جستجوی مقالات مرتبط با کلیدواژه « semi » در نشریات گروه « کشاورزی »

Rangelands as dynamic ecosystems respond to the disturbances such as climatic fluctuations and grazing management patterns. Prediction of spatial trend of these changes could be contributed to management planning and rehabilitation of degraded landscape. In this study, changes in the function of ecosystem, affected by livestock grazing, were investigated along grazing gradient. To this end, in the winter rangelands of Gorgan, functional features of the rangeland ecosystem including: nutrient cycling, infiltration and stability were measured at the set of points along grazing gradient. Measured parameters were analyzed using statistical methods and regression models to determine changes in ecosystem function along grazing gradient. The results showed a significant trend in functional indices along the grazing gradient. Points close to the livestock camp had the minimum value of functional indices while those at the end of the grazing gradient were found to be maximized. Comparison of different regression models using Akaike Information Criterion revealed that, as per infiltration index four-parameter sigmoid model and also for stability and nutrient cycling indices, three-parameter sigmoid model had the lowest AIC value and were the best models to predict functional changes along grazing gradients. The results of this study may be promising as rangeland model input to identify critical areas and can be used to predict management effects on productivity and sustainability of rangeland ecosystems.

Weirs are the most important and very applicable barriers built across channels to control the flow of water or change its direction. They are also widely used in current measurement in open channels and many hydraulic engineering studies. The advantage of the semi-cylindrical and circular crested weirs as compared with other structures and measuring instruments is their higher discharge coefficient, stability of flow pattern, non-obstruction by floating materials, simplicity of design, durability, wide applicability and economics. One of the newest and most useful software in the field of computational fluid dynamics is Ansys CFX, which provides fairly reliable results. This software, which benefits from the continuity and momentum equations and the application of a turbulence model, was used to simulate flow over three semi cylindrical weirs with different radii in a laboratory study. After selecting the optimum mesh size for simulating the flow in the multiphase form of the fluid model, the k-ε, RNG k-ε and k-ω turbulence models were used to simulate the flow, and the results of the numerical solution was compared with the collected data extracted from experimenting with the physical models. The mesh size selection was based on the optimum mesh, root mean square error, mean absolute error and the coefficient of determination. The results showed that for cylinder with 4, 6, 7 cm radius, the discharge coefficient ranged from1.2 to 1.4. Furthermore, both the flow and the discharge coefficient increased with an increase in the radius. Moreover, the location of minimum pressure on the weir moved upstream with incremental discharge in conformity with previous studies.

Rill erosion is one of the most important soil erosion types in the hillslopes which occurs due to concentration of surface runoff. In general, rills are a small, ephemeral concentrated flow paths which function as both sediment source and sediment delivery systems for erosion on hillslopes. Rill development is common in overgrazed land where soil water retention capacity is diminished and also in freshly cultivated soil where the soil structure has been loosened. Rill erosion can be a large portion of the channel erosion in these areas, particularly in semi-arid regions. Rill development in the hillslopes can be affected by different factors including topographic characteristics, vegetation cover condition, rainfall characteristics, soil properties, and management practices. Knowledge of factors affecting rill erosion development is necessary to control this erosion in the hillslopes.
This study was conducted to find factors influencing rill development in semi-arid rangelands in the TahamChai catchment, north west of Zanjan, Iran. Toward this, ten sparse hillslope as affected by rill erosion were selected and all rill characteristics along with some soil properties were determined in the rills. Rill characteristics, slope steepness, and soil properties were compared among the hillslopes. Effects of slope steepness and soil properties on the rill erosion were recognized using the correlation matrix method. Multiple linear regression analysis was used to develop an equation for estimating rill erosion in the hillslopes.
Results indicated that all rills characteristic expect length were significantly differed among the hillslopes. Significant differences were found among the hillslope soils in sand, silt, clay, saturated hydraulic conductivity, and exchangeable sodium percentage. Rill cross section area varied from 0.01 to 0.29 m2 with an average of 0.07 m2 in the hillslopes. It was recognized to be the most important rill characteristic to describe rill erosion development in the hillslopes. Significant correlations between this rill characteristic were observed and slope steepness, sand, silt, clay and saturated hydraulic conductivity. Rill cross section area was the highest where either the hillslopes tend to have higher slope steepness or they have higher percentage of silt and clay. Multiple linear regression analysis appeared that rill cross section area in the rangeland hillslopes was significantly related to slope steepness and silt (R2= 0.38, p
With regarding to the importance of slope steepness and silt in the rill erosion development, maintaining vegetation cover through preventing over-grazing in the hillslopes of the area where slope steepness is higher and the soil is sensitive to water erosion processes is very essential. According to the developed equation there are also other variables which may control rill development in the hillslopes. Land shape, soil profile characteristics and land surface cover can be introduced as unknown variables which can be investigated in the next studies in order to develop a reliable model to prediction of rill erosion in the hillslopes.

