فهرست مطالب s. m. mirlatifi

The purpose of this study was to evaluate the accuracy of SEBS remote sensing algorithm to determine the actual evapotranspiration of an alfalfa field located in Isfahan province. An automatic weather station was installed in the alfalfa field to measure and to record the required weather data for the calculation of reference evapotranspiration by the Penman-Monteith equation. Daily and hourly grass reference evapotranspiration (ETr) were calculated by FAO Penman-Monteith equation (FAO56), using the meteorological data measured during the satellite passing time. The FAO 56 crop coefficient was used to obtain alfalfa evapotranspiration from ETr. The actual hourly alfalfa evapotranspiration (ETc-h) from an extensive alfalfa field surface at the time of the passage of the LANDSAT 8 from the study area was computed by SEBS algorithm and at the same time it was measured by a Scintillometer and they were found to be 0.7 and 0.65 (mm/hr), respectively. The actual ET obtained by SEBS usually overestimated values measured by the Scintillometer (LAS). The actual hourly and daily alfalfa evapotranspiration values obtained from SEBS algorithms were compared with the corresponding values measured by the Scintillometer (LAS) and values calculated by the FAO Penman-Monteith equation and R2 of 0.75( p<0.01) ,0.86( p<0.01) and RMSE 0.04 (mm/hr) , 0.43 (mm/day) were obtained , respectively.

A field research was carried out to ascertain the effectiveness of the application of Improved Farm Practices including adjusting border size, improving soil fertility by changing the fertilizer application program, and using cleaned and disinfected seeds on water consumption and crop yield in four barley farms located in the Miandoab region. The new farm technological practices were applied in treatment farms in order to compare the results with the corresponding values obtained from the control farm, where agricultural practices were performed by the local farmer according to his own knowledge. Crop growth indices such as leaf area index, cluster and plant height during the growing season and thousand seed weight and grain yield at the harvesting time were measured. Soil water moisture content of the root zone layer during the growing season and the depths of the irrigation water and the surface runoff of each irrigation event were measured. In order to qualify the effectiveness of the new technological practices applied, the performance indices such as Water Productivity (WP), Water Use Efficiency (WUE), and Water Application Efficiency (Ea) were calculated by collecting the required field data from each one of the farms. The results indicates that the application of new farm technologies increased WP of the treatment farms as compared to the control farms about 20% and improved WUE about 24%. Adjusting the border size decreased the irrigation time and the depth of deep percolation. It furthermore, increased the Ea of treatment farms about 20%.

This study was conducted to evaluate the water productivity of Amir kabir sugarcane agro-industry farms using landsat 8 satellite data. Actual evapotranspiration and yield of the final product were estimated using satellite data and then were compared with measures corresponding values collected from fields during 2012-2013 growing season. The total volume of sugarcane actual evapotranspiration during the growing season from 9328.5 hectares of cultivated farms was 160 million cubic meters and the yield of wet sugarcane was 520230 tons, which is equivalent to 56 tons per hectare. Average of water productivity for sugarcane according to the evapotranspiration and the irrigation water were 3.4 Kg/m3 and 1.6 Kg/m3 respectively. The water productivity data analysis in ARC-10 showed that there was a direct relationship between irrigation intervals of planted plots and water productivity. Therfore, it can be concluded that , by increasing irrigation intervals, and applying the same volume of irrigation water would cause, water productivity to increase. Also, the water productivity of CP48 103 variety was found to be higher than of CP69-1062 variety. The water productivity of sugarcane was inversely related to the age of the cultivated crops. As the age of the sugarcane crop increased from planting to R7, its water productivity decreased. It was concluded that the difference between the water productivity of various plot of Amirkabir sugarcane agroindustry farms could be attributed to the depth of applied irrigation,irrigation time and intervals, and also to the large difference between the ages of sugarcane plantations (plant to R7).

