مجله تحقیقات آب و خاک ایران
سال چهل و ششم شماره 4 (پیاپی 23، آذر و دی 1394)

In the current paper, the combined effect of seasonal fluctuations of Persian Gulf and Mediterranean Sea Surface Temperature (SST) on the forecast of monthly streamflow of Karkheh River has been investigated. For this purpose, Singular Value Decomposition method (SVD) has been used to determine the effective nodes of the seas on the climate of the region and to produce correlated series of sea surface temperature and streamflow. Moreover, Generalized Regression Neural Network method (GRNN) based on cross-validation technique has been applied in order to determine the best predictors from several combinations of predictors for each month. Results for the forecast the inflow to Garsha dam show that the Mediterranean sea SST in autumn affects the streamflow from February to April, and summer and autumn SSTs of Persian Gulf affect the streamflow in April and May such that applying these two indices for streamflow forecast in April and May results in an average increase of 118% and 282% in Nash-Sutcliff index during calibration and validation phases, respectively.

The aim of this research, study of effects climatic drought on hydrological drought in Hashtgerd plain. In this study, the SPI (standardized precipitation index) for climatic drought and GRI for hydrological drought was calculated. The Mann-Kendall trend test were used to assess data (rainfall and water level). Pearson correlation calculated through the cross-correlation between SPI and GRI. For detailed study of the correlation, the SPI time scales were calculated from 0 to 200 months and the lag time from 0 to 150. The results showed high correlation relate to interaction between the SPI and the lag time with the GRI. Also, the behavior patterns of piezometers caused three groups of time actions in study area.

By measuring the annual growth of tree ring and make their chronology, the possibility of study and reconstructions of streamflow in the habitats areas is provided. The aim of this research is to reconstruct streamflow using dendrochronology, and modeling and classification of hydrological drought in Karkheh basin. In this research the chronology index of two tree species, Quercus brantii, and Quercus infectoria, in the central Zagros region during the period 1840-2010 were used to reconstruct streamflow in Karkheh basin. Three gage stations in Karkheh basin were selected, and their high flow periods were determined. Correlations between streamflow in high flow period and regional chronology index for gage stations were positive and significant at 1% confidence level, and with regard to this fact, the average streamflow in high flow period of these three gage stations from the year 1840 to 2010 were reconstructed. The values of observed and reconstructed streamflow in common statistical period are properly consistent with each other. In the following, hydrological conditions during chronology period were studied and accordingly, hydrological drought was analyzed in the Karkheh Basin for years 1840 to 2010. Severity and duration of the droughts as well as low flow and high flow decades were determined. In addition, the results were compared with other researchers as well. After reconstructing streamflow a probabilistic neural network model were utilized in order to classify the periods of very low flow, low flow, high flow, and very high flow. The results showed that provided model is able to recognize the mentioned periods with a high accuracy in the region.

Splash detachment and transport of soil particles by raindrops impact on the soil surface are the initiating mechanisms of water erosion. However, mechanistical analysis of different effective factors has been less taken into account. The present study has been therefore formulated for comparative analysis of effective intensities and slopes on Raindrop Impact Induced Erosion (RIIE) components in laboratory scale for a sandy clay loam soil. Towards this attempt, a total of 81 rainfall simulation experiments were conducted in a set of 1 × 6 m plot with varying slopes of 5, 15 and 25% using current situation in the region and in three replications and simulated rainfall intensities of 30, 60, and 90 mm h-1 using region IDF. The experiments were adopted using rainfall simulation system and upward and downward Morgan’s splash cups situated at upper, middle and lower part of the plot. Results indicated that all study variables viz. total and net splash and upward and downward splash were significantly (p ≤ 0.01) influenced by rainfall intensity and cups locality but net splash was not statistically influenced (p ≥ 0.13) by spatial variation of cups. In addition, the results showed that slope did not affect any study variables (p ≥ 0.11) except the net splash (p ≤ 0.01).

