نشریه دانش آب و خاک
سال بیست و ششم شماره 3 (پاییز 1395)

Soil unsaturated hydraulic conductivity is one of the most important soil physical properties in recognizing, investigating and modeling the transport of water, solutes and pollutants in the soil. The objective of this study was to estimate the soil unsaturated hydraulic conductivity using easy to measure soil physical, mechanical and chemical properties by regression and artificial neural networks (ANNs) methods. In this study, 148 soil samples were taken from five provinces of Mazandaran, Kermanshah, West and East Azarbaijan and Hamedan. Pedotransfer functions were developed using soil physical, chemical and mechanical properties to estimate unsaturated hydraulic conductivity parameters of the van Genuchten- Mualem model (n and α) in 8 steps. The parameters estimated in each step, were used to simulate unsaturated hydraulic conductivity curve in the range of 0 – 1500 kPa. The accuracy of the estimated curves in each step was evaluated using curve by curve comparison with the fitted (measured) unsaturated hydraulic condoctivity curve. The ANNs performed better than the regression method, because, the AIC criterion values were obtained between -4101 and -1169 for the ANNs and between -1379 and -382 for the regression. Among the ANNs developed pedotransfer functions, the step 8 which utilized the tensile strength as an estimator along with basic soil properties, performed better than the other models in estimating the hydraulic conductivity. The results showed that the variables with little variability did not improve the estimates of hydraulic conductivity but the parameters with high variability such as tensile strength improved estimates of hydraulic conductivity.

Soil fertility management through use of organic and biological fertilizers is a crucial component of sustainable agriculture. A greenhouse experiment was carried out to investigate the effect of vermicompost and plant growth promoting rhizobacteria (PGPR) on the growth and nutrient uptake of sesame seedlings. This experiment was conducted in factorial based on completely randomized design with four replications. Experiment factors included four levels of (zero (V0), 1 (V1), 2 (V2) and 4 percent (V3)) and five bacterial levels (without bacteria (B0), inoculation with an isolate from fluorescent pseudomonads group, having ability to dissolve inorganic phosphate (B1), Azospirillum sp. (B2) and Azotobacter sp. (B3) with ability to fix nitrogen, and a mixture of three bacteria (B4). The results showed that the main effects of vermicompost and PGPR significantly enhanced the leaf area, stem diameter and chlorophyll index in comparision to the control. Also, the combined application of vermicompost and PGPR significantly increased the shoot dry weight, plant height, number of leaves and nitrogen, phosphorus, iron, manganese, zinc and copper uptake in sesame seedling (P

Longtime sediment routing and determining the location of sedimentation and erosion in rivers provide useful information for engineers to design hydraulic structures and river management. Therefore, in the present research a computer model was developed to simulate sediment movement in a river, in which after flow calculation at each time step, sediment continuity equation was solved numerically to predict bed change at the same time step. After model verification, using Meyer, Parker and Wilson equations for bed load prediction, bed variation of the river with 18.5 km length for 5 and 10 years was calculated. Also by numerical solution of 1-D depth average differential equation to calculate suspended load concentration the effect of suspended load on sedimentation and erosion pattern during 5-year simulation was investigated. The results showed that the erosion phenomenon was dominate pattern at the river reach. Also calculated volumes of sedimentation and erosion using the Wilson equation were more than those from the other relations. In addition the result showed with considering the effect of suspended load, variations and amounts of sedimentation and erosion were increased. Therefore, significant mistake would occur in prediction of sedimentation and erosion pattern in the mentioned river reach if the effect of suspended load was not considered.

Water deficit is one of the most important abiotic stresses which affects plant growth and yield. Application of the mycorrhizal fungi and plant hormones are fundamental for controlling of water deficit. For this purpose a factorial pot experiment based on completely randomized design with four replications was carried out. Experimental treatments included three levels of water deficit as 0.0, 40 and 70% of field capacity and inoculation of basil (Ocimum basilicum L.) plants with mycorrhizal fungi Glomus intraradices and Glomus fasciculatum and no inoculation and also foliar spraying of the plants with 100 and 200 mg L-1 concentrations of salicylic acid and control plants sprayed with water, in two stages after exposing of plants to drought stress. Results indicated that by increasing the water deficit severity, the vegetative growth parameters, relative water content, stomatal conductance and phosphorus uptake were reduced and the proline accumulation and potassium uptake were increased, while drought stress had no significant effect on root colonization by mycorrhizal fungi. Fungal inoculation and salicylic acid foliar spraying both significantly increased the vegetative growth parameters and relative water content of plants. Stomatal conductance and phosphorus and potassium uptake were increased by mycorrhizal fungi inoculation. Maximum phosphorus and potassium concentrations (0.466 and 3.14 percent) were obtained in plants inoculated with Glomus fasciculatum respectively. In general, results of this research revealed that mycorrhizal fungi inoculation and salicylic acid foliar spraying could play important roles in enhancing of growth and nutrient uptake in basil plants under water deficit conditions.

