Journal of Water and Soil Conservation
Year:2019 | Volume:26 | Issue:3 |Papers Count:20

Background and Objectives: To improve soil fertility, increase water and nutrient holding capacity in soil, increase water penetration in soil, reduce soil erosion and improve plant growth and yield, use of different organic fertilizers in soil is of high importance due to lack of organic matter in most soils of Iran. However, these fertilizers alone can not meet the needs of the plants and are not sufficiently available to farmers. On the other hand, the high consumption of chemical fertilizers causes environmental pollution and increases production costs. Therefore, in order to increase effectiveness of organic and chemical fertilizers and to achieve sustainable agriculture, integrated application of organic and chemical fertilizers is recommended. The deficiencies of micronutrients in the most agricultural soils often reduce the yield and quality of wheat (Triticum aestivum L. ) as a strategic crop in Iran. Therefore, the appropriate concentrations of these nutrients in wheat seed and straw are important not only for the optimum yield of the wheat plant and its quality improvement but also for the health of humans and animals. In order to improve micronutrients nutrition of wheat and its quality the integrated management of soil fertility is essential. Materials and Methods: This research was carried out to study the effects of urea combining with farmyard manure (FYM), municipal solid waste compost (MSWC) and municipal sewage sludge compost (MSSC) on concentrations of micronutrients and sodium in seed, leaf and stem of wheat cultivar Alvand. The experiment was done in a randomized complete blocks design with 15 treatments and three replications under field conditions at Khalatposhan Agricultural Research Station, University of Tabriz, Tabriz, Iran. The treatments included were: 1) control (without fertilizers), 2) 150 kg urea/ha, 3) 300 kg urea/ha, 4) 30 ton MSWC/ha, 5) 30 ton MSWC/ha + 150 kg urea/ha, 6) 60 ton MSWC/ha, 7) 60 ton MSWC/ha + 150 kg urea/ha, 8) 30 ton MSSC/ha, 9) 30 ton MSSC/ha + 150 kg urea/ha, 10) 60 ton MSSC/ha, 11) 60 ton MSSC/ha + 150 kg urea/ha, 12) 30 ton FYM/ha, 13) 30 ton FYM/ha + 150 kg urea/ha, 14) 60 ton FYM/ha, 15) 60 ton FYM/ha + 150 kg urea/ha. The size of each plot was 2. 0 m × 1. 9 m. At the end of growth period, the plants were harvested and the concentrations of iron (Fe), copper (Cu), zinc (Zn), manganese (Mn) and sodium (Na) in their seeds, leaves and stems were measured. Results: The results showed that the effects of treatments on the concentrations of Fe, Zn, Cu and Mn in different sections of wheat (except seed Cu concentration) were significant (P<0. 01). The application of 300 kg urea/ha significantly increased Fe concentration in seed and stem, Cu concentration in leaf and stem, Mn concentration in leaf and Na concentration in stem as compared with the control. There was a significant positive correlation between Zn concentration in leaf and urea fertilizer level. The use of FYM, MSWC and MSSC significantly increased the concentrations of Fe and Zn in seed, and concentrations of Fe, Zn and Mn in leaf and stem relative to the control. The concentrations of Fe, Zn, Cu and Mn in different sections of wheat in integrated treatments especially in combined application of 150 kg urea and 60 ton FYM, MSWC and MSSC per hectare were greater than other treatments while the seed Na concentrations in these treatments were lower than other treatments. The mean concentrations of Fe, Zn, Cu, Mn and Na in different sections of wheat were in the order of leaf > stem > seed, seed > leaf > stem, seed > leaf > stem, stem > seed > leaf, and stem > leaf > seed, respectively. There were significant correlations between the concentrations of the elements in different wheat sections. Conclusions: In general, to reduce the use of chemical fertilizers and to achieve sustainable, improvement of Fe, Zn, Cu and Mn nutrition of wheat plant, and improvement of wheat seed and straw quality, the combined application of 150 kg urea and 30 or 60 ton manure or municipal solid waste compost or municipal sewage sludge compost per hectare could be recommended at similar conditions.