Modeling of water flow through vadose zone under unsaturated conditions necessitates the knowledge of soil hydraulic properties, which are water retention curve and water field capacity of soil. Indirect prediction of these characteristics based on readily available soil properties in the form of pedotransfer functions (PTFs) as a fast and low-cost solution has been widely practiced and very useful in irrigation and drainage. This study aimed to present the proper PTFs using mathematical modelling for estimating soil moisture at point of field capacity for Khuzestan province soils under laboratory and field conditions. The buried probes of the time domain reflectometry device (TDR) were inserted at various depths in order to monitor soil moisture conditions in both the physical model and experimental field under a surface-point source drip irrigation with discharge rates of 4 lph. Then, physical soil properties and soil water contents at their specific matric potentials were measured to calculate the hydraulic parameters of Van Genuchten-Mualem model with the RETC program. The results of this research to evaluate the performance of several well-known Point-PTFs showed that quasi-empirical models based on physical principles that have been tested in the field can be a good alternative to traditional methods for estimating water field capacity of soil. So that, the PTF of Twarakavi et al. could carefully predict that water field capacity of soil with indices of normalized root mean square error (3.1 percent) and standard error (0.5 percent) and more accurate than Rosetta artificial neural network approach or Dexter equation. Accordingly, another two PTFs were proposed to improve the accuracy of the water field capacity prediction in the form of regression equations on the basis of the parameters of Van Genuchten model and readily available soil properties for the semi-arid region of Khuzestan province. Results of obtained PTFs showed clearly negative effects of soil compaction and the amount of sand on the water field capacity of soil. On the contrary, the amount of clay and silt had positive and increasing effects on the water field capacity of soil, significantly.

Miniature rose (Rosa hybrida) are well known as one of the world’s most popular ornamental plants cultivated worldwide as potted and/or bed plants. Nowadays, more than 100 million pots of miniature roses are propagated by stem cutting in the commercial greenhouses of European countries such as Denmark and Germany. Some treatments such as application of plant growth regulators and suitable rooting medium could be required for accelerating root formation in rose cuttings. Using plant growth regulators like natural or synthetic auxin is a pre-requirement for the initiation of adventitious root in some stem cuttings and it has been reported that the division of the first initiator cells of root depends on internal or synthetic auxin. Methods of application of these chemicals and suitable concentration could be related to several factors, importantly the plant varieties, type of cuttings and the time of cutting preparation. Various kinds of media such as soil, peat moss, perlite and vermiculite are used as bed substrate according to required ratio. Rooting media must provide appropriate moisture and air ventilation for cuttings establishment, which highly affect the cuttings root formation. Appropriate procedure for using wastes materials as culture bed, especially those materials that produced locally, is main aim of some studies to find an alternative medium in ornamental pot plant production. In this regards, evaluation of agricultural wastes to be used to culture bed and introducing suitable materials could be considered. Accordingly, the objective of the present study was to determine the effects of two types of plant growth regulators and bed combinations on rooting percentage of semi-hardwood cuttings in miniature rose.
In order to evaluate the effects of different concentrations of indolebutyric acid (IBA) and naphtaleneacetic acid (NAA), and two media with different composition on root formation of miniature rose stem cutting, this research was carried out as a factorial on the basis of randomized complete design (RCD) with three replications. Plant growth regulators including IBA at concentrations of 0, 1000, 2000 and 3000 mgl-1, concentrations of NAA at 0, 500, 1000, 1500 and 2000 mgl-1 were applied together with two types of rooting media. Media including mixing volume of perlite, tea waste compost and sand in a ratio of 1: 2: 2, and perlite, peat and sand in a ratio of 1:2:2 were mixed and applied in this experiment. Using SAS software, data was analyzed based on a generalized linear model (GLM) analysis and tested by least significant difference (LSD) at (P-value Results showed that the highest rooting percentage of cuttings was obtained with 2000 mgl-1 of IBA, while no significant effect of NAA treatment and different rooting media on percentage of rooting was revealed. The two-fold and three-fold interaction of treatments on other measured traits such as primary and secondary root number and root diameter were significant. The two-fold interaction of NAA treatments and rooting media on the trait of primary root number were no significant. The highest root number and root diameter measured in medium containing perlite, tea waste compost and sand in a ratio of 1:2:2 for cutting received combined plant growth regulators.
Compost, the final product of organic residues degradation, improves soil physical characteristics such as soil aggregate formation and stability, water penetration, porosity, compressing resistance and nutrients availability. As well, it improves soil biological characteristics and in result, integration of compost with soil can increase growth, yield and quality of crop. There are also some evidences that in contrast of peat, compost contains plant growth regulators improved plant growth and development. Totally, considering our obtained results, in order to accelerate rooting formation in miniature rose cuttings, treatment of cuttings with synthetic plant growth regulators in medium containing perlite: tea wastes compost: sand (2:2:1) under alternate mist system is recommended. Organic materials activate root area as well as improving fertility of soil. They also play a role in supplying and releasing absorbable nutrients, root establishment, enhancing field capacity, reducing evaporation from soil surface and reducing expenses. Therefore, we emphasize on appropriate using of these components in order to obtain better productivity.

