Journal of Water and Soil Conservation
Year:2018 | Volume:25 | Issue:1 |Papers Count:23

Background and Objectives: Arsenic is one of the metalloid that recently attracted much attentions because of its chronic effects on human health. Long-term exposure to As can cause skin, bladder, lung and prostate cancers. The presence of As in soil and water leads its transfer to the different parts of plants. So far the effect of hematite nanoparticles (α-Fe2O3) on the concentration of As in plants grown in contaminated soils has not been evaluated. Therefore this study was conducted to evaluate the effects of hematite nanoparticles on the concentrations of As, P, Fe, Zn and Mn of corn plant grown in contaminated soils. Materials and Methods: A factorial experiment was conducted using a completely randomized design and three replications. The experimental factors were hematite nanoparticles (0, 0. 05, 0. 1 and 0. 2%) and soil As (0, 6, 12, 24, 48 and 96 mg/kg) levels. The soil was artificially contaminated with different levels of As using Na2HAsO4. 7H2O salt and incubated for 5 month. Hematite nanoparticles were synthesized from iron nitrate and their properties were investigated by XRD, SEM and TEM techniques. At the end of incubation time, the hematite nanoparticles were added to the As contaminated and control soils and after 1 month the concentrations of available As was measured. Then, the corn plant was used as bioindicator. After 75 days, the plants were harvested and the dry weights as well as concentrations of As, P, Fe, Zn and Mn of aerial parts and roots were measured. Results: The spherical morphology of the hematite nanoparticles was diagnosed by SEM and TEM images and the mean diameter of the particles were predominantly less than 30 nm. The results showed that the concentration of soil available arsenic and arsenic concentrations of root and aerial parts increased as the concentration of soil total arsenic increased. The accumulation of arsenic in the root was higher than the corn aerial parts. Contamination of soil by As increased the concentrations of P and Mn and decreased Fe and Zn in corn root. The concentrations of P, Fe and Zn in the aerial parts of corn decreased while Mn increased as a result of As application. As also reduced P translocation from the roots to the aerial parts of corn plants. The application of hematite nanoparticles significantly decreased the concentrations of arsenic in soil and in root and aerial parts of corn. The application of hematite nanoparticles increased the dry weight of root by increasing Fe and Zn concentrations in root and decreasing the accumulation of As, P and Mn in the plant root. The nanoparticles utilization also increased the dry weight of aerial parts as a result of increased concentrations of P, Fe and Zn and reduced accumulation of As and Mn. However, in case of uncontaminated soils, nanoparticles decreased the concentrations of P, Fe, Zn, Mn and dry weight of root and aerial parts of plants. The most effective level of application of hematite nanoparticles was 0. 2% in which the decrease of As concentration in root and arial parts of plant were 54. 64 and 40. 20 percent, respectively for the soils with total As of 96 mg As/kg. Conclusions: As at the concentrations of less than 12 mg/kg increased root and aerial parts growth and dry weights but at the concentrations higher than 12 mg/kg, by producing toxic effects and disrupting the balance of nutrients, reduced the growth and dry weights of root and aerial parts of corn plant. Hematite nanoparticles have been effective in reducing the concentration of arsenic that is absorbed by the soil, which reduces the concentration of arsenic in the plant and increases its growth. In general, these results suggested that hematite nanoparticles can be used for remediation of arsenic contaminated soils, if further research is carried out on their environmental effects.

Background and Objectives: The increasing flooding trend in recent years suggests that most of the country's regions are vulnerable to invasions of periodic and destructive floods. In this aspect, many cities, villages, industrial and agricultural facilities and residential areas are prone to flood occurrence, as well. Therefore, the basic identification of flood process within the catchment area is one of the most important measures in flood control and the mitigation of damages. The main objective of this research is to investigate and identify the flood source regions and the effect of watershed management on flood peak discharge at the outlet of the Bar watershed, Neyshabour, located in Razavi Khorasan province. Materials and Methods: For this purpose, the basin was divided into 20 subbasins and the physical properties of the whole basin and subbasins were determined using the geographical information system oodand in a digital format. Then, by using the HEC-HMS hydrologic model, the corresponding flow discharges were calculated for each subbasin. Then, by successively deleting subbasins at each model runtime, i. e. Single Successive Subwatershed Elimination method (SSSE), the whole basin water discharge was calculated after the flood routing in the main streams without the considered subbasin by using the kinematic wave routing approach, Thus the effect/share of each subbasin in the production of flood is identified. Also, the specific flood discharge and the flood index (f) was computed to be the basis for the sub watersheds’ prioritization. Results: In calibration process, two parameters of curve number and manning coefficient were selected as the most effective parameters on flood discharge. The high Nash-Sutcliffe coefficient in flood events showed that calibration of the model in the watershed was satisfactory. The results showed that the subbasin B1 (in the northern part of the watershed) in the return periods of 50 and 100 years had the hieghst peak discharge of 38. 9 and 44. 1 cubic meters per second at the outlet of the subbasin and the subbasins B11, B13 and B19 (in the western parts of the watershed) showed the minimum peak discharge. Also, according to the index (f), in flood plains with return periods of 50 and 100 years, the subbasins B4 and B3 (in the northern half of the watershed) ranked first and second, respectively and the subbasins B6, B11, B12, B13, B14 and B19 (in the southern part of the watershed and in the eastern and western parts of the watershed) showed the lowest priority in terms of their participation in basin flood. In subbasin B1, the highest level of peak discharge reduction has been observed in the highest level of biological operations, ranging from 41. 27 to 44. 73 percent. On the other hand, the results showed that the higher the proportion of the biological activity to the subbasin area, the more obvious the role of these projects in reducing peak discharge. According to the study, the role of structural activities in reducing the flood peak is lower than biological activities and increasing the number of structures along the river route will reduce a higher level of peak discharge. Conclusion: By investigating the effect of biological activities and the construction of gabion check dams on the flood discharges, it can be said that the role of biological activities in reducing peak flow and flood volume is much more effective than structural activities (construction of gabion). Therefore, the CN factor is an effective and controllable factor for flood discharge of the basin and effective on reducing peak flow.

