, parabolic diffusion and two-constant rate equations adequately described the data, but two-constant rate equation was the best. To evaluate the temperature effects, P sorption was measured at four temperatures, namely 10, 20, 30 and 400C. According to the results, P sorption, before and after SOM removal, increased with temperature raises indicating the endothermic nature of the sorption reaction. The negative values of Gibbs free energy at different temperatures indicated the spontaneous nature of P sorption in the studied soils. Before SOM removal, ∆G0 in the first sorption site ranged from -32 to -38.2 kJ mol-1 and from -25.4 to -28.4 kJ mol-1 in the second site. While after the removal of organic matter in the first site ∆G0 ranged from -32.9 to -39.3 and in the second site from -30.9 to -36.9 kJ mol-1.

Nowadays, wind erosion and dust have become environmental problems, not only in desert areas, but throughout the entire country, which have imposed many costs on the country budget. Combating wind erosion in many deserts using adapted plants and oil mulch has 40 years history. But the widespread use of petroleum mulches in addition to environmental problems is not economically justified due to the involved high cost of purchasing these materials, moving and spraying of them. In this study effects of non-oil and chemical mulches on germination and survival of plants used to biological regeneration of the areas which were subjected to the wind erosion were investigated and the best mulch was introduced. Accordingly, survival and establishment percentage of seeds, cuttings and seedlings of Calligonum comosom and Haloxylon persicum plants in a randomized complete block with 6 treatments under 6 mulches, namely: Polymer, Fars, RB,Paya, cement and DC400, in 3 replications, were investigated. The results showed that in the method of seeding, pots with Paya and cement mulches had the highest survival and height, and Paya and Polymer mulches produed the highest survival percentage. In the Cutting method, cement mulch had the highest survival, survival percentage and height. In the Seedlings method, the highest survival and survival percentage were observed in the Fars, Paya, Polimer and cement mulches and the maximum height was observed in the cement and R.B mulches. Therefore, the cement mulch is the best cover for combating wind erosion.

Weirs provide a simple method for measuring the volumetric flow rate in small to mediumsized streams or in industrial discharge locations. Sharp crest weirs can be built in different shapes, such as rectangular, triangular, trapezoidal, circular and parabolic. In general, the discharge of these weirs is expressed byQ = Khn , where the value of n varies with structure shape (e.g. / for rectangular weir and 5/2 for triangular weir) and isn’t usually an integer number, then manual calculation of the discharge is facing a problem. In this study to facilitate the discharge calculations, the governing equations of parabolic crest weirs were reviewed and a simple equation was developed for computing the flow rate. Also, by using a physical model with different angles and heights, hydraulic characteristics of these weirs were investigated. The experimental results showed that with increasing the angle and height of parabolic weirs, the discharge coefficient was increased. The average discharge coefficient of experiments was calculated as 0.605. Furthermore, a proper regression-based equation to determine the discharge coefficient, with coefficient of determination R2=0.922, was obtained.

This research was conducted to minimize the dimensions and costs of spur dikes through cutting the edge of them. For this propose, a physical model of spur dikes in series in river bend was employed. The results of tests for spur dikes in series without any changes in their nose shape showed that the local scour commenced from the nose of spur dikes. Generally, in all spur dikes with new shape, as the spur dike surface reduced, the approach flow velocity in front of the spur dike was also reduced. The new shape decreased the shear stress in the upstream of the spur dike and reduced the scour depth. The results also showed that the new shape of the spur dikes (L=5.5,ɵ=85,ɸ=30, e) was able to reduce the scour depth at the nose of the spur dike up to 89 percent.