Achieving the potential properties of sourdough such as inhibition of microbial spoilage, nutritional, staling delay and physicochemical properties in bread is prominently associated with controlled fermentation. In new fermentation technologies therefore, sourdough potential capabilities to create adequate alternatives for bakery additives is increasingly enhanced. In this study, the effect of sugar contents (0.5, 1, 1.5%) and sourdough fermentation times (8, 16, 24 h), containing specific starter culture (Lactobacillus plantarum) isolated from a traditional sourdough were evaluated on semi-volume physicochemical and crust properties. For this purpose, after preparation of sourdough semi-volume bread under mentioned treatments, the texture profile analysis (TPA) and porosity were determined by measuring crumb cohesiveness, springiness and chewiness during 4 days, based on split plot statistical design and browning index (BI) and chroma (C)* index were investigated bread crust 2 h after baking. According to the results, the minimum and maximum bread crumb cohesiveness after 96 hours, were observed respectively in samples produced with sourdough after 24 h fermentation and 1% sugar content, and after 24 h fermentation and 0.5% sugar content. Furthermore, minimum and maximum bread crumb springiness, were observed respectively in samples produced with sourdough after 8 h fermentation and 0.5% sugar content, and after 8 h fermentation and 1.5% sugar content and minimum and maximum bread chewiness in samples produced with sourdough after 24 h fermentation and 1.5% sugar content, and after 8 h fermentation and 1% sugar content after 96 hours. Furthermore, the maximum amount of porosity was obtained after 24 h sourdough fermentation and 0.5% sugar content, while the lowest amount was obtained after 24 h sourdough fermentation and 1.5% sugar content, 48 h after baking.