Background and Objectives: The occurrence of dust storms as a global threat poses annually a lot of financial and human losses to the country. Hence, according to the topographic-climatic conditions and the significant increment in the dust storm occurrence frequency, investigation and survey to mitigate the harmful effects is inevitable. Materials and Methods: In this research, dust storms were evaluated based on the spatio-temporal frequency of 25 synoptic meteorological stations in western and southwestern Iran during the statistical period of 22 years (1995-2016). Daily data were analyzed using eight observation points in the form of special codes using geo-statistical methods. The average dust storm occurrence in the hourly, monthly, annual, warm and cold time periods was calculated and plotted using R software for all stations. Results: The results of the annual survey of dusty phenomenon indicated that Abadan station had the highest number of days in the whole region with the average frequency of 16 days in year, after which the Bostan, Sarpol-E-Zahab and Ahwaz were the most frequent. 63. 02% of the outsider dust storms events occured from 9: 30 to 18: 30 local time and 83. 47% of the local dust storms events occured at 3: 30 local time. The highest frequency of dust storms was in June and July while the lowest in November and December. Also, the percentage of local and outsider dust storms frequency during the statistical period showed that 74. 94% of the dust storm days were of outsider origin and 25. 06% of the local sources. The average frequency of dust storm in the studied area was 36 and 22 days in warm and cold period of the year, recpectively. In all studied stations, most of the dusty days were related to the warm period of the year. Conclusion: As the dust wave differs from its source, its intensity and continuity decreases. Therefore, it can be mentioned that the primary sources of dust phenomena in the studied area, are Iraq, Saudi Arabia, Syria and North Africa deserts. The study of the spatial pattern showed that dust storms linearly increase along the north to south of the studied area. While, along the west towards the east, follow the Quadratic polynomial fuction, indicating an increase in the frequency of the dust storm along west to east and then the reduction of the dust storm to the east of the study area. The Zagros Mountains are located along the Northwest-Southeast, which is itself a barrier to the dust storms in these areas and exist of this phenomenon is also more time-consuming than other regions.

Background and Objectives: Improvement and development of forecasts in ungaged catchments needs to understand the interaction between the catchments parameters and hydrological response of catchments in different climates. Flow duration curve is one of the best methods for showing the hydrological response of basins and have different application in the fields of hydrology and related sciences. The shape of flow duration curve also reflects the impact of climate parameters, geology and physiography on the flow of the river and the hydrological response of the catchment. In the past decade, several studies have been done on the impact of geometric and hydrological parameters of basins on the shape of flow duration curve. Most of these studies are empirical and classified in graphical and statistical methods. The graphical method, focus on the effect of physiographic and climatic characteristics on the shape of flow duration curve. While, the statistical methods focus on statistical distribution and correlation of the physical characteristics of the catchments. Factor analysis of parameters affecting the flow duration curve will lead to accurate modeling and interpretation of catchments hydrology. The aim of this study was to determine the most important hydro-climatic and geometric factors affecting the shape of flow duration curve and investigation of relation between them in the different climates. Materials and Methods: In this study, for factor analysis of effective parameter on the shape of flow duration curve, climate maps were prepared and intersect with the layer of fourth-order watersheds and watersheds located in every climate were selected. Then at least 30 hydrometric stations with appropriate data and common period (1976-2001) in each climate zone were selected. Then 10 geometric and hydrological parameters affecting the flow duration curve including: average height, area of the watersheds, Gravelius coefficient, slope, main river length and hydro climatologically parameters including: annual rain fall, base flow index, curve number, permeability and the number of rainy days, were calculated for each basin. Flow duration curves plotted using daily flow data and the slope between Q33 to Q66 was computed as an indicator of the shape of flow duration curve, using coding in MATLAB programming environment. Factor analysis was performed and effective factors on the shape of curve were identified. The regression between the flow duration curve index and selected factors in different climate zones were extracted and analyzed. Results: The results showed that the parameters of first factor including: curve number, base flow index, recession index and the number of rainy days in all climatic zones were common except dry climate zone. Also, curve Number in all the climate zones has the highest weight of influence. The weight influence of geometric parameters in all areas was higher than hydrological parameter, except in very humid zone. The selected parameters for factor analysis in the humid zone were found the highest variance explained with 88 percent and the lowest in the Mediterranean zone with 72 percent. The normal distribution of errors, the coefficient of determination of more than 0. 90 and the coefficient of Durbin Watson between (1. 5-2. 5) reflects the confidence on the regression equations to estimate the slope of flow duration curve in untagged catchments in different climatic zones. Conclusion: Overall, the factor analysis results in different climatic zones revealed that some of the parameters classified in the first class including: curve number, base flow index and number of rainy days were common in all climatic zones. With one exception that in dry zone, the number of rainy days was less effective and placed in second class. The factor of curve number in all climate zones was more effective than other parameters.