One way to reconstruction of climatic variables, especially temperature, is dendroclimatogy or the use of trre-ring width chronology. There is no tree-ring based reconstruction of long term temperature in Caspian Ecosystem. In this research, temperature was reconstructed using Fagus Orientalis tree-ring chronology collected from high elevated regions of Koliak (Nowshahr). To this target, a correlation between annual tree ring width with meteorological variables in local and global scales was considered. Correlation analysis showed that the reduction of maximum temperature is a limiting factor of tree growth, particularly in the period March-September. So, the average of March-September maximum temperature based on data measured at Nowshahr’s station was reconstructed. The results of temperature reconstruction showed that this region has experienced very cold years more than very warm ones in two past centuries. Also 1900th, 1950-1970 and 1830th, 1930-1950 were the warmest and coldest periods, respectively. Besides, the significant effect of negative NAO on temperature rising in the early months of growth period was revealed. Reconstructed temperatures of this research like the results of other researchers in Eastern Mediterranean didn’t show the warming trend in recent years.

Longitudinal dispersion coefficient is normally affected by many hydraulic parameters. So far three approaches namely, integral method, dye tracing filed measurements and empirical formulae have been widely used to estimate the above mentioned coefficient, in rivers and streams. In this paper a new equation of the longitudinal dispersion coefficient is determined and evaluated using an environmentally safe tracer and the basic empirical equations. To achieve this aim, a length of 500 meters of a mankind concrete canal was chosen, to carry out the tracer tests. A set of experiments was conducted in three different mixing lengths, including 45, 75 and 100 meters in Feb. 2015. The results show that differences of average, variance and maximum concentration between measured and estimated data using the past equation are equal to 79, 6, and 99 mg/lit and using the equation in present study equal to 66, -1 and 44 mg/lit, respectively.

Side weir is a flow control structure that used extensively in irrigation and drainage networks and sewer networks. In this research, a study with 162 experiments has been done on sharp-crested circular side weir. Since the height of this side weir varies along its length, this feature enables it to control flood better than rectangular side weir in different flood conditions. The governing differential equation of circular side weir has no analytical solution, and thus it is necessary to use numerical methods to solve it. Since numerical methods have computation cost, normal weir equation and linear assumption of water surface profile are used to solve the problem. Lastly, by doing three other experiments under completely different conditions, it was found that the method of considering linear water surface profile has less error in comparison with other methods used in this research.

In this study some vegetative and reproductive characteristics of Rosa damascene under three levels of irrigation water amounts (100, 70 and 40 % potential evapotranspiration) though surface and subsurface drip irrigation systems has been investigated. The investigated morphological characteristics were included the number of branches per plant, shading diameter, plant height, number of blooms, petals weight, fresh weight of one flower, percentage of dry matter of flower and total dry weight. The experiment was performed as a split plots design based on the randomized complete blocks with three replications at Research Center for Agriculture and Natural Resources of Kerman province (Research Station Joopar) during 2012 and 2013. Results showed that the plant height, number of blooms, fresh weight of one flower, petals weight and percentage of dry matter of flower were not significantly different for the two types of irrigation systems but all plant traits except percentage of dry matter of flower were significantly different under different irrigation management regims. Due to water resources limitation in the study area, the 70% potential evapotranspiration treatment was recognized as the best treatment because having 30% decrease in irrigation water amount, there were only 5.8% and 15% decrease in the number of blooms and the shading diameter, the most effective traits on yield (correlation coefficient = 0.99), respectively.

In recent years, several models have been presented for water, soil and plant relationships that one of them is AquaCrop model, which in this study were used to predict sugarcane yield and soil salinity profiles under salinity stress in the southern Khuzestan. In order to achieve the required number of input factors, model was calibrated and the amount of soil surface covered by an individual seedling at 90% emergence, maximum canopy cover and harvest index were determined. These coefficients were determined 7.2 (cm2), 90% and 40% respectively. Then the model was performed and simulated and measured values were compared using statistical indicators. The coefficient of determination between measured and simulated yield data was achieved 0.97, the normal root mean square error 8%, Nash-Sutcliffe efficiency 0.83 and coefficient of residual mass -0.09. The results showed that the model has acceptable performance to estimated sugarcane yield and the model in condition of current study was over estimated. Also, coefficient of determination of soil salinity was more than 80% and the model estimated the amount of soil salinity more than measurement.