Water shortages has always been a great concern as a limiting factor for agricultura l production in Kerman province. Rainfed sowing may be recommended to bypass the problem. Because of high rates of potential evapotranspiration and limited water resources in arid and semiarid areas, it is expected more attention will be paid to study of the effects of rain fed culture on quality of medicinal plants. In order to investigate the establishment, growth and yield of some of perennial medicinal plants (Thymus caramanicus, Elaeagnus angustifolia, Olea europaeain, Thymus vulgaris, Rosa damascena, Thymus daenensis, Artemisia persica, Ferula assa feotida, Glycyrrhiza glabra, Rosmarinus officinalis, Lavandula officinalis, Salvia officinalis, Achillea millefolium ), the study was conducted using a randomized complete block design (RCBD) with 3 repli cations during 3 years from 2012 to 2014 in the Kohpanj mountains in the west of Bardsir city. During the growing seasons, the phonological and morphological events were recorded and finally analyzed by SAS software and the means were compared using Dunca n's Multiple Range Test at 0.05 level. The results showed Thymus caramanicus, Elaeagnus angustifolia and Olea europaeain destroyed in the first summer because of environmental drought. Thymus vulgaris, Rosmarinus officinalis, lavandula officinalis, Achille a millefolium and Salvia officinalis Survived in the first year, but destroyed in the second year. Rosa damascena 85%), Thymus daenensis (60%), Artemisia persica (77%), Ferula assa feotida (100%) and Glycyrrhiza glabra (100%) had the most survival rate am ong the species. With aging, dry weight of the plants were increased. The greatest dry weights were in Thymus daenensis, Artemisia persica and Ferula assa feotida respectively equal 188, 135.6 and 16 g/m 2 . The greatest dry weight of root in Glycyrrhiza gl abra (173.3 g/m 2) obtaind in the third year. The most number of flowers in Rosa damascena (31 flowers per plant) obtained in the third year.

In this research, the performance of a semi-greenhouse solar kiln was evaluated for dying different wood species in different season in Karaj. This study was carried out in two separate parts. In the first part, the flat-sawn boards of oak and fir with a nominal thickness of 50 mm were dried during summer of the year 2012. In the second part, the flat-sawn boards of beech and poplar with the same thickness were dried in autumn, 2014 and spring, 2015. For both parts, the boards were also air-dried. The temperature measured inside the solar kiln was 35 ºC greater than that outside during daytime and also the kiln temperature ranged from 55 to 75ºC during 10 a.m. to 2 p.m.. In both parts of research, all wood species dried in the solar kiln faster with better quality compared to those air-dried. The severity of casehardening and surface checking in the boards dried in the solar kiln was lower and more homogenous moisture profile was observed. In addition, the final moisture content was lower for the boards dried in the solar kiln.

The aim of this study was evaluation of the effect of controlled fermentation of Lactobacillus plantarum on sensory properties and staling of semi-loaf wheat bread. For this purpose, the effect of fermentation times (8, 16, 24 h) and sugar contents (0.5, 1, 1.5%) on activity of mentioned starter in fermentation of wheat flour (with 76% extraction rate) in a split plot design were examined. After processing of semi-loaf breads with sourdough treatments, the staling of these breads were evaluated 2, 48 and 96 h after baking, based on their specific volume, crumb firmness (texture analysis) and amount of porosity (Image j method). According to the results, different fermentation times and sugar contents had significant effect (p≤0.05) on sourdough total titerable acidity and 96 h after baking, the lowest specific volume and the maximum amount of crumb firmness were observed in sample produced with sourdough after 16 h fermentation and 1% sugar content. The maximum amount of specific volume and the lowest crumb firmness were also observed in sample produced with sourdough after 8 h fermentation and 0.5% sugar content, 2 h after baking. Furthermore, the maximum amounts of porosity and the best sensory properties were obtained after 16 and 24 h sourdough fermentation and 1.5% sugar content, respectively. Based on these results, for production of sourdough bread with longer shelf life and better sensory properties, effective control of microbial starter and affective parameters on its fermentation is necessary.

An experiment was conducted to estimate the bioavailability and evaluation chemical properties of different zinc sources such as zinc sulfate, zinc oxide A, zinc oxide B and Bioplex Zn in broiler chickens fed by semi-puirfeid diets., At first, for chemical and solubility evaluation of different zinc sources in different solvents based on standards methods, 3 samples each containing 1 and 0.1 g, respectively, were used the results showed that zinc concentration is varied from 15 % in Bioplex Zn to 75 % in zinc oxide A. The highest solubility about 100 % obtained in the double distilled water, 0.4% HCL and 2 % citric acid is related to zinc sulfate but the lowest solubility observed in the double distilled water, 0.4% hydrochloric acid and 2 % citric acid is related to Bioplex Zn. In the following, for study the bioavailability of different zinc sources, of a 13 semi-purified diets supplemented by 50,100 or 150 mg of different zinc sources per kg of diet in feeding of 260 Ross-308 male broiler chickens in completely randomized design with 4 replicates and 6 birds per each in cage system from 8-21days of age were used. For estimation of relative bioavailability slope ratio method was used. In this method relative bioavailability of different zinc sources, calculated by dividing of regression equation coefficient to regression equation coefficient of zinc sulfate as a standard sources. The highest bioavailability value, based on weight gain, was obtained in diets supplemented by 100 mg zinc oxide A and B, but the highest bioavailability value for Bioplex Zn was found in 50 mg zinc supplemented per kg of basal diet (P