Prediction of groundwater table through specific models, provide a valuable information for water resources management and consumption planning. Among the different available methods, the multivariate nonlinear regression is of utmost importance for prediction of hydrological phenomena. The data bases of this research were the amounts of precipitation amounts, water table elevation and water consumptions in monthly time scale for the period of 2001- 2011. The cross correlation analysis indicated that the one lagged monthly precipitation as well as the two lagged monthly consumptions values had the highest impacts on water table elevation with the determination coefficients of 0.39 and 0.86, respectively. Then, the general relationship of these three variables obtained with 2=0.87 and root mean square error (RMSE) =0.35m through a multivariate nonlinear regression analysis. For prediction of the water table elevation in the coming years, initially, the consumptions and precipitation data extended up to 2014, using ANN and Thomas-firing methods, respectively. So, the outcome of putting them into regression equation gave the water table elevation. On the other hand, the artificial neural network was used to predict the water table elevation, for which, the resulted values of R2 and RMSE were 0.82 and 0.39m, respectively. The comparison of two methods showed that the multivariate nonlinear regression model represented more accurate results in predicting the elevation of water table, in the studied plain.

Generated runoff has significant effects on quality and quantity of the surface and groundwater resources, soil erosion and even vegetation cover in watersheds. In recent years, different computer models have been applied for estimating and forecasting the runoff and its effects. In this study, the performances of WetSpa hydrological model and ANN and ANFIS intelligent models were evaluated in simulation of the rainfall-runoff and estimation of the daily discharge in Balukhluchay watershed of Ardabil province. The required data including the needed information for the digital elevation model, land use and soil maps and also the climatic and hydrological data of the daily precipitation, temperature, reference evapotranspiration and discharge time series were prepared. The data of 2007 to 2010 were used for calibration and training and the data of 2010 to 2012 were used for validation and test of the models. Different evaluating coefficients such as Nash-Sutcliffe, Correlation Coefficient and Root Mean Square Error (0.457, 0.696 and 1.719 for WetSpa, 0.724, 0.865 and 1.232 for ANN and 0.289, 0.603 and 1.968 for ANFIS, respectively) showed that the highest accuracy among the used models belonged to the ANN, WetSpa and ANFIS, respectively. Despite high accuracy of the ANN, since it is a black box model, its usage for investigating the land use and topography effects on the runoff has some limitations in comparison with the completely distributed Wetspa model.

Low level of efficiency is a main problem of surface irrigation systems that is due to their poor design and management. Furrow inflow rate and cut off time are the most important design parameters that affect the efficiency of furrow irrigation. In this study, furrow irrigation condition of Amir Kabir Agro-Industry sugarcane fields was simulated with WinSRFR3.1 Model. Then, irrigation performances of the relevant fields for different cut-off times and inflow rates were evaluated. Water flow was simulated for the both open and block-ends furrow positions. Selected furrows for flow simulation had a length of 250 m, with a slope of 0.04 percent and 1.83 m spacing between the furrows. The input data of the model were measured in these furrows for an inflow rate of 1.5 Ls-1. Four performance evaluation indices namely, the application efficiency (Ea), distribution uniformity (DU), deep percolation ratio (DPR) and tail water ratio (TWR) were computed for evaluating the irrigation performance in the selected furrows. Prior to simulations, the model was calibrated for local conditions by using measured and simulated flow advance time. The results showed that the best option for furrow irrigation of Amir Kabir Agro-Industry fields is the use of end-blocked system with inflow rate of 1.8 Ls-1 and irrigation duration time of 5 hr.

Soil micromorphology is a branch of soil science which studies undisturbed soil samples using microscopic methods and the image analysis technique can promote speed, accuracy and ability of micromorphic studies. Soil pores due to their effect on the most of processes and properties of soils and also on interaction between soil, water and plant, have spacial importance. In this study, soil pores type and total porosity of saline-sodic soils were studied using micromorphic and Image Analysis techniques in a transect composed of eight soil profiles in the west of Urmia Lake. According to microscopic observations, pore types in these soils were vughs, channels and planar voids but Voids size and frequency in different horizons of each profile and all eight profiles were different. Average values of vughs, channels and planar voids in each thin section were about 45- 50%, 35-45% and 5-25%, respectively. Comparison between thin section description and Image Analysis showed that frequency and the range of size of pores in Image Analysis technique was greater than that of thin section description. The differences of measured total porosity between Image Analysis and thin section description in profiles 1 to 4 were 10.7, 7.83, 6.7 and 9 percent respectively. The reason of this difference is that, in thin section description technique, some of voids are too small, so they cannot be seen and are not measurable, whereas, in Image Analysis technique the measurement of size and frequency of voids were based on the number of pixels and this leads to greater values in Image analysis technique.