Background and Objectives: Locating in arid and semi-arid region, Iran is always affected by sloping instability and erosion, especially gully erosion. This erosion pattern has occurred in different parts of Iran continuously over many years, and during erosion process and transferring the high amount of sediment has caused the destruction of roads, infrastructures, pasturelands, hillslopes, etc. which makes it necessary to identify high-risk areas and to develop sensitivity maps. In recent years, the processing of satellite images as an advanced method with the aim of increasing the accuracy and saving time and cost has been widely used by researchers. The object-oriented analysis of images is one of the most important methods for extracting information from satellite imagery, which is based on spectral, form and spatial characteristics and using expert knowledge to identify complications. Materials and Methods: In this research, the Lighwan watershed was studied as one of the most important sub-basins of Aji Chay in the East Azarbaijan Province. The images of Sentinel-2 (2016) with spatial resolution of 10, 20 and 60 meters were used for the processing and identification of gully erosion sites. The images were processed using the eCognition software and applied with different types of algorithms to design a semi-automatic model based on object-oriented analysis. Finally, in order to evaluate the accuracy of the model, the identified gully affected area were mapped out and calculated using ArcGIS software to match the ground truth map and to calculate the error matrix, manufacturer accuracy, user accuracy and kappa coefficient for each of the algorithms. Results: The results showed that the density and compactness algorithms had the highest and lowest accuracy of the manufacturer (manufacturer accuracies were 88 and 78), respectively. While based on Kappa coefficient, the asymmetry algorithm had the highest accuracy compared to other methods (kappa = 0. 91). Then, the shape index and density algorithms with kappa coefficient of 0. 89 and 0. 85 provided acceptable accuracy for the classification and identification of the gully. Conclusion: In the present study, semi-automatic semi-automatic model for ditch identification was presented using spectral and geometric properties of Sentinel-2 satellite images and object-oriented processing in eCognition software environment. The use of object-oriented methods due to the increased accuracy of classifying and identifying surface effects and phenomena can be used as a suitable solution for future soil studies and natural phenomena.

Background and Objectives: Considering that General Circulation Models(GCMs) exhibit the state of airflows and main atmospheric characteristics of macro-scale, and are not capable of detecting small-scale climate behavior, and especially in predictions of regional precipitation that might affected by small-scale processes should convert these models to regional scale. The schemes in dynamic models such as RegCM allow the simulation of small-scale atmospheric physics and the sub-network that the model is not able to detect. The aim of this study is to investigate the sensitivity of the Regional Climate Model (RegCM4) for selection of different convection schemes, to make the model optimally configured for prediction of climatic parameters. Materials and Methods: The present study was carried out in west of Iran including: Hamedan, Kurdistan and Kermanshah provinces in an area of 72336 square kilometers. The selected region is located 45 degrees, 20 minutes to 49 degrees and 36 minutes longitude East, and 33 degrees, 37 minutes to 36 degrees and 30 minutes latitude North. Regarding the studied period and the overlapping of recorded rainfall data in the meteorological stations, 13 synoptic stations including Hamedan, Toyserkan, Nahavand, Malayer, Kermanshah, Islamabad, Sarpol-e-Zahab, Kangavar, Sanandaj, Baneh, Bijar, Marivan and Saqez in three provinces were used. RegCM4 model has been run for 10 years by definite and constant boundary conditions for all four schemes including Grell, Kuo and Emanuel. Grell scheme itself has been divided into two different schemes of Arakawa-Schubert (AS) and Fritch-Chapel (FC). In order to investigate errors of model outcomes, simulated and observed rainfall for the 13 selected stations in Hamedan, Kermanshah and Kurdistan provinces were extracted using coding in the NCL environment. Results: In all three provinces, Emanuel Scheme has the lowest value for RMSE, and Grell A. S. Schema has the highest amount of RMSE in the provinces of Kermanshah (49. 84 mm) and Kurdistan (55. 35 mm), and for the Hamedan province, the Kue Scheme has the highest value (36. 13 mm). In case of Bias Error, in Hamedan and Kurdistan provinces the least amount of error is devoted to the Emanuel Scheme (about 18 mm in both provinces), but in Kermanshah province, KUE scheme has the lowest value of the Bias Error (24. 96 mm). In winter, except the KUE scheme, the three other schemes simulated the rainfall values more than real values, and Emmanuel scheme had the highest over-estimated (about 63 mm). Also, in this season, Grell F. C. with an average of 13 mm, the difference from the actual values, showed the lowest error. In spring, Kue Scheme also simulated rainfall values for all stations less than actual values, but the other three schemes simulated the rainfall values more than real values, and the Emanuel Scheme with an average of 62 mm error was the best for the whole study area. In summer, all schemes simulated rainfall values more than real values, and KUE (1. 2 mm bias error) and Grell A. S. (122 mm bias error) showed the best and worst performances for the whole region, respectively. In autumn, only the Kue scheme simulated the rainfall values less than actual values, and the best simulation was for Malayer station with a 99. 2 mm error. The other three schemes, like the other sSeason, simulated rainfall values more than real values, and Grell F. C. with an average 6 mm error in the region and Kue with an average of 143 mm bias error in the region, showed the best and worst results, respectively. Conclusion: On an annual scale, for all three provinces, Emanuel Scheme showed the least RMSE values (18. 96, 28. 95 and 20. 69 mm for Hamedan, Kermanshah, and Kurdistan provinces, respectively). In addition, Grell A. S. Scheme has highest RMSE and MBE errors for Kermanshah (49. 84 mm) and Kurdistan (55. 35 mm). On seasonal scale, Emanuel scheme shows the lowest RMSE for the autumn (68. 76 mm) and winter (66. 8 mm). However, for spring and summer seasons, the lowest RMSE errors (54. 4 mm and 4. 59 mm, respectively) are attributed to the Ku scheme. Implementing the selected convective scheme is helpful in reducing the time and cost and generating more accurate seasonal simulation of precipitation in west of Iran.