Study of the climate change impacts on agricultural products and agro-climatic variables can improve the management strategies regarding to the agricultural demands in future decades. The objective of this study is to evaluate the effects of climate change on growing period and evapotranspiration of wheat inMashhad. In this study the LARS-WG model was used to simulate the weather data of Mashhad station under A1B, A2 and B1 scenarios in the time periods of 2011-2030 and 2046-2065. The effects of climate change on growing period and evapotranspiration of wheat was simulated by the CERES-Wheat model. The obtained results in this study show that the temperature will be increase however, rainfall is going to be decreased. The temperature and rainfall variations will be sever in the A2 scenario compared with the other scenarios. Also, the results show that the time interval from planting to full maturity of all wheat varieties will decrease in the future. Evapotranspiration will be increased in the period of 2011-2030 while it will be decreased in the period of 2046-2065 compared to the base period. The increase of evapotranspiration in the period of 2011-2030 in A1B, A2 and B1 scenarios will be 3.51, 1.75 and 3.8 percent, respectively and the decrease of evapotranspiration in the period of 2046-2065 in A1B, A2 and B1 scenarioswill be 4.09, 4.68 and 4.39 percent, respectively. In general, in effect of climate change, the growing period and then the total water requirement of the crop will decrease in the future. So the cultivars of crop with a shorter lifetime and having the higher yield must be used.

The velocity distribution is almost the most important argumentation in all of the open channel flows studies, since it is necessary for study of the mean and maximum velocities, estimation of discharge as well as for evaluation of shear stress on channel sides. The flow velocity distribution in a channel cross section depends on the shape of the section, the roughness of the channel, and the presence of the bends. So, it should be investigated before solving many of hydraulic problems in open channels. Characteristics of the roughness which mostly affect the flow are the size and shape of the roughness elements and spacing between them and also, the roughness concentration. In this study, velocity profiles in open channels with rough bed were investigated. FLUENT CFD package was used to implement the numerical method on the basis of the finite volume method. Results showed that the flow velocity along the canal increased over the rough bed. So, the shear stress, slope of the water surface and energy lose were increased in the flow direction. The skin friction coefficients were determined for different rough beds which were in good agreement with the numerical model values. As the number of roughness elements became more, their effects on velocity profiles were increased.

Due to the proximity of dumping sites for mine tailings to agricultural lands, the migration of contaminants to these lands is possible. In this study, a total of 30 points along a track line of approximately 10 km in downstream of Mazra’eh copper mine (Ahar-East Azarbaijan) covered with a mixture of transferred tailings and bed sediments of Mazra’eh seasonal river were selected. The composite samplings were carried out fromsoils at depths of 0-10, 10-30 and 30-60 cmand fromsurficial sediments. In addition, six non-covered points (controls) with minimum distance from the sampling points were selected. The total concentrations ofcopper in surficial sediments as well as soils were determined using aqua regia method. Then, the relationships between these concentrations and soil properties were assessed. The results showed very high concentrations of copper (1116 mg kg-1, on average) in the surficial sediments. The concentrations of copper in the soil depths of 0-10, 10-30 and 30-60 cm were 105, 86.4 and 79.8 mg kg-1, respectively. Based on results, 13% of 0-10 cm soils, all of 10-30 cm soils and 57% of 30-60 cm soils were very contaminated, medium contaminated and low contaminated, compared to controls (48.4 mg kg-1, on average for three depths), respectively. Soil copper concentration showed significant positive correlations with surficial sediment copper concentration, thickness of surficial sediment and soil cation exchange capacity (CEC) in all three depths of the studied soils.