Piano Key weirs (PKW) used in spillway of dams and regulating structures in irrigation and drainage network because of increasing the discharge efficiency. In the present study, the effect of geometric shape of piers, where are placed under outlet keys, have been evaluated on hydraulic efficiency. These structures increase the water level and water storage volume in the reservoirs of dam. In the previous study physical model has been used to extract discharge coefficient of Piano key weirs without any research on pier shape. Also some dimensionless relationships have been derived for discharge coefficient.
To achieve these purposes two weirs built with the ratio of height to width of one cycle, P/Wu, 1.33 (Model 1) and 0.50 (Model 2). As a comparison to the hydraulic efficiency the different piers were constructed including of continues, Triangular, half cylindrical and without piers. However, eight models were made and the hydraulics experiments with various discharges were performed. Both of the free and submergence flow on the weirs could be considered with the variation of discharge. The Minimum and Maximum discharge in the all of experiments were 1 L/S and 130 L/S, respectively. The Weber Number as surface tension was controlled in the minimum of discharge. All of tests were performed at a flume with 0.8m width and 12 m length in physically and hydraulically models laboratory of Shahid Chamran University (SCU).
Generally, the results of this study showed that hydraulic discharge efficiency in model 1 with P/Wu=1.33 is more than model 2 with P/Wu=0.5. So this condition is independent of piers shape. However, discharge of weir with triangular pier was more than the other states in the same heads of both models. In addition, analysis of experiments result in both models showed that head-discharge curve of weirs is linear trend which it does specify this structure have an appropriate regulating of upstream water level. The general discharge equation of weirs was used for hydraulic efficiency analysis. In this stage results showed that the hydraulic efficiency of triangular pier is more than other piers. In addition, the half cylindrical piers is placed at second rank and there are no significantly different between continues and without piers. The streamlines with smoothly trends become curved at the half cylindrical pier and friction head losses decreased. Hence, the maximum of measured discharge coefficients in models 1 and 2 are more than continues and without any piers, 15 and 17 percents, respectively.
Using the piers with various forms has a significant effect on the efficiency of the discharge Piano Key weirs. So that the maximum discharge coefficients are 0.61, 0.54, 0.48 and 0.46 for triangular, half cylindrical, continues and without piers at model 1, respectively. However, these coefficients obtained in the constant Ht/P (Ht is upstream head water and P is weir height) which was about 0.1.