Nitrate contamination of water resources is becoming a serious environmental problem worldwide. Application of natural materials to remove nitrate can be considered as the most valuable solution. This study aims to investigate the use of date palm fiber in the production of adsorbent material. Palm fibers were burned at temperatures of 450, 600 and 750 °C in a limited supply of oxygen condition. The produced biochar at temperature of 600 °C was chosen due to its high ability in removal of the nitrate from aqueous solution. Biochar made from these fibers washed with hydrochloric acid 0.5 N and then with distilled water to increase performance. The FTIR method was used to investigate groups of the adsorbent. Additional studies were performed to measure the effects of pH, adsorbent dose, time and temperature on nitrate sorption. The optimal conditions for removal of nitrate were found to be: 0.5 g of adsorbent in 20 ml solution, temperature of 10 °C, 30 min and neutral pH. Under these conditions, the nitrate removal efficiency was over 96 . The adsorption data were explained using the Langmuir and Temkin adsorption isotherms. Kinetic studies showed that the pseudo-second order was the best fitted model to the sorption data.

The change of forest to agricultural lands has serious effects on the amount of soil organic matter and physico- chemical characteristics. Noting the increasing change of forestry land use in Mazandaran province, this study was conducted to investigate the effects of land use change on soil characteristics in the Nekaroad watershed. For this purpose, soil samples were collected from the two depths (0-10 and 10-20 cm) and three different land uses (forest, pasture and agriculture). Then the sample were compared based on a randomized complete block design. The results showed that the bulk density, Calcium carbonate, pH and sand percent of the soil were increased while the soil porosity, cation exchange capacity, silt and clay percent were decreased with the change of forest land use to pasture and agriculture. The amounts of organic matter in the soil layer with the depth of 0-10 cm at the agricultural and pasture lands compared to forest land were decreased about 35.70 and 21.85 %, respectively. Similarly, the reduction of organic matter in the soil layer with the depth of 10-20 cm in the same lands were 36.22 and 22.64%, respectively. The maximum total nitrogen was 0.37 %, which was observed in the soil depth of 0-10 cm at forest land while the minimum of it was 0.16 % in the soil depth of 10-20 cm at agricultural land which showed a reduction of 56.75%.

Irrigation scheduling under water and salinity stresses is more difficult than normal conditions. To investigate the effect of water stress on crop growth, numerous indices have been introduced which one of them is crop water stress index (CWSI). To evaluate the suitability of this index for irrigation scheduling of corn (maize) with using saline water, a field experiment consisted of irrigation water with five salinity levels (S0: Caroon River (EC= 2.3 dS m-1), S1: EC= . dS m-1, S2: EC=4.5 dS m-1, S3: EC=5.5 dS m-1 and S4: EC=6.5 dS m-1) was conducted at the research station of Shahid Chamran University, Iran. Results showed that the lower baseline equation (without stress) for the summer corn was (Tc-Ta)ll=2.161-0.221 VPD and the upper baseline equation (with full stress) was h=3.690C. The CWSI value as a base for irrigation scheduling was calculated to be 0.23. Also it was found that increasing water salinity caused to increase the foliage temperature. Thus, CWSI may be used for irrigation scheduling under conditions of using saline water. By increasing water salinity from 2.2 to 6.5 dS m-1, the temperature difference between the canopy and air was increased by 30C, approximately. In this research, CWSI values at the day just before the irrigation were 0.23 for S0, 0.35 for S1, 0.46 for S2, 0.58 for S3 and 0.73 for S scenarios. Also results showed by increasing water salinity from 2.3 to 6.5 dS m-1, CWSI increased about three times.