General assumption in designing cut off walls is that the seepage be held in a limited amount. In order to control the seepage, the foundation drains are located in parallel to cut off wall at downstream. The main aim of foundation drains construction is to collect seepage water and decrease uplift force. Numbers, distance, and diameters of these drains need technical judgment about characteristics of foundation stones. The depth of drains depends on cut off wall characteristics. In this study, the performance of drains in foundation of concrete gravity dam was investigated using finite element method (FEM) via Seep/w software. Among influential parameters in studying the drain effects, one might consider diameters, center to center distance, and distance of the drains from upstream of dam. In this paper effective parameters on uplift force were analyzed and it was found that increasing the drain diameter had lesser effect on decrease of the uplift force slightly compared to the other parameters. In the other words, selecting the best diameters depends on executive consideration. But decreasing the distance of drains and also their distance from upstream of dam would play an important role in decreasing the uplift force. Focusing to the simulated range of parameters, the drains with 15 centimeter diameter and distance of 3 meters had the optimum performance and the best operation in decreasing uplift force. For validation, the numerical method used in this research was compared with the other analytical methods and the proper agreement with them was observed.

Drought monitoring and evaluation in water resources systems, are basic steps in systems analysis as well as the optimal water resources allocation for different demands. Therefore, in this study, whole of Iran country was selected as the study area, and it was attempted to determine the simultaneous droughts which had been occurred in the period of 1981-2010, using monthly rainfall data of 31 synoptic stations. In order to perform the drought monitoring, the Herbst drought index was used and drought intensity and duration were determined for the studied synoptic stations. Additionally, the IDW method was used for interpolation and delineation of drought intensities and durations. The study results showed that in the periods of 1998- 2000 and 2007-2009, the country had faced droughts. Northern and Southern coastal regions and Central region exhibited less susceptibility to drought periods in comparison to the other regions. Also, the East and West of the country, which are the rainfall systems entrances, are more sensitive to rainfall reduction and thus, to drought. According to the results of the spearman's test, the most severity of negative trend belonged to the stations in central, South-east and South-west of the country.

One of the non-linear weirs is horseshoe-shaped weir that determination of its hydraulic parameters for designing of that is necessary. Sometime due to limitation in dam site and also reduction in soil excavation volume, tunnel and intake location of hydro-electric power this structure is needed to be constructed near the dam and its intake. In these cases, a combined structure of both the intake and spillway can be constructed by using horseshoe-shaped weir to achieve a proper economic condition in dam construction. In this study, by making physical models of the horseshoeshaped spillway in laboratory dimension, some hydraulic parameters like discharge coefficient, velocity and water surface profiles in different parts of the horseshoe-shaped spillway were investigated. Results showed that in horseshoe-shaped spillways, with increasing the ratio of head to spillway length, discharge coefficient was decreased about 0.6 to 0.7. This reduction in discharge coefficient had different trends for spillways with length of greater or less than 112cm. Comparison of the results between the rectangular weir and the horseshoe-shaped spillway by consideration an equal width for them showed that horseshoe-shaped spillway could reduce head above the weir about 54%. Investigation of the water surface profiles showed that overflowing of waters into the horseshoe spillway, created the rooster tail type hydraulic jump.

This research was carried out to study the effect of different ratio of Na/K in soil solution on dispersible clay, aggregate tensile strength and soil friability using the cation ratio of soil structural stability (CROSS) index. In order to apply different potassium concentrations, 6 treatments with the same EC (3 dS m-1) including 0 to 27.2 meqL-1 K and another six treatments with EC=6 dS m-1 including 0 to 54.4 meqL-1 K were prepared and added to soil. Soil friability was calculated and compared through two methods i.e. the coefficient of variation (F1) and ranking order (F2). The results showed that increasing the K concentration in treatments relative to Na could increase the water dispersible clay. Also, the results of aggregates tensile strength test showed that in treatments with EC=3 dS m-1 by increasing the K value, the soil strength decreased but with increasing the SAR value, soil strength increased. Maximum amount of tensile strength (142 kPa) was observed in treatment 1 with CROSS = 25.7 and SAR=22.9 and the minimum amount (87 kPa) was in treatment 5 with CROSS=14.8 and SAR=0.99. This trend was not observed in treatments with EC=6 dS m-1 and the aggregate tensile strengths were almost similar in all treatments. The results demonstrated that soil friability (F1 & F2) increased with increasing the dispersible clay at EC=3. Comparison of the results of tensile strength and friability revealed that F1 was inappropriate parameter for expression of soil friability while F2 showed the good agreement with the strength and friability amounts (in treatments with EC=3). In treatments with EC=6, the effect of dispersible clay on tensile strength and friability was not observed, probably due to the higher concentration of the soil solution.