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

Recently, researchers have made significant efforts to investigate tide induced groundwater fluctuation in coastal aquifers. Different methods have been adopted for developing solutions to the problems using analytical approaches, numerical techniques, and experimental studies. Although numerical solutions lack many interesting features, compared with analytical ones in providing accurate results, they are the only alternative which enables one to satisfy necessary conditions on irregular boundaries in dealing with aquifer with different geometry. To the best of our knowledge, analytical solution for a heterogeneous coastal aquifer system with finite length has not been reported in any published literature.
Coastal aquifers are usually heterogeneous due to variations in depositional and post depositional processes. In this paper, an analytical solution was developed to tide induced groundwater fluctuations in a heterogeneous coastal aquifer system with finite length. This aquifer system contains an unconfined aquifer on the top, a semi-confined aquifer at the bottom, and an aquitard between them. The storage coefficient of the aquifer is assumed to be negligible with respect to those in the unconfined and confined aquifers. All the layers have been considered to be heterogeneous. The coastal aquifer system is infinite in y direction, and it is finite in x direction. The coastal aquifer system is influenced by the tide fluctuation from both left and right hand sides. The linearized Boussinesq equation is considered for the unconfined aquifers. The flow in the unconfined aquifer can be described by the linearized Boussinesq equation when the thickness of the unconfined aquifer is much greater than the tidal amplitude. The analytical solution is developed using the method of separation, and the closed form solution is obtained for hydraulic head in both unconfined and confined aquifers.
A hypothetical example is given to illustrate and investigate the effect of inhomogeneity on the tide-induced groundwater fluctuation. To address the effect of inhomogeneity, dimensionless hydraulic parameters are defined for the unconfined, semi-confined aquifers and the aquitard, as Lm=L1/L2, Sm=S11/S12, Tm=T11/T12, SB=S21/S22, TB=T21/T22, where L1 and L2 represent the leakage of the left and right aquitards, respectively, and S11 and S12, are storativity of the left and right unconfined aquifers, respectively, T11 and T12 are the transmissivity of the left and right unconfined aquifers, respectively, and S21 and S22, are storativity of the left and right semi-confined aquifers, respectively, T21 and T22 are the transmissivity of the left and right semi-confined aquifers, respectively. The results showed that the amplitude of groundwater head fluctuation in the unconfined aquifer increase with the leakage, however, the fluctuation in the semi-confined aquifer decreases as the leakage increases. When l1=l2=100 m (l1 and l2 are the length of the left and the right aquifers), the minimum groundwater fluctuations in the unconfined aquifers occur at the x=100 m for all leakage values, while in the semi-confined aquifer, for Lm=1, Lm=0.25, and Lm=5, it occurs at x=100 m, x= 120 m, and x=90 m, respectively. Time lag decreases as Lm increases in unconfined aquifers, however, it does not change significantly with varying of Lm, in semi-confined aquifer. Also, the results show that time lag is greater in semi-confined aquifer with respect to that in semi-confined aquifer. In the left unconfined aquifer, the groundwater head fluctuation increases with increase of Tm, and in the right unconfined aquifer, for Tm>1, it increases as Tm increases. The amplitude of head fluctuation in the semi-confined aquifer increases with increase of TB, however, the rate of increasing decreases with increase of TB. The reason may be, with increasing of transmissivity the velocity increases, therefore tide propagates rapidly in the aquifer. For Lm=0.25, and for large values of TB groundwater head fluctuation is almost constant. Also, the results show that, the groundwater head fluctuation in the unconfined aquifer decreases as Sm increases, the reason seems to be, with increasing of Sm, the damping effect of the system increases, therefore the head fluctuation in the aquifers decreases, this result had been in agreement with the results of previous researchers. The groundwater head fluctuation in the semi-confined aquifer is almost constant with variations of SB, meaning that SB has less effect on the head fluctuation in the semi-confined aquifer. It is interesting to note that, previous works that they considered a coastal aquifer system with infinite length, would be a special case of this work, when l1→∞.

The combined weir-gate is one of the structures, which can be substituted in channels instead of weirs and gates. Curvature of the semi cylindrical of the weir- gate structures lead to hold the water snap to the structures body which increases the amount of coefficient discharge the weir- gate structures in comparison with the sharp crested weirs. In this research, the affection of some dimensionless parameters on discharge coefficient in the semi cylindrical weir- gate model was investigated. The experiments were conducted in a horizontal channel with a length of 8 m and width of 0.282 m through using PVC pipes with diameters of 70, 120 and 160 mm as wire and wire-gates. The research findings show that the coefficient of discharge increases by increasing the dimensionless parameters including H/P, Hw/H, Fr and Hf/H for both upstream and downstream curvatures in all alignments of the structure. Hence, the maximum and minimum discharge coefficients occur in the 60 degree and 30 degree angle, respectively. Also, at a constant H/D and Hw/H, the coefficient of discharges is larger for upstream curvatures than the downstream ones. The results show that not only the angle of the semi cylindrical curvature from the horizontal line but also the structure diameter affect on the discharge coefficient

Different grazing intensities will cause substantial changes in ecosystem function. In order to evaluate the effectiveness of existing management, monitoring of ecosystem structure and function is essential. This research was aimed to investigate the effects of different grazing intensities on surface indices and soil quality properties in the semi-arid rangelands of Cheshmeh-Anjir, Fars Province. For this purpose, three sites including under exclosure, light and heavy grazing were studied. Landscape Function Analysis (LFA) method was used to investigate the changes among the study sites. One-way ANOVA and Duncan's multiple range test were used for data analysis in SPSS statistical software. According to the results, soil surface indices showed significant differences among the study sites at p