Background and Objectives: Many built structures in rivers have been destroyed or damaged due to lack of proper understanding of scouring. Therefore, it is important to know the maximum amount of scouring around the structures constructed in the rivers. Groins are widely designed and constructed in order to river organization in the country. This method, which is considered as one of the most effective methods for the stabilization of riverbanks, developing and expanding day by day. In this research, bed deformation around permeable and close groins with different percentage of permeability was numerically simulated by using some of turbulence closure models. In this regard, numerical simulation results were compared with experimental results (Nasrolahi 1380). Then, by using the best model of turbulence and calculating the transverse flow criteriaes created by the presence of a groin, the effect of the permeability of groine on the transverse flow power are calculated. Thereafter, the effect of the groine opening percentage on the cross-flow power and the distance from the downstream that the transverse flow continues continues has been investigated. Materials and Methods: In other to compare the obtained results from numerical simulation with laboratory results, laboratory results around closed and permeable groins with 30, 50 and 70 percent of permeability in a flume were used. For numerical modeling, Flow-3D software was used. In order to study the performance of the permeability on the transverse flow, valid criteria that indicate the transverse flow power are calculated and compared. Results: The comparison of results of numerical simulation and experimental results shows that numerical model is effective in predicting scour pattern and bed topography around permeable groins with different openings and closed groins. Investigating the power of vortices created around permeable groins by computing and comparing some of the criteria for expressing the power of transverse flows indicates how changes and continuity of the transverse flow power before and after the groins, are compared to the rate of permeability of groin. The results for calculated cross-flow criteria indicate that the deviation of the flow by a groin can be almost ignored with a permeability more than fifty percent and for impermeable groin, transverse currents longitudinally extending more than 1. 4 times the length of the groin. The calculation of cross-flow power criteria using artificial neural network (ANN) also indicates the ability of this method to calculate transverse flow power. Conclusion: The power of the transverse flow in the upstream and downstream of the groin is related to the percentage of opening of the groin. Therefore, if one of the purposes for the construction of a groin is longitudinal velocity deviation, the increase of more than 50% permeability of the groin will reduce this role very much. Also, the results of the neural network in the calculation of transverse flow power criteria were found that the artificial neural network (ANN) could provide acceptable results for these criteria in different transverse sections.

Background and Objectives: The prevailing rainfall in warm and dry areas is thunderstorm and causes the great floods. Destruction and sedimentation of floods cause a lot of damage. In this study, the effect of flood waves on the bed load transfer in a laboratory channel with unsteady flow was investigated. Materials and Methods: The width, height and length of channel were: =0. 3, 0. 4 and 10 meters respectively. Two channel longitudinal slopes were: 0% and 1. 5%. Three rivers sand with d50=0. 85, 1 and 1. 2 mm were applied. Three triangular hydrographs with discharge peak were applied: 20, 30 and 40 lit/s/m. Results: Peak of discharge, bed slope and bed particle size play an important role in sediment transport. The results showed that with increasing slope from 0 to 0. 015, the length of hole due to erosion was 1. 92 m. The experiments showed that by decreasing the diameter of non-cohesive particles, the length of eroded hole increased to 1. 84 times. Also by doubling the peak discharge from 20 to 40 liters per second, the length of eroded hole was 2. 2 times and the maximum scour depth increased to 56 percent. To reduce the transfer of bed loading to the bottom of the blades, they were zigzag, diagonal and perpendicular. The results showed that using the blade, the sediment transport to the downstream decreases. In this case the perpendicular vortex of the substrate had the best performance and reduced the length and depth of the eroded hole by the inputs. Finally, the amount of sediment transfer volume decreased by 89% relative to the non-blown state. Conclusion: The results showed that the increase of discharge peak in sediment transfer was effective and also the bed sloping and reduction of the particle diameter average size caused a greater increase in bed loading. Based on the experiments, the most critical mode was selected and the blade effect on the erosion of the bed was investigated. The results of the surveys showed that the greatest reduction in erosion was due to the vertical placement of the blades, the crowns of the blades being flattened.

