Plant Protection
Year:2017 | Volume:39 | Issue:4|Papers Count:20

Irrigation scheduling under water and salinity stress, is much more difficult than full irrigation scheduling. To investigate the effect of plant water stress, there are many indicators. One of them is crop water stress index (Idso method). To evaluate the ability of this index for irrigation scheduling of summer Maize (SC704 variety) and winter Maize (Mobin variety) - in conditions of using saline water, a research was designed at the research station of Shahid Chamran University in 2013-2014. This research consisted of five quality treatments of irrigation water, including S0: Water Caron, S1: EC=3.5dS / m, S2: EC=4.5dS / m, S3: EC=5.5dS / m and S4: EC=6.5 dS / m. In the both of the growing seasons, result showed, The upper and lower base lines were affected by salinity stress. The amount of upper and lower base lines for summer Maize were higher than the winter Maize. The lower and upper baseline's equation for summer Maize were (Tc-Ta) l.l=1.641-0.178VPD and h=2.52 oc and for winter Maize were (Tc-Ta) l.l=2.161-0.221VPD and h=3.69 oc. CWSI, which is the base of irrigation scheduling, was calculated 0.23 for summer Maize and 0.17 for winter Maize. By increasing water salinity from 2.2 to 6.5 ds/m, the temperature difference between canopy cover and air was 3oC for summer maize and 2oC for winter Maize. At this research CWSI was calculated on the days, before irrigation for all treatments and result showed that in the both of seasons, CWSI was increased about three times when water salinity increased from 2.2 to 6.5 dS/m. The effect of salinity stress was calculated separately according to the days, after irrigation (at These days, the effect of salinity is sensible). results showed that CWSI increased about 3.5 times for summer Maize and around 3 times for winter Maize when water salinity increased from 2.2 to 6.5 dS/m. Comparing the results of the two seasons showed that CWSI is affected by irrigation water salinity and it's trend was nearly the same in both of the growing seasons.

Utilizing spur dikes is one of the common methods of organizing and controlling side erosion in river bends. In this research study the effect of permeability of spur dike on scour-hole dimensions was experimentally investigated in a flume with 0.7m width, having a 90 degree bend with relative curvature of 4.0 and water depth of 0.14m for non-submerged condition. The results indicated that for a constant Froude number, scour decreases significantly with increasing the percentage of spur permeability. For spur with 33% permeability the relative depth, length and width of scour-hole decreased 63.9, 38.1, and 35.5 percent, respectively in comparison with impermeable spur. The same results were obtained for spur with 64% permeability with 67.1, 88.2 and 53.8 percent, respectively.

Pieve scour is one of the most important cause of bridge failure. Covering methods such as using riprap is among techniques which are widely applied for the existing bridges. For those places where the stones of adequate size are not available, use of six-legged elements which is the subject of this, study is a good choice. In this study the effect of placement of a single row six- legged around a rectangular bridge with 100% density in three different cases of above, mid and below the bed under five different Froude numbers of 0.24, 0.22, 0.19, 0.17 and 0.16 have been experimentally investigated. Comparison of the bed topography with mean measure of bed deposit of 0.7 mm of tests with six- legged and tests without elements showed that generally the elements can reduce the scour depth significantly. The elements placed on the mid of bed have shown better performancewith maximum reduction of about 57%. The general recommendation is to use these elements with geo-syntactic filter or placed in more rows.

Aim of this study is to measure shear stress in smooth rectangular and trapezoidal open channels. A new approach is presented to measure direct shear on wet perimeter of open channels. A water flume with a section on a frictionless support (called knife edge flume) along with a system of load cell was used to measure total force on the wet perimeter. The local boundary shear stress in rectangular and trapezoidal cross sections was measured using a 4mm diameter Preston tube connected to a differential pressure transducer and a data acquisition system. The calibration curves proposed by Patel were used to convert the pressure readings to shear stress. Local and total shear measurements were used to differentiate the channel wall and bed shear forces. This method allows minimizing of the error as result of the Preston tube diameter. Comparison of the results confirmed advantage of the momentum method over the energy method in term of accuracy. Results are presented for smooth rectangular and trapezoidal channel cross sections with side slopes of 1, 1.5, and 2.