Background and Objectives: Nowadays, water scarcity is a major challenge for our country, Iran. Therefore, storage and optimal operation of limited resources, including water stored in dams' reservoirs, is one of the issues of interest for researchers in the field of water resources. In this paper, optimization of single-reservoir operation problem is solved by using one of the newest heuristic algorithms, named Charged System Search algorithm. Generally, this algorithm is based on the electrostatics laws to determine the quantity of resultant force. Kaveh and Talatahari (2010a) proposed this algorithm for the first time and examined its capabilities for solving engineering problems and sample functions. Results showed that the algorithm has good performance. Therefore, its use for solving engineering optimization problems is recommended. However, a review of literature shows that using of this algorithm is very limited in the field of water resources engineering. Materials and Methods: In this paper, the simple and hydropower operation of Dez Reservoir, over 5 and 20 years of operation period are solved using the proposed algorithm. In order to solve these problems, two different formulations are proposed considering water release or storage volume as decision variables of the problem in the first and second formulations, respectively and the results are compared to other available methods. Results: Comparison of the results shows the capability of the proposed algorithm, in which the results of first formulation are better than the second one’ s. In other words, the results of first formulation for solving simple operation problem over 5 and 20 years are reduced by 11. 29% and 16. 69% in comparison with the results of second formulation and also the results are improved by 20. 06% and 37. 66% using the first formulation for solving hydropower problem. Furthermore, the results of the proposed algorithm for solving simple operation problem over 5 and 20 years are reduced by 33. 64% and 74. 97% in comparison with the results of Particle Swarm Optimization algorithm and also the results of using the proposed algorithm for solving hydropower problem are improved by 6. 53% and 41. 48%. In addition, the results of the proposed algorithm for solving simple operation problems over 5 and 20 years are reduced by 7. 79% and 35. 59% in comparison with the results of Genetic Algorithm and also the results of using proposed algorithm for solving hydropower problem are improved by 11. 32% and 67. 43%. Conclusion: Investigating these results with the results obtained by using other existing algorithms indicates a better performance of the Charged System Search algorithm for solving the reservoir operation optimization problem. According to these results, the use of this algorithm is recommended for solving other problems in the field of water engineering.

Background and Objectives: For sustainable development, water recourses quality control has special importance. In this way, recognizing the stratification of reservoirs is very important. Also surveying water quality in the case for salinity of surface water resources of dams that figures as the main resource of drinking water of a country is one of the challenges of water resources management. For studying the stratification in reservoirs, turbulence dynamic and internal flows must be analyzed in reservoir. Because of many phenomenons that effect on stratification, studying this phenomenon is possible just with the using of dynamic models. In this way using numerical models beside yield measurements are unavoidable. Materials and Methods: Because of the the Taham dam's water usage as for drinking water of Zanjan city, so studying the water quality of has more importance, so in this research for studying the status of the water quality of taham dam, modeling of temperature and TDS (Total dissolved solids) with CE-QUAL-W2 software in one year period from (December 21, 2011) until (December 20, 2012) was done. The value of observed temperature and TDS were compared with modeled data. With the results of modeled data, variation trend of said parameters and the stratification phenomena in taham dam was studied. Results: In this research, the value of the observed temperature and salinity were in good agreement with modeled data. The results showed that the stratification phenomena happens in reservoir and lasts 8 months in the year. This phenomena begins at the end of March and improves in August and September (with 20 degrees difference between temperature of upper and lower water layers). Turbulence is also seen from January until March. In fall, because of decreasing the difference between temperature of upper and lower water layers, stratification in the reservoir is decreased and in winter it disappears. Results also shows the salinity stratification happens simultaneous with temperature stratification in the reservoir. Conclusion: From the view point of stratification, Taham dam is in the case of Thermal Monomictic reservoirs. In fall and summer seasons, the value of salinity for all of depths of dam is a constant value. This process is continued until May and after this time because of beginning the stratification phenomenon the difference between layers in depth increase and at summer the difference become maximum.