The low irrigation application efficiency is the major problem of surface irrigation systems due to weak management and poor design. The purpose of this study was improvement of border irrigation performance based on four variables including inflow rate, cut off time, slope and border length. For this purpose 8 series of the field experimental borders were considered with open-end downstream condition. Calibration of infiltration parameters of borders were conducted based on multilevel optimization method. The results indicated that the multilevel optimization method for prediction of infiltration parameters in border irrigation was an acceptable method. According the multilevel optimization method, the mean relative error for the volume of run-off prediction was determined to be 0.5% and the average of root mean square error for advance and recession times predicting about 3.1 and 3.2 minutes, respectively. The performance of borders was optimized using application efficiency and distribution uniformity performance contours of the WinSRFR. Based on flow variables (inflow rate and cut off time), the average of application efficiency could be increase about 12 % (with adequacy equal to 100%) for 8 series of the field experiments compared with current evaluation. Results indicated with considering geometric variables (slope and border length) more over the flow variables as decision variables, affected on optimal irrigation performance partially and in terms of all flow and geometric variables, the average of application efficiency could be increased about 13.35 % compared with current evaluation.

This study was conducted to determine the best drainage distance and duration in mid-season drainage of paddy fields in 2014. The experimental field was located in Rice Research Institute of Iran in Rasht, Giulan province, with 49.63˚ E and 37.16 ˚ N and altitude of 24.6 m above sea level. The experiment was carried out on Hashemi cultivar in the plots of 3×4m as a completely randomized design in three replication with factors of drain distance in three levels of 7.5, 10 and 15 m and depth of 90 cm and drainage duration in two levels of 7 and 11 days. The characteristics such as plant height, number of tiller, panicle length, filled grains, 1000-grain weight, dry matter, harvest index, yield, soil moisture and discharge of drains were measured. As a result, the effect of mid-season drainage duration on yield showed that the maximum yield was gained in 7-day drainage duration with amount of 3987 kg ha-1. Also, based on the effects of drains distance on yield, the distance of 15m obtained the maximum yield with amount of 3446 kg ha-1. Statistical analysis of drainage distance and mid-season drainage duration interaction on yield represented that the maximum yield (4384 kg ha-1) was gained in treatment of 7-day mid-season drainage duration and drains distance of 15m that is recommended for study area.

Rainfed wheat is a food resource for developing countries that various factors may contribute in its production. The aim of the present study was developing a model that estimate rainfed wheat grain yield based on physico-chemical properties of the soil. Therefore, wheat grain yield was measured at 53 rainfed wheat fields over Zanjan province in agronomical year 2014. Also, 18 soil physico-chemical properties were measured in triplicates in the fields. Using partial least square regression, a model was developed to explain the relationship between rainfed wheat grain yield and soil properties (n=40, R2= 0.6). The highest and lowest standardized coefficients of the model belonged to silt and calcium carbonate percentages which were equal to 0.23 and -0.24, respectively. The results of the present research revealed that some soil physico-chemical properties, in order of priority, including silt, calcium carbonate and potassium has more effects on rainfed wheat grain yield.

The aim of this study was to compare the performance of multiple regression and neural network models to predict the activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POX) in shoots of wheat (Triticum aestivum), Alvand cultivar in a soil contaminated with cadmium. The treatments consisted of four levels of cadmium (0 (as control), 25, 50 and 100 mg cadmium kg-1 soil), respectively. After 30 days (almost simultaneously with stage of the plant's stem elongation) plant samples were harvested. The following ten different parameters measured included wet and dry weight, chlorophyll a and b, Concentrations of cadmium, copper, iron, manganese, zinc and potassium, respectively. The amount of enzyme activity of SOD, CAT, APX and POX were measured. As next stage, the correlation coefficients between ten parameters and the activity of antioxidant enzymes were determined. The results of multiple regression and neural network models optimized showed that the efficiency of artificial neural network in predicting the activity of SOD and POX enzymes was more of than multiple regression models. Coefficient of multiple determinations (r2) between measured and predicted values of SOD activity for multiple regression and neural network models was 0.76 and was 0.87 respectively. Coefficient of multiple determinations (r2) of POX activity for multiple regression and neural network models was 0.96 and was 0.98 respectively. Coefficient of multiple determinations (r2) between measured and predicted values of CAT activity for multiple regression and neural network models was 0.97 and was 0.98 respectively. In regarding the APX enzyme, coefficients for multiple regression and neural network models was 0.97 and 0.99 respectively. According to the results of this research, generally efficiency of artificial neural network model in predicting the activity of antioxidant enzymes of wheat shoots, under toxicity of Cd was more than the multivariate regression model.