Increasing growth of population and consequent development of industries and refinery plants cause high amounts of hydrocarbon pollutants enter to environment. Bioremediation or biological removal of petroleum hydrocarbons from soil or water is more efficient than the other physical and chemical remediation technologies. Indigenous bacteria are important because of their long term exposure and compatibility to hydrocarbon contaminants. Therefore, the aim of this study was isolation and comparison of oil consuming bacteria efficiency in the oil contaminated soils in southern of Tehran oil refinery plant. Six samples from the contaminated soil were collected and then the superior oil degrading bacteria were isolated through three laboratory steps: i) Isolation and purification of indigenous oil degrading bacteria in a soil extract agar as a selective media, ii) The study of efficiency of the isolates in a liquid mineral based media with 7% (V/V) of gas oil. iii) The comparison of the respiration rates of the isolates in a media containing 3% (W/W) gas oil. At the end of three steps, among all the oil degrading isolates, two isolates of BJ.1 and BM.1 with respiration rates of 2.1 and 1.8 mg CO2 per gram sand-perlite per month, were ultimately selected as the most powerful and efficient isolates for oil degradation, respectively.

Dispersivity is one of the important parameters for simulating solute transport in porous media. In this study, laboratory tracer tests were conducted to investigate the spatial variation of longitudinal dispersivity. The tests were carried out in a sand tank with dimensions of cm3 with two kinds of saturated homogeneous coarse and medium sands, respectively. The solute transport process was studied at three hydraulic gradients of 0.017, 0.025 and 0.034. The solute transport parameters were estimated using CXTFIT2.1 software. Based on the obtained results, the average dispersivity values of the medium sand and their range were higher than those for the coarse sand. This pointed out that the dispersion was the dominant process in solute transport in the medium sand. Under the various hydraulic gradients, the dispersivity increased with increasing distance from the contaminant source. The dispersivity increasing followed a non-linear function of travel distance at hydraulic gradient of 0.017, while it followed a linear function of travel distance at hydraulic gradients of 0.025 and 0.034. In general, the dispersivity of the medium sand, especially under a small hydraulic gradient, was strongly space-dependent and its variations followed an exponential function.

Analysis of the temporal variations of reference evapotranspiration (ETo) declares climate changes and their effects on water demands. In this paper, an analysis of the monthly ETo (calculated by the FAO Penman– Monteith method) was done at 19 stations, located in different climatic regions, during 1961– 2003 in Iran. The annual ETo time series were derived, and the moving t test and Morlet wavelet were conducted to analyze the comprehensive time series for characterizing abrupt change and period in the ETo data sets. The annually and monthly spatial distibuations of ETo were produced by the inverse distance weighting (IDW) method. Based on the moving t test over annual ETo time series there were 4 abrupt changes in 1981,1982,1983, and 1984 years which were coiencidnce with ETo trend. Also moving t test detected abrupt changes in 1976- 1986 period in arid and semi-arid climates. KhoramAbad station in semi-arid climate with 21 abrupt changes had the largest changes and Isfahan, Tehran, and Birjand stations with 3 changes had the smallest changes. The presented methodology in this paper can be extended to hydrological time series, water resources and drought studies to infer their abrupt changes and monitoring periodical changes pattern.

Global climate change may have serious impacts on the frequency, magnitude and duration of hydrological extremes. Variation in the hydrologic ultimate limits can have impact on designing of hydraulic structures in future, development of flood-plain, and management of water resources. This research, investigated the potential impact of climate change using weather generator K-nn and HadcM3 models under A2 scenario and also the rainfall-runoff HEC-HMS model. First, downscaling of GCM data using HadCM3 model under scenario A2 in stochastic model called K-nn was carried out. Then, land use map and soil group map were prepared and required parameters were determined for the HEC-HMS model. Thereafter, and the model was calibrated and validated using 4 flood events. The results of RMSE, R and t-Student test indicated that simulated peak flow had significant correlation with observed peak flow. Results of storms analysis of 2 hours with 100- year return period showed that the base period (1980-2011) decreased by 32 percent as compared to future period (2040-2069). After determination of intensity-duration-frequency curve, distribution of precipitation values for Nahalestan station imported to the rainfall-runoff model and peak flow with different return periods 2, 5, 10, 20, 50 and 100 years were calculated for sub-basins for the base and future periods. Results of the frequency analysis showed that peak flow in period 2040-2069 with 25 years return period would decrease by 21 percent as compared to the base period.