Background and Objectives: Rivers are source of any civilization formation and also any societies. As a result of many factors like human interferences, earthquake, flood and sand removing from river margins the dynamic balance of rivers changes. The consequences of these undesired phenomena's are erosion of river banks and lateral migration. On the other hand, these derbies could fill dam reservoirs. Decreasing useful life of dams and also producing operation difficulties are other two side effects of erosion. Hence bank erosion and lateral migration creates a lot of economic and social problems. Noticing above mentioned notes we conclude that investigation about hydraulic of rivers and also understanding dike hydraulic and characteristics is necessary and important. One of the common and simplest method of coastal protection is using spur dike that are useful structure to improve the flow pattern and used for control and reduce the coastal erosion of rivers. Bandal like is new type of spur dike that is compound from a submersible and no submersible spur dike. Materials and Methods: In this research we focus on Bandal-like dikes. Explicitly we investigate the effect of dike submersion on erosion and sediment formation around a 90 degree mild bend. Experimental tests are performed under various hydraulic characteristics. Three types of dike are provided. Heights of dike are 6. 5, 8. 5 and 12 centimeters and the width of dike is 20 percent of flood width. Also three discharge 25, 27, 30 and 33 liters per second for two type (submersible and no submersible) of spur dikes were tested. In this study used a 90 degree bend flume with 0. 7 m width. Results: The result of this study show that the maximum of scouring rate, occur for submersible theme test and the minimum is for Bandal – like with 12cm height. Also the result show that depth of scouring with Bandal like spur is reduce than no submersible theme structure and with increased the height of structure depth of scouring will be reducing. The result show that with increased the discharge, the Thalweg divert to middle of canal. Conclusion: The results of this study can be summarized as: The maximum of scouring is for theme non submersible test. The minimum of scouring is for Bandal like with 12 cm height. Between Bandal like spurs, the maximum of scouring is for structure with 6. 5 cm height. Increasing the height of structure reduce the depth of scouring.

Background and Objectives: Groundwater as one of the valuable water resources that has always been of interest to researchers. Preparing an interpolated water level zoning map is one of fields that can be acquired via best interpolation methods among different available methods. The Kriging method, based on semi variogram analysis, is one of traditional geostatistical methods. Interpolation precision is depended on the suitable selection of variogram. Empirical Bayesian Kriging (EBK) method is developed to estimated semi variogram parameters during simulation process. The objective of this study is investigation of EBK to increase the precision of groundwater level interpolation zoning. For this purpose, the results of this study were compared with the results of other other deterministic interpolation method including inverse distance weighted, radial basis function and local and global polynomial functions. Materials and Methods: This study was carried out based on the annual mean groundwater level of 57 deep well in Ghareh-Sou aquifer located in Golestan province during 2005-2016 period. In order to groundwater level zoning, different deterministic and geostatistical interpolation methods were evaluated using cross validation technique. The best semi variogram selected for Kriging and EBK methods and finally the model with minimum error was determined and mapped. Results: The results of cross validation in study area showed that among deterministic method, degree two local polynomial method has higher accuracy and even less error in comparison with Kriging method. The EBK methods, with simulation of fitness of suitable variogram on groundwater level data, led to decrease in Kriging error (23 to 16 meter) and had close precision to local polynomial method. Conclusion: Although the error of the maps prepared based on EBK and local polynomial methods have no significant differences, there are considerable discrepancies between these maps. The EBK basis map shows smoother spectrum of groundwater level changes and the drawn pattern with this method is also proportional to general slope of study area.

Background and Objectives: Plant cover as a major element of natural ecosystems has high influence from climatic indices. In this regard many models and indices were produced with the aim of clarifying the relationship between climate and plant cover. The air temperature variations have a major role in management of plant cover distribution especially in humid region. The most studies about Plant cover in Iran were based on statistical methods and remote sensing technology and only monitor vegetation changes. So presentation of climatic indices for prediction of natural plant cover is necessary. The aim of this study is evaluation and introduction of most suitable climatic thermal index and use of this for prediction the appropriate elevation for exotic species cultivation especially conifers in north of Iran forests. Materials and Methods: In the first step, three indices of WI (Warmth Index), BWI (Biological Warmth Index) and EWI (Effective Warmth Index) were calculated based on monthly mean temperature data of 34 north strip synoptic stations of Iran in decade of (2005-2014). Variation of indices with elevation was achieved as altitudinal gradient relations and the variation map of them was drawn. In second step to investigate the efficiency of calculated indices in determination the plant cover distribution, the study region was smaller and limited to educational and research Kheirud forest. In this stage the forest type’ s distribution maps of Kheirud was collected and compared with indices predicted plant cover distribution maps. Results: In this research, some new thermal indices with plant and tree cover distribution in Golestan, Mazandaran and Gilan provinces have been comparatively studied and predicted tree cover by these indices was compared with available map of Habitats forest types of Patom and Baharbon. With respect to recorded species of the region, all of the indices present good predictions for the plant cover of the region under study. The results of statistical analysis showed that effective warmth index (EWI) with highest correlation (R2=0. 96) and a lowest error value (RMSE=3. 9 oC) is the best indicator for estimation the plant cover of the region. This index by considering both range and average of the annual temperature presents the most accurate prediction (better differentiation) for plant cover especially in region that their WI index is similar. As well, the changes of indices with elevation were studied and related regression equation was presented. Furthermore, suitable height in terms of temperature conditions was proposed for exotic species that have thermal potential for importing to the north of Iran forests. Conclusion: Predicted plant cover by EWI index has more overlapping with north of Iran plant cover in compare to other two indices. Furthermore, with lower error in estimation the elevation of boundary variation has more accurate prediction. With respect to the passage of 5 decades from entering coniferous species in northern forests and cultivation of them in various elevation and The failure of most forest cultivation that conducted on the average height of less than 900 meters above sea level, based on this study proposed that in future forestry the best elevation will estimated with respect to more suitable predicted elevation by EWI index.