Background and Objectives: The high use of pesticides in agriculture and the entry of some of these compounds in water and then products has led to one of the issues of concern to researchers, less use of pesticides and the maximum separation of pesticides in contaminated water before release in The environment. Most of the toxins, especially those with an aromatic ring, can be not easily decomposed. Therefore, their separation from water using suitable adsorbents is one of the methods that researchers are interested in. The purpose of this study was to remove a typical aromatic compound called methylene blue from aqueous solution using its adsorption by β-cyclodextrin / Zinc oxide composite. Materials and Methods: β-cyclodextrin / Zinc oxide nanocomposite was synthesized by sol-gel method in aqueous solution under nitrogen atmosphere and successfully identified using FTIR, SEM and XRD techniques. The maximum methylene blue absorbance wavelength was determined using a UV-VIS spectrophotometer and a range of 400 to 800 nm wavelength range at 665 nm. The methylene blue adsorption on β-cyclodextrin /Zinc oxide composite was evaluated discontinuously. The initial pH (1, 4, 7, 9 and 12), the initial amount of adsorbent (0. 005, 0. 01, 0. 015 and 0. 02 grams), the initial methylene blue concentration (5, 10, 20 and 30 mg/L) and contact time up to 40 minutes as well as the desorption process were studied. Langmuir, Freundlich, and Tempkin isotherm adsorption models were investigated. Experimental data were studied with different kinetic models. Thermodynamic parameters in surface adsorption including Gibbs free energy change (Δ G0), entropy change (Δ S0) and enthalpy change (Δ H0) were measured by examining the adsorption process at several different temperatures. Results: The lowest amount of adsorption was observed at pH 7 and highest in acidic pH=1. It seems that increasing methylene blue adsorption in acidic pH is due to the conversion of the pigment to anion, which results in more potent adsorption. Up to 15 minutes after the start of the process, adsorption is performed at more and then performed at a lower rate. The adsorption takes to equilibrium after 30 minutes. The maximum adsorption capacity occurs at a concentration of 5 milligrams per liter than the contaminant in the presence of 0. 005 grams per liter of adsorbent material at 20 degrees Celsius. The process of adsorption is accompanied by the reduction of entropy. The thermodynamic constants of Δ H0 and Δ S0 are 55. 15 kJ / mol and 195. 62 j/k. mol respectively. At 20 ° C, the amount of Δ G0 is 2131. 65 j/k. mol and increases with increasing temperature up to 37° to 5457. 19 j/k. mol. The Langmuir isotherm has a good correlation with experimental data with a correlation coefficient of 0. 871 and a constant KT of-0. 178. The kinetic model of pseudo-second order with a correlation coefficient of 0. 9578 and a constant speed of 0. 07 min-1M-1 is a suitable kinetic model for describing adsorption. Conclusion: The highest adsorption rate occurs at low and high pHs, because of the pigment transformation to ionic form, so at low and high pH, β-cyclodextrin / Zinc oxide composite are useful for removing methylene blue contaminant from aqueous solution.

Background and Objectives: Forest degradation and land use change are among the factors affecting the changes of soil properties. Microbial characters and enzyme activity, as soil health indicators, are the most dynamic and sensitive soil properties, which play an important role in the nutrient cycle, long-term fertilization and energy flow in the soil. These characteristics provide useful and complete information on the biogeochemical cycles, since they react quickly to changes in the soil environment and provide comprehensive information on the soil physical, chemical and biological properties. Materials and Methods: With the aim of studying and evaluating the effect of forest, rangeland and crop cover on soil microbial and enzymes activities, the mountainous habitat of Kodir was considered from the Kojur region in the south-east of the Noshahr city. In this study, four types of vegetation including natural forest (Carpinus orientalis-Quercus macrocarpa), rangeland dominated by Astragalus balearicus-Teucrium subspinosum, rangeland dominated by Stachys byzantina and agriculture field (Triticum aestivum) were selected. Following field trip, in each of the studied land uses, three transects (50 meters apart from each other) with 200 meters in length were considered. Soil samples (25 × 25 cm area) were taken from a depth of 15 cm at the first, middle and at the end of each transect. In total, nine soil samples from land uses were transferred to the laboratory for analysis of soil physico-chemical, biological, microbial and enzyme activities. Results: The ANOVA indicate that the higher values of aggregate stability, clay and water contents, organic carbon, total nitrogen, particulate organic carbon, dissolved organic nitrogen, phosphorus, potassium, calcium, magnesium, fine root biomass, nitrate and nitrogen mineralization and the lower amounts of soil bulk density and carbon to nitrogen ratio were found in forest site. The greater amounts of sand content and the lower values of silt and dissolved organic carbon were observed in the agricultural field. Soil pH, electrical conductivity, particulate organic nitrogen and ammonium were not significantly different among the studied land uses. The highest values of basal respiration, substrate induced respiration, microbial biomass (carbon and nitrogen, phosphorus) and enzyme activities (i. e. urease, acid phosphatase, arylsulfatase and invertase) were found in forest ecosystem, while the studied microbial indices (i. e. qCO2, microbial ratio and carbon capability index) did not show statistically significant differences among the studied land uses. The principal component analysis (PCA) also showed higher values of soil microbial and enzyme activities, biological and fertility in the forest site with a completely different location on the axis. Conclusions: In general, the results of this study showed that different soil properties in forest ecosystem have better condition than the other studied land uses, while deforestation and land use change decrease soil microbial and biochemical activities due to decreasing organic matter quality.

