Plant Protection
Year:2016 | Volume:39 | Issue:3|Papers Count:18

The quantitative and qualify limitations of agricultural water resources and fertilizer management are the important problems in Khuseztan Province. This study was conducted to evaluate the effect of deficit irrigation and different nitrate levels on the maize yield. The treatments were included irrigation (100, 75 and 50 percent of irrigation requirement) and urea fertilizer (300, 375 and 450 kg/ha). The experiment was carried out in the framework of a factorial using randomized complete block design with three replications. The result showed that the biomass, plant maximum height, grain yield and harvest index significantly increased (P>0.01). Also the results showed that in the 100 percent irrigation level, grain yield and biomass increased 6.6% and 4%, respectively, to compared with the free drainage. The results illustratedthat the use of groundwater can be decreased water drainage entrance into the surface resource as well as increased plant yield.

Using riprap is one of the common and economical methods for rivers bed protection against scouring. In this study, some stone sizes, under different hydraulic conditions have been tested to determine the criteria that affecting the stable size, of riprap at the threshold and failure conditions. In this investigation, it was found that in a constant flow ratio (Qr), with decreasing tail water depth and with increasing tail water velocity, the stability size of riprap was increased. Also it revealed that a constant size of riprap, with increasing flow ratio (Qr) in the threshold situation, tail water depth was increased and tail water velocity was decreased. At the constant size of riprap, with increasing total flow (Qt), in the threshold situation, tail water depth was increased and the stone with larger size will begin the incipient motion.

Today, flood management is one of the most important topics in river engineering due to reducing the fatality and damages caused by it. Several hydrodynamic models including 1D, 2D, 3D and couple hydraulic models have been developed in the world. One dimensional models have a short computation time and only compute the hydraulic parameters of main river channel. They provide nodetails about inflow or overbank flow and flow changing between river and floodplainds. Dez river in Khuzestan province (Case study) is surrounded by wide low elevation plains. Since the elevation of floodplains is lower than the main channel, when overbank flow occurs, two flows with different velocities and depths should be considered in the main channel and floodplains. In the present study three different modeling including: 1D simulation using existing cross sections, quasi 2D simulation using LINK CHANNELS, 1D-2D modeling with MIKE FLOOD, were investigated. The results indicate the quasi 2D model, despite of the limited computational time than 1D-2D model, has an acceptable accuracy in predicting discharge, water level, inflow and overbank flow simulation and reduction in inundation volume, which is compatible with the fact of inundation volume storing in the floodplains and it can separately compute hydraulic parameters of main river and floodplains. In contrast, there is no possibility for 1D model with the original cross sections to simulate overbank flow, discharge and flood volume reduction. It provides the average of hydraulic parameters throughout the whole cross setions. Moreover, flood routing is imposibe to be investigated in this model.

Accurate quantification of ET in irrigated agricultural lands is crucial for planning for water allocation, optimizing crop production irrigation management, evaluating the effects of changing land use on water yields. For this purpose in the research, evapotranspiration calculated by three kind of different methods remote sensing, agro-hydrological model and computational method for maize field located in Neyshabour plain. Methods of evapotranspiration determination consist of Surface Energy Balance Algorithm for Land (SEBAL) algorithm and Modis product satellite in the long of during growth, SWAP agro-hydrological and computational methods of FAO Penman-Monteith and Hargreaves-Samani and FAO Blany Criddle. Correlation coefficient 0.67 to 0.91 between SEBAL algorithm with SWAP model and computational method showed high potential for SEBAL algorithms in the evapotranspiration estimation. In between methods forpotential evapotranspiration determination, FAO Blany Criddle method has better result in comparison with Penman-Monteith and Hargreaves-Samani methods. Also, this study found that the SEBAL algorithm could be used to determine evapotranspiration in areas with shortages of data and for evaluation of computational methods and hydrological models.