In this research, the applicability of DRAINMOD model for simulating water table fluctuations and subsurface drain discharge variations was evaluated at the consolidated paddy fields of Sari Agricultural Sciences and Natural Resources University. During free drainage period of a canola season (November 28, 2011- April 2, 2012), water table depths and subsurface drain discharges were measured in three subsurface drainage systems including drainage system with drain depth of 0.9 m and drain spacing of 30 m (0.9L30), drain depth of 0.65 m and drain spacing of 30 m (D0.65L30), and drain depth of 0.65 m and drain spacing of 15 m (D0.65L15). The reliability of the model was tested using the statistics including model efficiency (EF), percent error (PE), coefficient of determination (R2), root mean square error (RMSE) and mean deviation (AD). Mean values of measured and simulated water table depths in the calibration treatment (D0.65L15) were both 32.4 cm. For validation treatments, such values were, respectively, 24.1 and 14.1 cm for D0.65L15and 2.1 and 19.7 cm for D0.9L30. EF, PE, R2, RMSE and AD values for predicted drainage discharges ranged from 5.1 to -1.3, 9.1 to 21.6, 0.2 to 0.35, 0.08 to 0.11 and 0.07 to 0.1, respectively. Comparison of measured values with the simulation results showed that DRAINMOD model can be used as a practical tool for predicting the general pattern of water table and drain discharge variations in the study area.

The main purpose of irrigation is to achieve an optimum amount of yield with an economical use of water according to the crop water requirement. An improved irrigation scheduling would lead to the reduction of the excess water use, and the enhancement of crop production. In order to develop a proper irrigation scheduling, actual crop water requirement must be determined. Accordingly, it was attempted to determine the water requirement of tuberose (Polianthes tuberose L.) irrigated by a drip irrigation system and grown in a glass greenhouse located in Varamin during 1392. In order to calculate the water requirement of the tuberose, a simple water balance method was applied.. Tensiometers were installed at two soil depths and were used to determine the time of irrigation events. Irrigation was applied at any time when the soil suction reached to 30 centibar. The Water requirement of Polianthes tuberose for a 144 day growing season (Jun. to Oct.) was found to be 350 mm. The average actual evapotranspiration of Polianthes tuberose was 2.5 mm/day. Based on the data collected from a Class A evaporation Pan located inside the greenhouse, the monthly crop coefficients for tuberose were between 0.5- 0.7.

Pistachio is a strategic product with high economic value in Iran، which is cultivated in arid regions withlimited water resources and poor water quality. Therefore، it is essential to use irrigation systems capable of yielding high irrigation efficiency along with effective management of soil water and salinity. In recent years، application of Subsurface Drip Irrigation (SDI) system has been widely accepted by manypistachio growers. Since، irrigation water is of poor quality in major pistachio plantations، utilization of this irrigation method will result in accumulation of salt in the vicinity of soil surface، hence a reduction in pistachio yield. In addition، appropriate irrigation interval for Pistachio orchards irrigated by SDI systems is unknown. A field experiment was conducted on 15-year old pistachio trees grown on loam silt soil and irrigated by subsurface drip irrigation with saline water (EC= 4. 2 dS/m) in a region under desert climate to investigate the effects of different irrigation regimes on the soil moisture and salinity distributions as well as pistachio yield. Two irrigation frequency treatments، namely I3 (Once every 3 days) and I14 (Once every 14 days)، replicated three times were applied to one hectare block of a farm in Sirjan. The results revealed that irrigation frequency had significant effects on the spatial distribution of soil water content within 0-100 cm depths with a higher soil water contentforI3. In contrast to I14، salt accumulation in the root zone for I3 was significantly (p<0. 05) low due to more water application. Pistachio yield for I3 and I14 was 3. 3 and 3. 7 kg/tree، respectively، indicating non significant difference. However، I3 showed marked enhancement in quality traits such as osteoporosis and smiling.