Side weir is a hydraulic control structure that is widely used in irrigation, drainage and urban sewage purification. In this research, 220 tests were carried out to study discharge coefficient and water surface profile of one-side semi-circular labyrinth side weir under subcritical flow condition. The effects of upstream Froude number, the ratio of length to width of the channel, weir height to upstream water depth, number of cycles and the radius of the Labyrinth on the discharge coefficient of the weir were investigated. The results showed that discharge coefficient of the semi-circular labyrinth side weir was 21 percent higher than rectangular side weir. Using SPSS software, a general equation based on the dimensionless parameters was presented for calculating the discharge coefficient of the semi-circular labyrinth side weir. The determination coefficient and NRMSE of this equation were obtained, 0.93 and 0.28 respectively. The water surface profile along the central axis of the main channel was almost horizontal.

Nowadays, due to population increasing and agricultural land loosing, optimum usage is essential, so land susceptibility must be evaluated prior to land suitability. The models generally are the simplified facts of reality which can be applied for determining yield production and site speciation of suitable strata. Geostatistical observations were integrated with GIS to create continuous soil properties maps. Hereby, number of 56 and 15 samples were collected for modeling and geostatistical analysis, as well as testing the accuracy of maps, respectively. Spherical and exponential models were identified as the best fitted models due to higher R2 and lower RMSE. The results revealed that pH, Pabs, clay and CCE in the vast area while EC and CEC in a part of studied area were recognized as limiting factors for Damask rose cultivation. Proper management decisions will be beneficial for improvement of some soil temporary limitations. Correcting of pH in an area of 22 ha (i.e.) may improve the land. Leaching the soil (3.459 ha) with high quality of water is also required to move the salinity with low cost to achieve the best suitable land for purpose. On the contrary of other parameters, clay has limiting impact on 15.83 ha which it is not possible to be corrected.

Researches show that one of the most effective factors on bridge destruction is bridge abutment scour. In this research, the role of collar as a control structure of bridge abutment scour was investigated along with the effect of its roughness. The results were then compared with smooth collars at the same condition. The results showed that the rough collars installed above the bed level showed a better performance in comparison to the smooth collars so that installation of the rough collar at a distance equal to 20 percent of the water depth above the initial bed level caused the performance of collar to be increased 14 percent, as compared to the condition with smooth collar. In the condition that the collars were installed above and below the bed surface, the performance of rough and smooth collars didn’t have a significant difference due to the small space under the collars.

A side weir is being installed as a flow control structure on the side of the main channel. When the water level exceeds the crest level of the side weir, the additional flow will spill over the weir crest and divert into the side channel. This type of structures has wide application in urban sewage disposal, water supply systems, drainage and flood diversion networks. In this study, the free surface of flow and the side weir discharge were simulated using FLOW-3D software. The RNG k- ε turbulence model was used for simulation of the flow field turbulence. Also the volume of fluid (VOF) scheme was applied to predict the variations of flow free surface. Comparing numerical simulations with experimental results showed the acceptable accuracy of numerical model. Next, the discharge coefficient of side weir and the free surface of flow variations were evaluated for different discharges of the main channel. Then the variation of the width of the separating stream surface from bed of the main channel toward the free surface of flow was investigated. Also, the circular channel effects on the pattern and strength of the secondary flow were studied. The effects of the main channel discharge on the stagnation point height and bed shear stress pattern were investigated. According to the subcritical flows pattern, the flow depth was increased from the side weir upstream end towards its downstream end. For all longitudinal profiles with increasing discharges within circular channel, the flow depth was increased along the side weir.