The most common underlying cause of unsteady flow, opening and closing the valve fusing of current. This action will cause pressure waves in the system. Pressure wave speed depends on the type of valve, the valve opening and closing speed, hydraulics system and property of elastic pipes. One of places where it is important to calculate hammer, water conveyance systems are hydro power plants. If for any reason during the operation of the hydro power station turbines out of the circuit, the water hammer will be caused. This phenomenon not only pipelines, but also damage the turbine and power plant installation. Therefore, issue of water hammer in the transmission system is a concern for many researchers' hydro power plants. In this study to determine the effect of unsteady shear stress in fast and slow closing of the wicket gate valve used computer code. In order to calculate the shear stress from two equations Daily et al and the equation of friction developed Brunone et al a computer code was used. The results obtaines that the pressure wave in a fixed the Reynolds number in the first cycle was almost identical in both methods of friction and in the next cycle, pressure waves generated by the second method (equation developed Brunone et al) dampingis greater than the time. In which case, both fast and slow closing of the wicket gate valve, the non-dimensional maximum damping the second method by 75%.

Determination of the appropriate time to irrigation is an important decision that farm planners are faced to it. Using canopy temperature for plants irrigation scheduling is one of the methods that have been attention by many researchers. In this way, several indicators have been proposed among which can be noted Idso Crop Water Stress Index (CWSI) method. This research intends to investigate irrigation scheduling of summer maize using crop canopy temperature in Ahvaz climatic condition in farming years 2013-2014 under sprinkler irrigation (fixed irrigation system) with two levels of salinity irrigation water (S1=2.5 dS/m, S5=5 dS/m) in three replications. Accordingly, the amount of crop water stress index in September was estimated for two treatments S1 (minimum salinity) and S5 (maximum salinity), respectively, 0.14 and 0.29 and in October, 0.18 and 0.27, respectively. Upper baseline equations for the S1 treatment, in September and October was calculated (Tc – Ta) u.l=5.75oC and (Tc – Ta) u.l=4.70oC, respectively. For theS5 treatment the upper baselines equations in September and October were (Tc– Ta) u.l=2.94 and (Tc– Ta) u.l=2.85oC, respectively. Lower baseline equations were calculated in S1 and S5 treatments and showed that the water stress in S1 treatment was lower than to S5 treatment due to the lower baseline. By using of measured data, for scheduling irrigation of maize in October and September with sprinkler irrigation method, some equations were determined. By using of the equations and comparing difference between leaf and air temperature measured by leaf and air temperature calculated (calculated allowable amount) can be detect time of irrigation in both treatments.

Generally soil preferential flow occurs through soil macropores. These flows can transport a large amount of water and any type of pollutant to groundwater in a short time. This issue causes the water and soil pollution and in terms of environmental and health, affect the lives of animaland human. In this study the movement of water in preferential routes in the soil was investigated using a physical model. Also this movement was evaluated using Kinematic–Dispersive Wave (KDW) model which is a second degree non-linear partial differential equation and optimization of its coefficients. At first, the model coefficients were obtained using Particle Swarm Optimization (PSO) method. After that, the model was validated using experimental observation of rainfall hydrograph which was passed through the preferential routes of physical model and was recorded from the bottom of soil column. The results showed that the numerical model has very good agreement with experimental observations, and this prediction is better in lower rainfall intensity. Since dispersive mechanism was applied in this model and the effect of dispersive is disappeared graduatly with increase of input rainfall intensity, this effect in lower velocities causes the model to predict much better the observation. Consequently, this model can be a way to predict the preferential water flow and contaminant in soil to be eligible to make a reasonable decision in environmental management planning.