Effects of calcium carbonate and pH on the kinetics of P fixation were studied on four non-calcareous soils which had been treated with different levels of pure CaCO3, and also on six soils which were adjusted for pH in the range of 5 to 9. Soils were also treated with K2HPO4 at rate of 45 mg P/kg before they were incubated for a period of 100 days at 25○c. Olsen-P was measured at certain intervals time. It was indicated that the reaction of P with soil was biphasic, composed of a set of fast reactions and a set of slow reaction. The rate of reduction in available P (Olsen-P) was very fast during the first day, then it diminished gradually up to 50 days, and thereafter approached to zero in most of the soils. In addition, an increased in the amount of CaCO3 in soils resulted in a significant (5% level) increase in the mean P recovery of the soils, however, the effect was not the same in all soils, and in one of the soils an increase in the amount of CaCO3 up to 35%, had no effect on P recovery. The effect of pH on P availability was not the same in different soils. In some soils an increase in the pH from 5.2 to 8.8 had no significant effect on P availability, while in others, the amount of Olsen-P was higher or lower at higher pH values. The different effects of pH on P availability was explained by the variable effects of a change in pH on the available-P related parameters such as solubility of P minerals, change characteristics of the soil surface, speciation of soluble P and change in concentration or activity of P species and the rate of organic P mineralization.

Extraction and refinement of fossil fuels have led to contaminate of soil resources and also caused to make a considerable part of lands out of reach. This study aimed to evaluate the effect of different levels of organic matter and hydrocarbon decomposing bacteria on nutrient uptake of Cordia myxa seedlings. Treatments included crude oil (0, 3 and 6 w/w) municipal solid waste compost (0, 5 and 10% v/v) and bacteria (with and without bacteria of psu141 and psu27ps). The results showed that the highest concentrations of nitrogen in shoot, phosphorus, potassium, manganese, iron and zinc in shoot and root were found in compost 10%, with 3.69%, 0.22%, 0.15%, 1.82%, 1.52% and 94.91, 123.66, 110.15, 1086.01, 32.44, and 79.67 mg/kg, respectively, and the concentrations of these elements in the presence of bacteria were significantly higher than the control. In general, the presence of biological factors caused an increase in the absorption of nutrients and improvement of the nutritional status of plants under oil pollution stress conditions.

Wetting and drying cycles are important environmental processes that often act as a mechanism of soil pore system changes. Also, clay content and organic matter are the soil intrinsic properties which involved in soil structure properties. The aim of this study was to investigate the relations of number of wetting and drying cycles, clay content and soil organic matter with structure stability, particles size distribution and pore system. Some soil physical properties were determined after one (T1), three (T3) and five (T5) wetting and drying cycles and were compared to the aggregate stabilities of initial untreated soils (soil without wetting and drying cycles). The Results showed that the improvement in aggregation most pronounced for the clayey soils especially with high amount of organic matter. After one and three wetting and drying cycles, only two clayey soils more aggregated than soils with less clay; but further wetting and drying cycles (5 cycles) resulted in decreasing of stability of aggregates. Our finding indicated that the macroaggregation depended mostly on soil texture attributes rather than organic matter content; and the former were more effective in aggregating when combined with high amount of clay. Also the compaction caused by sampling can be repaired by wetting and drying cycles and the alternation of these cycles is an important mechanism for soil structure improvement.

This research conducted in a part of the dry farming lands in the southern Guilan aimed to examine the impact of tillage erosion on the soil displacement and productivity. In order to achieve the research aims, 18 sampling points were considered in different locations of the landscape in seven adjacent fields, based on the adjacency to the filed ridges (borders). The soil fertility characteristics at 0-30 cm depth and wheat yield components were determined at each sampling point. The cluster analysis by the Ward method grouped the soils in three groups based on their fertility and productivity. The criteria for grouping soils fertility were nitrogen, phosphorous, potassium and organic carbon. The soil productivity was classified based on ear number, one thousand grain weight, grain number in ear and grain yield. There was no significant relationship between the grouped points in terms of fertility and productivity probably due to differences in crop management of the adjacent fields. The terrace elevation formed between two fields was observed to be 1 to 3.2 meters in the slope direction, and 1 to 1.3 meters in the lateral direction. In addition, the soil volume displaced in the two directions was estimated to be 8 to 36 and 5 to 22 tons per hectare per year, respectively.