The soil fungi play important role in degradation of organic substrates, especially in crude oil hydrocarbons. Due to lack of studies on use of fungi in degradation of petroleum hydrocarbons in Iran, fungi isolation from oily soils in Ahvaz and Omidiyeh was done to determine the relative growth of fungi on crude oil, and to measure the growth rate and degradation capacity of them in crude oil. The samples were cultured on Potato Dextrose Agar medium supplemented with Streptomycine and mineral salts medium (MSM) with 1% crude oil. Their abilities were compared for degradation of crude oil on liquid MSM and mycelia biomass and residual crude oil was measured. Finally, seven species selected from oily soils, and the abilities of Aspergillus terreus, A. flavus, Penicillium spp. and Fusarium spp. for degrading crude oil were compared. The highest level biomass was obtained by Penicillium spp. (71.40 ± 22.60 mg/50ml) and the lowest level by Fusarium spp. (24.0 ± 15.00 mg/50ml). The highest percentage of crude oil utilization was related to Penicillium spp. (46.10%) and the lowest Fusarium spp. (19.20%). All the organisms used in this study were indigenous to the environment from which they were isolated. In conclusion the biodegradation of contaminants is the best way to eliminate oil pollutions.

With regard to the crucial role of cyanobacteria in molecular nitrogen fixation, the present study was aimed to isolate the native strains of cyanobacteria from paddy fields in Guilan province, and also examined their important physiological characteristics for production of bio fertilizer. After isolation, purification and identification of efficient cyanobacterial isolates, chlorophyll content, phycobiliproteins and nitrogenase activity of isolates were determined, and then efficient strains for pot cultivation of rice plants were selected. The results showed that the Nostoc sp. GGuCy-47, Nostoc sp. GGuCy-46, Anabaena sp. GGuCy-21, Cylindrospermum sp. GGuCy- and Anabaena sp. GGuCy-42 had the higher phycobiliproteins content. Thus isolates which had higher content of phycobiliproteins also had a greater nitrogen fixing capacity, especially the two isolates Cylindrospermum sp. GGuCy-25 and Anabaena sp. GGuCy-42 possessed the highest nitrogenase activity. Based on the results obtained, the efficient isolates of cyanobacteria increased grain yield and improved the growth of the rice (cv. Tarom Hashemi) but the amount of growth varied among different isolates. Finally, Cylindrospermum sp. GGuCy-25 and Anabaena sp. GGuCy-42, as two more efficient isolates can be used as biofertilizer in rice paddy fields.

Attention to the potassium releasing bacteria is due to high demand of plants to this element. Therefore, in this study the effects of 15 bacterial isolates (S5-5, S5-9, S6-6, 10-3, S11-2, S12 -3, S14-1, S14-3, S15-1, S16-3, S17-4, S19-1, S19-2, S20-7 and S21-1) and Pseudomonas putida strain P13 on the growth and potassium nutrition of tomato were assessed. The experiment was performed under sterile condition in a bed of sand and Muscovite and other nutrients, except potassium, during the growing season were supplied through Hoagland solution. The results showed that the application of the 16 isolates didnt affect the wet and dry weight of shoot and the concentration and content of root potassium but the plant height, wet and dry weight of root, total dry weight of plant, concentration and content of shoot potassium and the concentration and content of root phosphorus significantly increased in some isolates in comparison to the un-inoculated treatment. The highest height of the plant with an increase of 16.56% compared to the uninoculated control was observed in the isolate S21-1 (48.08 cm). The highest total dry weight of plant was measured with the strain S19-1 (6.35 g pot-1) and maximum concentration of potassium in shoot (14.3 mg g-1) was observed in the isolate S10-3. The most content of the shoot potassium (78.67 mg pot-1) gained in isolate S10-3 which in comparison with the non-bacterial control showed an increase of 70 %. Molecular and biochemical identification results (16S rDNA) showed that efficient isolates belonged to the genus Pseudomonas.