Global warming and climate change has caused serious impacts on water resources of the world, including the glaciers with reducing their surfaces and volumes. Surface and volume decreasing of the glaciers, could have the serious impacts on the discharge of the glaciers rivers downstream as well the soil erosion of watersheds. The increasing amount depends on the local and regional conditions. Changing in the rainfall amount, land using, vegetation covers and erosionable potential could influence the rate of river discharge and watershed erosion. In this paper, the impact of climate change on the Sardabrood river in the west part of the Challoos city in the North of Iran has been studied with statistical methods for a fifty years period (1958-2008). In this regard, the Hodric-Prescott filter as well as regression method, for investigation the randomized and non-randomized trends of the discharge and sediment. The results showed that the discharge and sediment trends increase in this glacier watershed. The general conclusion is that sediment increase by increasing the discharge, and indicates further erosion in the basin.

For optimization autumn sugarbeet irrigation water, an experiment was conducted at Safi-Abad Agricultural Research center in the years 2010 and 2011 with silty clay loam soil.The experiment was arranged in randomized complete blocks design with three replications. Tape irrigation levels (25, 50, 75, 100 and 125% of water requirement with T25, T50, T75, T100 and T125 respectively) and furrow irrigation was conducted. Production, cost and water function and thresholds indexes basis of irrigation depth was compared and computed. Although full rrigation in field experiment (T100 treatment) and maximizing level of applied water index (Wm) had maximum yield, T100 treatment had not significant difference with T75 and T50 treatments. On the other hand irrigation water application depth in water limited condition (Ww) was almost equal to minimum rate of water application, T25 treatment. Although Ww index had not maximum net benefit per unit of irrigation water, caused to decrease 43 percent consumed water and 21 percent of root yield and caused to increase sugare content and decrease irrigation costs. The results showed that in a view economic deficit irrigation in North of Khouzestan climatic conditions was applicable.

Soil water retention curve in many studies, including simulating the movement of water and solutes, irrigation and drainage issues is required. This soil hydraulic property was determined by direct (field and laboratory) and indirect methods. Direct methods are costly and time consumingtherefore the indirect method such as pedotransfer functions (PTFs) are the alternative to estimate this property. PTFs are developed to estimate drying branch of soil water retention curve whereas little research has been done for wetting branch of soil water retention curve. In this study, Shani field method was used to obtain wetting branch of soil water retention curve in agricultural area in 39 site of Boinzahra county. At the first, 10 national and international parametric PTFs were evaluated to estimate wetting branch of soil water retention curve. Results showed that simulated soil water retention curve using PTFs were not consistent with the measured soil water retention curve. In order to improve simulation of wetting branch of soil water retention curve, non-linear regression is used between simulated and measured value. The results showed that the using derived non-linear regression causes the Root Mean Square Error (RMSE) of PTFs of Mayr-Jarvis (1999), Wosten et al. (1999), Campbell (1985), and saxton et al. (1986) decreases 174, 140, 132, and 113 percent, respectively and consequently improves estimation of wetting branch of soil water retention curve. The results also showed that the using derived non-linear regression causes Geometric mean Error Ratio (GMER) closes to one and prevents over and under estimation of PTFs.

Suitable soil and water resources in the great Karun river basin, extensive areas of natural resources, favorable climate conditions and energy resources have led to the development of agriculture, industry and population growth in the Karun and Dez rivers margins. This study aims to identify, quantitatively and qualitatively review and determine the pollution load ofagricultural drainages in the basin of great Karun (Karun and Dez rivers), determine the volume of drainage water and the impact on the quality of production resources. After field study, sampling (N=96) was done during four seasons in 2013-2014 in 24 input points of drainage water to water sources. The EC, pH, TSS, NO3-, DO, BOD, PO4-3, COD features, Cations, Anions and discharge were measured. Results showed that agricultural pollutants with a volume of 2, 374 million cubic meters per year are causing pollution of types TDS and NO3- with 11862 and 65.51 tons per day, respectively. Pollution load of organic materials based on BOD and COD is 29.7 and 211 tons per day, respectively. Results also showed that, the Dez river reach has the largest share in terms of volume of drainage water and incoming pollution load. Moreover, the agricultural drainages of Shoeibieh, Haft –Tapeh Sugar cane, Ajirub and Salimeh, Karun (K), Myanab and Kharur within the Dez river reach, the drainages of Sardarabad (N) and Zahuabad within the Shatit reach and the fish-farming wastewaters within the Gargar river reach are among the most important drainages affecting the quality of water resources and agricultural lands in the downstream basin.