Background and Objectives: Iran and accordingly the study area due to placing on the dry belt region of the world are always faced with the drought phenomenon and shortage of rainfall. Accordingly, the efficient use of water and the management of these areas are integral component requirements of such areas. Precipitation pattern in arid areas occurs as storms with the high intensity usually in short time and causing huge runoff in the basin that will carry valuable surface soil and decreasing water infiltration opportunity in the soil. Different techniques of rainwater harvesting from natural lands, improved micro-catchments or agricultural micro-basins will lead to developing sustainable economical agriculture and store runoff into soils, dams, terraces, ponds, ditches and reservoirs. The study area with 470 mm rainfall and runoff coefficient of 0. 26 has the high potential of water harvesting at the basin scale. Previous studies show that lower gammas fuzzy logic values target macro-catchment systems of water harvesting well, but in micro-catchment systems with using fuzzy operators are less researched. Materials and Methods: In this research for finding suitable areas for water harvesting, 3 systems including semi-circular bunds, contour furrow and bench terrace with using GIS in Nazlu basin with 908 km2 area, of west Azarbijan were investigated. Watershed factors such as climate, physiographic and hydrological factors, six important layers of precipitation, slope, land use, hydrologic soil groups and drainage and soil depth were selected. For intersecting and making layers dimensionless, Fuzzy logic with trapezoidal membership function and Fuzzy logic with the analytical hierarchical process (AHP) were used for the quantitative and qualitative variables respectively. AND for combining of layers Boolean AND, Boolean OR, Fuzzy algebraic Product, Fuzzy algebraic sum, Fuzzy gamma of 0. 1 to 0. 9 methods were examined. Results: The “ measure of similarity” is used for comparisons of filed observed and combination outputs. The results show for the crescent bankette and the Gamma-0. 9 Fuzzy, this figure equals 0. 824 and for counter furrow, equals 0. 906. These figures indicate that fuzzy gamma 0. 9 has better suitability than other method and also Boolean logic model do not show suitable results. Similarity index in fuzzy logic increases up to 0. 9 gamma and returns below 0. 9. High Gamma for site selection of Micro-catchment water harvesting systems shows better results. The 30% of the basin is suitable for semi-circular bunds, the 11. 5% for contour furrow and 6. 3% for bench terrace. Conclusion: The results show that for determining the locations suitable to micro-catchment water harvesting methods, Boolean methods are less useful due to low precision and the usage of newer methods of gamma fuzzy logic should be considered, instead.

Background and Objectives: Garlic (Allium Sativum L. ) is an herbaceous herbaceous plant of the Liliaceae family which has been ranked second in the world in terms of production of onions after onions. Due to lack of water resources, saving and optimizing water use is inevitable. Generally, the highest yield and water use efficiency are achieved in full irrigation and mild stress, respectively. And with the use of organic fertilizers such as vermicompost, the negative effects of water stresses are reduced. Considering the importance of applying water stress in irrigation programs and increasing the amount of effective material of plants by applying stress, this study investigated the effects of different levels of stress and vermicompost on yield, yield components and active compound of Allicin in garlic herb which is the second highest among the onion plants. Materials and Methods: The experiment was carried out in a split plot design in a randomized complete block design with three replications at the Research Farm of Torbat Hadiriyah University during the cropping season of 2015-2016. Different irrigation levels including 100 (control), 120, 80 and 60% of water requirement were considered as the main factor and vermicompost fertilizer at four levels of 0, 5, 10 and 15 ton / ha as sub factor. Results: The results showed that simple and cross effects of drought stress and vermicompost on plant height, leaf length, fresh and dry weight of the plant, fresh and dry weight of the tuber, fresh and dry weight of root, leaf area, leaf dry weight and garlic yield were significant. The results show that with increasing drought stress, plant height, dry weight of bulb and leaf area decreased. Consumption of 5, 10 and 15 tons of vermicompost increased 25, 18 and 10 percent of garlic yield, respectively. The highest and lowest yield of garlic was obtained in 100% water requirement and 5 ton per hectare of vermicompost (with a yield of 10170 kg ha-1) and 60% water stress without vermicompost consumption (with a yield of 3048 kg ha-1), respectively. Drought stress reduced and vermicompost increased the amount of allicin. Conclusion: Garlic is susceptible to drought stress and Water scarcity decreases and application of vermicompost fertilizer improves its performance. The application of vermicompost while improving the growth characteristics, yield and yield components of garlic and reducing the damage caused by drought stress during the cultivated season, the continuation of plant performance improvement in subsequent years, as well as the improvement of soil physical and chemical properties.