Background and Objectives: Dams and diversion dams are structures that prevent of fish migration to upstream. Fishways provide access of fishes to their favorite habitat. Canoefishway channel is considered friendly environment because of having maximum compliance with it in many countries. In this fishway, synthetic vegetation grasses are used for energy dissipation, opposite of other usual fishways. In fact synthetic grasses are organized of vertical elements that play role of vegetation stems. In addition to creating a safe environment for fish passage, small boats can pass on it easily, because of having proper stems bend radius. Brushes are placed with different arrangements in the Canoe-fishway channel. Each of the arrangements has different effects on amount of dissipation. The main object of the research is experimental investigation of arrangements effect on water depth in the basins and velocity in the slot fish inlet. Also in terms of hydraulic condition is introduced the best arrangement. Materials and Methods: Tests were done in a channel with length of 12 meters and width of 0. 5 meters, with four arrangements of brushes that were designed with the number of fixed elements. For making of brushes, polyethylene pipes are used with the diameter of 6mm and 20cm length that placed on PVC plates with the thickness of 16 mm. by considering each arrangement, brushes were placed on the bed of the channel. Depth of Flow in the center of basins was measured by depth gauge and velocity in the slot fish inlet was measured by flowmeter in 1cm distances from the bed upto water surface. Also by dimensional analysis be determined effective dimensionless parameters on roughness coefficient (n). Results: Results show that submergence depth (y/h) has the most effect on roughness coefficient (n) in comparison with other parameters. By increasing the submergence depth (y/h), the Manning coefficient (n) increases and it decreases when submerged completely. The maximum coefficient (n) occurs at the base of submerging. In non-submerged condition in comparison with submerged condition, increase rate of roughness coefficient (n) is for, first arrangement 18%, second arrangement 5%, third arrangement 6% and forth arrangement 20%. This research shows process of velocity diagram (V) is increasing from the bed upto water surface. The velocity range is between 0. 6-0. 7 m/s. The velocity profile shows increasing process upto height of grasses is very slow. But in higher depth is so fast. Also the process of discharge-depth curve is always increasing that it increases with more slope in non-submerged conditions than submerged condition. According to dimensionless discharge (Q*) are found that roughness coefficient (n) range has difference in constant experimental condition for different arrangements. Roughness coefficient (n) increases 90% for forth arrangement. Conclusions: According to the obtained results of this study, brushes are effective in roughness coefficient. In this research forth arrangement creates more roughness coefficient, because of having the most overlapping against water flow. So this arrangement in the canoe-fishway provide safe place for fishes, as well as canoes.

Background and Objectives: Prediction of runoff in order to effective operation of flood control reservoirs and earth flood walls is essential. Predictions also make possible emergency operation of reservoirs by estimating time of floods occurrence and expected damages. Predictions are based on recent meteorological and hydrological conditions of the basin and may include future conditions. Although, most of applications are for flood prediction, these may support water supply, hydroelectric requirements, environmental needs and other requirements for operation. Thus, various complex relations and models such as conceptual rainfall-runoff, linear time series and hybrid models are developed. However, because of the lack of precise knowledge and the complexity of the factors affecting the discharge of rivers, in many cases, the amount of calculated values from different relationships has been significantly different. The objective of this research is assessment of precision of HMS-SMA conceptual model and bilinear model in prediction of daily runoff of Maroun basin located in Khouzestan province of Iran. The distinction between the current study and previous studies is that the comparison of the HEC-HMS and bilinear time series models has not been considered so far to predict daily runoff in Iran. Materials and Methods: In the current study, daily discharge data of Maroun river for 17 years (1995-2011) at Idenak hydrometric station located in Maroun basin were analyzed. Maroun basin to upstream of Maroun dam according to topography and location of hydrometric stations was divided to four sub-basins and each of the sub-basins were introduced to HMS-SMA conceptual model independently. Amongst different convert rainfall-runoff models in HEC-HMS conceptual model, Clark’ s unit hydrograph was used because of its applicability and acceptable performance in large basins. Furthermore, according to literature review and suggestions, SMA model of linear reservoir base flow was used for estimating the base flow. Flood routing in various reaches were performed by Muskingum method. Additionally, due to possibility of snowfall in the basin, for modeling of snow melt, index temperature method was used. Bilinear models were introduced by Granger and Anderson. In fact, bilinear models are extension of second order Taylor series. Considering the non-persistence of mean and variance of time series of discharge of Idenak station, the differentiation methods, Box-Cox transformation and radical function transformation were used to stabilize the mean and data series. Results: Considering various hydrograph shapes in verification and calibration processes, it is evident that HMS-SMA model has a good precision in estimating low flows compare than high flows. The differentiation method and the Box-Cox transformation were used for stabilizing the mean and variance, respectively. Then various bilinear models with various orders were fitted to time series data. Verification of the fitted bilinear models to daily discharges of Idenak station was achieved by portemanteau statistic. Finally, bilinear model in the form of BL (2, 2, 1, 1) with the least Akaike criterion was selected as the best model and was applied for comparing to the predicted daily discharges by the HMS-SMA model. Conclusion: An overview of assessment criteria of the HMS-SMA and bilinear models showed that bilinear model in the form of BL (2, 2, 1, 1) with a coefficient of determination, sum of residual errors and mean square root of errors equal to 0. 91, 8. 9 and 17. 8 respectively, is the best model with high precision in modeling and prediction of daily discharges of Maroun basin compare to HMS-SMA model. Furthermore, it is concluded that by increasing order of moving average in bilinear models, their ability for predicting daily discharges decreases.