Due to the quantity and quality limitations of available water resources, the measurement and analysis of water and economic productivity indices in various irrigation systems (including surfaceand pressurized systems) has a great importance. The objective of this study was to compare water and economic productivity of pressurized and surface irrigation systems. For this purpose, the data of irrigation systems as well as crop yield in Qazvin Plain in 2011 were used. The required data were collected using the survey in the studied fields, questionnaires, the design report of irrigation systems and Qazvin Agriculture Organization. The results showed that the irrigation water productivity for barley, alfalfa, maize and wheat was 0.75 to 2.5, 0.2 to 1.76, 0.3 to 2.78 and 0.61 to 2.2 kg/m3, respectively, in sprinkler irrigation systems. In surface irrigation system, the water productivity for barley, alfalfa, maize and wheat was 0.43 to 1.42, 0.12 to 1.64, 0.22 to 1.58 and 0.43 to 1.25 kg/m3, respectively. The minimum and maximum amounts of economic productivity of surface irrigation systems in Rials/m3 were 1387 and 4617 for barely, 382 and 5050 for alfalfa, 905 and 6474 for maize and 1447 and 4159 for wheat. The minimum and maximum values of economic productivity of sprinkler irrigation systems in Rial/m3 were 2442 and 8126 for barley, 673 and 5420 for alfalfa, 1283 and 11395 for maize and 2016 and 7319 for wheat.

In this study, Pedotransver Functions and geostatistical methods are compared for estimating soil saturated hydraulic conductivity by soils texture. Data collected from 196 soil profiles related to soil and land reform Agricultural Organization of Ardebil. Results showed that among the geostatistical and Pedotransver Functions methods, ordinary cokriging with soil texture as Covariate has the best estimation in the region with Coefficient of Determination equal to 0.93 and Root Mean Square Error equal to 3.21 (Centimeters per day) and other goestatistical methods without covariate have lower accuracy estimations. The best fitted variogram in ordinary cokriging, was determined asexponential model with zero nugget effect and 156 of sill range that showed the strength of the spatial structure of the region and the full impact of the spatial structure on region variogram. Accuracy of Pedotransver Functions methods respectively decreased from Ferrer-Julià et al (2004), Roseta, Dane and Puckett (1994), Cosby et al (1984), Puckett et al (1985), Campbell and Shiozawa (1994).Among Pedotransver Functions methods Ferrer-Julia (2004) has more accuracy with coefficient of determination equal to 0.89 and Root Mean Square Error equal to 2.1 (Millimeters per hour) for estimating soil saturated hydraulic conductivity by soils texture.

Due to the problems of hydraulic structures at blocking bodies in debris flows this research has been carried out. Hence, in this study the effect of the trap drop bodies such as logs and branches of trees on piano key weirs at individual step was considered. The debris flows, decreasing in discharge capacity and raising the water level can be expected in the piano key weirs. The experiments of this research were performed on two piano key weirs with 10 and 30 cm in height on an experimental flume, 12 meters in length, 80 cm width and height of 70 cm. On these weirs three parapet walls with 2.5, 3.5 and 4.5cm height were installed. As a hydraulically criterion, Individual branches and logs in debris flow were studied. Individual experiments showed that the diameter and the upstream head of spillway affect the likelihood of blockage. However, both the increasing in diameter and head decreasing, increase the blockage. Therefore the probability blocking increases in D/H>1 and it decreases at D/H<0.3.