Background and Objectives: Heavy rainfalls cause flood events in Iran’ s watersheds and huge damages every years. Forecasting of heavy rainfall is an essential step in development of a flood warning system. In recent years, the Numerical Weather Prediction (NWP) models were widely used for weather forecasting. Several meteorological centers and services offer weather forecasting using numerical models. It is necessary to mention that the forecasts of these center are meshed at a large scale. One of the widely used dynamical downscaling method is the weather research and forecasting (WRF) model. In this paper, the performance of the WRF model is evaluated for heavy rainfall simulation in Kan Watershed, Tehran. Materials and Methods: The initial and boundary conditions of the model uses data at the start time of Global Forecast System (GFS) (Coordinated Universal Time). Three domains were used in the implementation of WRF model. Horizontal resolution of the domains are 27km, 9 km and 3 km for big, middle and small meshes, respectively. The evaluation was conducted on the short-term forecasting (24 hours). For this purpose, three heavy rainfall historical events which caused floods in the study area were selected and simulated using the WRF model. Precipitation forecasts were also downloaded from NCEP's Internet web site. Then, the heavy rainfall simulated by WRF model and presented by NCEP were compared to the observed rainfall data from rain gauge stations. Results: The results showed that rainfall has been underestimated by NCEP forecasts and also the time of precipitation events has not been correctly predicted. Moreover, the results indicates that the WRF model functions relatively perfect in forecasting the heavy rainfall events, as by running this model, error indices were significantly reduced compared to global model. Furthermore, the comparison of three convection scheme shows that the Grell 3D ensemble scheme results less error that two other schemes in forecasting heavy rainfalls in the study area. Conclusion: Applying the WRF model increased the accuracy of precipitation forecasting compared to the global model. Therefore, it is recommended to use the WRF model coupled with a hydrological model to development a flood warning systems in the flash flood-prone watersheds.

Background and Objectives: Population growth as well as global freshwater shortage problem have necessitated the use of unconventional water resources in agricultural sector, as the largest consumer of fresh water, especially in arid and semi-arid regions. On the other hand, salinity is one of the most important environmental stresses that limit plant growth and yield. One of the methods to overcome the salinity stress is determining the extent of salinity tolerance in agricultural and horticultural crops. The present study investigates the possibility of utilization of Caspian Seawater for irrigation of Sweet pepper (Capsicum annum) cv. California wonder under greenhouse conditions. Materials and Methods: In this study, five levels of mixed sea water and urban water were used to study effects on yield and yield components of Sweet Pepper (CV. California wonder). The research was done based in completely randomized design including three replications as pot planting under greenhouse conditions in Gorgan University of Agricultural Sciences and Natural Resources during 2016. The greenhouse was located in northern Iran at 36° 51' N latitude and 54° 16' E longitude and 13. 3 meters above sea level. Soil texture was silty clay. In this study, salinity levels of irrigation water were 0. 5, 3. 0, 5. 5, 8. 0 and 10. 5 dSm-1. Obtained data (Fruit Fresh and dry weights, Fruit number, Yield, Water use efficiency) were analyzed using statistical software SAS. Ver. 9. 0 and the means were compared using LSD range test at 5% percent. Results: The results showed that effect of irrigation water salinity on fresh and dry weight of fruit, number of fruit per plant, yield and water use efficiency were highly significant at 1% level (P>0. 01). The result showed that the 10 percent mixture of seawater and tap water irrigation regimes compared to other regimes after control regimes had the highest fruit fresh and dry weights, number of fruits, yield and water use efficiency. Conclusion: The result showed that increasing salinity level decreased all measured characteristics, so increasing salinity of irrigation water from 0. 5 to 0. 3 ds/m resulted in fresh weight loss and yield of 50. 5 and 48. 4%, respectively. The results indicated that sweet pepper plants are sensitive to salinity and the mixing of seawater and urban water for irrigation of this plant is not feasible in greenhouse conditions.

Background and Objectives: Nowadays, extensive attention has been paid to removal and remediation of heavy metals from polluted sites. Biosorption is a cost-effective method for removing heavy metals from aqueous solutions. In this study, biosorption of Cd has been examined by shrimp shell. Materials and Methods: The adsorption of Cd on shrimp shell was studied as a function of pH (Cd concentration: 8. 0 mg L-1) in the range of 3. 0-8. 0 and as a function of metal concentration (Cd concentration in the range of 15-100. 0 mg L-1) using a 24h batch equilibration experiments. The amounts of Cd adsorbed on the adsorbent were calculated from the difference between the metal concentration in the blank and equilibrium concentration of Cd in the solutions. Chemical species of Cd in the solutions was also predicted using Visual MINTEQ, a computer code developed to simulate equilibrium processes in aqueous systems. Infrared spectrums of untreated and Cd-loaded adsorbent were obtained using a Fourier transform infrared spectrometer. Results: The results of pH dependent experiments showed that the percent removal of Cd on the sorbent increased with the increase of suspension pH. The experimental data showed that shrimp shell used in this study removed more than 99% Cd from solution at pH=7. 5. The Freundlich and Langmuir isotherms were described satisfactorily equilibrium data. Maximum sorption capacity (qmax) of the sorbent was 5. 1 mg g-1. Pseudo second order kinetic model provided a perfect fit for the kinetic data of Cd sorption onto shrimp shell. Biosorption kinetics of Cd consisted of two steps: An initial rapid step where adsorption was very fast. The second phase is the gradual biosorption stage before the Cd uptake reached equilibrium. Based on the estimates obtained by Visual MINTEQ, the Cd2+ and Cd(OH)+ species were the dominant species present in solutions in pH≤ 8. 5 and pH≥ 8. 5, respectively. Infrared spectrum analysis of adsorbent before and after adsorption showed that the N atoms of the amine functional groups played a major role in shrimp shell for adsorption of Cd. Conclusion: Based on the results obtained for Cd removal by this sorbent, it may be concluded that shrimp shell is an effective adsorbent for Cd and may be considered for environmental remediation in future studies.