Background and Objectives: The relation between water table depth and evaporation rate from bare soil is of great importance in arid and semi-arid areas. In this region, due to over irrigation, the water table is very close to the ground surface which leads to salinization of the soil. Evaporation from soil columns in the presence of a water table is of importance and has received great attention for many decades. The soil-drying process has been observed to occur in three recognizable stages. The first stage is evaporation with constant intensity. The second stage is evaporation in descending order. The third stage is the residual evaporation of low intensity, which begins after excessive drying of the surface layer of the soil and its effect on reducing the hydraulic conductivity of the soil. Given the importance of evaporation from the surface of the station in arid and semi-arid regions, it is necessary to measure this parameter accurately. The purpose of this study was to determine the effect of water table depth on the evaporation from soil surface, as well as the determination of different evaporation stages. Materials and Methods: The soil used in this experiment was loam with a bulk density of 1. 32 gr/cm3. The experiment was conducted in a greenhouse and the duration was 74 days. Soils were sived through a 2-mm mesh and then packed into the soil columns using soil funnel. PVC tubes with a diameter of 250 mm were used to provide test columns. Water table was stabilized at depths of 400, 600 and 800 mm from the soil surface, and the experiment was repeated twice. For stabilizing the water table in different depths, each soil columns contained a pipe from the bottom, to supply water from bottles that maintained the water table constant. The water losses from the soil profile was measured at different depths and times using Delta-T Device Moisture Meter. Results: The results showed that water content between 0 and 160 mm in the soil column decreased during the experiment and the lower layers remained saturated. In the steady-state, the rate of water loss from bottle next to the soil column is equal to the rate of evaporation from the soil surface. In a non-steady-state, the evaporation rate from the soil surface is equal to the total loss of water from the water table and the water lost from the soil profile. The cumulative evaporation in the 74-day interval from the stopping surface, 400, 600 and 800 mm was 384. 6, 312. 3 and 293. 4 mm, respectively. The maximum evaporation from the water table was related to a depth of 400 mm and equal 384. 6 mm and the highest water loss from the soil profile was related to a depth of 800 mm and equal 51. 3 mm. By increasing the water table depth from 400 to 800 mm (increased 100%), the evaporation rate from the water table and the total evaporation from the soil surface decreased by 24 and 16. 5 percent, respectively. The length of the first stage of the evaporation for the water table depth 400 mm was 2 days and for 800 mm less than 1 day. Conclusion: The results of this study presented information for us regarding the flow of water above the shallow water table. Water content changes in the soil surface soil are higher than close water table. Movement of water close water table is liquid and close the soil surface is in the form of vapor. The duration of the first stage of evaporation has decreased with increase water table depth. In general, it can be concluded that evaporation from the water table can provide a large portion of the water requirement by the plants.

Background and Objectives: The hydrological simulation models represent a simplified representation of the real hydrologic system that helps to study the functioning of the basin in response to various inputs and better understanding of hydrological processes. These methods are able to estimate the runoff values of ungauged catchments with the lowest possible time and costs using the simulation of rainfall-runoff process. Despite high efficiency, these models have uncertainty. One of the most important issues among researchers is the elimination of these uncertainties. The application of the combination technique is one of the most important approaches to improve results of simulations. In this study, four models including the simple combination models (SMA), Weighted Average Method (WAM), Multi Model Super Ensemble (MMSE) and Modified Multi Model Super Ensemble (M3SE) were used analyze the hydrological simulations, in the Gharesou catchment, located in Kermanshah province. Materials and Methods: The Gharesou catchment, with nearly 5354 km2 area, is located in the northwestern parts of Karkheh basin and the western parts of Iran. In this study, the baseline daily data including observed temperature, rainfall and runoff during the period of 1997-2008 were gathered from selected stations in the study area. 70 percent of the data was used for the calibration period (1997-2005) and the remaining 30 percent for validation (2006-2008). To this end, the models in the RRL package such as Simhyd, AWBM, Sacramento and TANK and the SCS-Milc and Hymod models, which are coded in the Matlab programming language, were used. Then, four combination methods including SMA, WAM, MMSE and M3SE were used to improve the results. Finally, the performance of each method was evaluated using normalized root mean square error (NRMSE) and Nash-Sutcliff (NS). Results: In the present study, all simulated models provide acceptable results. The results of the combination methods showed that the application of these methods led to improve the simulation results. Also, the most improvement of results was achieved by M3SE and MMSE, respectively. For the M3SE method, the value of the NS and NRMSE evaluation criteria were 0. 80 and 0. 97 in the calibration period and 0. 87 and 0. 53 in the validation period, respectively. Conclusion: As resultant it can be expressed that Multiple Combination techniques improved the results of simulated flow by each simulation model obviously. It also may be resulted that recent technique (M3SE) is more efficient than other due to incorporating the bias correction step. Finally it is observed that multimodel simulation generated by M3SE can be better at least comparable to the best-calibrated single-model simulations.