In this article, downstream scour patterns were investigated for submerged jets with different diameters and shapes (circular, rectangle, diamond and square) for single jets and also effects of different angles of crossing compound jets. For this aim, all effective parameters of submerged jets behavior were studied and the effective dimensionless relationships were derived according to dimensional analysis. In order to analyze this relationship, a physical model was built in KWPA laboratory and tests were run with different discharges. Then dimensions of scour patterns were measured in downstream of jets. The results indicated that the best development in pattern of scour belongs to diamond jet with average of 22% increasing in comparison by rectangle jet and the minimum of outer diameter with average of 183% increasing in comparison by the maximum one, also threefold increasing of crossing jets angles cause 58% increasing in the parameters of scour.

Using saline water for irrigation of crops is a strategy for irrigation water management. In this study, the cyclic application of saline and non-saline water was investigated. Field experiments were carried out during a growing season in 2012 under drip irrigation for maize crop with nine treatments in randomized complete block design in Karaj. The treatments were based on alternative irrigation management of saline and non-saline water on three salinity levels of 0.4, 3.5 and 5.7 dS/m and freshwater application in every one, three and five saline water application (1: 1, 3: 1 and 5: 1, respectively). The 1: 1 management was better than the other managements in terms of crop yield. The results showed that while the highest wet weight yield (56.2 t ha-1) was obtained in the F treatment (irrigation with non-saline water constantly), but the highest irrigation water use efficiency based on wet weight (14.9 kg m-3) was acquired in the 3S1: 1F treatment (thrice saline water (3.5 dS m-1) andonce non-saline water, alternatively). Thus irrigation water use efficiency was increased in cyclic using of saline and non-saline water because of less water use in saline irrigations, despite the relative reduction of crop yield. The results indicated that the percentage of crop yield decreased by 10.3 for every 1 dS m-1 increase in salinity level of irrigation water in fixed management. In this study, the crop yield in alternative management was higher than mixing management.

Precipitation is one of most the important parameters of climate that affects water resources directly. In this research changes of precipitation pattern in Iran investigated by means of PCI index. In this order 25 synoptic stations of Iran during two periods of 1961-1986 and 1986-2010 used to calculate PCI index and then significance of this index evaluated by t-test method.Results of mapping this index over Iran showed that precipitation changes had the same pattern in the two studied periods of time. Also results indicated that PCI index was high in the central part of Iran and in the low-precipitation provinces such as Kerman, Hormozgan, Yazd, Zahedan, Shahrekord, Birjand, Booshehr, Ahwaz and Isfahan. These stations according to the Oliver (1980) classification showed high irregular precipitation pattern. According to the results most parts of northwest followed irregular precipitation pattern. Two stations of Rasht and Gorgan had intermediate PCI index values and Zanjan and Tabriz stations had almost intermediate PCI index values. In none of stations uniform precipitation pattern (PCI<10) found. Finally trend of PCI index analyzed in the regional and stational scales and non-significant upward trend detected at 5% level at clusters 2 and 5 while in other clusters non-significant downward trend observed.

In open channels, when water flows through obstacles, boundary layer on upstream and the separation of streamlines on downstream of the obstacles and therefore vortex shedding will occur. The overlap of vortex wave reflecting from the walls of channels may produce surface waves which are perpendicular to the direction of the flow. When the vortex frequency of obstacles and flow natural frequency become equal, resonance will occur. The purpose of current study was to determine the relative amplitude of transverse waves in submerged flow while resonance occurs. The submerge processing started from 0% into max percent while the waves are visible. This research included 71 tests in different prism obstacles with two style of water strike toward edge and face of the obstacles and in two different inline and staggered arrangements in two modes of transverse waves. The obstacle distances were 120 millimeters from each other. The maximum relative amplitude of the flow depth was 0.2 for mode one and 0.14 for the second modes of transverse wave. By using software and statistical analysis, a formula was suggested for determining the maximum relative amplitude of the flow depth. Finally, the data determined by suggested formula were compared with the laboratory data.