Background and Objectives: Land suitability evaluation is inevitable for soil protection. Selection of an appropriate land suitabiliyty method seems to be necessary due to the limitation of the FAO method as a conventional method. In this regard, multi-criteria desision methods (MCDM) such as electrothermics can be helpful due the consideration of effective factors weights and experts oponions in land suitability evaluation. Materials and Methods: In this research, Square Root Method and ELECTRE Tri multiple criteria method were used for suitability evaluation in an area about of 5000 ha of Chalderan region located between 47° 19′-47° 23′ East longitude and 39° 01′-39° 08′ North latitude for potato cultivation. Sixty soil profiles were dug, described and sampled. After soil samples analysis, soil texture, gravels, calsium carbonate, gypsum, EC, ESP, slope, flooding, drainage and region climate in different profile were produced by weighted coefficients. Criteria weights via pair-wise comparison matrix method and ELECTRE Tri profiles and thresholds limits determined using requirements table, soil and land properties data. In two selected land suitability method, land production potential was also calculated by multiplying the soil indices and radiation thermal production potential and compared using different statistics. Results: The classification of soils is based on Entisols, Inceptisols and Aridisols based on 12th Keys to soil taxonomy. The comparison of the mean values of allocated grades mean to suitability classes in the ELECTRE Tri method with the Duncan test showed a significant difference, indicating the accuracy of this method in differentiation of land suitability classes. The potential of potato production in the Chaldoran region was estimated to be from 9330 to 30200 and from 10140 to 32350, respectively, using Root means squre method and ELECTRE Tri method. Considering the statistical indices including R2 (0. 87) and RMSE (241. 2) the ELECTRE Tri method has more accuracy than the parametric method with R2 of 0. 79 and RMSD of 197. 6. The GMER index also indicated lowestimation of two selected land evaluation method. On the other hand, the precision of this combined method depends on determining the transition suitable limits, appropriate values of thresholds and criteria weights as well as usage of fuzzy logic principals on calculation processes. Conclusion: Based on the obtained results, it seems that ELECTRE Tri method, by integration of expert opinion, is better suited to the problem of land suitability for agriculture. Also, there was a considerable time saving during the development of the land suitability evaluation for potato culture. The coherence of the obtained results with observed yield confirms the effectiveness of system.

Background and Objectives: Pressurized flushing is one of the common methods in sediment flushing of dam reservoirs. In this method, sediments settled in the reservoir are drained out of the reservoir through the bottom outlet of the dam and under pressure. In order to increase the performance of pressurized flushing, it is attempted to reduce the level of the reservoir water to minimum height of operation. Also, in the previous researches, the performance of different hydraulic and structural methods has been evaluated in order to increase the pressurized flushing. The researchers have always tried to propose effective operational solutions that can increase the flushing performance by recognizing the flushing process and effective parameters. The aim of this study is to investigate the effect of the number of rows, height and arrangement of submerged vanes on the enhancement of flushing of reservoir. Materials and Methods: To carry out this research, a physical model including sediment reservoir, settling basins and water supplied tank was used. Submerged vanes with two heights ( V H / D  1 and V H / D  1 ) and different number of rows (one, two, three rows) were set up in front of bottom outlet. In tests, in addition to the parallel arrangement, the flushing performance of new type of submerged vanes arrangement named radial arrangement was investigated at three different depths of reservoir water ( W H  20, 30, 40 cm). Sediment particles was made of washed sand with 0. 51 mm diameter. The tests were carried out at a constant discharge of 2 L/s for an hour and at the end of each experiment, weight of flushed sediments were determined. Results: The results showed that with decreasing the raw number of vanes in parallel arrangement, the performance of sediment flushing increased. On the other hand, one-raw submerged vanes (double vanes) with relative height V H / D =0. 5 and 2 have the best flushing performance with 173 and 231 percentages, respectively, compared to the control model. Also, submerged vanes with relative of height V H / D =2 had better performance compared that in case the relative height of V H / D =0. 5. The radial arrangement of vanes effectively increased the flushing performance; as the flushing performance of submerged vanes with relative height of V H / D =0. 5 and 2 increased about 11. 33 and 4. 1 times when compared with the control model. In the radial arrangement, the flushing performance of vanes with relative height of V H / D =2 were lower than V H / D =0. 5, due to the concentration of the inlet flow of the valve behind the side plates. Conclusion: The radial arrangement of submerged plates could increase the flushing intensity (especially with increasing the reservoirs water depth). This condition is a relative advantage for flushing. In the other words, the flushing operation has more efficiency in the full condition of dam reservoirs and it is not necessary to fall down the water level of reservoir.