Precise estimate of evapotranspiration (ET) or crop water requirements crucial for improving water resources management and eventually increasing water use efficiency. Considering the vast varieties of crops cultivated on large scales, calculating precisely the crop water requirement from ordinary methods of estimating reference evapotranspiration is difficult and in some cases even impossible. Therefore, it is necessary to develop methods to compute crop water requirement in large areas with sufficient accuracy. One of such methods is to use remote sensing data which covers a much larger areas as compared with methods depending on field weather data. One of the most well known methods to compute actual ET from remote sensing data is SEBAL method (Surface Energy Balance Algorithm on Land). In SEBAL method, all fluxes of the energy balance at the earth's surface including net radiation, soil heat flux, and sensible heat flux are calculated from satellite images and finally actual ET is computed based on the energy balance at the earth's surface. It is intended to evaluate spatio-temporal variation of daily ET in Mirza Kochakkhan sugarcane Agro-Industry farms located in southern part of the Khosetan province using MODIS images for 10-day periods during a growing season in 2006-2007. The results obtained indicated that the SEBAL method was an efficient method to estimate actual ET during the growing season. Maps of actual ET generated by ERDAS and GIS software showed that fields which were well irrigated or had a good crop cover had the highest values of ET. However, actual ET decreased for areas with less crop cover or dry fields. The data obtained from the generated maps of actual ET were closer to the data obtained from the field with a coefficient of determination of R2=0.77.

Reference evapotranspiration (ETo) is an essential parameter required for proper management of agricultural crop irrigation. ETo is influenced by many different hydrological variables and as a result is a very complex procces. ETo is usually estimated by empirical or process-orinented models (mathematical relationships) from historical weather data. The need for accurate estimates of ETo and the complexity of developing models to describe such complex process magnifies the need for developing new data mining methods. In this paper, the possibility of using a combined method of multiple linear regressions with principal componenets analysis (MLR-PCA) for estimating reference evapotranaspiration was investigated. In this analysis, measured daily meteorological data of Kerman synoptic weather station recorded from 1996 to 2005 were used. Three principal componenets that explained 80% of the total variance of the data were recognized as the principle componenets and others as disorder. Using the extracted principle componenets, a multiple linear regression model was developed to estimate ETo. The statistic index of t for assessing the results of a fixed constant and each componenets of PC1 and PC2 were determined. According to the results, all coefficients were significant at the level of 95% and PC1 had more importance than the other component namely PC2. This revealed that the variables of radiation intensity, relative humidity, sunshine hours, minimum temperature and maximum temperature had more importance in estimating reference evapotranspiration than other climatological parameters. Comparison of MLR-PCA model with Penman-Monteith results showed that about 82% of the total amount of the ETo variance is defined by the three aformenstioned principle componenets.

A computer model (SprinklerMod) was developed to simulate hydraulics of sprinkler irrigation systems. The objective of this paper is to describe mathematical background of this model for simulating pressures and discharges of sprinklers along the laterals. The model is capable of designing two types of laterals: laterals with fixed sprinklers and laterals with portable sprinklers. The model shows the simulation results in the forms of tables and graphs. Laterals with one or two diameters on uniform or non-uniform slopes can be designed. The model provides graphical presentation of percentage of sprinkler pressure variations for different lateral inside diameters. The Hazen- Williams equation was used for the calculation of friction losses. The required input parameters for lateral simulation are lateral type, desired sprinkler operating discharge and pressure head, spacing between sprinklers, distance of first sprinkler from lateral inlet, number of sprinklers operating on the lateral, riser height, Hazen- Williams pipe friction coefficient and lateral longitudinal slope or field elevations at each of the sprinklers on the lateral. Laterals are simulated such that average sprinkler pressures and discharges become equal to the values requested by the designer. Iterative procedures were implemented to simulate sprinkler pressures and discharges on laterals and the Newton- Raphson iterative method was used for calculating pressure of each of the sprinklers on the laterals with portable sprinklers. In order to evaluate the model, some example results of the model were compared with classical design results. Since there is no formula for the calculation of the required lateral inlet pressure in classical design of laterals with portable sprinklers in the scientific references, a new formula was developed. Averages of absolute percentage of variations of lateral inlet pressures for laterals with fixed sprinklers and with one or two-size diameters ranged from 0.3 to 0.7 percent, respectively. This value for laterals with portable sprinklers was 0.1 percent.