In recent decades, increasing of population and limitation of arable lands have led to consider production level increasing and land suitability assessment. Several methods such as limitation (Maximum, Number and intensity), parametric (Story, square root) and a new fuzzy logic based methods have been developed to assess the suitability of lands. Classical methods of land suitability assessment are not able to express the continuous nature of soil properties and define the land suitability classes as non-collectible. Therefore, using of the fuzzy sets in studies of land suitability assessment can lead to a better understanding of them. Also fuzzy clustering and kohonen artificial neural network can be used for homogenous soils determination and requirements data completion. In this study, for comparison of the fuzzy set theory and FAO method, calculated correlation coefficients values between the land index and yield of the sunflower and canola by fuzzy method were (0.709 and 0.617, respectively), more than those with the Parametric method 0.709 and 0.617, respectively).These results demonstrate the high accuracy and potential of the fuzzy logic method in relation to the classical methods of land suitability assessment, and can be described by the capability of the fuzzy logic in expressing the continuous nature of the processes. Obtained results showed that representative profiles of 1 and 4 were homogenous based on landform clustering methods and these results could be used for information completion.

If there is a high speed flow on a spillway and it is impossible to use a stilling basin because of its high cost or installation condition, the flip bucket may be used for energy dissipation. Flow-3D software was used in this research to simulate the flow on the chute spillway with ogee crest and flip bucket by volume of fluid (VOF) procedure and k-ε (RNG) turbulence model. At first, the numerical simulated trajectory of the jet flow was compared with the trajectory of the flow in the physical model, and also with the results of USBR, US Army and Kavakami equations. Then the effect of gate opening on the range length and the maximum height of the jet flow trajectory was studied. At last, the effect of the circular flip bucket shape and the two kind of triangular flip bucket named A and B on jet trajectory were studied. Results showed that USBR equation was more accurate than the numerical model and other empirical relationships in determination of the jet range length. Based on the results, two relationships were presented between gate opening VS reduction percentage of the range length and the maximum height of the jet. Comparison of the hydraulic characteristics of the circular and triangular flip buckets showed that the characters of the triangular flip bucket type A was more similar to that of the circular flip buckets in comparison to the type B and due to its easier implementation could be used instead of the circular flip bucket. In addition, results of the numerical model showed error ranges length of 12 and 8 percent for the maximum jet range length and maximum height, respectively. Therefore, applying numerical model of Flow-3D in estimating effects of bucket shape is recommended.

Effect of land use type on soil functioning within an ecosystem can be assessed by soil quality indices. Such studies that are carried out to improve land resources quality, lead to control the land degradation and help us to identify the sustainable management. In order to study the effect of land use change from pasture to agriculture on soil quality and clay mineralogy, Valarude region of Zanjan province was selected. Composite soil samples were taken from 0 – 30 and 30 – 60 cm depths of both land uses with three replicates and totally 60 soil samples were prepared. Important soil quality indicators such as bulk density, weighted mean diameter of aggregates, quantities of organic carbon, and total nitrogen, soil microbial respiration rate, amount of microbial biomass C and urease and alkaline phosphatase activities were measured. Results revealed that the land use change from pasture to agriculture, led to a significant reduction in the amounts of organic carbon (62%), total nitrogen (70%), mean weight diameter of aggregates (32%), microbial respiration rate 75%) and microbial biomass C quantity (47%). The assay of enzyme activities showed that alkaline phosphatase activity did not change significantly but urease activity decreased in agriculture land (87%). Mineralogical studies showed that the both land uses had illite, kaolinite; chlorite, smectite and mixed layer minerals and change of land use did not have a significant effect on soil clay minerals. Overall, it can be concluded that a change in land use from pasture to agriculture with widespread agricultural practices, especially intensive tillage activities, may lead to decrease soil quality.