Piano key weirs are a new type of Weirs that are designed to improve dams discharge capacity.Generally in increasing the upstream head water decreases the discharge capacity this tyre of weir. Thus, in this research, the effect of discontinuous parapet walls with and without slope at the crest was evaluated.Hence, the various lengths B ¢ = (0.25, 0.5, 0.75 and 1) ´ B were investigated at the weir with sloped parapet walls. Also two weir height were considered with P/Wu = 0.5 (Model 1) and P/Wu = 1.33 (Model 2).All the experiments of this research were performed in a experimental flume with 10 m length, 0.8 m width and 0.6 m height. The results showed that the weir efficiency increases up to 20 percent in model 1 with un-sloped parapet wall. Moreover, these walls have no significantly effect on the weir efficiency at the more head water in the sloped parapet wall of model 1. Moreover, findings showed that the continuous unsloped parapet wall increases the discharge capacity up to 4.6 times of linear weirs.

Watershed structures are among of expensive projects that are constructed to decrease erosion and sediment load and decreasing flood in watershed. Constructing any structures in flood bed can change the flood behavior. This research tries to study check dam effects on flood and water way properties in Gorgandooz watershed. For this goal, HEC-RAS model is used to simulate hydraulic in 4 Scenarios: without structure, 20 structures with 1.5, 10 structures with 3 and 8 structure with 3.75 meter for comparing of specified plan effects with each other. The results of this research show that the influence of 1.5, 3 and 3.75 meter check dam on pick flow comparingwith structure was not created on the upstream of the watershed is 0, in the middle 1 and at the downstream is 2.49, 8.8 and 17.5% respectively. Also the effect of 1.5, 3 and 3.75 meter structure on decreasing of flood volume in respect of without structure is 1.16, 8.1, 13.9, respectively. The study of flow velocity shows that the construction of higher structure cause that the flow velocity decrease that shows the power of flow erosion in water way become less. Shear stress parameter that shown friction rate between flow and water way confirm the velocity results and show that shear stress decrease with increasing of structure height. The multiplying of shear stress on speed is another important parameter that is studied. This parameter shows the sediment transport power of flow. This parameter indicates the strength of sediment transport by flow that showed strength of sediment transport is less in higher structural. Not only reduce of sediment transport will cause less damage to the waterway but also sedimentation into check dam was occur soon and sediment balancing gradient is reached. As whole various Scenarios of check dam shows that the influence of structure on flood and water way become more by increasing of structure height and cause that the condition in deal with flood become well.

In this research, chemical properties of groundwater of Mehran and Dehloran areas was considered by using of geostatistical analysis. For this purpose, 29 groundwater samples were studied from 2001 to 2014 and the water conductivity and sodium adsorption ratio were chemically analyzed. Semi variogram of parameters was computed by GS+software and were fitted by Goussian, sphrical, Expotential and Goussian models. The results showed that the spatial structure of qualitative data of groundwater in these region is reconciled the Gaussianmodel. Then, using of Arc GIS 10.3 software the Kriging interpolation, inverse distance weighted and Radial basis functionmethods were done. to select the appropriate model to fit the experimental variogram of the RMSE were used less and more stronger spatial structure. The results of kriging with Inverse distance weighted and radial basis functions using the RMSE and ME RDF Criteria which measure the accuracy rate, were evaluated. Eventually the results of calculating the RMSE and ME showed that kriging method is superior than two other methods and has high precision and low error.so Interpolation was done using this method. In the end, using fuzzy logic, WILCOX classification and WHO classification, zoning map of the study area, for agriculture were prepared. Then Hot spot analysis were used to illustrate the spatial concentration of elements. According to the final map, 38% groundwater of the region is appropriate and sort of appropriate for agriculture and 62% is inappropriate. So can be said that water quality of the study area is not appropriate for agriculture.