Zinc (Zn) is an essential micronutrient for plants, animals and humans. Bioavailability of Zn for plant root is controlled by sorption process in soils. In order to evaluate the effect of citric acid on Zn sorption, a batch experiment was conducted with two soil samples (S1, S2) which were different in clay and calcium carbonate content. Three levels of citric acid (0, 0.5, 1mM) and various Zn concentration (0 to 450 mg L-1) were applied at background solution 0.05 M NaCl. Adsorption data were fitted to Langmuir (R2=0.76-0.95), Freundlich (R2=0.83-0.95), Temkin (R2=0.62-0.92), Dubinin-Radushkevich (R2=0.44-0.92) and Elovich (R2=0.54-0.90) isotherm models. Sorption parameters including maximum adsorption of Langmuir (qmax), Freundlich capacity and intensity factors (KF, n), coefficients of Temkin equation (A, KT) and maximum adsorption capacity Dubinin-Radushkevich (qm) decreased by application of citric acid; above mentioned sorption parameters of S1 (with low clay and calcium carbonate) were lower than those of S2 (with high clay and calcium carbonate). The sorption energy parameter of D-R isotherm and Gibbs free energy change (ΔGr) indicated that the Zn adsorption processes were physicaly and spontaneity. The results of this experiments showed that the application of citric acid significantly decreased Zn sorption by soil particles probably due to formation of soluble complexes, and consequently increasing Zn availability for plants. Therefore, by modifying plants to secrete higher of citric acid can increase zinc absorption by plants.

Zinc (Zn) and Copper (Cu) are known to be essential micronutrients for plants. High concentrations of these elements, stressing factor for the plant growth and it can act as a limiting nutrient uptake and growth. The aim of this study was to investigate the effect of different concentrations of Cu and Zn on micronutrient (Cu, Zn, Fe and Mn) and macronutrient (P and K) uptake in dragon’s head plant with soil in a Zn and Cu deficiency,suficcient and toxicity levels. The treatments consisted of three levels of Cu (0, 5 and 25 mg/Kg CuSO4) and three levels of Zn (0, 10 and 50 mg/Kg ZnSO4) and their combination. This study was investigated to the effect of different concentrations of Cu (zero, 5 and 25 mg per kg of soil) and Zn (zero, 10 and 50 mg per kg of soil) on the uptake of Cu, Zn, Iron (Fe), Manganese (Mn), Potassium (K) and Phosphorus (P) in the root and shoot of Balangu (Lallemantia iberica F. & CM). The results showed that all treatments had a positive effect on the uptake of Cu and Zn in roots, but in shoot, Cu and Zn at low concentrations (5 and 10 mg per kg of soil, respectively) and high concentration (25 and 50 mg kg soil), had a positive and negative effects on uptake of these element, respectively. The negative effect of high levels of Zn on Cu absorption more higher than the levels of Cu on zinc absorption shoot. K upateke of root and shoot increased in all treatment except of high levels of Cu and Zn combined treatment with high levels of copper. These findings can be alert useful as a controlled use of Cu and Zn in Balangu cultivation.

Phosphorus deficiency is a common disorder for agriculture in calcareous soils. To study the effects of spent mushroom compost (SMC) and sugar cane bagasse biochar (B) on alkaline phosphatase activity and phosphorus availability in three soil types (that is) loam, clay loam, and sandy loam, an incubation experiment was conducted. The treatments included levels of biochar B1 and B2 (15 and 30 ton.ha-1), levels of spent mushroom compost SMC1 and SMC2 (20 and 40 ton.ha-1) and the control (C). After applying treatments in 14, 60, and 120 days, T1, T2, and T3 respectively, available phosphorus and pH were measured and alkaline phosphatase activity at T3 period was also measured. The results indicated that in all soil samples SMC increased phosphatase activity, But biochar was ineffective in sandy loam soil. Average phosphatase activity in control treatment was 2090, 2931 and 2888 µg PNP.g-1Soil. h-1 at sandy loam, loam and clay loam, respectively and was increased to 3034, 3709 and 3533 µg PNP.g-1Soil. h-1 in SMC2 treatment, respectively. Both levels of SMC also caused increase in phosphorus availability, while biochar was less effective on that. SMC2 treatment showed the best effectiveness on increasing phosphorus availability. So that available phosphorus average was increased from19.4, 8.8 and 3.9 mg.Kg-1 in control treatments to 37, 28 and 22 mg.Kg-1 in SMC2 treatment for sandy loam, loam and clay loam soils respectively. Application of SMC reduced soils pH while biochar increased that. Results indicated that SMC has a positive effect on phosphorus availability and improves other properties including pH in calcareous soils.