Background and Objectives: The retention and hydraulic conductivity are important characteristics of porous media in relation to imposed contaminants. Retention curve and hydraulic conductivity are dependent on soil and fluid characteristics. When entering groundwater, Chlorinated contaminants cause contamination due to the type of compounds. Thus preventing these materials to enter soil and water is crucial to avoid any contamination. In order to investigate the hydraulic behavior of Trichloroethylene in soil, the retention of Trichloroethylene and water were determined. Determining the saturated hydraulic conductivity and estimating the unsaturated hydraulic conductivity by Mualem-van Genuchten, Mualem-Brooks-Corey and Mualem-Kosugimodels in the two-phase NAPL-air systems were other objectives of this study. Materials and Methods: In this study, the hydraulic behavior of both Trichloroethylene fluid and water were examined. In order to draw the water and Trichloroethylene retention curves in silty loam soil texture, the hanging water column method was used. The constant head method was employed to determine the saturated hydraulic conductivity. The soil retention parameters for Trichloroethylene and water were obtained based on van Genuchten, Brooks-Corey and Kosugi retention models, using the RETC program. The unsaturated hydraulic conductivity, for both fluids as a function of Matric potential was obtained based on Mualem-Brooks-Corey, Mualem-van Genuchten and Mualem-Kosugi models. The performances of these models were assessed by some statistics including ME, RMSE, EF, CD and CRM. Results: The obtained results indicated that in a certain amount of liquid phase, Trichloroethylene has lower retention and larger hydraulic conductivity compared to water in soil. According to lower surface tension and viscosity of Trichloroethylene compared to water, the saturated hydraulic conductivity of Trichloroethylene and water were 136. 75 and 94. 50 cm/day, respectively. For water, the van Genuchten retention model demonstrated highest EF (0. 93) and lowest RMSE (0. 018) values compared to Trichloroethylene fluid. The other two models were also provided better efficiency for water than Trichloroethylene. In case of Trichloroethylene, the van Genuchten and Brooks-Corey models showed highest efficiency. Generally, the accuracy of all three models for Trichloroethylene was less than water. Conclusions: The validation results of hydraulic models shows that the van Genuchtenmodel provides better prediction for retention in soil compared to Kosugi and Brooks-Corey models in the two-phase air-water and air-Trichloroethylene systems. Finally, due to the higher hydraulic conductivity and less maintenance of Trichlorothene fluid than water, if entering the soil, it will move faster towards groundwater and, if introduced into the aquifer, will cause contamination and change in water quality.

Background and Objectives: Ber (Ziziphus spp. ), is as one of the most important of tropical fruits that adapte to weather conditions of southern of the Iran and is cultivated in the provinces of Khuzestan, Hormozgan, Bushehr, Sistan and Baluchistan and county of Jiroft and kahnuj. Due to the climatic conditions of these areas such as low rainfall and high evapotranspiration, water deficit is one of the most important environmental factors that influences on cultivation of plants include of Ber in these areas and it has caused problems for farmers, and finding a solution to this problem is necessary. On the other hand, one of strategies for challenge with the water deficit problem and reduce the adverse effects of drought stress on the growth and yield of crops and fruit trees in tropical regions is the application of the super absorbent materials. Materials and Methods: In order to evaluate the effects of superabsorbent polymer on survival and vegetative growth of Ber (Ziziphus spp. ) grafted seedlings under drought stress, an experiment with 3 irrigation levels as main plot including: 100, 80 and 60% of cumulative evaporation from pan class A, 4 levels of superabsorbent polymer: 0, 40, 80 and 120g from A200 source as sub plot, carried out in split plat based on completely randomized block design with three replications on 36 Ber trees, during two years in Date palm and tropical fruits research center in Ahwaz. Results: Based on the results of variance analysis of data, different levels of irrigation and superabsorbent and interaction effect of them on survival and vegetative growth characteristics such as seedling height, root stock diameter, mean number of leaf and internodes in per stem length at 5% probability level is significant. Comparing the mean of different levels of irrigation, treatments of 80 and 100% of water requirement were in the same group and did not show any significant difference, but showed significant difference with 60% water requirement. On the other hand, the results showed that under drought stress, application of different levels of irrigation and superabsorbent and interaction effect of them on some vegetative growth characteristics such as chlorophyll content, scion diameter and length of internodes in per stem length had no significant effect. Conclusion: Based on the finding of this research, the application 80g superabsorbent and irrigation with 80% of water requirement for each Ber seedling, saved 20% of water consumption, with no significant decrease of the survival and vegetative growth. Therefore, consumption of 80g superabsorbent at the planting time of Ber (Ziziphus spp. ) seedlings is recommended to farmers.