This study was carried out to investigate climate change impact on cultivated area in the Yaz-Ardakan plain considering the possible alterations of evapotranspiration and irrigation requirements. The data used in the analysis represented two time periods: (i) present, (values for the period 1971–2010), and (ii) future, called year 2030 (values for the period 2011–2030). To predict future climate changes, daily climate data from Yazd Synoptic station for 1971-2010 period have been used. Data including, rain, maximum and minimum temperatures and sun shine hours have been investigated through regional climate models driven by A2 scenario of HadCM3 global climate model using LARS-WG software. Crop evapotranspiration and irrigation requirements for two periods, were estimated following the standard procedure described in the FAO irrigation and drainage paper 56 and CROPWAT software. The results show that the climatic changes should significantly affect the studied area in terms of minimum and maximum temperature and precipitation up to the year 2030. Annual maximum and minimum temperature are projected to increase by 1.19 °C and 1.83°C respectively. In the other hand, mean precipitation increase by 9% in 2010-2030 period compare to present period and thedistribution of precipitation will have significant changes, as autumn precipitation decreases, the spring precipitation will have increasing trend.Results of this study showed that, due to higher temperature, crop evapotranspiration and irrigation requirements will be increased up to 7% under climate change conditions.

Existence of heavy metals in the water resources is of the major environmental problems in many communities. The purpose of this study is the research about chromium absorption on nanoparticles of Zizyphus Spina-christi leaves ash. After preparing of nanoparticles of Zizyphus Spina-christi leaves ash, various characteristics of absorbent such as SEM, FTIR, CHNSO and XRF were investigated. Then effect of initial pH, contact time and adsorbent dose on chromium adsorption efficiency was investigated. The results of kinetics adsorption were evaluated by kinetic models of pseudo-first order, pseudo-second order andintraparticle diffusion. Also experimental data were analyzed by using isotherm models of Langmuir, Freundlich and Sips. The results showed that at pH=3, efficiency of absorption was high. In this study, equilibriumtime occurred 180 minutes and the optimum adsorbent dosage for chromium adsorption with initial concentration of 10 mg/L was obtained 5 g/L. Based on the results obtained, the best kinetics model was Pseudo second-order and the best isotherm model was Sips. Adsorption capacity maximum of nanoparticles of Zizyphus Spina-christi leaves ash by using Langmuir model was estimated 411.2 mg/g.

In this research, the effect of lattice collar on reducing scour around the bridge pier was experimentally studied. A series of experiments were conducted in a flume with length of 6m and width of 0.6m. For evaluation of scouring phenomenon a cylindrical pier 60 mm in diameter, four different sizes for collars and three various levels for collars placement were used in clear-water conditions. The results revealed that the minimum scour depth occurred with lattice collars with width of 2.5 and 3 times of the pier diameter (2.5Dp and 3Dp) that has been installed at the 0.1Dp level under the bed, where the maximum scour depth decreased by 73%. Whereas scour depth decreased by 40% due to installation of lattice collars with width of 1.5Dp and 2Dp at the 0.5Dp levelunder the bed. Also, the result showed that the efficiency of lattice collars was about 20% more than non-lattice. Generally the scour volume around bridge pier at the 0.1 Dp, 0.5 Dp and Dp level under the bed decreased by 58%, 60% and 10%, respectively due to lattice collars installation.

Soil erosion is a complex phenomenon involving the detachment and transport of soil particles, storage and runoff of rainwater. The relative magnitude and importance of these processes depends on a host of factors, including climate, soil, topography, cropping and land management practices, control practices. The rainfall intensities and frequency are the effectible factors important on magnitude of the soil loss. The purpose of this research is the assessment of effect and contribution of the high intensity rainfalls (return period 100 years) rather than the low and medium intensityrainfalls (return period 2 and 20 years) on soil erosion rate and flow hydraulics parameters and also the awareness hypothesis that the high intensity rainfalls are more effective than the periodic numbers of low intensity rainfalls. The study carried out on Marl soil of degraded rangeland from Heshan sub-basin by using of the rainfall and erosion simulator laboratory. The results of 18 experiments rainfall-runoff test showed that changes in return periods of rainfall from 20 years to 100 years and from 2 years to 20 years, respectively, has growth 2 times and 6 times flow unit, that it lead up increases accelerated from 3.3 times and 16 times of the amount of the Marl soil loss. So the rainfalls with high return period have aggregation periodic impact less than of the rainfalls with the low return period. Also increases the return periods to higher rainfall intensity have the progressive, direct and nonlinear effect on the amount of soil loss is Marl lands. Also, the slope percent show exponentially impacts in progressive 3 to 6 times on the discharge flow and then on the soil loss. Finally, the slope gradient and rainfall intensity factors separately and interaction effects on soil loss have high significant at one percent level.