In many flood control projects, watershed management and water resources development, calculation of the river flow discharge is of the paramount importance which requires a comprehensive hydrological modeling of the region of interest. In this respect, lack of the existence of hydrometric and meteorology measuring stations in most of watersheds, has caused numerous problems in development and management of water resources planning. The hydrological models which are used to simulate watersheds are generally categorized into two groups of lumped anddistributed models. In this study SWAT and HEC-HMS models were used to compare the capability of semi-distributed and lumped models in watershed simulation. For this, 31-year data of Abakhsha Watershed - including the whole information of hydrometer and meteorology stations in the region which are located in Bardsir County in Kerman province - have been used. The obtained results indicate that both models have acceptable accuracy; however, semi-distributed SWAT model is superior to HEC-HMS model. Being semi-distributed is one of the most important reasons for SWAT’s superiority which gets the advantage of considering climate components and using hydrological response units.

Because of the fairly simple equations for accurate flow measurement and controlling the water level, weir and gate method is more useful than the separate weir, gate and partial flume methods. Since the flowing water in the channel always contains sediment particles and floating debris, they are deposited at the gate inlets and behind the weirs which reduces the size of the channel in the structure range and which reduces some problems such as neighboring land flooding due to overflow of water from the channel banks, threatening the structure stability and reducing the measurement accuracy. Using a combination of weir- gate model, in comparison with other conventional devices, will make it possible to get the actual conditions closer two main hypotheses derived from the relations and accurately measure the discharge coefficient. In this model, the deposited materials are easily passed through the gates and the suspended debris are easily passed over the weirs. One of the combined weir- gate structures is semi cylindrical weir- gate structure. Regarding about the form of the combined weir- gate structures, it has some advantages , including simple design, sediments and floating material flow, high flow discharge coefficient compared with other replaceable structures and its being economic. Semi Cylindrical gate turning around center Axis, for reason of rotation the center becomes Conversion to wire, wire gate with opening with different height.
The experiments were conducted in a rectangular flume with the length of 8 m, width of 0.282 m and height of 0.3 m in Soil Conservation and Watershed Management Research Institute. In this research, PVC pipes were used as semi cylindrical gate structures. The experiments were conducted for three diameters 70, 120 and 160 mm with height of the opening between zeros until radius, angles zero, 30, 45, 60 and 90 degree and differently discharging. Experiments were performed at a discharge limit of 2-27 l/s. In order to decrease turbulence of the flow, the gate was installed at the end 4 m of the flume. The ratio of cylindrical structure diameter to channel width (D/B) was in the range of 0.25 to 0.57 and the Froude number was in the range of 0.08 to 0.55.
Coefficient discharge of semi cylindrical structure and then dimensionless parameters of [H/P], [a/H], [ /H] and [Fr] against the discharge coefficient in the studied gate opening between zero until radius were investigated. According to result with decrease dimensionless parameter of a/H, discharge coefficient increased, So that the maximum Coefficient discharge rate of angle 90 degrees and minimum angle 0 degrees. Also in a constant of a/H for the curvature of the downstream and upstream, with increasing the diameter of semi cylinder, discharge coefficient remains and has no change, shows that changes in diameter of semi cylinder have no significant impact on discharge coefficient. With increasing H/P for both curves upstream and the downstream, discharge coefficient increased. Also in a constant of H/P for the curvature of the downstream and upstream, with increasing the diameter of semi cylinder, discharge coefficient remains. With constant of angles with increasing Freud for all angles, both the curvature of the downstream and upstream, /H decreased. Also in a constant of Freud and angles, with increasing the diameter of semi cylinder, /H remains. According to the result, discharge coefficient of semi cylindrical gates varies, in Experimental limit, from 0.45 to 1.45 which is more than that of sluice gates reported by the USBR. One of the reasons, this is ascribed to this is the difference between the amount of entrance, head loss in this structure, because when the flow approaches cylindrical gate, due to curvedness of the wall upstream, a gradual gathering of flow lines gives the aerodynamic method to entrance section, thus decreasing resistance against the flow and entrance head loss and increasing discharge coefficient. However, in sluice gates the vertical wall in entrance section is conducive to fast gathering of flow line, thereby increasing resistance against flow, increasing entrance head loss, and decreasing discharge coefficient relative to a semi cylindrical method.
The results showed that increasing Froude coefficient and decreasing the a/H (ratio of gate opening to upstream water depth) dimensionless parameter decrease, respectively increase the discharge coefficient and decrease head loss in all aspects of structural alignment. Within addition by increasing the H/P dimensionless parameter (ratio of upstream water depth to structure diameter) discharge coefficient increased. Results showed that the maximum and minimum values of discharge coefficient are related respectively to 90 degree and 0 degree angle.