Background and Objectives: The hydraulic jump is one of the applicable phenomenons in energy dissipation of rapid flows. The hydraulic jump is one of the rapid varied flows that with converting from the super-critical state of flow to the sub-critical state in a short distance results in sensible energy dissipation and increase of the flow depth. In this experimental study the hydraulic jump is formed on the smooth bed and the bed with attached floating objects. A set of sphere objects with a density lower than the density of the water were attached to the bed, where the bearing length had flexibility. The goal of this study is to investigate the sphere objects bearing length effect on the hydraulic jump length, the relative secondary depth and relative energy dissipation of hydraulic jump and finally comparing the obtained results with other related work. Materials and Methods: The experiments were performed in a flume with transparent walls, 8 m length, 35 cm width and 40 cm heights. In order to form the hydraulic jump, the height of the walls were extended up to 80 cm in the beginning part of the flume and a shut with 30 degree angle and the height of 40 cm was set up. Then, for modeling the floating objects the size of the applicable diameter of the objects was set to 4 cm. To analyze the effective variables, the dimensional analysis using the Buckingham л-theorem was applied. In total 30 experiments were performed with bearing length and Froude number as variables, where 0 cm, 1. 5 cm, 2. 5 cm, 3. 5 cm and 4. 5 cm were considered as the values of bearing length and 5. 1-8. 3 was considered as the value interval for the Froude number. Results: Based on the performed analysis, one of the main achieved results is that the flexibility and the oscillation in the applicable objects as the fixator of the jump results in the increase of energy dissipation while increasing the bearing length, results in the more energy dissipation. However, this effect is more significant for the Froude number between 5. 1-7. 5. Conclusion: The obtained results show that the energy dissipation using the floating objects in average is around 69% that is approximately 10. 2% greater than smooth bed. Additionally, other characteristics of the hydraulic jump were a part of the obtained results based on which, the length of the hydraulic jump and the relative secondary depth, respectively, in average are 35. 5% and 19. 3% lower than the classic stilling basin. It was observed that the bearing length has a significant effect on characteristics of the hydraulic jump, where as a result of changing the bearing length between the Froude number interval, 5. 1-8. 3, the jump length and relative secondary depth, respectively, decrease in maximum 19. 1% and 15. 2% compared to the bearing length of zero that does not have oscillation and in maximum the amount of energy dissipation difference is 10. 6% greater than the bearing length of zero.

Background and Objectives: Evapotranspiration (ET) is an importantparameter for climatological and hydrological studies, aswell as for irrigation planning and management. Evaluation of simple reference evapotranspiration (ETo) methods has received considerable attention in developing countries where the weather data needed to estimate ETo by the Penman– Monteith FAO 56 (PMF-56) model are often incomplete and/or not available. So, The purpose of this study was evaluation and comparison 30 different methods according to PMF-56 method and determination the best equation as a replacement to PMF-56 in the warmarid climate of Zahedan city. Materials and Methods: In this study, 30 commonly used ETo equations that belonged to four groups: (1) pan evaporation-based methods, (2) temperature-based methods (3) radiation-based methods, and (4) mass transfer-based methods were evaluated against the PMF-56 standard model; and the best and worst equations of each category were determined from the Zahedan station located in a warm arid climate. Results: Initially, in each group the monthly mean values ETo (using 30 model) were determined and compared their relativeperformancewith respect to PMF-56 ETo estimates in the study. The ETo calculated by the Snyder equation (R2=0. 85, NRMSE=0. 08, PE=8. 30), Hargreaves-4 (R2=0. 93, NRMSE=0. 04, PE=8. 33), Turk 24 (R2=0. 96, NRMSE=0. 03, PE=6. 52) and Dalton (R2=0. 81, NRMSE=0. 18, PE=12. 89), pan evaporation-based, temperature-based, radiation-based and mass transfer-based respectively bestmatched the ETo estimates by the PMF-56 equation withthe lowest errors rates. Conclusion: In general, the comparativeresults showed that the mass transfer-based equationshad the worst performances, while the radiation-based andtemperature-based models (as Turk, Jensen-Haise, Hargreaves-4 and Blaney-Criddle) were the best-suited equations forestimating ETo in this warm arid climate (Zahedan). Considering the unavailability of full weather data for applying the PMF-56 model for estimation of ETo in many regions of the worldand in different parts of the Iran, especially in developing countries, the results will be useful for choosing the simpler ETo methods in warm arid climates.

Background and Objectives: Soil moisture characteristic curve is one of the most important soil hydraulic properties and shows the relation between soil suction and moisture content. Also, many models have been presented for fitting to measued data of this curve. Materials and Methods: In this study, 30 surface soil samples with high variaty texture from the depth of 0 to 30 cm in different regions of Fars province have been used. Selected soils were classified into three textures of fine, medium and coarse. Then, 10 different soil moisture characteristic curve models were fitted on the data and the parameters of each medel in each soil sample were determined and then the most appropriate fitted model in each soil group was determined. To determine the best model, the combination of statistical equations and linear correlation was used and then the value of mean square deviation (MSD) was calculated to evaluate the different models for fitting soil moisture characteristic curve. Results: The results indicated that the fitted models were better in medium texture group than the fine and coarse texture groups. Also, the results according to the MSD values indicated that the model of Dexter et al. was the most appropriate model for fitting to the measured data of soil moisture characteristic curve. Conclusion: The results of this study investigated that the model of Dexter et al. was better than the other models for three textural group (fine, medium and coarse) for 30 soil samples of Fars province.