Waves are one of the most important parameters for designing marine and coastal structures. It is required to analyze design waves for designing coastal structures. One of the most important parameters which affect wave propagation pattern and design wave is calibration coefficient. It isvital to provide accurate and proper calibration factors. The main goal of present research is performing sensitivity analysis on wave breaking and bottom friction coefficients and evaluating their effects on wave propagation pattern and also design waves with different return periods. Considering previous experiences which have been gained from research and analytical projects that have been performed to model hydrodynamic phenomenon of coastal zones, Mike 21-SW module is chosen in this thesis to model and analyze wave characteristics. Time series of height, period and mean direction of incoming waves are considered as boundary conditions. These time series are extracted from ISWM wave data. Regarding modeling and forecasting of design waves in strategic region of Persian Gulf and importance of Iranian southern ports, coastal region of Lengeh port is selected for modeling wave propagation to analyze wave propagation pattern and effects of wave breaking and bottom factors on design waves. Results of present study showed that bottom friction factor has more considerable effects on wave propagation and wave diffraction pattern in comparison with wave breaking factor. Variations of bottom friction factor can change wave propagation pattern of local models. Additionally this factor has considerable effects on increasing or decreasing of design waves. In contrast to this factor, lower values of wave breaking factor (less than 0.8) can affect design wave height. Therefore sensitivity of wave propagation model to bottom friction factor is more considerable than wave breaking factor and then it is recommended that for calibrating wave propagation model and achieving results which are closed to field measurements, in the first step bottom friction factor would be studied.

Increased use of nitrogen fertilizers due to high dynamics of soil nitrate is a serious threat to groundwater and as a result for human health. The purpose of this study is evaluation of nitrate dispersivity values in the sandy soils of coarse, medium and fine-distance transmission at 80, 40 and 20 cm in laboratory conditions with three models including, Brigham, Fried-Combernous and CXTFIT code. For this purpose, pure potassium nitrate salt solution as sustainable contaminant under the steady regim with concentration of 160 mg/lit was added to the soil column. In order to obtain the required parameters for the three models, output nitrat concentration were measured in the different nolum porosity and Breakthrough curves were plotted for each column. The results showed that in all three models with a moderate increase in transmission distance of medium and coarse sand, the amount of nitrate dispersivity increased. At various distance of transportation, dispersivity values were measured for fine sand from 0.09 to 3.06 cm, 0.23 to 1.6 cm for medium sand and 0.43 to 2.18 cm for coarse sand, respectively. But the Brigham and CXTFIT models showed that the dispersivity of fine sand increases when the distance increases. It was also found that for the fine sand with reduction of transport distance, Brigham model and CXTFIT code showed better results.

Nowadays the shrimp farming is one of the major commercial issues in some countries. The aim of this study was to evaluate the water quality of the input and output vannamei shrimp farms in Abadan Chavibdeh. In this cross-sectional study in a period of 6 months (May to October) conducted in 2012, the physical and chemical parameters of water samples were performed on a monthly basis.3 stations were selected; 2 station on the river Bahmanshir station and 1 in the leachate was located for to evaluate the quality of the water inlet and outlet vannamei shrimp farms. In water samples taken from the inlet and outlet were measured Parameters BOD, TSS and DO. Based on result this study, all parameters during the study in the field of exhaust effluent were standard range and are not a threat to the environment. Thus, can be concluded that reverse osmosis, an ideal method to BOD, TSS and DO removal in areas with contaminated water to this Parameters.

Sediment control at lateral intakes is known as a complicated issue for river engineers. In this study, numerical simulation of the impact of submerged vanes and spur dike on sediment control at lateral intake has been performed. For guiding flow into the diversion channel and increasing the vane performance, a single spur dike in opposite side of the intake has been utilized and the effects of spur dike length, the location of intake, and the angle of attack on reducing the movement of bed-load sediment into the diversion channel have been investigated. Obtained numerical results consisting with the experimental data confirmed this face that the effective performance of the vanes can increase using a proper spur result in eliminating the bed-loadsediment ingestion rate into diversion channel. Then, numerical results were compared with experimental results and there was good agreement between them.

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.