Soil compaction has become a widespread problem in the world and it is considered as one of the main factors affecting land degradation in arid and semi-arid agricultural land. Compaction in arable soils, is a gradual phenomenon that appearing over time and most important factors that influence it include: soil properties, high clay content, low organic matter, frequency of wet-dry in the soil, impervious layer of soil, load heavy agricultural implements and soil and water mismanagement. Compaction induced soil degradation affects about 68 million hectares of land globally. The vast majority of compaction in modern agriculture is caused by vehicular traffic. Carbon sequestration by long-term management operation of the plant and soil, not only increase the soil carbon storage but also lead to reduce the carbon exchange and greenhouse gases emissions like CO2 from the soil profile. The aim of this study was evaluating the effect of soil compaction on carbon and nitrogen sequestration of wheat and soil and some soil physical properties such as: aggregate stability, saturated soil moisture content, bulk density and soil porosity.
This experiment was accomplished in which is located near Aq Qala in a randomized completely block design (with 4 treatments and 3 replication). Soil compaction was artificially created by using a 5/7 ton heavy tractor. The treatments arrangements were: 1) T1: control, 2) T2: twice passing of tractor, 3) T3: four time of passing tractor, and 4) T4: six time of passing heavy tractor. Utilize of all agricultural inputs (fertilizers, herbicides, etc.) has been identical for all treatments. Since rain-fed farming is the common method to cultivation of cereals in the study area, so no complementary irrigation was carried out in this period. In this study, after the measurement of the parameters, the data were analyzed by using SPSS 16.0 Software. LSD test was used for comparison of means.
The results showed that the different levels of soil compaction significantly increased soil bulk density. All the soil compaction treatments have caused a significant reduction on carbon and nitrogen sequestration in soil and wheat, soil aggregates stability and saturated soil moisture values. In the other hand the amount of soil pH and EC has increased significantly by increasing soil compaction levels that Indicates the negative effect of compaction on salinization of arable land.
The results of this study showed that the negative effects of soil compaction on soil physiochemical attributes are dependent on escalation of compaction. In total, even low levels of soil compaction (the treatment of two passes of a heavy tractor) is able to remarkably alter soil physiochemical attributes and thus carbon and nitrogen sequestration in soil and wheat. Induced changes in nitrogen and carbon sequestration levels are important for who concerned of global warming and climate change. Regarding the inability of deactivating soil compaction adverse effects in the deep soil layers of agricultural fields is the best way of handling and preventing soil compaction. Using these sluggish renewable resources should be consistence with land capability and its physical nature. This type of land use will result in sustainable development. From the remarks given here, it might be concluded that revising agricultural regimes and production methods is inevitable. On this ground, revisiting current agricultural systems should be considered and an urgent demand for state-of-the-art methods consistent with environmental objectives is being felt. To prevent soil compaction as much as possible, tractors and machinery traffic must be avoided to an acceptable level and this is of high priority during the time which soil is wet. It is more preferable to perform the operations with lighter machineries. As much as possible in a sophisticated agricultural plan these recommendations must be considered: Increasing soil organic matter, leaving crop residue from the previous crop at the soil surface, using crops with deep-and-vertical-penetrating roots during crop rotation, tillage depth variation in different years, using super absorbent for better ventilation and reduces soil compaction, implementing no-tillage system to reduce traffic of farming machineries, maintaining plant residues at the soil surface, applying lacking nutrients to the soil, and subsoil operations to reduce the detrimental effects. As a field-based study, the results could be transferred to the local farmers. Authorities have to remove the obstacles to deliver the message to the farmers in order to enhance production and reach nation self-sufficiency.