Background and Objectives: Access to hourly temperature is of fundamental importance in crop modeling and freezing studies due to the more detailed analysis of plant growth processes. Also, hourly data is needed for more accurate analysis of climate change effect and atmospheric hazard phenomena on the growth and development of plants. The Bi-sinusoidal model is a precise method in daily temperature modeling which, while considering the sinusoidal nature of temperature variations, is very accurate in detecting the time of minimum and maximum temperature of the day. So far, the accuracy of this method has not been studied in different climates of Iran. The objective of this research is to evaluate Bi-Sinusoidal model for estimation of hourly temperatures from maximum and minimum daily temperature in different climates of Iran. Materials and Methods: For investigation of the efficiency of Bi-sinusoidal model, the data of meteorological stations in different climates from ultra-dry to very humid climates were used. For this purpose, daily and three-hour recorded temperatures at eight stations include: Ahwaz, Ardabil, Bushehr, Gorgan, Mashhad, Rasht, Tehran and Zahak in 2000 and 2005 were used. In this model, sunrise time is considered as the occurrence time of minimum temperature and maximum temperature occurrence is assumed after passing two-thirds of daytime length. These times can be accurately calculated with astronomical calculations. All the modelling calculations were performed in MATLAB software environment. To evaluate the mean error and mean bias of the model, RMSE and MBE indices were used, respectively. Results: The results showed that in arid and extra-arid stations, RMSE vary between 1. 5 to 2 and in humid and sub-humid stations it’ s close to 3 ° C. Also, it seems that the performance of this model is not related to the season, in other words, the hourly temperature error estimation in hot and cold months is not significantly different. The MBE showed that the model underestimate hourly temperature in warm months and overestimate in cold months. However, the bias error is negligible in most of the months and is less than 0. 5 degrees. Variation of actual and modelled temperature showed that circadian fluctuation of temperature in dry region is more similar to sinusoidal changes than humid area. Conclusion: Investigation of circadian temperature fluctuation showed that this model has some trouble in detection of occurrence time of minimum and maximum temperature in humid stations that this is one of the main sources of this model error. However, this model simulates the sinus trend of temperature variations properly. According to development of this model based on ordinary circadian temperature fluctuation, in days with the meteorological phenomena such as warm and cold advection to the region, or in rainy days, the model accuracy in estimating hourly temperatures maybe reduced.

Background and Objectives: Monitoring and evaluation of hydrological drought has become a necessity due to its frequent occurrence in various basins of Iran, and in order to prevent and manage the resulting crisis. In most studies, drought indices have been used to investigate that. Drought indices like Stream flow Drought Index, using statistical calculations on river flow data, ultimately leads to a number that does not have the ability to completely investigate and analyze drought in the studied area. Low flow or minimum river flow is one of the most important drought indices that by using different criteria can get a comprehensive understanding of the hydrological drought situation in the region. In most studies, deficit characteristics or low flow frequency analysis have been used. Using different low flow indices is necessary to recognize different aspects of drought and its management. Therefore, the aim of this research was to study hydrological drought of Armand river using all of the low flow indices including flow duration curve, deficit characteristics, low flow frequency analysis and base flow index, which can be used to determine characteristics such as dry and wet periods, amount of flow during drought, drought threshold, duration of drought, volume and intensity deficit and frequency of low flows. Also, in this study, the environmental flow of river was calculated and analyzed. Materials and Methods: The Armand River basin with 9961 Km2 area located in Chaharmahal and Bakhtiari province was selected as the study area and the daily flow statistics of the Armand hydrometric station were used from 1957 to 2013. First, by plotting the flow duration curve, three low flow indices Q70, Q90 and Q95 also, the river status including wet, normal and drought periods were determined. Then, the minimum environmental flow was calculated based on the two indices Q75 and Q90, and the deficit characteristics using the threshold level Q70. In order to estimate the return period of low flow series (AM7), a suitable two-parameter gamma distribution function was considered appropriate. Finally, the base flow index was calculated using recursive digital filter method in different time scales. Results: Based on the results, the Armand River in 28, 22 and 14 years (from 57 years of statistical period) has a flow of less than Q70, Q90 and Q95, respectively (45, 32 and 27 m3/s). Due to the gentle slope of the flow duration curve of basin, also the high value of the BFI index (0. 95), it was concluded that groundwater had a high participation in the river flow. The dry period in this river begins when the flow reaches less than 45 m3/s (the threshold level Q70). The results showed that the deficit volume and intensity increased over the past 50 years. Based on the frequency analysis of low flow, in the return periods of 2, 5, 10, 20, 50 and 100 years, the low flow was 34. 26, 26. 8, 23. 1, 21. 1, 19. 1 and 17 m3/s. Comparison of these values with the minimum environmental flow showed that the river flow becomes less than its minimum environmental flow on average every two years. Conclusion: Despite the sustained flow in the Armand River (due to the snow-rainy regime of the region, the ability of the basin to save water and drain it during the dry season), the dry periods with different intensities occurred over the past 57 years. Also, the severity of drought has increased due to the increase in the volume deficit of the river in recent years, and if this continues in the future, the severity and frequency of the drought occurrence will increase and the overall flow of the river will decrease.