Density current occurs when a fluid flowing through another fluid with different density. Lot of research can be found in the literature about density current, but in all of them one of the fluids is stationary. Since no study can be found about density current when fresh water is flowing in the same direction of density current, therefore in this research attempts are made to study this especial case with the aid of experimental flume. The experiments were conducted in a flume with 35 cm wide, 8.8 m long and 70 cm height. The dense fluid was salt water with discharges of 0.5, 1 and 1.5 L/s and the discharge of fresh water were equal to 2, 3 and 4 L/s. The concentrations of dense fluid were 10, 15 and 20 g/L, and the bed slop of the flume was 0, 1 and 2%. The results showed that the head velocityis a function of the velocity of fresh water and therefore the relative head velocity is selected for further analyses. Finally, an equation is suggested to find relative head velocity.

Due to the scarcity of water resources and significant population growth, water supply has become a challenge. In such circumstances, efficient and cost-effective technologies such as nanotechnology in water treatment is recommended. The latest in water purification, desalinationsystems, Nano-filtration can bepointed. Nano-filtration separation mechanism of the effect of molecular size, The difference in permeability, and solubility of the feed components and electrical interaction between the membrane and ions are present in the feed. The purpose of this study of Nano-filter system to remove contaminants is challenging. This study, using a Nano-filtration system with a nominal capacity of 300 m3/d and Recovery rate of %60, and activated carbon filtration system and sand filterconsists of three vessel was Molasani Nano-filter water treatment plants in 2013. Experiments using the standard method carried out and the results were analyzed using the Excellsoftware. The results showed that the removal efficiency of the system in EC (%98.47), TDS (%98.45), total hardness (%98.74), calcium (%98.55), magnesium (%99.15), chloride (%96.48), sodium (%96.48) and TOC (%98.57).Due to the low renal solute dissolved in water and the nutritional value of the elements of water, particularly calcium and magnesium and absorption of these elements of water and nutrients through the body is necessary and the relationship between drinking water hardness and reduced incidence of cardiovascular disease in the community is in the long term this can be a contentious issue.

Accurate estimation of river discharge is an important issue in forecasting of drought and floods, designing of water structures, dam reservoir operation and sediment control. So far, several methods such as time series models, Artificial Neural Networks, Fuzzy models and Genetic programming have been used for accurate predicting of river flow. In this study, Genetic Programming and Bayesian Networks methods were used to forecast daily discharge of Barandoozchay River. The daily discharge data of Barandoozchay River measured at the Dizaj hydrometric station during 2007 to 2011 was used for modeling, which 80% of the data used for training and remaining 20% used for testing of models. For assessing the role of memory in increasing or reducing of model accuracy, we tested different combinations of input variables.The results showed that at first, the accuracy of models increase with increasing of memory, as the most accuracy obtained in third combination of input variables in both of methods. After that with increasing of memory the accuracy of models decreased. Comparing the performance of GP and BNs models indicated that the accuracy of the GP method with the R=0.978 and RMSE=1.66 (m3/s) was slightly more than BNs method with R=0.964 and RMSE=1.96 (m3/s). In addition, the performance of GP method was better than BNs method in predicting minimum and average discharges.

Flip buckets are commonly used to discharge flow from a hydraulic structure to the downstream as ski jump when flow velocity is large. One way to increase energy dissipation in flip bucket spillways is the deflector application. In this study deflector is a wedge-shaped structure which creates changes in part of flow trajectory. In this study, the deflector was continuously used across the channel, and energy dissipation caused by the mentioned deflector was measured. For the purpose of this study, after making the physical model, experiments were conducted by using four Froude’s numbers 5.55, 4.72, 3.93 and 3.13 by using deflectors with 3, 6, 9 cm lengths, and angles equal to 12˚, 17˚, 22˚, 27˚, 32˚, 37˚ and 42˚. Data analysis showed that deflectors with different anglescause an increase in energy dissipation. Also when the Froude’s number increases, the amount ofenergy dissipation will increase. The greatest difference of energy dissipation with state without deflector which occurs in Froude’s number of 3.93 was equal to 22.7% and was belong to deflector with 6cm length and 27 degree. In average the deflector with angles of 27 degrees has the greatest energy dissipation. This amount of energy dissipation for deflectors with 3, 6, 9 cm in lengths were equals to 68.2%, 72.5%, 51.6%respenctively and which occur in Froude’s number equal to 5.55.