Many researches on time series modeling have been carried out without investigation of data series stationarity. If series stationarity and its effective parameters on non-stationarity are ignored, the results will not be accurate and therefore, will lead to error in modeling time series. On the other hand, the decomposition of time series into their components can help to interpret the existing relationships among the hydrologic processes. In the present study, application of the modified KPSS test with the Fourier analysis in stationarity analysis of multiple frequency hydrologic time series was investigated. The Lake Urmia level time series had multiple frequencies. Therefore, data of the Lake Urmia water level in monthly time scale was used as a case study in the period 1965-2008. The trend component was investigated using the Mann-Kendal test and Şen innovative method. The frequency component and stationarity test were studied using the Fourier analysis, traditional KPSS and the modified KPSS with Fourier analysis, respectively. The effect of periodicity on stationarity test was investigated. The results showed that the KPSS test had no ability for detecting the stationarity of the time series while of frequency and non-linear trend exist in data series. Differentiation of time series could not change it to a stationarity one. The Fourier analysis method was used as an alternative method and the results showed that the mentioned method could change the non-stationary time series into the stationarity time series.

In order to simulate surface runoff and depth of flow on surface area of watershed and outflow rate, a new hydrological model with numerical structure has been designed and presented. In this model, surface flow governing Saint- Venant equations in one- dimensional and two- dimensional forms along with the Parlang infiltration model parameters, have been solved using a finite difference numerical method, for the kinematic wave approximation using an implicit scheme. In order to solve the system of nonlinear equations resulting from discretization of the flow and infiltration equations, the Newton Raphson method was used. An algorithm and program of this model in one- and two-dimensional modes have been developed by using MATLAB software and their results have been analyzed. For checking the accuracy of the presented numerical model in estimation of the height and volume of the surface flow, the model was implemented for the Maroon valley watershed in Fars province. Topographic condition and slope of the basin surface used in the surface flow equations and the parameters required in infiltration equation have been prepared using the GIS maps and elevation models for feeding the numerical model. Comparison of the model computational hydrographs with the observed results at the hydrometric station in the basin outlet and also investigation of the statistical coefficients calculated from the results showed similarities and good accuracy in simulation of the flood hydrographs by the numerical model. Also, the kinematic wave had a good approximation in predicting the amount and occurrence time of the selected floods peak discharges. The average accuracies of the one- and two- dimensional models in predicting the amount and occurrence time of the selected floods peak discharge were c 97.3 and 97.2 percent and 95.45 and 98.47 percent, respectively.

Precipitation is one of the most important climatic factors with high variations in time and space. Determination of the amount of precipitation in different regions is very important in development and management of agricultural lands especially in rainfed farming. In this research, in order to estimate and provide maps of the variation of annual, seasonal (spring and autumn) and monthly (November, May, December and June) precipitations in the agricultural lands of Gorgan county, different interpolation methods such as Kriging, inverse distance weighting (IDW), radial basis functions (RBE) and local polynomial interpolation (LPI) were used. The performance criteria for evaluation of these methods were Mean Absolute Error (MAE) and Root Mean Square Error (RMSE). The results showed that, based on the minimum of these indices, local polynomial interpolation was the best method to estimate the annual, spring, November, May and autumn precipitations. In estimation of December and June precipitations, Gaussian (Kriging) and multi-quadric (RBF) presented the most accurate results, respectively. Also, the inverse distance weighting (IDW) was found to be the worst method, with the highest error statistically. The produced maps in Gorgan county showed that most rainfall variables were in high suitable condition for rainfed farming of cereals, and these values were increased from north to south. In general, 53.75 and 27.77 percent of the studied areas were suitable and less-suitable for these crops according to June and spring rainfall maps in the central and north lands of the county, respectively.